Narendran (Naren) KS, who lost his wife Chandrika on MH370, on Twitter says: Yes, give us the truth. Not too many people we know are convinced that 459 pages of the 2018 report is the sum total of all that is known regarding the disappearance of MH370. The following note accompanies his Tweet.
Friends,
My family and friends in India send you their greetings.
Unlike previous years, I have been ambivalent about making this trip. I have searched hard to understand this. It is almost 5 years since I saw off my wife, Chandrika, and the last we heard from Malaysia Airlines flight MH370, the flight she boarded en route to Mongolia.
It has been a long haul dealing with loss and rebuilding a life, a task that remains incomplete. What became clear is that lately the cloud of sorrow and despair, the listlessness with life in general, and the restlessness with the MH370 search and investigation has become less intense.
What remains is the solidarity with the MH families, their loss and struggles to cope, to envision a future and reconstruct their lives. This only grows as each nuance in a shared language of loss, grief and reconstruction becomes more widely shared and understood.
5 years is a long time.
Among the MH families, the old have grown older. Some whose will to live was broken by irreconcilable loss believe they have nothing left to live for.
Among the young, some have by now moved on to pursue studies, take up jobs, moved home, find partners, have babies, … Somethings to cheer about and remind ourselves that winter is not the only season, each day isn’t always drab, and the sky isn’t only grey.
However, many among us continue to struggle while applying ourselves to the chores of daily existence. For all of us, knowing what happened to MH370 remains the key to unlock a part of our lives, our energies.
Our prayers have remained unchanged: Find the plane. Find the passengers. Give us answers to ‘what’, ‘why’, ‘how’ and if it comes to it, ‘who’.
Give us the truth.
Yes, give us the truth. Not too many people we know are convinced that 459 pages of the 2018 report is the sum total of all that is known regarding the disappearance of MH370. Those who know more but have chosen silence, if indeed there are some, will eventually die a thousand deaths each day, for guilt is a latecomer but an unforgiving squatter. It is the order of things and not what we would wish for them.
In this search for the truth, there isn’t a Malaysian truth, an Australian truth, a British truth or an American one. Or (even) an Indian and a Chinese one. There were 239 passengers from 14 countries. An international mix of nationalities. A Boeing 777, an American company’s product. The incident is believed to have occurred in the Indian Ocean, in international waters. The investigation is governed by the conventions written in by the International Civil Aviation Organization. Experts from across the world when consulted or otherwise, have weighed in with their analysis and recommendations regarding the search. It is an event that concerns, every airline, every passenger and perhaps almost every family across the world exposed to civil aviation.
To suggest as some do that it should be left to Malaysians to script the story and the end game does not cut ice. If anything, the fact that it was a Malaysian airline’s flight under Malaysian air traffic control and Malaysia’s leadership of the investigation places an unshakable burden of responsibility to the world at large….to persist, to mobilize the funds necessary, and to hunt for the credible evidence for further search that it never tires of reminding us as being a requirement. It also has responsibility to test the claims of those who proclaim new knowledge, new evidence and fresh coordinates, and offer a public, transparent well-argued refutation if indeed that is what will end misguided or false narratives.
The best tribute we can offer to those we have lost is through demonstrating the will to find credible answers, fix the issues and assure the world that more lives will not lost in future to similar incidents.
A new Malaysia under this new Government has been the source of new fledgling hope.
To those who have fallen silent travelling on MH370, we remain respectful and eternally indebted for the time they shared with us. To those who have offered silent support, those who have lent their voice and those who have sent their prayers, we remain grateful. We draw strength from your little acts of kindness, words of solidarity, and your quest for the truth – whichever corner of the earth you seek it from.
Questions have a way of persisting and even outliving you and me till satisfactorily answered. I go back to pick up the threads of my life in Chennai secure and with faith that one day we will know.
Thank you.
@all,
A crawler on Fox News just reported Malaysia MOT is now interested in re-opening the MH370 search. Ocean Infinity was also reported as being interested in resuming the search using new technology developed during the last year.
@all
Fox News story linked below along with the Malaysian fisherman’s claimed GPS location of crash.
https://www.foxnews.com/world/5-years-on-malaysia-open-to-proposals-to-resume-mh370-hunt
https://photos.app.goo.gl/ixuJkNhaq6UjYVgm7
Fox News: Malaysia open to proposals to resume MH370 hunt 5 years after mysterious disappearance
Pipped at the post!
@Victor
I sympathize and agree with with the NoK on “give us the truth.” However, I would say ICAO and international law basically gives sovereign right to countries like Malaysia to control airline investigations. In so many words, public does not not have right to know unless the responsible country so desires. Sorry but there is a conflict of interest between what the global public wants and what a country needs to do in its own self-interest. In the case of MH370, many of us feel it may strike to heart of Malaysian politics, so it is probably not an event that Malaysia has a realistic option to be completely open about.
@Oddball
Re: drag of open window, I was not thinking the cockpit window is open for long. Maybe toss out the co-pilot cell phone, maybe put an external wire out to get reception on a Iridium sat phone.
The current Malaysian administration seems much more interested in finding the plane than the previous one. However, there are still the obstacles of crafting a credible proposal that is acceptable to Malaysia and the willingness of Ocean Infinity to take the financial risk.
@TBill: I can point to a handful of instances where important information was either officially or unofficially released, despite the initial opposition by the Malaysian government. I think there is always hope that we learn more.
@Victor
As you probably know, both Atlas Air “black” boxes have reportedly been found as of today. Fingers crossed that the Data/Voice was recorded to show what happened.
@TBill: Yes, in short order, we’ll know more about 5Y3591 from both the FDR and CVR. The CVR was found first and will be easier to analyze, so perhaps they will provide some information before a more in-depth analysis is performed on the FDR data.
Since the ATSB’s photo here,
https://www.atsb.gov.au/media/5772906/mh370_inboard-section-of-flap-12.jpg
the rear of the rib at the broken outboard end of the outboard part-flap has been removed, presumably for inspection and access, together with a variety of fasteners in that vicinity:
https://www.9news.com.au/content/2019/03/03/19/37/60-minutes-inside-mh370-
wreckage#5
Quite likely there has been further investigation of the character of the break. It would be interesting to learn of the exact reason and results. (I have not yet watched the show: possibly noted and addressed there.)
The second URL does not open as I sought.
That photo is No.5 at:
https://www.9news.com.au/2019/03/03/19/37/60-minutes-inside-mh370-wreckage
[From previous thread]
@Tim
My apologies! You were correct:
MRO was carrying just over 1200kgs of water. So you could go to the galley and jam open a tap
@Don Thompson
Many thanks for that info and correction.
Would you please forgive me if I am a little obtuse? I don’t quite understand your closing paragraph, beginning:
The present objective is “where“: best to deal with facts, simple compliance to Occam’s Razor, …
I don’t want to fight with anyone, but I’m keen to debate and get facts clear. I’m also very keen to contribute my ideas, if they are of any value. I don’t know if I’ve said anything new so far, but I’d like to keep trying.
I agree with you: the current objective is to figure out where.
However, in my mind, to do that, we need as far as we can to establish the outer limits of that where, then narrow down to most likely, and to do that, I think we need to look at how, why, and I would strongly argue, who. If we can get an idea of who, we might get a better idea of why, then how and where. I know I’m hopping around those like a flea, which may be annoying! My apologies, but that’s how my mind likes to operate. When doing a jigsaw puzzle, the best way to start is usually to find the four corner pieces first.
As Einstein reportedly said: “Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution.”
Regardless, imagination is of little use without facts to build from.
As Victor suggested earlier, progress seems to have slowed, but without more data and/or ideas to work with, that must be expected.
Do you mind if I continue my hopping about all four corners?
@TBill
maybe put an external wire out to get reception on a Iridium sat phone.
Ahhh!!! Now we’re talking. Has anyone followed that line of thought? Is there any evidence of an Iridium sat phone pinging (or calling / being called) in the SIO at the relevant times? Or do those satellites not relay any of the relevant info? “Privacy concerns” maybe…
“maybe put an external wire out to get reception on a Iridium sat phone”
Come on guys ! Connect the wire to what? Iridium satphones operate in L-Band, i.e. about 1.6GHz. An external wire out the window is not going to help. Probably degrade the signal actually.
As for opening a window at a few hundred knots . . . get real.
The Malaysians had no interest in the Pemba flap when it was discovered.
Some time went by, before it was obtained by the ATSB, and subsequently shipped to Canberra.
It is now in Malaysia.
The French have retained the flaperon.
When, how, and why, was the the Pemba flap, sent to Malaysia ?
Ventus45. The ATSB spokesman told me some time ago, after I raised questions about that item, that it had been despatched to Malaysia. Presumably that was when the ATSB wrapped up its work.
ATSB debris investigations appear to have been limited to establishing provenance, whether the accompanying mollucs, barnacles, minerals etc were consistent with drift track estimates and recovery sites, and whether damage might help with the search for the underwater wreckage.
I suspect a reason for sending it to be that any further analysis that might help with cause was up to the Malaysians as the acccident investigators.
The French judicial system led to their retention of the flaperon as you know, though its release to Malaysia would allow a closer comparison of the flaperon/Pemba flap mutual damage.
While the french reports on the flaperon’s condition were comprehensive, relevant information has come to light subsequently so some review is needed.
@Andrew,
Further to your very helpful answers re Emergency O2 in the previous thread:
The passenger oxygen system installed in 9M-MRO used chemical oxygen generators with a nominal duration of 22 minutes, regardless of altitude
may I ask some further questions, please?
Would I be correct in thinking that, once activated, the passenger oxygen generators simply run to exhaustion? They cannot be stopped, then resumed again later, as in depressurization, then restoration, and later, another depressurization?
Do you know what releases the face masks? Any way to activate the oxygen generators without masks dropping?
Similarly, what of the pilot’s oxygen supply? Can that be turned on and off at will, i.e. under manual control?
I’m thinking that even for the pilot, extended flying depressurised at high altitude is going to be pretty unpleasant, if not uncertain with respect to continued consciousness. Would you agree?
@oddball,
Here is my calculation for the extension of endurance if the aircraft was 1200kgs lighter. A B777 burns 3%/hour of any weight change. So…
1200×0.03x 7hrs=252kgs less fuel. Therefore as burning 6000kgs/hr that’s an extra 21/2 mins endurance.
As for the O2 systems, the pax O2 once activated cannot be turned off, and if the aircraft doesn’t descend will probably not keep the passengers conscious for the full 22 minutes. It is activated automatically or by a switch in the flightdeck, there is no stop switch. The pilot’s O2 is an on demand mask, so can be stopped. It is not designed for continuous use at high altitudes either, so there is a real risk if used above 40000ft it would render the user unconscious. Hope this helps
Re ATSB Flap analysis: In Feb 2018, I visited ATSB in Canberra. The Flap Segment had already been sent to Malaysia at that time, but I discussed the flap analysis at length with Pete Foley and the people that conducted the detailed analysis. They walked me through their process, analysis and results. Their conclusion was:
• The right outboard flap was most likely in the retracted position at the time it separated from the wing.
• The right flaperon was probably at, or close to, the neutral position at the time it separated from the wing.
Note that, in both cases, they say: “…at the time it separated from the wing…”, NOT “at the time of impact”. We discussed this important distinction in the context of the theory that the flap and flaperon may have separated in flight, seconds before impact. Separation before impact is possible given the speed implied by the BFO derived descent rate. Pete was reluctant to draw any firm conclusion, but agreed it was a possibility in light of the BFO data, physical evidence and analysis. Their analysis can be found on pages 19-26 of the following document: http://bit.ly/2QdhCe7 published 2Nov2016.
@oddball
The pilots have special pressurized O2 masks, that allow operation at much higher altitudes. Yes it could be uncomfortable and risky, but in theory it unfortunately facilitates intentional depressurization as a nefarious tactic.
My understanding the PAX O2 mask are low pressure and essentially useless above about FL350.
TBill: Passenger O2 masks/systems are “constant flow” 100% O2 devices. They provide a constant flow rate for ~20 minutes. Constant flow O2 systems in general are suitable for continuous use up to ~20,000 feet. In an emergency at FL400, the passenger masks provide adequate supplementary O2 to allow for a rapid descent (~5 min) to a safe flight level, typically below 14,000 feet. The Pressure Demand masks/systems available to the cockpit crew will work up to FL450 (some are only rated to FL400) continuously.
Personal experience: Because nearly all sailplanes are un-pressurized, those that are flown to altitudes above 25,000 feet are typically fitted with Pressure Demand systems. I had A14 systems in my Standard Libelle, Twin Astir and Ventus-B sailplanes. During wave flights (one to 39,500 feet), I always switched to 100% and pressure mode above ~30,000 feet. I did not find it particularly difficult to breath even over longer wave flights. (-70C OAT is a bigger issue!) It feels a bit odd having air forced into your lungs, but it would not a problem to fly with a mask on for an hour or two. Maintaining the straps tight enough to form an airtight seal is where most of the discomfort comes from, not the pressure.
We do not know for if 9M-MRO was depressurized. However, we do know:
1. depressurization for the period circa 17:21-18:22 would be consistent with other facts and observations,
2. the PF could easily have flown for that length of time using the Pressure Demand system on board,
3. and the passengers and crew could not have survived on constant flow O2 alone at 40,000 feet for an hour.
@airlandseaman, @TBill & Tim,
Many thanks to you all for your very helpful answers. Exactly what I was after.
Yes, thanks, I understand we don’t know that this happened, but it’s part of the hypothesis I’m considering.
In line with Occam’s Razor and KISS principles, this confirms there would be no need to try to surreptitiously bleed off the emergency cabin oxygen supply, as the pilot could easily sit this out without needing to descend, (which would be counter to his intentions, in my model).
This leads to my next questions, if anyone can help, please.
1. Is there any credible / reliable evidence of any changes in altitude prior to exiting radar coverage? I know the media raved about all kinds of ascents and descents but I believe this was later discredited… Where did that end up?
2. Could someone please help me understand the relationship between bleed air supply and cabin pressurization? If bleed air is turned off, will the cabin inevitably be depressurized? Or can the outlets (& inlets?) be closed to maintain cabin pressure? I guess there is no way to maintain cockpit pressurization independently. Presumably, it’s only the cockpit side windows that can be opened (which would not be helpful!)
3. Does anyone have any ideas how far a skilled pilot could manually glide the plane following flame out, versus how far it would go on AP as per Victor’s earlier description, from say 40,000′?
4. Does anyone know if ZAS was fanatical about physical fitness, like he was about other things? Did he keep himself extra fit, does anyone know?
oddball: Re #3…given all other conditions equal, the distances would be the same from any altitude.
Reminder: There is ZERO evidence the plane glided, but several lines of evidence it did not.
@ALSM. Was it the ATSB that removed the rear end of that rib?
They say that besides the damage that led to their retracted conclusion (I prefer the conclusion that they were retracted when they collided to retracted on separation), “Numerous other discrete areas of flap damage were analysed.”
Do you know what those analyses were?
If the Malaysians removed it there is a report out there somewhere.
The following flap photo was taken in the ATSB Lab. This should answer the question: http://bit.ly/2He4C2W
Thanks but that is the other, seal pan, (inboard) end
@ALSM, Many thanks. Interesting. Boeing designed the Autopilot that way, I guess? So the idea it would perform phugoids is eliminated? Uhhh… Isn’t that still gliding (i.e. not performing phugoids) and descending slowly without power?
Less need for the pilot to “hang about” for the whole trip then. But I still think he would want to, to execute the “Final Act”. Of course I’m not saying it glided into the ocean… Is that what you are referring to?
What evidence is there (could there be, even) that it didn’t glide during the early final minutes?
Odball:
0019 BFO, no IFE logon, debris size & origin…
@airlandseaman
Re: We do not know for if 9M-MRO was depressurized. However, we do know:
1. depressurization for the period circa 17:21-18:22 would be consistent with other facts and observations,
2. the PF could easily have flown for that length of time using the Pressure Demand system on board,
3. and the passengers and crew could not have survived on constant flow O2 alone at 40,000 feet for an hour.
Mike, point 2 is highly debatable particularly if you assume that the Captain was the PF.
You’ve only got to look at the Connie [Kalitta] Flight 861 incident (NTSB Identification: NYC94LA062) to understand that even when using the crew oxygen system the effects of depressurisation vary considerably. In that particular instance you had a crew member of similar age to the Captain become incapacitated before the cabin altitude had even reached 35,000 feet, leave alone 40,000 feet.
Based on the Captain’s December 2013 Medical Examination Report we know that he was overweight, had Stage 1 hypertension, had a resting heart rate that placed him in the ‘Poor’ fitness range and that he was a smoker. He also had a family history of heart disease and high blood pressure. They are all risk factors for hypoxia and evolved gas decompression sickness.
Going back to your first point, what other facts and observations are consistent with the aircraft being depressurised?
odball: Re ” Boeing designed the Autopilot that way, I guess? So the idea it would perform phugoids is eliminated? Uhhh… Isn’t that still gliding (i.e. not performing phugoids) and descending slowly without power?”
I have no idea what you are talking about. I understood your question to be: Could an autopilot control the aircraft the same way a pilot could, to descend at best L/D speed (max glide range), after FE, in both cases assuming electrical power was available, and obviously in the first case, with the autopilot engaged. Under those conditions, the descent could be comparable. Neither of those cases would produce phugoids. Phugoids can and often do occur when the autopilot is NOT engaged AND no one is flying manually. Does that clarify?
@ALSM
In your photo linked above, you might also notice, that green oxygen cylinder, on the top shelf……..
It presumably is “a left over trophy” from tests conducted during the investigation of the pax O2 cylinder that failed on QF30 and shows evidence of a distinctive “incipient failure”.
The crew O2 cylinder in the MEC is still a “possible” cause IMO.
@Mick
Depressurization is not consistent with the accuracy of the BFO data at 18:25. It would be a lucky happenstance if depressurization occurred.
Mick Gilbert: Sorry, but you are wrong about #2. My statement is correct. It is not “highly debatable”. It is highly likely anyone in reasonably good health could go an hour using a Pressure Demand mask, properly fit. Both MH370 pilots were in reasonably good physical condition.
You neglect to point out that the captain of Flight 861 was the only crew member that suffered any problems. The others had no problems with their Pressure Demand masks. The Captain’s physical condition may have been a contributing issue, but he may also have not sealed his mask properly (likely). Whatever the reason for the 861 Captain’s problem, it is a rare case, not the norm, and not relevant to MH370.
Dennis: Hope your recovery is proceeding well and you are feeling better.
I do not understand your comment: “Depressurization is not consistent with the accuracy of the BFO data at 18:25.” Please explain. There is no relationship between the BFO accuracy and the cabin pressure as far as I know. Regardless, if there was deliberate depressurization circa 17:21, presumably MH370 would have been re-pressurized circa 18:20.
@ALSM
My assumption is that depressurization would affect the temperature in the aircraft. A single oven oscillator (again my opinion based on experience) is that a significnat offset would occur. We have been over this ground before. We just have divergent views. Likewise with a depowering of the AES. It won’t be settled until the FDR is recovered.
In the MSM news here, it was reported, that OI’s Oliver Plunket had sent a video to the NOK at the 5 year memorial, in which he apparently offered to return to the search, but there were no details. Has anyone here seen it, and / or got a link ?
Ventus45: Video of the IG and OI presentations can be found in the following link: http://bit.ly/2TdAmMK
IG presentation at -2:03
OI presentation at -1:18
ASLM:
Sorry, don’t follow:
I understand that the thinking is that the 00:19 handshake suggests a high speed descent, but IFE Logon? I guess you mean In-Flight Entertainment system? I don’t understand the significance. Why would it try to logon at that time?
Also not sure which debris you mean – flaperon & flap? Origin being 9M-MRO, or are you referring to the Drift Analysis PoO indications?
Can anyone tell me where the incoming RAT supply connects to, please? Across the batteries?
Is it true that the RAT is released automatically? On what condition?
I’m guessing the batteries continue to power the avionics etc after flameout, until the RAT kicks in. Is that correct, and if so, what would the (relevant) flameout trigger? Similarly, what would RAT “Power Good” trigger?
Could it be that the 00:19 handshake was triggered / generated as a result of actions relating to AP disconnect and/or the pilot taking control? That perhaps occurring upon the gliding descent having reached the pilot’s “Trigger Altitude”?
Are you thinking said pilot didn’t bother with gliding and took over right after flameout? Wouldn’t a glide down, say 30,000 feet, take longer than 8 minutes? Sully got 90 seconds from a slow climb to 3,000 ft in an A320.
If nose vertical from >= FL250, how many more surfaces would have parted company before sealevel? Would the windshields even take it? ==> B777-B (Balloon model)
odball:
The IFE system normally establishes virtual channels with the GES ~90 seconds after the AES logs on. That did not happen after the 0019 AES logon. Either (1) the plane hit the water by 0021, or (2) it was in such an unusual attitude that the AES antenna could not be pointed to the s/c at 0021. Take your pick. The implications are the same.
The origin of the debris on the aircraft includes pieces from the interior (seat back display, floor panel, several others), which indicate a very high energy impact, not a “water landing”.
You will need to do your homework on the rest. It has all been discussed in detail.
@ALSM
Thanks for the link.
The file is 705Mb and nearly 3 hours long.
Downloading it, but it is dead slow !
I only have 25Mb so far, and my computer is showing two hours to go !
May as well go and do the shopping !
Ventus45: You should be able to stream it and FF to the points of interest.
Dennis: OK. OCXO Temperature coefficient, not the pressure.
First, the OCXO has a double oven, not a single. And as previously posted here: http://bit.ly/2VAL4cJ
…the measured tempco is about -0.3 Hz/°C. An ambient temperature reduction from +30C to -30C only causes a change in BFO bias of ~-20 Hz. That is significant for path reconstruction, but not for the two primary conclusions that the plane went south (not north) and the descent rate at 0019 was very high. I agree that, if the cabin temp was lowered by say 60°, it would likely lower the transmit frequency at L band by about 20 Hz.
@mike
We are on the same page.
@ALSM
RE: ‘It is not “highly debatable”. It is highly likely anyone in reasonably good health could go an hour using a Pressure Demand mask, properly fit. Both MH370 pilots were in reasonably good physical condition.”
I’d say that really depends on the altitude. Positive pressure breathing (PPB) becomes increasingly difficult above FL400, because the system keeps increasing the pressure differential to ensure sufficient oxygen reaches the circulatory system. Breathing becomes increasingly difficult (and unnatural) against the higher pressure differential, and there comes a point where physiological problems start to occur, particularly in pilots who are not specifically trained in PPB techniques. The following is a quote from RM Harding, Pressure changes and hypoxia in aviation:
“The cardiovascular effects of PPB include peripheral pooling, impaired venous return, and reduced central blood volume; if there is a loss of peripheral arteriolar tone, then tachycardia and a gradual fall in blood pressure will lead to a collapse resembling a simple vasovagal syncope.”
The crew oxygen masks found on the B777 are typically rated to FL450, but they are only intended as emergency “get-me-down” equipment, not for continuous use at very high altitude. The aircraft itself is only certified to FL431.
@oddball
RE: “Could someone please help me understand the relationship between bleed air supply and cabin pressurization? If bleed air is turned off, will the cabin inevitably be depressurized? Or can the outlets (& inlets?) be closed to maintain cabin pressure? I guess there is no way to maintain cockpit pressurization independently. Presumably, it’s only the cockpit side windows that can be opened (which would not be helpful!)”
If the bleed air is selected off, the pressurisation system closes the two outflow valves in an attempt to maintain pressurisation. However, there is still some leakage and the cockpit/cabin will slowly depressurise. The cockpit cannot be pressurised independently of the cabin. Only two cockpit windows can be opened; one either side.
“Can anyone tell me where the incoming RAT supply connects to, please? Across the batteries?”
The RAT supplies the standby electrical system, which includes the main battery.
“Is it true that the RAT is released automatically? On what condition?”
Yes, the RAT is automatically deployed under the following conditions:
– both engines fail and centre hydraulic system pressure is low, or
– both AC transfer buses are unpowered, or
– all three hydraulic system pressures are low.
@ALSM,
Sorry for the crossed posts – an interrupted, delayed reply, without refreshing the thread.
Anyway, many thanks for the clarification. Yes, you understood almost exactly. I was surprised that an Autopiloted, unpowered descent and a well piloted glide would (could?) produce the same range, but guessed that Boeing must have designed for that, and it sounds like that’s true. And why not? It’s good design. And thanks also for clarifying about the phugoids. That makes perfect sense too. Like one of those square-nosed paper darts, it’s just aerodynamics.
However…
The IFE system normally establishes virtual channels
Sorry, but I think your assumption there is unjustified, and your choice of just two options too narrow, even if your conclusion may happen to be correct.
My reasoning: what happens “normally” is probably not relevant here. This is anything but a normal situation. If my hypothesis is anywhere near correct, the pilot switched off the IFE system hours earlier, to conserve fuel. I mean, if the passengers are all dead, why not? So, very near the end of a flight into oblivion, why would he turn it back on?
Besides, if the plane is out of fuel and all the engines have flamed out, I’m sure there won’t be power to it anyway.
Anyway, I have taken your suggestion to heart, and done some more reading on older threads.
@all
I noted quite a bit of discussion in earlier threads about certain AES logons being different from others, and from normal. This can probably be explained by certain items, such as the IFE, being unpowered. Most often, with properly written software, when something expected isn’t appearing at the other end of the wire like it should, the program starts a time-out loop, to give whatever it is expecting to hear from, time to finish booting up (or get turned on, or whatever). While it might normally already be on, booted up and ready, and so handshake immediately, the software doesn’t usually “learn” this, so it waits, causing other processes to be delayed. And, if it isn’t on, or is otherwise dead, disconnected or whatever, eventually the software will (ok, should) give up waiting and move on. However, depending on what the missing device is supposed to do, other things down the track may also fall over or go off the rails.
It’s at times like this that software bugs tend to rear their ugly heads. Typically, when everything is working normally, it works normally. But when things are unexpectedly unavailable, the software sometimes falls into a hole (though that may be entirely irrelevant here). There may be no bug, just the effect of device timeouts, with the software handling things correctly, or at least, as best it can. Airbus (in particular, I believe) has a history of poorly written software causing inappropriate actions under unusual conditions, so it’s not like this has never happened before.
In general, these bugs can be either unknown or unrecognised (due to inadequate testing or lack of thought during design or implementation), or known but not corrected due to time and/or budgetary constraints. An IFE, being a non-critical device, is more likely to have such software bugs, but if it’s off, it’s the AES’s job to figure that out and adjust itself accordingly.
That said, some of the incorrect, or undecipherable data observed in the satellite data may have occurred because an expected device was off-line. I have no idea what cables, connections or protocols apply between the AES and the IFE or other devices, but it is possible that poor design has allowed unpowered data cables to pick up electrical noise from who knows where, and that has been received by the AES.
I also note in the data that the Flight Number is recorded as MH0000 somewhere. This is probably because the device (possibly the IFE??) was off so didn’t send anything, and the AES filled it in with zeroes. This is acceptable programming, especially if there is no such flight number (as I’m sure there isn’t) and would indicate to those who know what they are looking at that the IFE (or whatever device it was) was off-line.
I’m sure the satellite logs contain lots of clues like this, if only one can find out where all the data items come from and what they mean.
Hope this is helpful.
Andrew: I agree it depends on the altitude. It does become increasingly difficult to last an hour above FL400. But would you not agree that there exists an altitude between say FL350 and FL400 where a pilot could go 30-60 minutes with the plane depressurized, killing everyone else on-board, while breathing from a Pressure Demand mask? We don’t know the exact altitude over that hour, other than the estimate at KB, which now looks like about FL380 (40,200 ft). Do you have any doubt that a depressurization scenario is feasible at FL380?
@ALSM
Sounds like you may have revised the altitude estimates at KB down a bit to FL380?
Tbill: Yes, same analysis but new KB PSR data files became available in Jan and Feb 2019. The new data is from the same radar, but it has accurate millisecond level time stamps and raw az & range data. The observations are essentially the same, but they are more accurate, especially near the CoS (less processing). The new data produces essentially the same family of speed profiles, but the CoS average speeds changed slightly, resulting in a slightly lower estimated altitude.
@ALSM
Returned from shopping, full video obtained, and segments IG, OI and Minister viewed.
Oliver was very upbeat on the difficulty of finding a submarine, by definition designed to be difficult to find by sonar, and their success in doing so, as being proof of OI’s capability (as if any was needed). He then effectively landed the proposed prospect of a new search, fair and square, in the Minister’s lap, who was sitting front row right, and on camera. Will be interested to see what comes of that.
Re the new radar KB data in your 12:56 post. I am perplexed. The previous data was presented to us at the time as the raw data. Now this new data relegates the previous data to “processed” data, does it not ? Why was it “processed”, in the first place, and by whom ? What is the providence of this new data ? Are the files available ?
@ALSM
RE: “But would you not agree that there exists an altitude between say FL350 and FL400 where a pilot could go 30-60 minutes with the plane depressurized…while breathing from a Pressure Demand mask?”
It’s difficult to say with any certainty. A young, fit individual probably could, but ZS was 52 years old, overweight (based on his BMI), was a smoker and had blood pressure that was borderline acceptable for a pilot. They are all significant risk factors for hypoxia and decompression sickness (DCS), as Mick said. DCS becomes increasingly likely above FL250, especially with coexisting hypoxia.
Correction:
What is the “provenance” of this new data ?
Are the files available ?
@Andrew,
i>If the bleed air is selected off, the pressurisation system closes the two outflow valves in an attempt to maintain pressurisation. However, there is still some leakage and the cockpit/cabin will slowly depressurise.
Excellent information, thank you. 😉 The plot thickens.
Of course, always another question to follow on…
Is it a big deal to turn the bleed air on and off at intervals to maintain acceptable pressurisation, and does it take long to repressurise the cabin, do you know?
There is a low cabin pressure [high altitude] alerting system, isn’t there?
@Oddball
“I was surprised that an Autopiloted, unpowered descent…”
Unpowered means no autopilot and the PFCs operate in secondary mode.
“The IFE system normally establishes virtual channels […] I think your assumption there is unjustified […] what happens “normally” is probably not relevant here.”
In the context of the AES performance at 00:19, the behaviour is entirely normal: it was repowered (the Previous Satellite ID parameter it transmitted in the Log On Request is consistent with prior loss of power), the AES received & processed ADIRU originated position and attitude data so as to operate the HGA, the GES Log On completed successfully. A L Main AC Bus power loss prior to 00:19 is consistent with multiple engine fuel exhaustion and auto-start of the APU which runs for a limited period to supply power to the Main AC busses.
“ … the pilot switched off the IFE system hours earlier, to conserve fuel.”
Selecting the IFE/PASS switch to OFF does not impact the PIIC & EPESC components of the IFE system. The PIIC and EPESC are involved in datalink comms and integration with other aircraft systems such as the CSS. The PIIC and EPESC are located in the MEC, not the IFE equipment centre in the cabin. The Log On session initiated at 18:22 shows that the expected two IFE switched virtual circuits were established over SATCOM logical channels. Those SVCs were not cleared prior to 00:19. Had the IFE system ceased low-level status exchanges with the SDU I expect the SDU would have cleared the logical channels. The two X.121 destination addresses defined for the IFE switched virtual circuits are consistent throughout all the Log Ons recorded in the log.
Replying to your @all comments…
“…undecipherable data observed in the satellite data […] Flight Number is recorded as MH0000 somewhere […] the satellite logs contain lots of clues”
You’re off in the realms of uninformed speculation, take care not to misrepresent that speculation as anything else. Previous conversations here will inform you.
The entire satcom log is understood.
It’s necessary for the Flight ID, MAS370 signalled as part of the Log On to the GES, to be communicated to the SDU. It isn’t signalled by the IFE, it originates from the FMC, normally communicated to the SDU via functions of the Data Comms Manager.
It is possible that the Flight ID field had been cleared on the FMC screen.
During the 18:22 Log On no ACARS correspondence was exchanged over the SATCOM link it is assumed that, sometime prior to the Log On restore at 18:22, SATCOM was deselected as an available datalink for the Data Comms Manager (DCM is not related to the IFE datacomms operation).
With SATCOM deslected it is also possible that no session related configuration data was communicated via DCM to the SDU, including the Flight ID.
An impact more than 25 NM from the 7th arc requires pilot inputs for the dive-glide-dive sequence and the APU to run out of fuel before the expected IFE log-on (which some here believe is possible). I haven’t been a fan of this scenario, but I also thought the plane would have been found already.
@airlandseaman
Mike, I am confident that the readers of this forum are intelligent enough to form their own view as to whether the case of the very rapid incapacitation of a 51 year old, obese smoker while on crew oxygen on a flight at a moderately high altitude in an unpressurized airplane is relevant to the likely outcome for a 53 year old, overweight smoker while on crew oxygen on an hour long flight at a very high altitude in an unpressurized airplane.
Peter Foley of the ATSB thought that the Kalitta incident was relevant enough to offer it in evidence to a Senate Budget Estimates hearing last May. As he said,
‘Most of the people sitting in their armchairs looking at MH370 are saying that the aircraft was depressurised for up to an hour. The pilot of this particular aircraft [Kalitta 861] was 51 years old and overweight, and, if you look at the pilot in command of MH370, he was 53 and overweight.‘
@Mick
You know that Kalitta flight it was the smoker old pilot was the one who stayed awake. That flight took off a few miles from here in Manassas where I fly all the time (on flight sim). Was he on O2? High altitude? No thinking so.
Re Pressure Demand breathing endurance: I think this thread is off track due to a hidden assumption. It seems Andrew and Mick assume Z is the only possible PF. We do not know the PF. I make no assumption about the PF in the context of Pressure Demand use endurance. I am simply saying that it is possible that the PF, whoever it was, could have depressurized the plane and flown for 30-60 minutes at an altitude high enough to kill all the other people on board. I have not heard any valid arguments that contradict that statement.
If one is inclined to believe Z was in such poor health that he could not have been the PF in this scenario, then I suggest in that case, the PF might have been someone else. Personally, I do not buy the theory that Z was in such bad health that he could not have done this.
And from in person conversations with Foley, I know he agrees that the plane was likely depressurized, not withstanding his public comments. I’ll leave it there.
@oddball
RE: ”Is it a big deal to turn the bleed air on and off at intervals to maintain acceptable pressurisation, and does it take long to repressurise the cabin, do you know?”
It’s no big deal to turn the bleed air on and off (or turn the a/c packs on and off) to keep the cabin pressurised, but what would be the point?
It shouldn’t take too long to re-pressurise the cabin.
”There is a low cabin pressure [high altitude] alerting system, isn’t there?”
Yes.
RE the Jan 2019 KB PSR data, I can summarize the difference with the April 2018 data this way:
1. The paths are essentially the same
2. The recorded observations are nearly the same over the same time period.
3. The absolute UTC timestamps differ by about 1 second
4. The range numbers are nearly identical, except close to the COS, where they differ by up to ~0.3nm (new data values are less)
5. The CoS time gap is 272 milliseconds less in the new data
4 and 5 above lead to the slight reduction in estimated altitude at KB.
It is believed that the April 2018 and Jan 2019 data sets both originated from the same radar head. However, the new data has true “observation timestamps”, where the April 2018 data had only approximate timestamps added by the Malaysian radar data communications network. Recall, we had to reconstruct the estimated “observation times” from these approximate network times by fitting the observations to a clock derived from the known antenna rotation speed and phase (az). In addition, it is believed that the April 2018 range and az values were probably not discrete independent observations. They appear to have been values derived by a process down stream from the radar head, “smoothed” for ATC displays. This explains why the values are essentially identical for longer ranges, but show a slight difference close to the radar head where the azimuth is changing rapidly.
The new data has not been been made public at the request of the source. However, a redacted file including all the basic data (Time, Az, Range) may be made available in the near future.
@Andrew,
Thanks again for your most helpful answers!
No time for a lengthy reply, but another couple of quick questions, please.
1. Does the APU have its own, separate fuel supply, or does it draw from the main tanks?
2. Can it be disabled / controlled so as not to Autostart when the power fails?
Will answer your question later today.
Cheers
@ALSM
RE: “If one is inclined to believe Z was in such poor health that he could not have been the PF in this scenario, then I suggest in that case, the PF might have been someone else. Personally, I do not buy the theory that Z was in such bad health that he could not have done this.”
Isn’t there still the possibility that Z did do it, but became incapacitated at some point?
@oddball
RE: “1. Does the APU have its own, separate fuel supply, or does it draw from the main tanks?”
The APU draws fuel from the left engine feed manifold. It does not have a separate supply.
“. Can it be disabled / controlled so as not to Autostart when the power fails?”
The autostart sequence can’t be disabled from the cockpit, but it can be interrupted by selecting the APU selector on the overhead panel to ON and then OFF.
@ALSM. Interesting to hear of the updated radar dataset. I don’t know if you are at liberty to share the data or your derived speed/altitude curves analogous to the ones previously posted? Considering the method by which we had corrected timestamps and smoothed speed estimates, I’m puzzled that the new result should be any different even with more accurate timestamps. Can you elaborate?
@TBill
Bill, you’re thinking of Kalitta flight KFS-66, a cargo flight flying from Manassas, Virginia to Ypsilanti Airport, Michigan back in 2008. That was a Learjet 25. In that case neither the PIC or FO were on oxygen; it was a hypoxic flight incident subsequent to a failure to pressurise. Astoundingly, there was no NTSB investigation of KFS-66 so the ages of the PIC and FO aren’t known.
Connie [Kalitta] Flight 861 was a 1994 incident involving a DC-8 flying from Ypsilanti back to Atlanta. It is one of the very few (perhaps the only) documented instances of an unpressurized flight continuing to fly on at high altitude (they reached FL330) rather than initiating a rapid descent. The fact that the PIC on 861 was of a similar age and physical condition to the PIC on MH370 is at the very least interesting, if not instructive.
NTSB press release re Atlas Air Flight 3591:
https://www.ntsb.gov/news/press-releases/Pages/mr20190305.aspx
The CVR shows that crew communications during the last 18 seconds of flight were consistent with a loss of control.
Just happened to see copies of Ean Higgins latest book on MH370 in a local bookshop today. Had a quick read of a few pages. Oh dear! Yet another collection of mis-information, conjecture and speculation.
I am surprised that these authors can’t even get basic facts correct. He continues to present the view that “pings” originate from the aircraft, and in particular can originate from the RR engines. Doesn’t mention ACARS in this context because he can’t distinguish these messages from the BTO measurements collected by Inmarsat. Seems that he is confused about what the BTO numbers represent. Tries to explain but explanation is very deficient and misleading. Conflates the BTO derived information with BFO numbers and offers a confusing explanation as to how they might be used.
Nothing new here, and hardly worth reading.
So Jeff Wise released his new book days before the 5th anniversary? Hmm…
@Andrew
Brilliant! Thank you once again for your help.
To answer your question for a change: It’s no big deal … to keep the cabin pressurised, but what would be the point? A couple of points:
1: On, the boost cabin air pressure to levels sufficient for (the pilot’s) continued consciousness;
2: Off, to save fuel.
As TBill said earlier (previous thread):
Cutting cabin bleed air allows 2-3% more range
I don’t know if you agree with those figures, but based on that, if he can keep bleed air off for 95% of the time, he can increase his range by ~1.9-2.8%. I don’t know what range benefit he could gain by cutting off all the cabin power supplies, A/C and IFE, but I’m sure it all adds up. Of course, he’d want to make sure the APU stayed off too.
On a different subject, I was disappointed (but not really surprised) to hear that ZAS was not really a very healthy specimen. But it fits.
Today was an interruption to my train… I’ll expound more a bit later.
Cheers
ob
1a: … and stave off DCS.
@Brian Anderson: Thanks for the review. You’ve persuaded me to pass on buying the book.
@haxi: For amusement, I purchased and read Jeff Wise’s book. For readers here, there is nothing new. It’s his same old Kazakhstan/BFO spoof theory that has failed to gain traction. His account of how certain events came to pass is both entertaining and self-aggrandizing.
In the “Speculative Scenario” he saves for the appendix (his title, not mine), he describes the trek to Kazakhstan, ending with an automated landing by unskilled pilots at the Yubileyniy runway at Baikonur. He acknowledges that at 00:11, fuel reserves were “very, very low”, but adds that Yubileyniy is “nearly within gliding range”. Wow. Obviously, he believes that his readers are both uninformed and gullible.
What is not amusing is his insinuation that the recovered debris was planted, and Blaine Gibson is a Russian agent that was complicit in this activity. He devotes an entire chapter to Blaine’s business dealings in Russia, and ends the chapter by saying does not know if Russia planted the debris, but the man that found most of the debris has ties to Russia.
The recovered debris represent a tremendous blow to Jeff Wise’s Kazakhstan theory, so he spends considerable effort attempting to discredit this evidence. As Blaine discovered so much of the debris, bolstering the Kazakhstan theory comes at the expense of unfair treatment of the man that is singly responsible for organizing the efforts that have led to the discovery of much of the debris. This paints Wise as an opportunist that has written a sensational book to make a buck.
@Mick
OK Thank you…I was not aware the other Kalitta flight incident, I’ll take a read on that one. Unrelated to flying, I saw a recent documentary about body acclimation (to altitude sickness). Interestingly it appears the human body acclimates over time to high altitude, and that capability seems to get soft-coded into you DNA, such that your children can inherit resistance to altitude sickness.
@Victor
Debris planting is only part of the disconnect associated with the Wise theory. Making the planted debris appear to have damage consistent with a water entry is also not trivial. Taking pieces from an aircraft and modifying them in a way to resemble crash damage is virtually impossible.
@Victor,
Oh my, he actually called Gibson a “Russian agent” in the book? That’s not decent.
@Dennis: The Kazakhstan theory hinges on an omnipotent, omniscient, malicious actor with numerous accomplices. If you believe this is true, it is impossible to refute the theory because whatever practical objections you raise are countered with the extraordinary capabilities and knowledge of the bad actor. In this context, the issues you raise are just small details that can easily be overcome. But despite the capabilities of this bad actor, it left small clues that only Jeff Wise was astute enough to detect and pursue. The whole scenario quickly becomes absurd if examined with critical eyes.
@haxi: Jeff Wise prefers innuendo and implication rather than direct accusation.
@Andrew
Re: Atlas Air CVR
Obviously the NTSB open communications are fantastic, if you are a concerned citizen, you get briefed on what they know on a timely basis. But it does not sound like the CVR is giving them the clear cause yet. My understanding is their techique is to establish an initial hypothesis and then establish facts to prove or disprove. So we are not hearing the hypothesis yet, unless it is just loss of control.
@TBill wrote “My understanding is their techique is to establish an initial hypothesis and then establish facts to prove or disprove.”
The process is to first gather facts, the investigative groups each prepare a factual report, if probable cause can be determined it will be described in the summary report.
You are correct to mentioned the open communications of the NTSB, it’s detailed here: NTSB Investigative Process.
Hypotheses may be necessary only after the facts are gathered.
@TBill
I agree insofar as the CVR does not necessarily provide the investigators with a cause for an accident. However, in this case it seems to have given them valuable information about the context, ie loss of control. The investigators will try to determine why that occurred by examining the FDR data, debris, aircraft maintenance records, etc. My guess is they will be particularly interested in recovering the tail components such as the horizontal stabiliser, the elevators and their actuators. Finding those components might prove very difficult, given the nature of the impact.
@TBill
Re: Interestingly it appears the human body acclimates over time to high altitude …
Yes, something like 2 per cent of the world’s population live above 9,000 feet with the highest permanent settlement up around something like 15,000 feet. Back when I worked for Rio Tinto I visited a JV copper mine at Escondida in Chile. It’s up around 10,000 feet. The locals have no problems whereas quite a few visitors do not fare well up there.
Re 2019 KB PSR data: Publication of the new KB PSR Data in a redacted form was approved by the source. The following paper provides some background and updated results. A link to the file containing the 2018 and 2019 data can be found at the end of the paper. The original files contained a large amount of other data unrelated to MH370. Nothing relevant to the MH370 KB PSR data of interest has been omitted or changed. http://bit.ly/2tTSps4
@Victor
Newly released video of Atlas Air descent
https://www.chron.com/news/houston-texas/houston/article/New-video-shows-Atlas-Air-plane-crash-into-13668603.php
In the #5Y3591 Sheriff video, the descent appears to be nearly vertical. However, the actual descent angle was ~49 degrees below the horizon. This chart explains the context: https://www.dropbox.com/s/jzotcl0v8c4sibc/Context%20for%20Chambers%20County%20Sheriff.pdf?dl=0
Hi again Andrew,
Would you mind me asking for some more information, please?
If not:
What Emergency Oxygen supplies were available to the Cabin Crew on MH370? Was there a fixed (built-in) supply, as well as portable oxygen bottles?
In the Helios Airways Flight 522 crash,
https://en.wikipedia.org/wiki/Helios_Airways_Flight_522
one of the cabin crew was still alive and conscious about 2 1/2 hours after the flight crew apparently succumbed to hypoxia, apparently surviving on one or more portable oxygen bottles.
How long would the cabin crew oxygen last in terms of total person hours, please? Could you also break it down by supplies, please? I believe there was a cabin crew of 10, all Malaysian.
As I see it, ‘dealing with’ the passengers would have been no problem at all, but the other pilot, and the cabin crew are a different story altogether. To my mind, if ZAS was able to pull this off single-handedly, is was absolutely masterful, if not miraculous. Would you agree, or can you see an easy way to also knock out the cabin crew?
@ALSM. Thank you for sharing your analysis of the new version KB primary radar data and the new range/azimuth series. Is there also a new dataset available for the Butterworth section?
Paul: Yes, I have new from BU. But it is not materially different from 2018 data since BU was further from the target. But I’ll put a file together.
@ALSM, many thanks.
@Victor, Dr B. One thing that bothers me a little is the way in which Victor’s range/azimuth to lat/long “engine” treats horizontal distance to radar head and lat/long. We’ve used a “flat earth” for purpose of calculating horizontal range where measured range (data) is hypotenuse, assumed altitude is opposite and horizontal distance is adjacent. And then obtain lat/long using arc distance on an oblate sphere. Does it matter, or are the effects too small to make any material difference over the distances in question? Secondly, I don’t know whether the radar’s “range” is actually raw, or if itself is a processed “horizontal range” that takes account of target elevation and earth’s curvature. You’d imagine that it must be processed to obtain reasonably accurate position at larger distances.
Paul: Re “…I don’t know whether the radar’s “range” is actually raw, or if itself is a processed “horizontal range”. Why not? I told you it was the true range.
The new KB radar data contains the true range and az data from the radar head. It is not processed (as was the 2018 data).
As for Victor’s “engine”, I’ll let him elaborate, but we went through this last April. It is good to a few meters.
@oddball
The Helios flight the air outflow valve was partially closed and bleed air was on, such that the flight maintained approx. 25000-ft altitude inside the aircraft, which is survivable especially with bottle air. If MH370 was intentionally depressured, it could have been much higher altitude, but of course we do not know. It takes time to depressure, but if you open the outflow valves and cut bleed air, it would not take too long.
@ALSM. “I told you it was the true range”. Yes, you said the same about the first dataset 😉
On another note, I wonder if the other sample data of other fly-bys that you have access to for this radar head gives us an alternative method of altitude estimation. Can the COS diameter/elevation characteristics allow us to estimate altitude if we can make a reasonable estimate of CPA for MH370? eg If COS boundary occurs when horizontal range is double the target’s height…
Paul: Not true. We said all along there were questions about the level of processing (coasting, etc.) on the April 2018 data set. I guess you missed that. In any event, the 2019 data was extracted from a very large file containing both data directly from the radar head (unprocessed) and data that had been processed for display on ATC screens. This new data is the best we are going to get.
@ALSM : ” The original files contained a large amount of other data unrelated to MH370.”
Did these other data are related to other planes? If yes, have you been able to compare some of them to known paths?
PL
PaxLambda: Yes. We found a good candidate for calibration of the KB radar and the method used. AIQ2932 (SQK 2254/8) passed very close to KB radar at FL380 at 15:44UTC. Unfortunately, all we have extracted (so far) is SSR records, which includes RHO and THETA. But these values appear to be “processed values”. We will do a deep dive in the big file to see there is any PSR data for this flight.
Here is a note on the status of efforts to calibrate the KB radar RHO/THETA errors and validate the altitude determination method. http://bit.ly/2EJwkle
@ALSM. Thanks for these “notes”. Another systematic anomaly exacerbated by proximity to radar head. It will be very interesting to see how this relates to the PSR data if you can get hold of it. I wonder has the software (or our assumed radar location) got the radar lat/long wrong?
Paul: No, the KB Radar lat/lon is correct, and the radar software is doing what it is programmed to do. The problem is that the track for ATC display purposes is calculated (an X-Y plot) based on assumptions that work when the target is farther away, but not close to the radar.
I looks like the radar network assumes the geo altitude is the FL altitude for X-Y plotting purposes. That is what is causing (most of) the error close to the radar.
@ALSM
Thanks for your continued perserverance relative to this issue (and others).
I took a quick pass at the new data, and did not see a significant change in the results. I think that reflects on how the analytics relate to the physics and measurables. I know you and DrB were never fans of my approach. I am not going to belabor it and open old wounds with a new publication.
@ALSM
The thing I notice is 39,000 to 40,000-ft is the altitude that pilot Ewan Wilson mentioned in his 2014 book Goodnight Malaysian 370. He also feels the aircraft could have done 45000-ft but Wilson sticks with 39000 to 40000-ft for his proposed intentional depressurization scenario. That book has always been one of my MH370 templates.
@Victor. Kok denies withholding key information, notes that none of his 7 counterparts dissented to the Safety Investigation Report and describes what might prompt a new search.
https://www.thestar.com.my/news/nation/2019/03/09/chief-investigator-denies-withholding-data/
@David: Thanks. Based on past behavior, Malaysia has a credibility gap that is difficult for them to overcome.
@Paul Smithson said: One thing that bothers me a little is the way in which Victor’s range/azimuth to lat/long “engine” treats horizontal distance to radar head and lat/long… Does it matter, or are the effects too small to make any material difference over the distances in question?
The approximation that I have used in the spreadsheet is to linearize the curvature of the WGS84 ellipsoid at the radar site. This produces a linear relationship between X and longitude and between Y and latitude, and the solution for latitude and longitude can be obtained non-iteratively.
The more exact solution is to transform from Latitude-Longitude-Altitude (LLA) coordinates to Earth-Centered Earth-fixed (ECEF) coordinates and then transform again to East-North-Up (ENU) coordinates. The calculated range and azimuth (and elevation) between the radar and target is directly obtained from the ENU coordinates, and these values can be compared with the measured range and azimuth. If the calculated values of the range and azimuth do not match the measured range and azimuth, the latitude and longitude of the target are iteratively adjusted until the calculated range and azimuth match the measured values.
Is the extra work of the iterative solution worth it? I looked at two targets corresponding to the first target of the inbound segment (range = 58.0 NM) and the last just before the Cone of Silence (range = 10.7 NM). For an assumed target geometric altitude of 39,542 ft, the errors introduced by the linearization were 0.068 NM (413 ft) for the first and 0.0080 NM (48 ft) for the second.
[These values were corrected as units were km, not NM.]
@Don Thompson
Sorry for the tardy response, restricted internet access.
“The call priorities are known, they’re evident in the SUs.” You are right, my bad, I had missed them.
I guess it is not relevant to the matter in hand but just out of curiosity, what was the 4th call attempt all about?
@ALSM
For clarity: the radar data you obtained is still from the civilian radar installations only? So “BU” is the one at WMKB? Is there any development regarding “Western Hill” data?
@Niels: Malaysia has not released the military radar data. According to the Chief Investigator Kok, there are no plans to do so because the data is classified.
At this point in time, there is no excuse for not releasing the data, as it poses no security risk. Whatever deficiencies in radar capabilities there might have been have long been attended to, or deemed not critical.
Neils: Yes. All Civil PSR data. We have some for BU too. Still working on the military radar data. Slow, but steady progress with that effort.
@Paul Smithson: I corrected an error in my previous comment. The error values were reported in km, but the units were incorrectly stated to be NM. The units and values now agree.
The errors introduced by the linearization are acceptably small, as even at a range of 58.0 NM, the error is only about the length of two B777s. At a range of 10.7 NM, the error is only about one-fourth the length of a B777.
@ALSM, Victor
Thank you for clarifying. Yes agreed there is no excuse to keep the military radar data classified. I understand this is done by “tradition”, but capabilities must already be well known to relevant players in the region. Given the gravity of the case it is unacceptable if it would not be released.
@oddball
RE: “Would you mind me asking for some more information, please?”
What Emergency Oxygen supplies were available to the Cabin Crew on MH370? Was there a fixed (built-in) supply, as well as portable oxygen bottles?
The cabin crew would have had access to both the passenger oxygen system (ie the ‘fixed’ system) and the portable oxygen bottles. There are oxygen masks at the flight attendant stations and spare oxygen masks at every seat row.
In the Helios Airways Flight 522 crash…one of the cabin crew was still alive and conscious about 2 1/2 hours after the flight crew apparently succumbed to hypoxia, apparently surviving on one or more portable oxygen bottles.
As @TBill mentioned, the cabin remained partly pressurised in the Helios Airways accident. The investigation report states:
“Based on calculations performed by Nord-Micro on data from the NVM, the cabin altitude during cruise was 24 000 ft. According to calculations by the Boeing Company, the cabin altitude was between 20 500 ft and 28 200 ft.”
A portable oxygen bottle would have been sufficient at those cabin altitudes. The other cabin crew members presumably relied upon the passenger oxygen system, which in this case only provided oxygen for about 12 minutes (B737).
How long would the cabin crew oxygen last in terms of total person hours, please? Could you also break it down by supplies, please? I believe there was a cabin crew of 10, all Malaysian.
Once activated, the B777 chemical oxygen generators that supply the passenger oxygen system have a duration of about 22 minutes. There are multiple generators throughout the cabin (eg every seat row, every flight attendant station, every toilet) and they are activated independently by pulling on an associated oxygen mask lanyard.
However, please note that the passenger oxygen masks are only designed to provide protection during an emergency descent. They are NOT designed for continuous use at high altitude. It is highly likely the occupants would have been incapacitated before the oxygen generators were depleted if the cabin was depressurised and the aircraft remained at its cruising altitude.
The Safety Investigation Report states the aircraft had 15 portable oxygen bottles, each of which had a capacity of 310 litres. According to the report, the oxygen flow could be controlled from 0 to 20 litres per minute, providing a minimum supply of 15.5 minutes at full flow.
As I see it, ‘dealing with’ the passengers would have been no problem at all, but the other pilot, and the cabin crew are a different story altogether. To my mind, if ZAS was able to pull this off single-handedly, is was absolutely masterful, if not miraculous. Would you agree, or can you see an easy way to also knock out the cabin crew?
I think the biggest obstacle would have been the other pilot. However, if the other pilot had left the cockpit for some reason and Z was alone, he could have easily locked the cockpit door and denied access to the cockpit. If he also disabled the SATCOM, he would have prevented anyone in the cabin from alerting the outside world. Of course, he would have had to orchestrate some reason for the other pilot leave the cockpit for that scenario to work.
@all
Another crash and disaster for the families, this morning (March 10 2019), of a B737-8 MAX, 6 minutes after take-off from Addis Ababa. Another “JT610” situation ??
Link : https://www.flightradar24.com/data/aircraft/et-avj
1st flight : Oct 2018. Delivered : Nov 2018
Link : https://www.airfleets.fr/ficheapp/plane-b737ng-62450.htm
@Louis
the guardian is reporting “unstable vertical speed after takeoff”… which would be similar to JT610 also.
The ADS-B data from FR24 for ET302 shows some interesting things:
1. The vertical speed was unstable and low for a takeoff.
2. The groundspeed was high for this part of the flight.
This does not appear to be a problem with engine thrust. Rather, it appears to be a problem with controlling pitch during the climb.
The QNH was 1029 hPa at the airfield altitude of 7625 ft. At this QNH, the altitude correction is -434 ft, i.e., the standard altitude of the airport was 7191 ft. Therefore, 434 ft must be added to the pressure altitudes to convert to geometric altitudes.
From the ADS-B data, the final position and pressure altitude were (9.01602,38.98415) at 8600 ft. From Google Earth, at this position, the altitude of the terrain is 8155 ft. The geometric altitude of the plane at that position was therefore (8600 + 434) = 9034 ft. The height above the terrain was (9034-8155) = 879 ft, and even lower before that.
The interruption of the ADS-B data was probably due either to the loss of line-of-sight of the receiver at the low aircraft height, or due to the crash.
[This comment was edited to more accurately calculate the geometric altitude.]
From what I have read the Captain was given permission to return to Addis Ababa after reporting technical problems with the aircraft.This will have to be verified
Here is a preliminary cut at the FR24 image data converted to text (by Don) and cleaned up by me. http://bit.ly/2HausWn I agree with Victor’s observations.
You will all know more about this technical issue than me.
Why haven’t Boeing grounded all 737 Max aircraft after the Lion Air crash instead of issuing pilots with instructions/ directive to override a switch on the computer when the stalling fault occurs?
To put it another way, Boeing is relying on remedial action by the Pilots to correct a potential fatal fault in its aircraft.
Ryanair has just ordered over 100 X 737 Max aircraft which will be in service next month
RE: Ethiopian 302
https://www.seattletimes.com/business/boeing-aerospace/a-sense-of-urgency-as-investigation-into-second-recent-crash-of-a-boeing-737-max-begins/
@Andrew. You said, “The Safety Investigation Report states the aircraft had 15 portable oxygen bottles, each of which had a capacity of 310 litres. According to the report, the oxygen flow could be controlled from 0 to 20 litres per minute, providing a minimum supply of 15.5 minutes at full flow.”
The CAL Training Manual 31-35-00 of 1995 describes another bottle that supplied via 2 regulators at 2 or 4 litres/min. If this was sufficient the 20 seems excessive except perhaps for medical emergencies. I imagine there are instructions as to how to adjust the flow to the proper rate though I suppose that varies with cabin altitude. If 2 does the trick inactive/low altitude and 4 is needed active/high, assuming the latter then each bottle could be expected to last five times as long?
@David
Typical human respiration at rest is about 8 liters of air per minute. Air is 20% oxygen. My assumption is that 2 liters of oxgen per minute would be sufficient at rest.
@DennisW. Thanks
AOPA is a pretty reliable source: https://www.aopa.org/news-and-media/all-news/1998/september/pilot/o2-issues
FAA O2 requirements: https://www.law.cornell.edu/cfr/text/14/23.1443
@Julia
Things are not looking good for Boeing right now. I would expect their stock to take a real beating on Monday. I too felt that the response to the JT610 incident was very poor on the part of Boeing. The reluctance to ground the jet is based on purely economic consderations. Frankly, I would not fly in one at the moment.
@David
RE: “If 2 does the trick inactive/low altitude and 4 is needed active/high, assuming the latter then each bottle could be expected to last five times as long?”
The portable oxygen bottles are primarily for therapeutic/first-aid use. My understanding is the 2 & 4 L/min settings you mentioned are based on the first-aid oxygen requirements stipulated in 14 CFR 23.1443 (d), which states:
“If first-aid oxygen equipment is installed, the minimum mass flow of oxygen to each user may not be less than 4 liters per minute, STPD. However, there may be a means to decrease this flow to not less than 2 liters per minute, STPD, at any cabin altitude…”
I don’t know where the information in the SIR originated, but on further investigation it’s probably wrong. The MAS Safety Emergency Procedures Manual indicates the airline’s B777 aircraft were fitted with SABRE portable oxygen bottles, which have a capacity of 310 L and two selectable flow rates: HI (7 L/min) and LO (2 L/min). The duration of each bottle is 44 minutes at HI and 155 minutes at LO.
As Dennis mentioned, the typical resting respiration rate is about 8 L/min, which requires an oxygen flow of about 2 L/min at sea-level. The required flow rate increases with both activity and altitude. The efficacy of the portable oxygen is also constrained by the mask. The typical ‘orange cup’ continuous flow mask fitted to the portable bottles (and the fixed oxygen system) is only effective for continuous use up to about FL250.
@DennisW,
You said: “I took a quick pass at the new data, and did not see a significant change in the results. I think that reflects on how the analytics relate to the physics and measurables. I know you and DrB were never fans of my approach. I am not going to belabor it and open old wounds with a new publication.”
I have no fundamental problem with your approach except that it assumes a straight path with no turns. I think that assumption may be violated in this case by a slight turn near the entrance to the COS.
@DennisW. Thank you for your reply.
https://news.aviation-safety.net/2018/11/07/faa-issues-statement-on-upcoming-actions-regarding-potential-erroneous-aoa-input-on-boeing-737-max/
@DennisW, @Andrew RE: MAX8
What do you think about this analogy?
“I must say that if i bought a car where the steering might go wrong under certain conditions and tbe solution was to pull a CB, i would pass”
From AFP ( Agence France Presse ) and FWIW :
https://www.afp.com/en/news/15/search-clues-ethiopia-crash-china-grounds-boeing-737-max-8-doc-1eg7v52
” The plane was already on fire when it crashed to the ground. The crash caused a big explosion,” said witness Tegegn Dechasa at the site, littered with passenger belongings, human remains, and airplane parts.
“The plane was in flames in its rear side shortly before the crash. The plane was swerving erratically before the crash.”
Farmer Sisay Gemechu, said: “The plane seemed to be aiming to land at a nearby level open field, but crashed before reaching there. “
Black box from crashed Ethiopian Airlines flight recovered
Reuters : https://af.reuters.com/article/worldNews/idAFKBN1QS13F
Latest info : both boxes recovered
@Peter Norton
RE: “I must say that if i bought a car where the steering might go wrong under certain conditions and tbe solution was to pull a CB, i would pass”
So you’ve already bought the car?? In that case it’s probably a bit late to ‘pass’!
Just so you know it does happen ………….
https://www.drive.com.au/news/holden-recalls-66-000-commodores-120412
CNBC: China and Indonesia ground all Boeing 737 MAX-8s after Ethiopia crash
“Boeing shares slid almost 10 percent in early trading on Monday. The move, if maintained through normal trading hours, would be the biggest fall in Boeing’s stock in nearly two decades, halting a surge that has seen it triple in value in just over three years to a record high of $446 last week.”
@Andrew: I didn’t say that, the quote isn’t from myself. I sourced it.
I merely wanted to ask your thoughts about it.
@Andrew
I’d be very interested in your opinion on this… and understand you might prefer not to answer. for sure there is not enough info yet… at least one eyewitness says Et302 was on fire before impact, which is very different to JT610. However it would appear there are some similarities between the behaviour of the 2 flights and for 2 brand new planes of the same model to fall out of the sky shortly after takeoff is unusual.
If you were a max 8 pilot right now… would you be concerned?
(again, understand if you don’t want to answer that. )
@Andrew: I would have been amazed if there was not a slide in Boeing stock price considering the financial importance of the B737 MAX and the growing movement to ground the plane. After the Lion Air JT610 crash, I would not have been hesitant to fly on a B737 MAX. Now, I would avoid it.
The ADS-B signal was lost due to the low height of the plane above the terrain. It’s hard for us to know exactly what occurred without the later ADS-B data. The reports are the plane was experiencing problems and received ATC clearance to return to the airport. Whether or not there were problems with MCAS or runaway stabilizer trim, the pilots seemed to be battling a problem with pitch and speed. That is eerily similar to JT610.
@vodkaferret
I agree, it’s unusual for two brand new aircraft of the same type to suffer an accident in what seem to be similar circumstances. However, I think it’s unwise to jump to conclusions when so little is known about this latest tragedy. There might have been a flight control problem, however, the FR data seems to show the vertical speed excursions occurred almost immediately after take-off, at a time when MCAS should not have been active. That’s somewhat different to what happened in the earlier Lion Air accident, where the flight control problems did not occur until after the flaps were retracted.
The eyewitness reports of a fire are interesting, however, such reports are notoriously unreliable.
Would I be concerned? I’d be lying if I said no, especially when we don’t know what caused the second accident. That concern might be tempered in the coming days, depending on the information that emerges.
@Andrew
thank you very much as always
Boeing stock had soared to new highs after the low of 304 just after Lion Air, for what it’s worth.
@TBill: Boeing is in for a rough ride in the short term. The impact will be much greater than after JT610 because now there is a higher probability that the deficiency is systemic. However, I think it is unlikely that the stock price won’t recover and do well in the long term. The company is financially strong with a solid order book, and Airbus has had it’s own issues. Any deficiency it finds in the design should be addressable.
@Peter Norton
I realise it wasn’t ‘your’ quote, I just think it’s a silly analogy. I don’t wish to underplay the seriousness of the apparent problems with the 737MAX, but new aircraft often enter service with teething problems. The aircraft type I currently fly entered service a little over four years ago and it still has a number of ‘temporary abnormal behaviours’ and several operations engineering bulletins that cover problems that could be quite challenging if they occurred.
Regarding your analogy and the 737MAX, this latest accident will no doubt have an effect on sales of the aircraft in the immediate future. However, those who have already contracted to buy the aircraft might find it a bit more difficult to back out, especially while the investigations of these accidents are pending.
@Andrew: As always, thank you for all your insights, and for giving us all reality checks.
@DrB
you said:
I have no fundamental problem with your approach except that it assumes a straight path with no turns. I think that assumption may be violated in this case by a slight turn near the entrance to the COS.
Yes, I also get the slight turn, but it appears to have little effect on the range data conclusions. I will try to take a closer look at it.
https://photos.app.goo.gl/BAfpPivzm5wJn6dJ7
As an aside, I find apects of the new data just as troubling as the previous data set.
@Victor
While we await possible findings of the recent air accidents, for MH370’s 5th anniv. I had prepared a new thought experiment essay below. I’ve struggled with this write-up probably 6 months, this is what I ended up with. Also posted on my Twitter page @HDTBill
MH370: What if Plausible Deniability was the Pilots Whole Strategy?
FAA Says Boeing 737 Max Remains Airworthy Despite Second Crash
@Andrew. Thanks for the extra digging on portable oxygen.
With access to unused passenger/lavatory etc oxygen generators and portables a crew member might last some time were the cabin altitude not to rise above the altitude where these can sustain useful consciousness in a resistant individual.
As to time, I have not seen any research done on the cabin altitude range that would sustain consciousness in a pilot of high resistance, conscious but irrational for a couple of hours or more before becoming inactive. Possibly an initial descent, discontinued, would extend that time.
The two (major) impediments to the likelihood of such a scene in MH370 are the evidence of the initial handling of the aircraft and its switches and the altitude alarm.
It seems possible though that cabin crew members could survive a deliberate incomplete or slow decompression for some time.
The FAA Continued Airworthiness Notification to the International Community (CANIC) re the 737 MAX:
https://www.faa.gov/news/updates/media/CAN_2019_03.pdf
The FAA has issued a “Continued Airworthiness Notification to the International Community“.
This CANIC details Boeing’s ongoing work…
“Boeing’s completion of the flight control system enhancements, which provide reduced reliance on procedures associated with required pilot memory items. The FAA anticipates mandating these design changes [to the MCAS] by AD no later than April 2019.”
@David
I agree that a crew member might remain conscious for a long period by using portable bottles, etc if the cabin altitude did not go too high. Unfortunately there is no evidence to confirm how, or even if a depressurisation occurred, even though we might suspect such a scenario.
I’d be really surprised if Z was ‘highly resistant’ to hypoxia, given his smoking habit. Various studies have shown the performance of chronic smokers degrades far earlier than non-smokers.
@ALSM@DrB
OK, my best estimates at this point are:
1> closest approach of 8.8nm
2> CoS path of 19.1 nm
3> Average CoS speed 520 knots
4> CoS altitude of 43,000′
I do not like conclusions 3 & 4, but they are what they are without making some adjustments to the raw data.
@Andrew. You said, “I’d be really surprised if Z was ‘highly resistant’ to hypoxia, given his smoking habit…”
Yes, I was thinking that his co-pilot might remain active the longer.
Boeing confirmed late on Monday (Mar 11) it will deploy a software upgrade to the 737 MAX 8, a few hours after the Federal Aviation Administration said it would mandate “design changes” in the aircraft by April.
https://www.channelnewsasia.com/news/world/boeing-737-max-crash-software-upgrade-planes-11334886
Dennis: You are in the range of 40,000 – 43,000 feet, considered now within the best guess range. And the speed is within 10 kts of the consensus value=530 kts. I think your analysis is further confirmation, by a different method.
The key question is: When did MH370 reach its max speed and level off? Was it ~17:36, or more like 17:38 or 39? It’s down to that question. If you think it got there early, then the altitude was around 40,000, and if you think it got there later, then more like 43,000 feet.
I was in the later camp until the new data started relieving speed vs. time detail from 17:30 to 17:45 we have need seen before. This new detail leads me to believe the time was sooner. I think the 20 kt spike in speed at 17:36 is real, and there were at least 3 descents between 17:30 and 17:36 to feel for the best combination of altitude and Ground Speed. I think the altitude at 17:30 was higher, and the altitude was traded for speed in steps you can see in the data.
Later, Boeing issued a statement confirming that “in the aftermath of Lion Air Flight 610, Boeing has been developing a flight control software enhancement for the 737 MAX.”
Boeing said the software changes to MCAS will address the input from the AOA sensor and limit how much MCAS can move the horizontal tail in response to an erroneous AOA signal.
https://www.seattletimes.com/business/boeing-aerospace/nervous-reaction-to-ethiopian-crash-creates-uncertainty-for-boeing/
Updated story here:
https://www.seattletimes.com/business/boeing-aerospace/a-sense-of-urgency-as-investigation-into-second-recent-crash-of-a-boeing-737-max-begins/
@David
RE: “Yes, I was thinking that his co-pilot might remain active the longer.”
He was a smoker too!
@ALSM
I think we agree that the KB passage was high and fast. Not sure how or if it contributes to a terminal location.
A colleague and good friend of mine has written a PhD thesis on the meta-analysis of MH370. In this case that refers to the combining the analytics of various contributors (many of you are featured prominently). I was unaware of the math techniques used to combine the results of different studies (used prominently for medical studies).
It is fascinating and traces the evolution of analytics (both the physical, and human variations) over time. When it is published, I will post a link.
@Andrew
I realize CVR content is considered confidential, but has Indonesia at least summarized what the Lion Air CVR indicates? For example, NTSB has already given some summary of Atlas Air CVR, without disclosing actual content.
@TBill
I’m not aware of the Indonesians having released any further information since the preliminary report. In the past they have included significant excerpts from the CVR as part of the final report. I suspect that will be the case here too.
Singapore has banned all 737 Max 8 from flying over Singapore airspace.
https://www.abc.net.au/news/2019-03-12/boeing-737-max-8-suspended-operations-australia/10894426
Australia now!
Boeing and the FAA must be 100% confident there will not be any further fatal 737 Max 8 crashes to issue these statements (and allowing them to continue to be flown) particularly before April when the new systems adjustments on these aircraft are made. I know this blog is for MH370 but right now, I am feeling as horrified about this recent crash as I was/still am about MH370.
Boeing will be gathering their top international lawyers and throwing money at them to exonerate them from mass murder or whatever the legal terminology will be. Of course we don’t yet know the official cause of the et302 fatal crash but Boeing and the FAA’s intervention tells me that they do.
@Andrew (& all others who contributed),
Again thanks all for the information regarding emergency oxygen supplies.
It’s an interesting puzzle, given that whatever air pressure existed (or didn’t) in the cabin was replicated in the cockpit, so trying to disable people in the cabin without also taking out oneself in the cockpit would be tricky. Although the Pressure Demand mask would be a great advantage, it would still be somewhat risky groping in the dark.
It’s also interesting that smokers may have an advantage over non-smokers when it comes to remaining conscious at low atmospheric pressures, but as has been shown with people who move to high altitude environments (on the ground), the body is very adaptable. I know from my one (thankfully failed) attempt at taking up smoking as a teenager, that a large draw on a cigarette leaves one severely oxygen deprived. In my case, my vision turned white and my sense of balance collapsed so that I had to grab the door frame to stay upright. That was enough to put me off for life, but as is apparent, smokers obviously adjust to these things. Perhaps smoking is an advantage in this scenario.
I believe that another likely factor is the presence of nicotine in the bloodstream / tissues – this is the highly addictive stimulant and stamina extender that smokers most crave. Being fully tanked up with nicotine before the flight might give greatly improved high altitude survivability and endurance, and maybe ZAS was aware of this.
From what I have gleaned about his personality, he had a great thirst for technical knowledge, and liked to be smart, so I can imagine that he would have planned this very thoroughly.
Of course I have now idea whether he might have known about this case, but given that it involved an airline pilot and an air hostess, he might have. This case provides various salutary lessons in how not to murder your wife.
https://en.wikipedia.org/wiki/Murder_of_Helle_Crafts
Perhaps Crafts’ biggest mistake was his failure to control his environment, running a woodchipper beside a lake, visible from the road, in the middle of a severe snowstorm – not at all a suspicious thing to be observed doing… It’s clearly a novel method, but despite disposing of the body, it left a mess of evidence.
On the other hand, an aeroplane at high altitude, at night, out of cellphone coverage and far away from almost all observers provides a pretty good environment for nefarious activities – especially for the suicidal pilot.
@Julia Farrington
I can’t help but feel that some of these groundings are more for show than safety. In Australia’s case, there are currently no Australian airlines that operate the 737 MAX and only two foreign airlines that operate the aircraft on routes to Australia. One of those, SilkAir, has already had its 737 MAX aircraft grounded by the Singaporean CAAS, while the other, Fiji Airways, only has two 737 MAX aircraft that operate a limited number of services to Australia. The Indonesian Transportation Ministry, on the other hand, is reported to have announced that 737 MAX operations will be suspended “temporarily for inspection”. I’m curious to know what they’ll be inspecting and how they will decide if the aircraft is airworthy (or not), given that the cause of this latest accident is not yet known.
@oddball
RE: “It’s also interesting that smokers may have an advantage over non-smokers when it comes to remaining conscious at low atmospheric pressures…”
You may have misunderstood; smokers do not have an advantage over non-smokers when it comes to hypoxia. In an oxygen deprived environment, smokers will become hypoxic earlier than non-smokers.
@DennisW: Does your friend as part of his doctoral work estimate the location of the crash site?
@andrew. Thanks. Interesting information
Here is the NTSB’s Investigative Update for 5Y3591:
https://www.ntsb.gov/investigations/Pages/DCA19MA086.aspx
@Victor
What do you make of it (Atlas Air)?
The thing I noticed was that the 270 heading was requested by ATC, so that was fine. Why would the pilots go full throttle and point the nose down intentionally?
@Victor
Does your friend as part of his doctoral work estimate the location of the crash site?
No
@TBill: I’m not a pilot, but here are two possibilities that I offer for discussion purposes only. Others more knowledgeable should feel free to weigh in:
1) Applying elevator down and increasing thrust is consistent with an attempt to escape from a stall. Perhaps the pilot falsely perceived a stall.
2) Deliberate act to crash at high speed.
Expanding on (1), near the end of the flight, fuel reserves are low, and applying full thrust would raise the nose (as was seen in the crash after the go-around attempt at Rostov-on-Don). The somatogravic illusion caused by the acceleration will amplify the pitch up sensation, which might have led to the over-correction. That said, it seems odd to me that a descent from 6,000 ft to the ground was not arrested at some point.
If the plane entered turbulence while at minimum maneuvering speed (MMS), it would be advantageous to increase speed to increase the stall margin. The turbulence might have been the precipitating event that led to the thrust increase.
Based on what we know, I think (1) and (2) are on the table. The contents of the CVR should provide the clues we need.
RE: Atlas 3591
”…the engines increased to maximum thrust, and the airplane pitch increased to about 4° nose up and then rapidly pitched nose down to about 49° in response to column input.”
Hmmm, there’s an obvious conclusion. The CVR transcript will be very interesting.
@Victor
I think (1) is unlikely. Never say never, but a well trained pilot would normally trust his instruments and not be fooled by the somotogravic illusion. In any case, a pitch down to 49° is extreme by any measure. I really hope it doesn’t turn out to be (2), but I have a bad feeling it will.
Further to the above, the initial pitch up following the application of thrust is a normal aircraft response in non-FBW aircraft with underslung engines like the B767.
@Victor @Andrew
I was speculating
3) One and/or both pilots and/or jump seat passenger did not have a seat belt on, and severe turbulence threw them around violently potentially taking out the pilots and bumping in to the flight controls.
4) Less likely but trying to adjust a load shift due to the turbulence
but SatCom Guru wasn’t buying my turbulence theory…he is at (2)
https://twitter.com/Satcom_Guru/status/1105502763709014018
@Andrew: Yes, you are probably right. If true, I wonder how this could occur with two pilots in the cockpit.
@Andrew@victor
I really hope it doesn’t turn out to be (2), but I have a bad feeling it will.
Wow, under the circumstances I certainly did not expect that response.
I would add:
3> Modern state control theory allows exploring for “hidden states” in a control system – MCAS is suffering from one or more of them.
A couple were actually discovered in the NASA re-entry vehicle which fortunately never occurred in practice. My best guess would be that the MCAS system on the 737 Max is still not completely understood. An airplane is a very complex system with dozens of states. Some of which are likely to be irrecoverable.
The CVR data will be interesting.
Interestingily, the wording in the NTSB’s update has been amended to remove any mention of control column input. It now reads:
”…the engines increased to maximum thrust, and the airplane pitch increased to about 4° nose up.The airplane then pitched nose down over the next 18 seconds to about 49° in response to nose-down elevator deflection.”
The previous wording was:
”…the engines increased to maximum thrust, and the airplane pitch increased to about 4° nose up and then rapidly pitched nose down to about 49° in response to column input.”
The NTSB has corrected its report to read:
The airplane then pitched nose down over the next 18 seconds to about 49° in response to nose-down elevator deflection.
Prior, the reference was to “column input”, not “elevator deflection”. It’s interesting that the NTSB is making this distinction.
@Andrew: Our comments crossed. What do you make of this distinction?
RE: Ethiopian 302
EASA suspends all Boeing 737 Max operations in Europe
How long before the FAA follows suit?
@Victor
I’m not sure what to make of the amended wording. The original version was either an error, or it might have been correct and the wording has been amended to avoid speculation about a deliberate act.
Re MH370
Using my WGS84 path generation tool I’ve made a small study. Based on the best-fit third order polynomial interpolation functions D(t) and r(t) (representing the partially compensated Doppler and BTO derived range) I have generated a number of near TT paths for a range of bias frequencies (FFB = 149 – 153 H). For each of the FFBs I “straightened” the paths (20:41 – 00:19) as much as possible by varying the starting latitude of the path. To select the “best” of the straightened paths I looked at the generated speed profile for each of the paths. For all paths I transformed the GS into TAS for 21:11, 22:41 and 00:11 using @DrB’s weather data file (based on 21:00 and 00:00 wind data). At the moment I only considered LRC speed setting. Using @DrB’s fuel flow analysis sheets, I selected the best fitting FL in accordance with the 00:11 TAS and assuming zero fuel weight at 00:11. Then I calculated back the weight and expected TAS at 22:41 and 21:11. Finally, I calculated the RMS error for the TAS at 21:11, 22:41 and 00:11 comparing path derived TAS and LRC/FF derived TAS. I find the lowest RMS error for a FFB = 150.5 Hz, LRC FL 360, resulting in a 00:19 latitude of S34.5. While there are some assumptions in this approach (the main being a TT path and a constant flight level at LRC setting), it is interesting to see that even with the FFB and FL as free/fitting parameters we end up close to the initial value (150 Hz), close to standard cruise altitude and close to a track of 180 degrees. It will take some time to write this out in a document; it needs to be checked by others.
If there are no mistakes in the models used and the calculations made, and as a follow up on this I would like to add possible errors to the D and r values before fitting the third order polynomial. This will result in a range of D(t) and r(t) functions, described by a range of coefficients. This range of input functions combined with the procedure above will result in a range of 00:19 latitudes. Also important would be to consider other thrust plans. All together this would probably require a higher level of automation than I have realized so far, as it possibly implies several hundred path calculations and analyses.
@Andrew
@Victor Iannello
Well, I know that if the ATSB made an unreferenced change like that to an update some sections of the media (well, one person in the media) would be all over them for secretly amending their report.
@Andrew
How long before the FAA follows suit?
It would be the right thing to do, IMO. Regarding the change in wording of the NTSB report, I also believe it is appropriate under the circumstances.
@DennisW
I agree, however, judging by the following statement, it seems the FAA is holding off for now:
https://pbs.twimg.com/media/D1fZ4GTW0Ac4Qsr.jpg
I suspect the economic impact of grounding the aircraft in the US was a factor in the FAA’s decision to allow the aircraft to keep flying. That could all change if a systemic problem is uncovered during the Ethiopian accident investigation.
@Niels: Is there a reason for omitting the data at 19:41? The 180° path along the 93.7° latitude looks fine at that time, too.
In a comment yesterday @ALSM makes reference to a higher resolution analysis of the speed profile. I have attached my write-up here [https://drive.google.com/open?id=1sGJg-N0iAJGYHJ0NTKbm9zIxQmWVDgny] and the final speed profile chart here [https://drive.google.com/file/d/1xilQXbg-HHY3k5_lJI8BOhi0t1AjZqYB/view?usp=sharing].
Long story short. I concur with ALSM’s more recent estimates of altitude. By my reckoning it is a smidgin below 40,000ft geometric. More importantly, I think it reveals a very strange speed profile. There are strong indications of speed instability throughout this period, including a very rapid (+40knots in ~60 seconds) acceleration approaching KB.
@all – Link below posted a half hour ago..
https://www.smh.com.au/world/north-america/us-pilots-reported-issues-with-boeing-737-max-20190313-p513t4.html
Paul: You say: “There are strong indications of speed instability throughout this period, including a very rapid (+40knots in ~60 seconds) acceleration approaching KB.”
I disagree with this characterization. It implies that something was out of control. On the contrary, the speed profile appears to be deliberate and under control. It was not a steady increase as first believed. The new data provides the resolution to see the 3 (or more) deliberate steps in speed associated with descents to trade altitude for speed between 17:30 and 17:37. That is not a sign of “instability”. It is a sign of manual control to seek in trial steps the highest altitude and Ground Speed combination possible after the turn back.
@airlandseaman
@Paul Smithson
Looking at that data I’m struck by Mike’s earlier ‘The key question is: When did MH370 reach its max speed and level off?‘
Does the data suggest that the aircraft ‘levelled off’ at any point?! That fluctuating speed profile suggests that the aircraft was not stabilised vertically. The military radar returns as detailed in the Safety Information Report have the aircraft between 24,450 ft and 47,500 ft coming across the Peninsula with speed variations that support the notion that the aircraft was indeed climbing and descending, that is, not stabilised vertically.
Mike,
‘… , the speed profile appears to be deliberate and under control.‘ or not.
This is yet another case of MH370 Rorschach syndrome. If it is ‘deliberate and under control‘ what’s the narrative for the earlier portion of the flight immediately after the turnback? If a fast and ostensibly high transit was the aim why was the aircraft dawdling around near its last known position at such a relatively low ground speed for so long? Had the HCM ATCC have managed the transfer by the book, they should have started chasing MH370 down at 1.25am, within three minutes of it not having radioed in. At the time when efforts should have commenced to locate the aircraft it now looks like it was less 20 nautical miles from where it went ‘missing’. That doesn’t strike me as being consistent with a ‘get out of Dodge’ strategy.
As to ‘It is a sign of manual control to seek in trial steps the highest altitude and Ground Speed combination possible‘ that is, to say the least, a somewhat fanciful interpretation. It’s not like we’re talking about an experimental aeroplane on its maiden flight into unknown conditions. The B777’s performance was a known quantity and the aircraft was ostensibly in the hands of a very experienced B777 pilot. Under those circumstances why would you be playing the trial and error game?
I am told that my new analysis of speed from the Kota Bharu primary radar doesn’t open so I’m reposting again.
1. The paper with a short description of the method and a series of speed profile charts for different altitudes in increments of 5,000ft, 1,000ft, 500ft.
https://drive.google.com/file/d/1sGJg-N0iAJGYHJ0NTKbm9zIxQmWVDgny/view?usp=sharing
2. Best fit speed profile chart (at 39,500ft geometric). Two versions, one with 10-step speeds (approximately 40 second time periods). The second with 4-step speeds (approximately 15 second time periods) overlaid.
https://drive.google.com/file/d/1xilQXbg-HHY3k5_lJI8BOhi0t1AjZqYB/view?usp=sharing
I’m with Mick on the above.
The data we have is not compatible with the “hang a turn at IGARI and get out of dodge” narrative. From the turn exit to the start of the KB radar trace requires an average speed of ~456 over 6 whole minutes. A similar constant speed (mean 458kts) was maintained over the first minute (to 17:31:30) of the KB radar trace. That makes a total of 7 minutes with average speed a shade below 460. Then, over the next 5 minutes, speed climbs erratically to a peak of ~540kts approaching KB. Then speed comes back down again – varying up and down 10kts per minute between ~530 and ~520 until the end of the KB trace. If somebody thinks any of the above is materially incorrect, kindly demonstrate.
1. Why spend 7 minutes at 460kt, then speed up to 540kt over the following 5 minutes, then slow down again?
2. How do we explain the erratic acceleration and erratic speed beyond KB?
3. What must the aircraft have been doing to gain +40kts in ground speed in one minute (173530 to 173630) at geometric altitude of ~40,000ft ?
@Paul Smithson,
How accurate are the data from which you calculate the erratic speeds mentioned above? Is this simply from radar returns, and could air conditions vs radar returns account for some of this apparent variation in speed?
I have a hypothesis for the slowdown immediately after the turn, but not for the later slow downs after a speed up, unless he really is playing with altitude vs speed for range. My argument would be that running with all unnecessary loads (including bleed air) turned off would (might) not be documented in the manual, so he might need to do some of his own ‘real life’ testing.
@Victor, all,
1) Applying elevator down and increasing thrust is consistent with an attempt to escape from a stall. Perhaps the pilot falsely perceived a stall.
2) Deliberate act to crash at high speed.
Why can’t it be:
(3) Elevator, actuator or linkage failure, similar to:
http://mh370.radiantphysics.com/2019/01/12/mh370-flight-around-penang/#comment-21986
or
(4) Blocked pitot tube al la AF447? (I know, different pitot tube manufacturers, not a know problem with 767, but also not impossible, I suppose.)
It was approaching or in a turbulent storm cell, and one of the videos shows the plane flying in clear air, so I would doubt loss of horizon, especially when they would have been flying on instruments anyway.
Also, 49 degrees down while maintaining GS into the wind doesn’t sound like stall conditions to me, but I’m not a pilot.
@oddball. The quantisation on the slant range is 0.016NM. That equates to 15kts for single step (3.814 seconds), 3.8kts for 4 steps and 1.5 kts for 10 steps. Apart from the resolution, there seems to be a bit of noise as well. A statistician would be able to give you a more definitive answer, by I think speed accuracy is about +/- 3 knots using the fitted azimuth smoothing method that I have described, particularly farther out from the radar.
Speed accuracy / confidence interval poorer close to radar (by which I mean the last ~40 seconds incoming, the outgoing less of an issue). I haven’t calculated how much poorer. But even if the trend shown is “noisier” it is undeniably there.
@Victor
Re 19:41 data
That’s an interesting aspect. First of all, practically, all paths I’ve recently generated start at 18:28 (based on backward extending the r(t) and D(t) curves). For FFB values close to 150 Hz I observe with my path generation tool a dip in the speed around 19:41 and a slight curvature in the path. Probably my 19:41 position is therefore slightly more south then you would expect for a path ending S34.5. The question is if the dip is real or if it is an artefact related to the 19:41 (and perhaps 20:41) BFO values. Anyway, because of this I decided to apply the procedure to the 21:11 – 00:11 interval. Note that if you assume the dip is real it becomes rather easy to “backward” connect the path to near IGOGU at the right time for a direct turn south.
The dip disappears for FFB values in the 156 – 158 Hz range, resulting in more straight paths ending in the S28 – S30 range, however for these FFB values I get rather high speeds in the 19:41 – 21:11 interval, while the 00:11 speed does not increase a lot. The rather big delta_speed from 21:11 to 00:11 then is hard to explain with the more standard speed settings.
The relative insensitivity of the 00:11 speed to changes in the FFB (as compared to the 19:41 – 21:11 interval) is an aspect which is interesting on its own and a bit unexpected; I’m trying to understand it better. Note that in my procedure with the shift in FFB the 00:11 position is shifting because of trying to keep the path straight.
I’m also comparing with your October 2017 results (great circle paths). Trying to bridge the different approaches, in your figure 2 it would be interesting to add a graph for the mean BTO error in addition to the RMS error (for LRC), and to see where this would be zero.
@Niels: When I generated the great circle paths, I should have recorded the average BTO (and BFO) errors in addition to the RMS error. It would take me a small amount of time to re-do those calculations and record the average errors.
I am curious to see details of the entire continuous path you are generating.
@oddball said: Also, 49 degrees down while maintaining GS into the wind doesn’t sound like stall conditions to me, but I’m not a pilot.
Of course not. That scenario was based on recovering from a stall by over-correcting.
Elevator, actuator or linkage failure…
That would be unlikely if the column input and stabilizer actuator position were both nose down.
@Victor
if the column input and stabilizer actuator position were both nose down.
Is that what the FDR shows?
To my mind, the NTSB’s change of wording suggests they (i.e. column input vs elevator deflection) were not necessarily in agreement. To me, it strongly suggests the elevator deflection said nose down, irrespective of what the column input was. That could suggest linkage failure or actuator error, but I don’t know how the NTSB would know what the elevator deflection was, independent of the actuator position. Is there a separate, independent elevator position sensor? Or would it be from the wreckage itself?
@Paul Smithson,
Many thanks.
I’d have to go with the “performance testing scenario” for the later speed reductions then.
In my hypothesis, the speed reduction immediately after the turn back would have been for “passenger confidence”, (as part of “controlling the environment” I mentioned earlier) followed by a gradual return to cruise speed, but I haven’t quite finished writing it all up / proof reading it just yet.
@Niels
I am not following exactly, but I think you are finding 180 South path to fit. In case you are interested, please see my essay below “On the straightness of the BFO Trend.” I tend to feel 19:41 point is off a little or maneuver is in progress. I actually feel like the 38 South paths fits best until Arc5, at which point I envision a heading change to the southeast.
https://twitter.com/HDTBill/status/1038108692611260417
@oddball. Are you different to the rest of us an have an inbuilt GPS? How do passengers have any idea how fast an aircraft is travelling?!! Why should 460 “settle” them compared to a higher speed.
@Victor, Andrew, others.
Can you comment on the feasibility of level acceleration at rate of +40kts from about 480 to about 520 TAS (~20kts tailwind subtracted from observed groundspeed) in ~60 seconds at this weight and geometric altitude of 39,500ft?
Could an you also comment on feasibility of maintaining ~440TAS at the same altitude?
I wonder whether we might be looking at a continuous thrust acceleration from 460 to 540 groundspeed, with a couple of step climbs along the way that create the pauses in the acceleration profile?
@Paul
I would also be curious if there is enough time to dip down to say FL200 consistent with the eyewitness report of low flying aircraft. On the surface in my simulations, I needed all the time to speed up. But if MH370 actually managed to complete the U-turn at IGARI in a little over 2 minutes, which would be an extreme sharp turn, then there is couple extra minutes I suppose.
The problem with all this is we need to know when the turn was started and when/where it ended.
@Paul
Interesting plots. I also took a pass at deriving velocity over time on the orginal data set. It was pretty trashy to say the least. Given some time (and enthusiasm), I may try again on the new data using spline interpolation on range, time, and azimuth. Last time I used simple boxcar filtering.
I don’t have an opinion relative to the reason for the variations or even if they are completely velocity related. Assuming a fixed altitude is not unreasonable, but it does constrain the source of the variations.
@TBill. My hypothesis on that is:
1. Complete the turn at IGARI onto the IGARI-BITOD leg at the last prevailing speed 471-473kts
2. Commence a 180 degree turn at 15 degree bank angle at 17:21:59 and TAS ~445kts
3. Continue with same TAS (now GS of about 458) all the way back to the start of the KB trace
I think you will find that this provides an excellent match to the maximum NE positions in the military radar (which I take to represent the radius of the turn when plane is at near constant slant range from radar – and gets “captured again” having been lost by radar when the turn started). It also gets you on the right trajectory for what we know of the return trace shape/direction.
It gets you back to the start of the KB trace right on time.
How did I arrive at this solution? With a “trombone” model, where the radius of the curve is a function of speed, the position of the trombone’s curve must provide a decent positional match to the military radar, starting from IGARI at last known speed and getting back to start of KB trace on time.
Each speed simulation gives you a different turn radius, required turn position and time back at start of KB trace. If you assume faster speed, the trombone must be further extended and has a wider radius – which produces increasingly poor fit to the observables from military trace and brings you back on the wrong trajectory.
But rather than get sidetracked on that discussion, I’m hoping for some more commentary on what the updated KB speed profile might tell us.
@oddball: We don’t have access to the FDR data. My possibility (2) was based on the version of the report which referred to nose-down column input. If the elevator deflection does not correspond to the column input, then we have to consider a failure. Another possibility for the change in wording of the report is the column inputs for the captain and the FO might not have been the same direction.
Also note that:
1. Model above predicted perfectly what we are now told was the position of turn exit/completion
2. The start of the return trajectory is near perfect reciprocal of the IGARI-BITOD bearing. Which is why I think that turn onto the IGARI-BITOD leg was completed and only then was a 180 turn made onto the reciprocal course.
@Paul
I am a little rusty but 15 deg bank is lazy wide turn? In my past simulations, I assumed the FI timing was correct, and they say the turn started almost immediately after 17:21:13…so I give it 10 seconds and start the turn. Then I would set A/P at 25 deg max radius, which I realize A/P may have been off and turn may have been sharper. That was before the Safety Information Report which gives some IGARI U-turn data points that investigators used to simulate, which gives a little different timing and location, and that I have not studied as much.
Sorry, Tbill. My bad – yes, 25 AOB not 15.
@Tbill. Interesting little discussion on bank angles here. Including the observation that if you want a tighter turn the operating procedure is to control speed rather than excessive AOB
https://www.pprune.org/tech-log/416502-built-bank-angle-limits.html
@Paul Smithson: Here is a quick and dirty estimate of acceleration capability at a geometric altitude of 39500 ft, or about FL374 at the conditions near Kota Bharu. I make the following simplifying assumptions:
1) The weight is 215 MT, and the (L/D) around cruise speeds is 17.
2) The thrust capability of the engines scales as the ambient pressure.
Using the maximum altitude table for LRC speeds, at 215 MT, a climb rate of 300 fpm (2.962 kn) can be sustained at FL404. The ambient pressure is 184.0 hPa. At M0.84 and ISA temperature, TAS = 481.8 kn. The maximum thrust at this altitude is therefore 215,000 kgf x (1/17 + 2.962/481.8) = 13,970 kgf.
At FL374, the ambient pressure is 212.5 hPa. The maximum thrust is therefore 13,970 kgf x (212.5/184.0) = 16,134 kgf. The maximum acceleration is due to the thrust in excess of drag, and is equal to (16,134 – 215,000/17)/215,000 = 0.0162g.
If I’ve done my math correctly, an acceleration of 0.0162g corresponds to a change in speed of about 18.5 kn/min. I’d use that as a first-order estimate of the maximum acceleration at FL374. At speeds lower than LRC, greater accelerations are possible. At speeds higher than LRC, the maximum acceleration is less.
@Paul Smithson: I suspect I am in the minority, but my first choice in selecting a configuration and route after IGARI is to consider that the autopilot and autothrottle are engaged. In a diversion, the workload for the pilot would be high at the turnback, and that is exacerbated by hand-flying at high altitudes, high bank angles, and high (and low) speeds.
This contradicts what the safety investigators discovered in their simulations, as reported in the SIR. However, that work was strongly dependent on exact coordinates of the entrance and exit waypoints, and when the turn was begun relative to the entrance waypoint.
Frankly, I don’t trust that these coordinates are accurate because they are from the military radar data. That same military radar data indicates an impossibly sharp turn to the left to start the turnback. My guess is that military data is inaccurate at the turnback, and also has numerous “missing hits” that were interpolated either by the radar system or by the analysts that interpreted the data.
President Trump says FAA will ground all B737-Max 8 and Max 9 aircraft in U.S.
The FAA has grounded the B737 MAX pending further review of data.
This excerpt is from the FAA’s Emergency Order of Prohibition for the 737 MAX.
On March 13, 2019, the investigation of the ET302 crash developed new information from the wreckage concerning the aircraft’s configuration just after takeoff that, taken together with newly refined data from satellite-based tracking of the aircraft’s flight path, indicates some similarities between the ET302 and JT610 accidents that warrant further investigation of the possibility of a shared cause for the two incidents that needs to be better understood and addressed. Accordingly, the Acting Administrator is ordering all Boeing 737 MAX airplanes to be grounded pending further investigation.
The satellite-based tracking refers the ADS-B data collected by Aireon’s satellite network. Aireon provided the data to the NTSB.
(I assume this data is no better than the data from the FDR. I read somewhere that the Germans were asked to read out the FDR, but they did not have the proper capabilities.)
Well…Boeing stock has not moved in response. Difficult to understand since the Max accounts for 1/3 of their revenue. Also a significant blemish on the brand. SW airlines is also unaffected. ??
Personally, I don’t see this as a problem with a quick fix.
Hi Paul,
@oddball. Are you different to the rest of us
Yeah, indeed! 😉 Clearly, I’m from another planet. Didn’t you realise?
How do passengers have any idea how fast an aircraft is travelling?!! Why should 460 “settle” them compared to a higher speed.
Ahh-ha! You miss the point, rather widely, I’m afraid.
I didn’t say “settle”, but I guess it’s relevant. The object is to control (as fas as possible), so maybe I should have used ‘reassurance’ instead of ‘confidence’ (which I like better), but the whole idea (in my #1 hypothesis) would be to keep the pax completely compliant, quietly in their seats with their oxygen masks activated, with nothing more untoward to think about than what they are already facing. FWIW, the primary objective of all that is targeted very directly at the young co-pilot…
So maybe it’s best if I let you answer your questions yourself. (Clue: You need to think outside the box. It’s not really about the speed. Did you ever see the movie “The Prestige”?)
I don’t (and didn’t) mean to offend you, but it seems maybe I have nevertheless. May I apologise? Or am I just being over-sensitive again?
@oddball. didn’t mean to be rude. just wondering how you reckon the aircraft speed would impinge on the passengers in any way. i reckon the vast majority of passengers are completely oblivious to aircraft speed
@paul smithson,
Ok, thanks, no problem!
I agree with you 110%. It’s extremely difficult to get any idea of how fast an aircraft is travelling from inside it. Oblivious is an excellent choice of word.
What they are not oblivious to is what matters – what the ears detect:
1. Sound
2. Balance/tilt and acceleration/deceleration.
3. (Ears &/or viscera?) G-forces.
4. (Possibly) Air pressure changes.
I think most can detect the difference between climb, cruise and descent, and more importantly, the transitions. After an alarming mask drop, many would (might) know that it must be followed by a rapid descent. So, a sudden deceleration and nose-down should trigger some degree of somatogravic illusion.
Plus, I would expect an audible sound difference, as the engine power is quickly reduced. All this would give the pax confidence that, despite an unexpected mask drop followed by an unintelligible pilot announcement in English (to a Chinese-only speaker) and a high rate turn (back), an (apparent) descent is all part of what you’d expect. The point of the magic trick example is that “magic” is about having the audience all believe a certain thing, when something else entirely is happening before their eyes.
And the point of that?
1. To maintain control, and prevent the outbreak of chaos in the cabin.
2. To apply intense social pressure to the FO now locked out of the cockpit in the cabin, to prevent him from considering looking to round up a posse and attempting to bust down the cockpit door. Imagine: If the entire contingent of passengers and cabin crew firmly (confidently) believes that the senior pilot Captain has it all under control, who in his right mind is going to allow an over-excited if not insane junior pilot to attack the cockpit door?
Then, after a few minutes “descent,” a slow return to LRC speed (and perhaps even, a slow climb) would be much less noticeable, if done over several minutes. Add a few “hops and bumps” (as seem to have occurred) and it would probably add to the impression of an on-going high-rate descent. Especially if they (those who could understand English) were told to expect that… And presumably they have English & Mandarin speaking cabin crew who would repeat it for the Chinese anyway.
Does that explain it (or anything)?
@Victor
Posts are getting weird. Do something.
@Victor
Atlas Air discussion…interesting point that if NTSB thought it was deliberate act, then FBI would take over, which has not happened.
https://pilotonline.com/news/nation-world/national/article_e7021264-247c-528f-a088-bc9440eba8ae.html
Posts are getting weird. Do something.
Now THAT’s hilarious!
Finally, Boeing recommends grounding the entire global fleet of 737 MAX aircraft:
In Consultation with the FAA, NTSB and its Customers, Boeing Supports Action to Temporarily Ground 737 MAX Operations
@TBill: The NTSB’s change in wording is curious, as it changed the implications tremendously.
When I began reading the article you cited, there was mention of “engine surge”, which I thought was new information. I think they are using this term for the rapid increase in thrust rather than the aerodynamic connotation.
I don’t know what to make of the claim about the FBI. The FBI was on the scene from day one, whether or not they are leading the investigation.
@Victor
“…change in wording is curious, as it changed the implications tremendously”
Yes this has been a mentally exhausting couple of days. That change of wording was discombobulating. Also we have a couple trips coming up on American/Southwest so we were trying to look up aircraft to see if was the MAX.
@paul smithson
RE: “Can you comment on the feasibility of level acceleration at rate of +40kts from about 480 to about 520 TAS (~20kts tailwind subtracted from observed groundspeed) in ~60 seconds at this weight and geometric altitude of 39,500ft?
Could an you also comment on feasibility of maintaining ~440TAS at the same altitude?”
Sorry, I missed this earlier. I note that Victor has already calculated the available acceleration at LRC and I agree with his math (‘maths’ in my part of the world!). The LRC TAS at FL374/215T is 482 kn, so the drag would have been increasing as the aircraft accelerated to 520 kn and the acceleration would have been decreasing. A level acceleration in 60 seconds does not seem possible.
I wonder if the aircraft initially climbed high to somewhere around FL400 but was then too slow (440 KTAS) and did not have sufficient thrust to accelerate in level flight. The pilot would have needed to descend to increase speed. The final groundspeed of 530 kn yields a TAS of 510 kn, assuming a 20 kn tailwind. A TAS of 510 kn gives M0.87 at FL380/ISA+10, which is the aircraft’s MMO.
@TBill
According to the NTSB Aviation Investigation Manual, the FBI does not ‘take over’ an investigation in the event of suspected criminal activity. The NTSB would continue to investigate and assist the FBI with its own investigation where necessary.
“Aircraft accidents in which criminal activity is suspected may involve the participation of law enforcement officials in the investigation. In such cases, law enforcement agencies are not parties to the investigation; however, the Board should provide the law enforcement agencies with necessary access to evidence. If evidence indicates that a criminal activity was involved, the Board investigation will be conducted to the extent necessary to determine probable cause, address any safety concerns, and, where appropriate, to furnish requested assistance to law enforcement agencies. In the absence of any such evidence, the Board investigation will continue in its normal scope.”
@Andrew: We have an airline pilot trained by an airline that is flying an airliner. If time was of the essence and he wanted to quickly turnback, do you think it was more likely that he would climb to or beyond the maximum altitude capability of the plane and aerobatically turn, or simply slow down to reduce travel in the wrong direction and reduce the radius of the turn?
Those seem to be the two limiting cases.
Fair question @victor and I look forward to hearing Andrew’s answer. But even if the latter, the next question you might ask is: having completed the turn (at around 17:24:40) he spends the next 7 minutes at average GS of 460, TAS of <450kts? How can that possibly be compatible with "time was of the essence"?
@Paul Smithson: In either scenario, the time at low speed seems too long. We are trying to guess “why” the plane was flown in a certain way, and that is not easy.
I’ll add that using the most recent set of radar data, I estimate that before the CoS, the speed levels off to 529 kn at a geometric altitude of 39,500 ft (FL374). However, the estimate of altitude assumes the time, range, and azimuth are reasonably accurate close to the CoS when the azimuth is rapidly changing. If the altitude is lower, there is more thrust available, and the increases in speed are less likely to be from descents.
I am trying to logically and scientifically assess possibilities without jumping to premature conclusions. That doesn’t mean that I believe that some of the scenarios that have been proposed are wrong. I just don’t know.
@Victor
As I said to Mike, I’m not a fan of high altitude aerobatic manoeuvres in wide-bodied airliners, even ones that might be classified as ‘gentle’. If time was of the essence, a level turn at a reduced speed might be preferable. However, if my understanding is correct, the radar data analysis suggests a speed increase at a rate that was not possible in level flight at FL380-ish. It seems to me the acceleration could only have been achieved if the aircraft was descending, possibly from an altitude close to the maximum. If that’s how it happened, then perhaps the pilot traded some speed for altitude in a bid to reach the maximum altitude as quickly as possible. In the process he might have ended up well below the min drag speed, with insufficient thrust to accelerate. That said, the motivation for climbing so high in the first place is unclear.
@Andrew: I am uncertain about my best estimate of FL374 across the CoS, and I am uncertain about the finer structure of the speed profile. Any small reduction considerably increases the thrust available for acceleration, and any “linearization” of the speed profile reduces the acceleration.
@Victor@Paul
My opinion for the low speed is based on a negotiation scenario. ZS was not in a hurry. He wanted to remain near landing fields for a few hours. Why would he possibly be in a hurry in any scenario?
@Andrew
My opinion for climbing to a high altitude is the motivation to avoid other aircraft in the airspace beyond KB.
@Paul
Isn’t is possible the aircraft slowed down well below 460 during a climb? If you look at @sk999’s digitized flight path, there is quite a speed drop during the turn at IGARI.
@Victor. What do you make the mean GS from end of Kota Bharu trace to the “phone registration” position (or adjacent primary radar positions)? Does mean GS 529kt fit all the way through to Penang?
@TBill
Re 19:41 BFO
“I tend to feel 19:41 point is off a little or maneuver is in progress”
I agree but I’m far from sure which of the two it is; you can make a case for both.
@Victor, others
Re “near TT” paths
Please find a quick summary of my recent preliminary results through the link:
https://www.dropbox.com/s/ralni6o1r2izoo7/MH370_TTpaths.pdf?dl=0
There are several steps included which are new for me (the WGS84 related coordinate transformations, the use of wind data, the use of FF model and LRC speed plan) so critical remarks are welcomed. Let me know if you see something unusual or questionable / if I should explain the procedures followed more in detail.
A new story reports that Blaine Gibson continues to keep a low profile amidst threats and false accusations of doctoring of evidence.
The poor treatment that Blaine has received from some claiming to be honest investigators is despicable.
Andrew, Victor, Paul: It is frustrating to keep hearing mis-characterizations of what I have proposed. Could we please stop exaggerating and start seriously considering what happened.
The evidence we have (radar, ads-b, etc.) and the statements in the Final Report (manual banked turn at 35 degrees) are consistent with a *relatively* steep turn to the left after IGARI. Relatively, meaning not a normal turn. I estimate roughly 5000 feet was gained in the turn (37200 to ~42000?) before the PF started heading back down. The low speed at 17:30 is consistent with a climbing turn. It does not have to be an “aerobatic turn”. It could all be in the 1±.2g range. Nothing all that dramatic.
As Andrew notes, you cannot explain the speed steps assuming level flight and thrust increase. It just makes far more sense to recognize that the PF was probing for the best GS and highest altitude possible.
@ALSM. 17:30:xx at the start of the KB primary trace is 6 or so minutes after the turnback, no matter what our theory of how that turn was made. Average groundspeed over this period appears to have been a shade under 460kt, as it was for the first minute of the KB data series. If low speed resulted from the nature of the turnback, why should that low speed persist for the following ~7 minutes?
@airlandseaman: What you propose is entirely possible. I am not nearly as confident as you for many reasons. That doesn’t mean that I am claiming you to be wrong. Some reasons are:
1) The 38° turn is based on simulations performed by Malaysian investigators that were designed to match two waypoints for the start and end of the turn as determined from the military radar data. That is the same data that produced the impossibly sharp turn after IGARI, and the impossibly low speeds reported in the DSTG report. I suspect the military radar data was at the limits of the detection range of the radar installation at Western Hill, and there was considerable measurement error as well as missing data. I suspect that the inaccurate, sparse radar data was supplemented by interpolation either by the radar system or by investigators interpreting the data. That same interpolation caused the rendering of the impossibly sharp turn.
2) A 38° turn is beyond the envelope protection limits of NORMAL flight control mode. When 35° is exceeded, the envelope protection attempts to return the bank angle to 30°. A pilot can overcome this by turning the wheel hard. That combined with a climb to an altitude equal to or exceeding the maximum LRC altitude might not qualify the turn as “aerobatic”, but it is far from normal.
3) The accuracy of our altitude estimations are limited by the accuracy of the time, range, and azimuth of the radar data near the CoS. We know that the azimuth near the CoS was rapidly changing. It might be that there was processing at the radar head that reduced the accuracy of these measurements, as we saw for the previous data set where the radar system introduced errors downstream of the radar head. For this reason, I advise that we use the current data set with caution until we are sure of what we have.
4) The available thrust for acceleration is highly dependent on the assumed altitude, as most of the available thrust balances the drag. As a result, relatively small changes in altitude have a large effect on the achievable acceleration. In a previous comment, I estimated the acceleration available at LRC speed at FL374 and 215 MT to be 18.5 kn/min. Over the course of the 6.16-minute inbound segment to Kota Bharu, that represents a change in velocity of 114 kn. Now, of course the acceleration would be greater than this at speeds lower than LRC, and higher at speeds greater than LRC, but over the course of 6 minutes, it is evident that substantial speed can be added, even if the maximum thrust was not applied for the entire interval. Because of uncertainty I believe exists in the estimation of the local slope of the speed profile and the estimated altitude near the CoS, I believe it may be possible to explain the speed profile with level flight.
I think assembling a scenario that involves a sharp turn and a steep climb followed by a descent is a useful exercise. I’m not trying to discourage you from doing this. I’m simply less certain than you that it occurred.
@Paul Smithson: As I said earlier, I think the duration of the low speed for any scenario remains unexplained. It’s not particular to Mike’s theory, is it?
Paul:
We do not really know (or believe) the path between 17:21 and 17:30 and won’t unless and until the Malaysians release the military radar data, and even then, we may not know. Therefore, it is impossible to say what the average speed was during that time period. All we know is the last ADS-B ground speed at 17:20:34 (471.3 kts/37200 ft) and the first civil PSR derived radar speed at 17:30 (~457 kts/43200 ft). Given the wind at different altitudes, the TAS was ~490-495 at 17:21 and 430 kts at 17:30.
What I’m saying is that I’m puzzled that he seems to be saying the slow speed at 1730xx is explained by events at 1722-1724. I’m not following the reasoning.
@Victor. BTW, also allow me to answer my own question regarding groundspeed between end of Kota Bharu track and Penang. Measuring from last 5 points of KB to the first five points of the segment crossing the west coast of the peninsular, I get mean groundspeed of 529.6kts. This based on the new KB data and the old Butterworth data as previously shared by @ALSM. It remains to be seen how the new Butterworth dataset changes this mean GS but I suspect nothing much over a segment of this length/duration (65nm/7.4 mins). I am looking forward to seeing how the whole primary radar trace speed profile pans out once we have spliced it together and applied some noise suppression.
Paul: The ground speed after KB remained ~530kts all the way to Penang. After the turn at Penang, the ground speed slowed because of the difference in tailwind after the turn, but the TAS remained about the same until 18:22.
I can see that I am going to have to write up properly and share my “trombone” model that joins IGARI transit to first KB radar position. It’s essentially very simple with regard to the assumptions employed.
Start at IGARI at known time and TAS per last ACARS
Complete the turn on to the IGARI-BITOD leg
Allow the time and position of the start of turnback to vary (that is your trombone sliding in or out, creating a longer path overall via the length of the “arms”)
Allow any speed from start of turn to the 1730xx as long as it is constant
Assume a turnback at max bank angle of 25, noting that the diameter of the turn is affected accordingly (this widens the width across the tubes of the trombone)
Make a 180 turn on to reciprocal course, then a single subsequent course adjustment towards KB (which is also suggested by the depictions of the military trace).
There are, of course, many speed scenarios that can get you back to 1730xx on time, but with this set of simplifying assumptions they alter both the position and the diameter of the turn (length and width of trombone). Only one solution matches the timing AND puts the turnback in the correct place AND matches the return trajectory (which is determined by turn diameter).
This model correctly predicted:
1) the turn exit position as subsequently published (to within 0.5NM)
2) the time of that position (to within 1 second)
3) the predicted speed at 1730xx, assuming a constant TAS from the start of the turn onwards.
I cannot prove that this is how the turnback was made, but it seems to me to be a pretty reasonable theory insofar as it matches the observable facts while relying on some parsimonious and reasonable assumptions.
Paul:
1. “Allow any speed from start of turn to the 1730xx as long as it is constant” Why constant? Very unlikely IMO. You already know there was a huge (~60 kts) speed reduction between 17:21 and 17:30.
2. “Assume a turnback at max bank angle of 25” Why 25? It may not be accurate for the reasons Victor cited, but 38 degrees is the only “data” we have. What is the basis for ignoring this?
3. “…it matches the observable facts …”. Well, we know the TAS was NOT constant.
@airlandseaman
‘All we know is … the first civil PSR derived radar speed at 17:30 (~457 kts/43200 ft).‘
Mike, you cannot ‘know‘ that the target’s altitude was 43200 ft at 17:30 based on the PSR data.
Mick: What is your estimate? How do you know mine is wrong?
@Paul Smithson: I don’t know how you are accounting for wind, but I would superimpose the (constant) wind field on top of the turn at TAS.
@Paul/ALSM/others
I’ve read your detailed “analytics” of the radar data. I have the very same feeling I had 4 years ago (or so) when people were sticking pins in the map at 38S. Just stop. You are extracting (trying to extract) more from the observables than the observables are capable of telling us. Having seen this movie a few times, I can tell you it does not have a happy ending.
@victor. yes, i used GDAS winds at FL340 1800z throughout
@mick @alsm the groundspeed at 1730xx is essentially insensitive to altitude assumption. it could have been at any altitude, within reason.
RE: Ethiopian 302
NY Times:
Boeing 737 Max Hit Trouble Right Away, Pilot’s Tense Radio Messages Show
Seattle Times:
737 MAX crashes make it the most troubled airliner debut in modern aviation
@All. Attached is the .kmz path that results from the azimuth-smoothed version of the KB primary radar data, assumed altitude 39,500 geometric. There are no doubt some further refinements that could be made to the azimuth fitting model. In addition, note that the azimuth fitting process will have the effect of obscuring (dampening & spreading out) actual course corrections that may have occurred. Changes in altitude would alter the course over ground shown here, particularly closer to radar.
https://drive.google.com/file/d/1IfLPwN2nvCb6mc8mXaJB78fnZm68xDJ7/view?usp=sharing
@DennisW,
Further to your recent comments, am I correct in thinking that you are vehemently opposed to the pure murder-suicide-by-pilot scenario?
Is that what you meant when you said: Posts are getting weird? Would you elaborate, please?
Personally, I now think straight murder-suicide is by far the most likely option, and negotiation is a pure and deliberate smoke screen, designed to throw us off the scent. (I think that’s a good analogy, BTW!) 😉
Anyway, to answer your question:
Why would he possibly be in a hurry in any scenario?
Let’s start with: what he was doing was highly illegal. That’s why criminals usually arrange their getaway cars in advance.
Second, while he was over Malaysia, he would be well within range of Malaysian fighter jets, which could come alongside and attempt to force him to land. If nothing else, this would very quickly demonstrate the situation to all the other 238 passengers and crew. If his plan was anything other than recovering from some unknown in-flight calamity, this would be very contrary to his intentions. It would also explain why he turned off the transponder, ACARS and SatCom – because he wanted to “go dark” and be very hard to find, right from the start, when he was most at risk.
As I see it, the only scenario in which he would not be in a big hurry would be if he was suffering a genuine in-flight problem. Then, he’d want all the time available.
Going to max altitude would have perhaps three purposes.
1. Again, to make himself harder to find
2. To enable his getaway to be quicker
3. To hasten the effect of hypoxia.
4. As you say, potentially avoid other aircraft.
Regarding your Just stop etc, what is your proposed strategy going forward? What is the purpose (of this blog), who is allowed to contribute, and what may they contribute?
Surely, this is group brainstorming, and to cripple that is to reduce its possible effectiveness, no?
Oops, sorry, faulty close tag after than…
vertical speed profile comparison between Lion and Ethiopian
@Andrew:
I previously thought about how confusing the situation could have been on LNI610. (penultimate paragraph, Seattle Times quote)
Similar thoughtshere
PS: Some alleged insights into Boeing’s project management.
vertical speed profile comparison between Lion and Ethiopian
FWIW (probably not very much)…
These graphs remind me of the first Hybrid Toyota I ever drove (A Camry). It was a rental, but still had the manual in it, so I read it up to try to find the problem (solution), but never got to the bottom of it and just returned it after a couple of weeks.
The problem with it was that it was impossible to achieve “moderate braking”. It would brake ok for a gentle slowdown, but anything more and it would start to brake hard. Dangerously hard, for anyone following. So you’d ease off and suddenly end up with no braking, and run the risk of rear ending someone at the other end. Quite often found myself yo-yo braking. Infuriating to drive!
I know the Toyota Hybrid system has a very complex brake actuator system, because for most braking above minimum Regen Braking Speed, it tries to use only regen braking. Brake harder and it then uses all it’s got, including those antiquated steel disk friction thingies. Then, when the speed drops too low for adequate regen, it switches over to all mechanical braking. As you can probably imagine, this is no easy task, and I don’t know whether it was because of a fault there, or somewhere else.
According to the manual, it also had a feature called something like “Emergency Brake Assist” which basically slams the brakes on for you if it senses “heavy” braking. It seemed to me that this might be what was happening, but it was adjusted badly, and thought that normal braking was an emergency. No, I’m not that crazy a driver, that I habitually stand on the brakes at the last second. In fact, I see idiots do that all the time, behind the last car in a queue at red lights, and it never ceases to amaze me. Especially the ones who overtake me to get there!
But it strikes me as similar, and reminds me of another report of a pilot and a plane (can’t remember which) where they were engaged in a similarly dangerous 10-minute battle for control before the pilot finally figured it out – he had the Autopilot in the wrong mode or something similar.
The fact that the prior Lion Air flight had the same problem but then fixed it suggested this new feature is doing something that the pilots just don’t grasp correctly – something contrary to what they are used to. Must be easy to work around, once you know! Kind of suggested by the earlier pilot not making a big fuss about it – probably cos it’s in the book.
@oddball
There is absolutely nothing to suggest a murder/suicide scenario was likely. Nothing!!! Nada!!!
ZS was a patriot. In love with his country and frustrated by the political situation and the graft. No way was he suicidal and a murderer.
@Peter Norton
RE: “vertical speed profile comparison between Lion and Ethiopian”
The thing that I find interesting is the time frame. The Lion Air aircraft’s vertical speed did not start fluctuating until after the flaps were retracted, about two minutes after take-off. The Ethiopian aircraft’s vertical speed, on the other hand, seems to have begun fluctuating almost immediately after take-off. MCAS should not have become active until after the flaps were retracted, so it seems that something else was happening during that period immediately after take-off.
RE: “PS: Some alleged insights into Boeing’s project management.”
Some people feel that the B787 project was the beginning of the rot that was responsible for the issues that aircraft had on introduction to service. There was a good article in The Seattle Times, but I can’t find it now.
@Dennis
First, and most importantly, I hope you are recovering well and feeling better!
Correct me If I’m wrong (and I very well may be), but in your own negotiation (Nothing!!! Nada!!!) scenario and by your own words and account(s), one of your tenets has been that Z HAD TO FOLLOW THROUGH with his threat, period. That he was NOT bluffing.
That sure looks a lot like suicide/mass murder, does it not?
I hesitate to mention (but apparently some need to be reminded) that the outcome here is not in dispute. It’s EITHER an accident (mechanical/non-nefarious), which any reasonable person has completely ruled out (sorry Paul and Mick) OR a murder/suicide. 2 pilots and 237 souls have perished.
The ONLY realistic wildcard scenario is a miscalculation by Z (fuel, hypoxia, cockpit breach) which prevented him from just what exactly (in your scenario Dennis)?
You can’t have it both ways. Landing on Christmas Island is a long ways off from disappearing into the southern ocean and murdering a plane load of human beings. But surely the threat put forward in your scenario by Z and/or others wasn’t to fly to Christmas Island?
Help me understand because I’m genuinely confused by your logic? Thanks in advance though I won’t expect a fleshed out and detailed response. You’ll just go to the “whacko” schtick as you’ve in truth got nothing that makes even a scintilla of sense.
@Andrew: If one of the AoA sensors was exhibiting very flaky behavior, I wonder if static pressure error (caused by an incorrect correction for AoA) caused altitude, vertical speed, and airspeed errors before the flaps were up and before the same bad sensor caused the MCAS issue.
@Victor
Perhaps, but my understanding is the static pressure correction provided by the AoA is relatively small, so a malfunctioning sensor might not cause such big fluctuations in the indications. The malfunctioning AoA sensor in the Lion Air aircraft did not seem to cause big changes in the indications either, until the MCAS activated after flap retraction. I guess we’ll just have to be patient until more information is released.
@airlandseaman
Re: ‘Mick: What is your estimate? How do you know mine is wrong?‘
Mike, I don’t have one as you can’t possibly generate an estimate for altitude based on range/azimuth data alone.
Just to be clear I’m not taking issue with issue with anyone estimating, guesstimating or guessing anything. What I have a problem with is the use of the word ‘know‘ when refering to said estimates, guesstimates or guesses. While some words have different meanings in the US and Australia I’m pretty sure that ‘know’ is not one of them.
@Andrew
Addis Ababa Airport HAAB is 7,625 ft amsl.
What flap setting(s) would be used, compared to JAKARTA WIHH which is only 64 ft amsl ?
I am thinking a lesser flap setting, so faster VR/V2, and thus flaps might have been retracted earlier (time wise) than on LionAir.
@Ventus45
I’m not familiar with the B737 operation, but these days it’s common to use reduced flap settings whenever possible. Flap retraction does not commence until after the aircraft reaches the acceleration altitude and accelerates past the relevant speed. The acceleration altitude varies between airlines/aircraft types, etc, but is normally between 1,000 – 1,500 ft AAL. I wouldn’t expect to see flight path fluctuations below that altitude if MCAS was the problem, even if a reduced flap setting was used for take-off.
Bloomberg:
Piece Found at Boeing 737 Crash Site Shows Jet Was Set to Dive
Atlas Air & others, credible or not?
https://www.pprune.org/showthread.php?p=10415572
@Andrew:
There was a good article in The Seattle Times, but I can’t find it now.
Is this the gist of it?
http://www.laobserved.com/biz/2013/01/boeings_troubles_cou.php
This gives much more depth…
https://www.forbes.com/sites/stevedenning/2013/01/21/what-went-wrong-at-boeing/#18eb56777b1b
@Andrew: I share your thoughts. Maybe this is the article you search? It’s about problems induced by outsourcing.
@oddball
@Peter Norton
Yes, that was the gist of it. I also remember an article about the close ties between the FAA and Boeing and a decline in independent regulatory oversight in some areas related to certification.
@Andrew
@Peter Norton
Was it this one? It’s an oldie.
http://community.seattletimes.nwsource.com/archive/?date=19950604&slug=2124639
@Mick Gilbert
That’s not the article but, again, the gist was very similar. The concerns expressed in the 1995 article are just as relevant today as they were over 20 years ago.
Mick: I guess you missed the memo. The 17:30 estimated ltitude is not based on “range and altitude “. It is based on conservation of total energy. Try to catch up.
@Donald
Yes, I am feeling good. Thx for asking.
@Mick
you can’t possibly generate an estimate for altitude based on range/azimuth data alone.
Thanks.
@oddball
Greg Feith’s comments on Atlas Air are interesting I have much respect. We should really ask Greg Feith to comment on MH370 at this stage, but I know he was thinking human factor in the early days.
@Victor @Paul @ALSM
Let me try to summarize the IGARI turn discussion, and correct me if I am wrong:
If we say MH370 flew a level U-turn at apporx. constant speed (per Paul and maybe Victor), then there is an uexplained mini-loiter where MH370 is going slow before a speed-up to KB. Historically Victor’s position has been constant speed/altitude for MH370 from IGARI to VAMPI, unless more radar data can be provided. Now we have more radar data, but we still do not know enough.
If we say MH370 flew a zoom climb to higher altitude during the climb (ASLM, TBill) there is a big slow down by the end of the turn, which explains the apparent “mini-loiter”.
https://www.bloomberg.com/news/articles/2019-03-13/doomed-737-caught-on-satellite-data-that-could-aid-investigation
Interesting for the satellite info. Aireon
Just an aside, had Boeing and the FAA not grounded Max 8, someone should have asked Boeing CEO’s etc to fly on a MAX with their families. I bet none of them would have taken up the offer.
@TBill said: If we say MH370 flew a level U-turn at approx. constant speed (per Paul and maybe Victor)
I am firmly in the undecided camp. Mike makes a persuasive case for a turn, climb, and accelerating descents towards Kota Bharu. But I also appreciate the work that Paul is doing to explore solutions that are more in line with how one might expect an airline pilot to fly a wide-body airliner. As we all know, if we had access to the military radar data, we’d be in a much better place.
@ Victor “As we all know, if we had access to the military radar data, we’d be in a much better place.”
Have those with access to the military radar data disclosed that they have performed like calculations to those being discussed or are willing now to do so? I presume not, which of course points to the moral duty of the Malaysian Government to make the data available.
@formula
The calculations being made here are not generally recognized as appropriate for the observables obtained. I still have absolutely no idea how ALSM and Paul are deriving altitude from the Kota Baru radar data. Further it is not at all clear to me how the radar data has in any way helped to refine a terminal location.
@ DennisW – given where the search has reached, failing to turn stones might look negligent perhaps?
There must be a general welcome for seeing whatever present endeavours produce (preferably assisted by data now available only to Malaysia) and then let experts opine as to what may have been learned to further the search.
@airlandseaman, @TBill,
FWIW, I really like the idea of a highly-banked, high-rate climbing U-turn which ultimately trades speed for altitude. It fits my intentions hypothesis very well, regardless of whether this is the normal way to fly a wide-bodied airliner. From the moment the transponder stopped, there’s nothing normal about the flight, so it fits all the better, and to my warped mind, possibly illustrates just how clever ZAS’s plan really was.
One of the benefits of such a turn is the virtual “blink-and-you-miss-it” factor, which is what all good magicians strive for! (Sorry DennisW, but having acquired a copy of Ewan Wilson’s book yesterday, I’m surprised by how closely his assessment of ZAS’s personality matches mine – if you can follow the deliberate ambiguity there?)
That said, I do agree with you (DW) that we are not necessarily getting any closer to locating the end point at this stage. In hindsight, we humans are not that smart, and 5 years down the track, a lot of valuable evidence (and opportunities to find it) will have been lost. Please allow me to throw in another of my oddball comments:
Lots of undersea wildlife would have known within hours where the plane went down. If we could have followed the right ones, we would have found it too. That said, it is probably still possible, if only we could detect the scent of corroding plane parts in the water (which are probably not of much interest to wildlife).
When we compare this with the crash of AF447, there are some worrying difficulties. As I now understand it, AF447 reported its GPS location via SatCom every 10 minutes. It hit the water on its belly, so the energy/momentum was dissipated over a large area. I think means the shattering of the plane would have been substantially less than in a high-speed nose-first impact (a la Atlas Air), where the energy & momentum of most of the rest of the plane is being delivered to the same impact point, at which the first arriving wreckage provides a more aggressive destruction zone for the later to arrive fuselage to destroy itself upon. Whew! Sorry about the long sentence.
What I’m suggesting is that if MH370 entered the water at a similar speed, more-or-less nose first, the disintegration would have been far greater than that experienced by AF447. If it went in faster under pilot control, then even more so. (From that, I think it safe to assume that was ZAS’ intention, whether achieved or not.) Meaning the pieces would be much smaller, would sink more slowly, and would therefore disperse over a greater area, especially since the ocean depth is probably greater. If small pieces are indeed making their way to the other side of the SIO, then it seems apparent that the wreckage would be very widely dispersed on the seabed, so no doubt is harder to detect (again, as intended). And we really don’t even know where to continue looking yet.
In summary, it took ~2 years to locate AF447, despite the location being known to within a few hundred square km. IMHO, it is highly possible that MH370 is within the areas that have already been searched, as per the following excerpt:
… had to take into account the failure of four different searches after the plane went down. The first was the failure to find debris or bodies for six days after the plane went missing in June 2009; then there was the failure of acoustic searches in July 2009 to detect the pings from underwater locator beacons on the flight data recorder and cockpit voice recorder; next, another search in August 2009 failed to find anything using side-scanning sonar; and finally, there was another unsuccessful search using side-scanning sonar in April and May 2010.
The searches all took place in different, sometimes overlapping areas, within 40 nautical miles of the last known location of the plane.
The full story is here: https://www.technologyreview.com/s/527506/how-statisticians-found-air-france-flight-447-two-years-after-it-crashed-into-atlantic/
Anyone know if anyone has successfully developed any “(under)water sniffing” sensors? We have two cats which are “not great” at hiding their scats in our garden, and as I have noted, even stupid dung flies can locate their dust and dirt covered target down to the centimetre, flying from God knows how far away.
Similarly, our fruit bowl happens to be located next to a wall, and again, simply by extremely sensitive scent detection, dumb fruit flies can find their way into the house to land on the wall just above the bowl, conveniently signalling that it’s time to check it for the piece of overripe fruit.
Maybe this is the kind of thing we need to start thinking about in our quest to find 9M-MRO?
@oddball
Your Wilson comment:
I’m surprised by how closely his assessment of ZAS’s personality matches mine
Wilson has two commercial failures in his recent history (the last as the CEO of a one plane aviation company). He is nothing more than an opportunist relative to the MH370 narrative. Wilson has yet to find something he is good at. Maybe he should try pyschology next.
Investigators find new clues pointing to potential cause of 737 MAX crashes as FAA details Boeing’s fix
https://www.wsj.com/articles/pilot-error-suspected-in-fatal-atlas-air-cargo-crash-11552680411
(paywall but you get to see a little)
@DennisW
Can I extrapolate that to “no other criticisms” then?
For example, WRT the dispersal field comparison? The possibility it has already been missed?
Thanks TBill,
(paywall but you get to see a little)
If you hold your mouth right, you can get to read it all clearly.
The deliberate blur seems to timeout after a while. Maybe it’s because I went to the author then to his latest article, then closed the sign up offer popup…
@oddball
Yes. I have no strong opinions on the debris field or why it was missed. The delay in the aerial search South was an avoidable mistake.
@airlandseaman
Re: ‘I guess you missed the memo. The 17:30 estimated ltitude is not based on “range and altitude “. It is based on conservation of total energy. Try to catch up.‘
Wow! ‘… conservation of total energy …‘. Maybe you missed the memo, Mike. A B777 is not a simple object in a Newtonian thought experiment. The good people at Boeing were thoughtful enough to fit their aircraft with a couple of features that allows it to alter its energy state on command. Those two fossil-fuel converters under the wing and a row of sheet metal on top of the wing allow it to add and dissipate energy.
Moreover, when it comes to the notion of conservation of total energy your assumption of a climbing turn requires energy to be added to the initial 17:20:34 state. You can’t turn a 215-odd tonne airplane tightly through 180° and climb 8,000 feet to its maximum ceiling just by trading 40-odd knots of airspeed. You’re assuming that thrust was added. So we’re hardly talking about a conserved energy state.
In any event, let’s not forget that this discussion started with your statement, ‘All we know is the last ADS-B ground speed at 17:20:34 (471.3 kts/37200 ft) and the first civil PSR derived radar speed at 17:30 (~457 kts/43200 ft).‘ As I thought I had made clear previously, my problem is with your use of the word ‘know‘.
You can dress it up anyway you like but when it comes to your stated ‘~457 kts/43200 ft‘, the ‘43200 ft‘ part is at best an estimate based on some assumptions that may or may not be correct. You cannot possibly know that the aircraft was flown at that altitude at that time.
And to the extent that I’m sounding like a pedant, well, good. If we are posting stuff that Joe Public can read then there is an implicit responsibility on us to be accurate. At least half of the nonsense surrounding MH370 started out with someone of standing stating their opinion, estimate, assumption or guess as though it were a fact. Next thing it has entered MH370 Lore. Mathematicians don’t use ≅ and = interchangeably. Surely it is not too much to ask to use words like ‘estimate’, ‘hypothesise’ and ‘assume’ where they more accurately convey the level of certainty. Let’s keep ‘know’ for facts.
And … yes, there you go. All caught up now, thanks.
@Mick
Good post. Long overdue, IMO. There is a lot of unpoliced arm waving going on. Frankly, I am tired of it. I will be very hard on it from now on, until Victor (who does not seem to mind) bans me.
@The Experts
Could one of you please point me to the latest accepted satellite handshake dataset, please, preferably with the currently accepted calculated values for speed wrt and distance from the satellite also included? I’ll accept whatever are the accepted BTO/BFO calculations and conversions so don’t require all those details for now, but happy to have if included. Likewise, satellite wobble compensation data/calcs.
TIA
@Paul
you said:
I’ll add that using the most recent set of radar data, I estimate that before the CoS, the speed levels off to 529 kn at a geometric altitude of 39,500 ft (FL374).
Could you please post a link that explains how you came to the conclusion?
@DennisW
I will be very hard on it from now on, until Victor (who does not seem to mind) bans me.
There’s nothing like autocratic opportunism, I say! 😉
So long as Sauce for the Gander applies!?
@Andrew: If the WSJ article is correct, it was disorientation that caused the crash of 5Y3591. (This was option [1] above.) Perhaps that the thrust increase led to the pitch-up moment and caused a somatogravic illusion and an overcorrection with nose-down inputs. Even though pilots are trained to recognize this, in this case it appears they did not. It’s hard to believe that 6,000 ft was not sufficient to recognize their predicament and recover.
By Andy Pasztor
March 15, 2019 4:06 p.m. ET
Federal air-crash investigators suspect that pilot errors, rather than aircraft malfunctions, led to an Atlas Air cargo plane’s nosedive near Houston in February that killed all three people on board, according to people familiar with the details.
National Transportation Safety Board experts, these people said, are focusing on a likely sequence of events that started with the crew of the Boeing Co. 767 approaching Houston’s George Bush Intercontinental Airport on Feb. 23 inadvertently commanding dramatically increased engine thrust. Turbulent air could have jostled the arm of one of the pilots, causing the engines to rev up to takeoff power, one of these people said.
The sudden surge in thrust, which the safety board disclosed in an earlier factual update, forced the nose of the plane to pitch upward and startled the cockpit crew, according to these people. Almost immediately, according to the preliminary data released by the safety board, the crew responded by sharply pushing down the nose of the aircraft.
The board previously said the nose was pointed downward at a 49-degree angle with the plane still about 30 miles from the airport, creating a much steeper descent than a normal landing approach.
The seemingly disoriented crew failed to regain control—despite commands to pull up from the jet’s high-speed dive—and the wide-body plane plowed into a marshy area.
The safety board said the crew had the required training and medical certificates.
The safety board hasn’t issued any final conclusions, and the leading theory currently pursued by investigators could change as more information is developed. A spokesman for the board said it had no comment beyond the factual update released earlier. Boeing had no immediate comment.
Atlas Air Worldwide Holdings Inc. and the union representing its pilots both declined to comment, citing the ongoing investigation.
But at this point, such cockpit slipups are considered the most likely cause of the crash. The plane was skirting around some storm cells before the plunge, but people familiar with the details said the turbulence didn’t cause any structural damage or lead any system to malfunction.
In its update, the safety board said the “engines increased to maximum thrust” as the plane was flying at roughly 6,000 feet. After a brief nose-up movement, according to the update, the Boeing 767 entered a steep descent in a “generally wings-level attitude until impact with the swamp.”
Many airline and aerospace industry officials have watched the probe closely because the 767 model is widely used as a passenger jet around the globe.
The Atlas Air flight, en route to Houston from Miami, was flying cargo for Amazon.com Inc.
The last fatal U.S. airliner crash also was a cargo flight. In 2013, a United Parcel Service Inc. Airbus A300 slammed into hill while approaching to land in Birmingham, Ala., killing both pilots. The safety board determined that a series of pilot errors and violations of safety procedures caused that accident. The aircraft descended too quickly toward a runway shrouded by clouds, and the pilots waited until the last seconds to try to initiate a go-around.
@DennisW
Thank you, Dennis.
@DennisW said: There is a lot of unpoliced arm waving going on.
What are you talking about? Did you see my previous comment where I said that Mike’s scenario was possible but not certain? Over the course of the 6-minute inbound segment to Kota Bharu, the energy added by the thrust might have come close to balancing the energy removed by the drag. However, the case of offsetting effects is a special case, and is in general not true, which is why I said the analysis was possible but not certain.
I think his analysis would be improved if he included the time-dependent thrust, drag, and flight path angle, and I told him so in private. That doesn’t mean that there are no insights we can learn by what he presented. Mike is a pilot with 50 years of experience, and even if I don’t always agree with him, I listen to what he has to say.
@Victor
What I am talking about it is very very simple. Tell me how Paul or ALSM have derived altitude at Kota Bharu. You claim to endorse Paul’s analytics. Back it up or shut up.
@DennisW: I believe the statement you attributed to Paul Smithson was mine. Here is the basis:
I looked at a very simple way of averaging the data by subdividing the inbound segment into 6 subsegments of about a minute duration, using a single segment across the CoS of about 2 minutes duration, and using 6 subsegments for the outbound segment of about 0.9 min duration, and calculating the average speed for each subsegment using the time, azimuth, and range at the endpoints of each subsegment. I estimated the geometric altitude by finding the altitude which minimized the variation in groundspeed for the subsegments starting with the one just before the CoS. The assumption is the plane accelerated towards the CoS, and then the speed was nearly flat. This assumption was then tested by calculating the variation about the average speed.
The best estimate of geometric altitude using this method is 39,542 ft, which corresponds to a standard (pressure) altitude of around 37,387 ft (FL374). For the eight subsegments starting at 17:35:42, the average speed is 529.3 kn and the standard deviation is 2.4 kn.
One might believe that my methodology of using the endpoints of the CoS to estimate the average speed across the CoS is flawed because of the distortion of range/azimuth data near the CoS. I don’t ascribe to this belief. The points near the CoS are the most sensitive to altitude, so are best used to discriminate the altitude. If we believe there is distortion near the CoS, then we should not try to discriminate altitude using any of these methods. Either the data near the CoS is valid, or it is not.
At the prevailing meteorological conditions over Kota Bharu, at a groundspeed of 529 kn, TAS = 509.7 kn, and M=0.877. That Mach number is above Mmo but within the thrust capabilities at FL374. It may be that the autothrottle was disconnected, and the acceleration and speed were manually controlled.
The calculated speed profile is shown here for the geometric altitude of 39,452 ft.
@DennisW: If you want me to ban you, I will. There is no need to stroke-out again because you don’t understand something.
@Victor
Look, my approach to the KB situation is the only approach that merits analytic cohesion. The others are simple arm waving. Good f’ing grief.
@DennisW: You last comment crossed with mine. You say You claim to endorse Paul’s analytics. Back it up or shut up. First, I don’t endorse his analytics. I am interested in learning more and testing it, and I tell him here and in private when I disagree with aspects of it.
As for shutting up, I’ll say here whatever I damn well please. This is my last warning. The next time you act like this, you are out of here. I try to be patient with your social ineptness, and I have warned you in private, but I have my limits. You act like a child having a temper tantrum.
@DennisW: If you want me to ban you, I will.
No need. I am done here.
@DennisW: Your analytic approach is a gross approximation that hides the altitude discrimination near the CoS that we are trying to extract.
Take a break Dennis or I’ll make the decision for you.
@Victor
It’s hard to believe that 6,000 ft was not sufficient to recognize their predicament and recover.
I reckon!
It’s hard to believe that none of the 3 pairs of eyes apparently in the cockpit would be able to take in a rapidly unwinding Altimeter. Or the disappeared Artificial Horizon, or the advancing ASI. Or the associated sounds and, I presume, Audible Warnings.
The similarities with AF447 are uncanny – except [maybe] that there, one pilot was countering the PF’s appropriate control inputs. Could this be the same but opposite? Maybe they thought the opposite to the initiating 447 pilot, that they were in a stall?
@Andrew. It will be interesting to learn what the defect write up and maintenance history of Ethiopian 302 was, noting that of JT610.
@oddball: If you are going to look for a similar crash, I would look at FZ981, where the pilots over-corrected for the pitch up and forward acceleration after go-around thrust was applied during an aborted landing. The plane was flown right into the ground, albeit from a much lower altitude than 5Y3591.
@Victor
Re: Atlas Air
Thank you for posting WSJ article which otherwise had a paywall.
NTSB gets high marks from me for letting everyone know on a timely basis what they are thinking about the crash on a timely basis, although WSJ is making the claim. If you are correct on (1) OK but I said (3) maybe the turbulence caused the pilot(s) to knock the controls. I was thinking a little like the Kalitta incident where the hypoxic co-pilot was hitting the controls. But in any case sounds like NTSB has a reasonable initial hypothesis.
https://www.boeing.com/commercial/customers/ryanair/boeing-launches-737-max-200-with-100-airplane-order-from-ryanair.page
I fly regularly on Ryanair and assume all 737 Max aircraft will be grounded including the one Ryanair has ordered;Ryanair max 200 which Boeing calls part of the MAX family. (I think Boeing will have to change that unfortunate nomenclature)
@Victor: I would look at FZ981
Thanks, done. Still like AF447, but agree, 981 also sounds like windshear induced, with the same result.
Regarding the Sat Data and speed/distance analysis, is there an accepted latest version somewhere, or do I have to search for it and hope I get lucky?
@Victor
RE: “It’s hard to believe that 6,000 ft was not sufficient to recognize their predicament and recover.”
Absolutely, and with two other pilots in the cockpit it’s hard to believe their predicament wasn’t recognised very quickly.
The pitch-up response to the application of TOGA thrust is very strong in non-FBW aircraft, to the point where, during a go-around, the pilot needs to push forward on the control column to prevent the aircraft over-pitching. In the FZ981 accident, the pilot pushed forward on the control column and simultaneously trimmed nose down continuously for 12 seconds, causing the aircraft to pitch down to an extremely nose-low attitude that was not recoverable. If the Atlas pilot pushed and trimmed forward at the same time, then I guess it’s possible that something similar occurred.
There are two things I’d interested to find out:
– What caused the thrust increase? I find it hard to believe the thrust levers could have been inadvertently ‘knocked’ to a high thrust setting, even in turbulence. However, it might be possible that one of the TO/GA switches was accidentally pressed. That said, the TO/GA switches on other Boeing types aren’t normally active until the flaps are extended.
– Was the autopilot engaged, or was the pilot flying manually?
@Andrew,
Been thinking about this too.
Would it be possible that they could have been slammed by a severe wind shear during the descent which suddenly tossed the plane from nose down to nose high. That might explain the leveling out just before the TOGA power and the dive began. I’m guessing something triggered severe somatogravic illusions in all three and was so intense that they thought they had stalled… Maybe they felt like the plane was suddenly “going backwards”, despite what the instruments said.
Maybe they were suddenly all thinking Bagram Air Base 747, or AF447, or GXL888T and reacted accordingly?
@TBill said: Thank you for posting WSJ article which otherwise had a paywall.
It’s the best American news source, and well worth the price.
@oddball
DrB has posted a lot of tools in particular CBTO/CBFO spreadsheet.
https://drive.google.com/file/d/0BzOIIFNlx2aUS05JcEhsUXprcFE/view
You can see the measured BTO/BFO and calculated for any time and position you want to enter. I mostly use DrB’s spreadsheet and ALSM has posted ping rings of the Arcs that can be displayed on Google Earth.
So if I want to make up a new proposed route, I fly with flight sim connected to Google Earth, and I can see when I fly past a ping Arc, and then I use DrB’s tool to calc BFO for the time and position.
Here’s an interesting segment on Blaine Gibson that will appear on HBO’s Vice News.
@All.
I promised to get the “trombone model” of the turnback written up properly. To my mind, it provides a very robust and plausible case that the turnback was a simple 180 turn onto reciprocal course, executed at AOB25.
This model accords nearly perfectly with:
1. The maximum NE extent of travel according to military radar
2. The bearing and positioning of the early part of the return trajectory
3. The speed expected at the start of Kota Bharu radar trace
4. The position/time abeam WPT2 (end of turn per Police Report) to within <2 seconds
If this hypothesis is correct, MH370 was flying at groundspeed of close to 460kts for a full 10 minute period: from the start of the turnback (17:22:01) to more than one minute into the Kota Bharu trace (17:31:55).
Depiction here
https://drive.google.com/file/d/1h0uGHk2lNo7EExNl977irF0yYtTpPW4w/view?usp=sharing
Paper here
https://docs.google.com/document/d/12D7BKDD7vOmFizjhtz-n8DFEA7jDCg35Dg7d8n5-ti8/edit?usp=sharing
Spreadsheet here
https://docs.google.com/spreadsheets/d/1G-rgWcxDMUbVWgCe6le_ksNZAQWbAKll6LI_qc_j9dk/edit?usp=sharing
Victor has kindly reminded me that WPT2 should be attributed to the Safety Investigation report, not the police report.
I should emphasise that the model doesn’t rely upon WPT1 or WPT2 at all. I am simply noting that WPT2 accords rather well with the model predictions. I believe, for reasons stated, that the discrepancy at WPT1 is due to an aberration of military radar coasting/signal processing.
If you think about the military radar position at Western Hill, it’s understandable why military radar lost the target (it had just turned right at IGARI and radar failed to follow it) and why it regained target during the turn (halfway through the turnback the course is perpendicular to the radar, so slant range is constant).
Paul: Comments on the turn model:
1. There is no factual basis to support the assumptions that the turn was at a constant altitude and constant ground speed. It’s reasonable to test that and other “flat cases” cases, but it is certainly not the only case, and not the most likely case IMO.
2. The simplified model assumes a constant ground speed (AKA no wind case?). As Victor noted, the wind is actually important here. At IGARI, there was a 20 kts headwind and at 17:30, a 20-30 kt tail wind, depending on altitude. Thus, the TAS changed from ~491 kts to ~430 kts between 17:21 and 17:30. This change in TAS over the time of the turn suggests a climbing turn, not a flat turn.
@Mike. I do *not* assume that the aircraft travelled at constant GS. The model works out the AVERAGE GS over the entire path that simultaneous matches the key parameters of x+r and turn diameter and gets you from LKP to KB_1 on time. Overlaying a wind vector on the model will not materially change this. It will simply reduce the average TAS (since the majority of the path has a tailwind).
You say there’s not factual basis for level altitude turn. I’d agree that there’s no evidence pertaining to altitude at all. And I’d suggest that constant altitude is a sensible default assumption unless we have good reason to believe otherwise. In addition, I can see no reason by a speed reduction resulting from a climb should persist over a period of ~10 minutes.
I you are so convinced that your posited climbing turn fits the observable facts, kindly model the resulting path and share the results.
Paul: You are missing the point. How do you explain a 60 kts drop in TAS?
Um. Aircraft slowed down. And stayed slowed down for the next 10 minutes. What am I missing?
I pointed out the other day in this pilots’ discussion on bank angle selection that the SOP would be to slow down and then make the turn, and the model results would be consistent with that.
“At least over here, if there needs to be a control on the radius of a turn, it will be done by limiting the aircraft speed and not requiring excessive bank angle.”
https://www.pprune.org/tech-log/416502-built-bank-angle-limits.html#post5719461
@oddball
RE: “Been thinking about this too.”
I doubt that it was anything quite as dramatic as you described. Something (or someone) obviously triggered a large thrust increase that seems to have caused the aircraft to momentarily pitch up. The subsequent pitch down might have been a gross overreaction by the pilot, but -49° is incredibly extreme. It’s hard to fathom how the nose got so low and why the pilots were unable to recover.
@Andrew: Some of the facts do line up with an intention to crash at high speed. What doesn’t make sense is how that was accomplished with two other pilots in the cockpit. Likely, the CVR will explain a lot.
The crew-ATC exchange at around 12:36L is also strange. The FO talked over the ATCO three times, as if he did not understand the one-way nature of radio communication. That could indicate a high level of stress.
Victor Iannello: “Some of the facts do line up with an intention to crash at high speed.”
I don’t believe in an intentional crash here. And neither does the NTSB apparently. Actually, there are facts that all but exclude this hypothesis:
• CVR suggests loss of control
• nose was pulled up from -49° to -20° before impact
« the cargo plane’s engines surged to maximum thrust and it briefly pointed its nose 4° up […]. The jet then rapidly swung to point 49° downward and began its drop toward the muddy bay. The NTSB […] says the plane’s stick shaker, which warns of an imminent engine stall, did not activate. That means it’s unlikely the pilots pointed the nose down to avoid stalling. The [NTSB] previously said cockpit audio suggests the pilots lost control […]. As the plane dropped, the [NTSB] says, it accelerated to 495 mph and gradually pulled up to a 20° descent. » (source: NBC)
@PaulS
Do we know the timestamps of WPT1 and WPT2? @sk999’s digitized flight path follows your basic curve, also hitting close to WPT1 and WPT2, but shows getting abeam WPT2 about 17:25:33 with quite a slow down from IGARI to completion of turn.
@Peter Norton: If the steep, high speed descent was intentional (and I present that only as a possibility), the pull up at the end could have been from an action of one of the two other pilots in the cockpit.
I wouldn’t be so certain that the NTSB has ruled out deliberate actions. Their statements to date have been ambiguous, at best.
@Andrew,
I doubt that it was anything quite as dramatic as you described.
Hopefully, not, but I suggested it because of an experience I had about a week ago. And I was basically on terra firma. I was parking my car, swinging in from the RHS beside a dark blue car. (Important detail [blue] – not really! But memorable.) As I was about 1/2 way into the parking space, I turned my attention to the left to check my distance from the blue car. Due to the coincidence of actions, I did not observe that the blue car had already started reversing out of its space, and the blue car was my frame of reference at that moment. Suddenly, I perceived that I was heading into my parking space much too fast and pressed much harder on the brakes. Nothing changed, and for a moment, I could not figure out why my car was not stopping. I instantly began thinking ‘brake failure’ and started working on what to do next – which completely disrupted my attention to the parking job I had previously been doing.
Just then, the front of the blue car passed the centre of my field of view and I could see the stationary ground beyond, shattering the illusion. I was already fully stopped, but did not know it until then. It was brief, but quite unnerving.
Probably the most interesting aspect was that my mind instantly chose ‘brake failure’ and not ‘perception failure’, suggesting we(I…) trust our perceptions more than we trust our experience. Looking back, the brake pedal felt normal, braking had felt normal, my speed was already low (much lower than the speed of the other car going backwards), and I had no reason to suspect brake problems, but the sudden and unexpected movement of the other car overrode all the other information I had available to me in that moment.
Maybe that’s like what is happening to the unfortunate pilots, in each of the several similar crashes?
but -49° is incredibly extreme.
Totally agree! I imagine this is the maximum designed descent angle for the 767, and only occurs with the elevator held hard ‘over’ (ok, under). I can’t imagine any normal pilot pushing the controls that far in, and surely, the resulting pitch down would just about lift you into your harness? Surely, they would perceive that. (No pilot would fly in bad weather with his harness undone, right?)
It’s hard to fathom how the nose got so low and why the pilots were unable to recover.
Elevator control failure, I’m still picking. Maybe the slow reduction to -20° was the result of a hurried manual elevator trim up adjustment, in the hope of being able to pull up despite the ‘hard under’ elevator. And maybe the Full Power move was also part of an attempt to “power out of it”? Maybe, despite the apparent stress in the cockpit, they did everything they could have?
@oddball
I agree, sensory illusions can be extremely disorienting, particularly when pilots are deprived of external visual references, as occurs while flying in cloud or sometimes at night. One of the most difficult things pilots must learn when they start flying on instruments is to trust the attitude indicator and to block out the sensations generated by their vestibular system. It becomes much easier with practice and experience because vision is such a powerful sense, but nobody is ever completely immune. Was it a factor in the Atlas accident? Maybe, but at this point we simply don’t know.
Victor Iannello: “the pull up at the end could have been from an action of one of the two other pilots in the cockpit”
Yes, but how would that square with “Crew communications consistent with a loss control of the aircraft began approximately 18 seconds prior to the end of the recording” and why wouldn’t the other 2 pilots have intervened in the first place (instead of only pulling up at the end)?
@TBill,
DrB has posted a lot of tools in particular CBTO/CBFO spreadsheet.
Many thanks. Prodigious! My thanks to DrB.
Should keep me quiet for a while.
BTW, JFTR, I genuinely did manage to get through the WSJ paywall somehow. Maybe I should clarify, my wife and I did. I was complaining to her about it after fiddling about on her iPad for a while, and she said “You can.” Sure enough, by that stage, somehow the article was clear, and dismissing the popup allowed me full access. But I didn’t Copy & Paste it, as I didn’t want to get Victor in trouble for a copyright violation. Anyway, I don’t know exactly what I did, and have never been able to do it again, so maybe it was just at the moment they were updating stories, or something. I wonder how Victor got it.
@oddball: There is no need to wonder. I subscribe to the WSJ.
@paul smithson,
I promised to get the “trombone model” of the turnback written up properly
Thanks for your efforts and for posting that. It’s much clearer as an image! However, may I beg to differ, please?
To my eye, the trombone pipe doesn’t follow the radar track after coming “around” IGARI, and even though the data is clearly a serious mess between ‘start’ and ‘end’ of the turn, couldn’t that be explained by a number of possibilities? The density of the “drawn” track is much less over that period, suggesting a lot of misses, so I suspect false returns and bad filtering. Not to mention the ~100° (“UFO”) turn near the ‘start’. Apart from that, I’d prefer to see a model that followed the consistent parts of the well-recorded track, rather than what seems to be trying to fit the data to a model.
To my mind, that would result in a turn back of about 190~200°, which I guess “changes everything”? But where the data looks clear and consistent, I think it should be given greater credence.
I’m wondering if any of the following points can explain the fade-out of the returns during the turn:
* The plane was climbing
* The plane was descending
* The plane was changing speed (slowing)
* The contrail boosted the return signals to and from (but not during) the turn
* Appearing out of the “shadow” of the contrail near the start of the turn created the apparent 90°+ turn.
(I’m not convinced of any of this myself [except maybe the 4th], but up for debate.)
@TBill sk999 digitised radar path is an integration of the DSTGs *KALMAN FILTERED* 10s military positions. It does not represent where the aircraft went, or even where the military radar thought it went. It is best regarded as a sort of “smoothed” version of the military radar. This should be fine during settled segments but not during the turnback.
I had worked out the implicit timestamp for WPT2 ages ago but I can’t work out now how I’d done that and I don’t have time to go back and relocate it. You need to establish where the “time zero” was from which the simulator sessions were being measured.
@PaulS
We know they were expecting about 2 minutes from WPT1 to WPT2 which would be fast or tight. In the report I do not see any times mentioned for WPT1 and WPT2.
Above you say the radar lost the target at IGARI, but the yellow line on your figure does not show that, so is that yellow line extrapolated?
@Victor
At Penang, do we have any idea why the Butterworth radar is showing the gaps? I noticed a really old post from you suggested maybe it was set for lower altitude aircraft making landing approach. I noticed on Jean-Luc’s video of air traffic, that some of the air traffic just before MH370 passed directly over Penang from the south.
@TBill: Cruising speed was maintained around Penang, and it is unlikely that MH370 did not remain at cruise altitude. I don’t know the reason for the gaps in the civilian radar coverage.
Thank you for prompting me to do this, TBill.
The Safety report has initial conditions GS=475kt passing abeam IGARI
We know that IGARI abeam = 17:20:31
Distance from there to WPT1 is 15.26NM which takes 116 seconds @GS475kt
So time at WPT1 should be 17:22:27
On p278 of the report they say that the target time, per radar trace, to get from WPT1 to WPT2 is “two minutes and 10 seconds”
Add 130 seconds to 17:22:27 gives you time at WPT2 of 17:24:37
Now we can calculate speed required to get from WPT2 to first point in the IGARI trace (new, 2019 version) at 17:30:39, distance 45.35NM.
And the answer is …drumroll… 451kts.
Unless there is a mistaken assumption above, this demonstrates conclusively that the military radar time & position at WPT2 requires mean ground speed from end of turn to the start of KB trace of 451 knots. I think it’s fair to characterise that as independent corroboration of my model prediction of slow speed from the turnback all the way to the start of KB primary radar trace.
I’ve had some private discussions with some very knowledgeable individuals about the B737 MAX crashes. Here is an interesting hypothetical scenario based on some of those discussions.
Suppose the crew of ET302 was fully aware of the circumstances of JT610, and after they entered a steep descent due to MCAS incorrectly trimming nose down, they opted to cut-out the electric stabilizer trim, as training advises. The question is, how difficult would it be to apply nose-up elevator and manually trim?
One of the knowledgeable individuals provided the following:
The relevant section [of the B737 FCTM] states:
“If manual stabilizer trim is necessary, ensure both stabilizer trim cutout switches are in CUTOUT prior to extending the manual trim wheel handles.
Excessive airloads on the stabilizer may require effort by both pilots to correct the mis-trim. In extreme cases it may be necessary to aerodynamically relieve the airloads to allow manual trimming.”
The pilot would pull back on the control column to raise the nose, which obviously causes the elevators to move upward, however, the elevators are not powerful enough to overcome the nose down pitching moment of the stabilizer. The upward deflection of the elevators causes a turning moment on the stabilizer that holds the stabilizer against the nose down limit (ie leading edge up) and if the air loads are excessive, it may not be possible to reposition the stabilizer using the manual trim wheels. The pilot would first need to unload the elevators and then manually trim, which would take quite some time and is counterintuitive.
Basically, pulling back on the control column would make it difficult to manually apply nose-up trim with the trim wheel. As the stabilizer has more pitch authority than the elevator, the only way to recover from the descent would be to push forward on the column (apply nose-down elevator) to unload the stabilizer so that it can be manually trimmed nose-up in order to arrest the descent.
That could be very difficult for a crew to work together to do this in the time available if the descent begins at a relatively low height above the terrain.
Victor: Interesting scenario and theory. Being so close to the ground when this started, it would be very difficult to unload the stabilizer enough without hitting the terrain. BTW…I have personally experienced a similar issue with the trim on Piper Super Cubs. The trim wheel tends to slip (does not move the stabilizer) unless the aerodynamic forces are close to neutral.
A new WSJ story on the B737 MAX crashes:
Ethiopian Airlines Black Boxes Showed ‘Clear Similarities’ With Lion Air Crash
Data from ET302 black boxes has been validated by Ethiopian, U.S. Investigators, transport minister says
By Gabriele Steinhauser and Robert Wall
Updated March 17, 2019 1:43 p.m. ET
ADDIS ABABA, Ethiopia—Data retrieved from the black boxes of a crashed Ethiopian Airlines plane showed similarities to that from the Lion Air flight that plunged into the Java Sea in October, Ethiopia’s transport minister said Sunday, adding to the pressure on aircraft maker Boeing Co.
“Clear similarities were noted between Ethiopian Air Flight 302 and Indonesian Lion Air Flight 610, which will be the subject of further study during the investigation,” Transport Minister Dagmawit Moges said. Both flights were on Boeing 737 MAX 8 aircraft.
Ms. Moges declined to give details of the similarities that had been identified, including whether Boeing’s new anti-stalling software that has been associated with the Lion Air flight had been activated. She spoke after French air accident investigations bureau BEA had sent the data from both the cockpit voice recorder and the flight data recorder to Ethiopian authorities.
Investigators from both Ethiopia and the U.S. National Transportation Safety Board have validated the data, she said, and a preliminary report on the accident will be published within 30 days. Representatives from the U.S. Federal Aviation Administration and its European counterparts were also present in the downloading of black box data.
U.S. authorities last week grounded the 737 MAX after saying it had found enough similarities between the two crashes to take the rare step of keeping the aircraft out of the air. The move followed similar actions by a number of regulators around the world.
American and Canadian officials cited satellite data showing a similar flight path between the two planes—both new jets that crashed after just a few minutes.
Boeing has said it believes the plane is safe but agreed with the grounding.
The Ethiopian findings of similarities between the two crashed planes come from an initial analysis of data retrieved from the plane’s black boxes. Voice recordings and flight data contained in these devices are typically the most important components in any crash probe. The similarities add a new level of scrutiny on the Boeing jet.
Boeing CEO Muilenburg Issues Statement on Ethiopian Airlines Flight 302 Accident Investigation
CHICAGO, March 17, 2019 /PRNewswire/ — Boeing Chairman, President and CEO Dennis Muilenburg issued the following statement regarding the report from Ethiopian Transport Minister Dagmawit Moges today.
First and foremost, our deepest sympathies are with the families and loved ones of those onboard Ethiopian Airlines Flight 302.
Boeing continues to support the investigation, and is working with the authorities to evaluate new information as it becomes available. Safety is our highest priority as we design, build and support our airplanes. As part of our standard practice following any accident, we examine our aircraft design and operation, and when appropriate, institute product updates to further improve safety. While investigators continue to work to establish definitive conclusions, Boeing is finalizing its development of a previously-announced software update and pilot training revision that will address the MCAS flight control law’s behavior in response to erroneous sensor inputs. We also continue to provide technical assistance at the request of and under the direction of the National Transportation Safety Board, the U.S. Accredited Representative working with Ethiopian investigators.
In accordance with international protocol, all inquiries about the ongoing accident investigation must be directed to the investigating authorities.
oddball: “If you hold your mouth right, you can get to read it all clearly.”
I’ll try. I have some doubts though … 😀
@Peter Norton:
I’ll try.
No need. Victor already copied it here:
http://mh370.radiantphysics.com/2019/03/03/mh370-family-member-give-us-the-truth/#comment-22382
And as above a bit, I could never repeat the fluke…
@Victor
Do the proposed software fixes cover that adequately? Presumably there will be less susceptibility to a single AoA reading, and the movement will be milder if triggered.
@TBill: My guess is there will be a software fix that will make it easier to recover from a configuration in which MCAS is incorrectly applied while still adequately correcting the relationship between pitch moment and elevator position at high angles of attack when it needs to.
The crash of ET302 will be problematic for Boeing, especially if proper procedures were followed for runaway trim in the wake of the crash of JT610. An important question is whether the crew cut-out the stabilizer trim, in accordance with training. If they did, but could not manually trim to avert a crash, that would not bode well for Boeing. The decision to not ground after JT610 will certainly be questioned.
@TBill
Previous reports suggest the ‘fix’ will include a requirement for no disagreement between the two AoA sensors and a limit on.the total amount of stabiliser trim that can be applied by MCAS, such that recovery from a runaway would be possible using only the elevators. Yet to be confirmed.
@PaulS
Ok but you are estimating the WPT1 and WPT2 timestamps. We probably have to look at total time and distance from IGARI to the first KB points. Conceivably an ascent could have started about when the transponder was turned off, before WPT1, and so the timing may be different. Wonder if we asked if they would tell us the WPT1 and WPT2 times.
[Derogatory comments about others deleted.]
I would like to end this comment by saying what a pleasure it is to read this blog over the past number of years and I refresh it daily – as I’m sure many other “lurkers” do – for the insights given by the protagonists led by Victor, who post detailed and astounding research on a regular basis.
@Victor Iannello
@TBill
@Andrew
Very interesting piece on the (self-)certification of the MAX here.
Just two of the interesting bits:
Current and former engineers directly involved with the evaluations or familiar with the document shared details of Boeing’s “System Safety Analysis” of MCAS, which The Seattle Times confirmed.
The safety analysis:
– Understated the power of the new flight control system, which was designed to swivel the horizontal tail to push the nose of the plane down to avert a stall. When the planes later entered service, MCAS was capable of moving the tail more than four times farther than was stated in the initial safety analysis document.
– Failed to account for how the system could reset itself each time a pilot responded, thereby missing the potential impact of the system repeatedly pushing the airplane’s nose downward.
– Assessed a failure of the system as one level below “catastrophic.” But even that “hazardous” danger level should have precluded activation of the system based on input from a single sensor — and yet that’s how it was designed.
The people who spoke to The Seattle Times and shared details of the safety analysis all spoke on condition of anonymity to protect their jobs at the FAA and other aviation organizations.
The original Boeing document provided to the FAA included a description specifying a limit to how much the system could move the horizontal tail — a limit of 0.6 degrees, out of a physical maximum of just less than 5 degrees of nose-down movement.
That limit was later increased after flight tests showed that a more powerful movement of the tail was required to avert a high-speed stall, when the plane is in danger of losing lift and spiraling down.
The behavior of a plane in a high angle-of-attack stall is difficult to model in advance purely by analysis and so, as test pilots work through stall-recovery routines during flight tests on a new airplane, it’s not uncommon to tweak the control software to refine the jet’s performance.
After the Lion Air Flight 610 crash, Boeing for the first time provided to airlines details about MCAS. Boeing’s bulletin to the airlines stated that the limit of MCAS’s command was 2.5 degrees.
That number was new to FAA engineers who had seen 0.6 degrees in the safety assessment.
“The FAA believed the airplane was designed to the 0.6 limit, and that’s what the foreign regulatory authorities thought, too,” said an FAA engineer. “It makes a difference in your assessment of the hazard involved.”
The higher limit meant that each time MCAS was triggered, it caused a much greater movement of the tail than was specified in that original safety analysis document.‘
Apologies, a bit of a spacing issue there.
The first extract ends with ‘… all spoke on condition of anonymity to protect their jobs at the FAA and other aviation organizations.‘
and the second one starts with
‘The original Boeing document provided to the FAA included a description …’
@Mick Gilbert
Wow, that’s incredibly damning. A major investigation into the FAA’s certification practices and the relationship between the FAA and Boeing is surely warranted.
Just wondering what other Boeing aircraft were “(self)-certified” ? this is alarming !!
@Andrew
Re: A major investigation into the FAA’s certification practices and the relationship between the FAA and Boeing is surely warranted.
Ask and you shall receive.
Feds probing regulators’ approval of Boeing 737 MAX jet following two fatal crashes
https://www.nydailynews.com/news/national/ny-news-transportation-department-investigation-boeing-faa-safety-approval-737-max-jet-crashes-ethiopia-indonesia-20190317-story.html
…and this:
Prosecutors, Transportation Department Scrutinize Development of Boeing’s 737 MAX
Reprinted in The Australian an hour ago:
Prosecutors join Boeing 737 MAX probe
Atlas Air crash – some clarification
https://www.flightglobal.com/news/articles/atlas-767-crash-probe-strives-to-comprehend-pitch-up-456702/
Other MAX issues…
https://www.businessinsider.com.au/pilots-made-complaints-about-boeing-737-max-8-2019-3
https://www.businessinsider.com.au/pilots-complained-about-boeing-737-max-for-months-before-latest-crash-2019-3
@Mick
I am retired engineer from the corporate world, not airline industry, but I see a lot of possible similarities with Boeing management philosophy. The one difference I see (from following MH370) is Boeing was held in such high regard as far as US public opinion (compared to my industry), so they were quite untouchable as far as criticism and regulatory changes due to extraordionary safety record. Probably less so going forward.
The AoA data for ET302 is very similar to JT610, according to this Reuters article.
PARIS (Reuters) – Investigators probing the crash of an Ethiopian Airlines Boeing 737 MAX jet eight days ago have found strong similarities in the ‘angle of attack’ data recorded by the doomed aircraft’s cockpit recorder and data from a Lion Air jet of the same model that crashed in October, a person familiar with the matter said.
Graphs of the two sets of data are “very, very simliar,” the person said on Monday, asking not to be identified because the matter is still in the early stages of investigation.
The AoA sensors are inherently reliable devices. I’m told that the same sensor type is used on the B737 MAX as the B767. We know that the AoA sensor was replaced prior to JT610 because of anomalous behavior. It is very unlikely that there were three bad AoA sensors.
When the AoA data for JT610 was published, the error in the faulty AoA reading seemed to jump around, but the smaller changes in AoA readings for the two channels seemed to agree. This suggested to me that perhaps there were bad “bits” either in the digitizing of the signal or in the software.
We now know that ET302 had similar AoA erroneous readings as JT610. This again points to a problem in the digital electronics or the software.
This figure shows some of the parameters from the FDR of JT610. Looking at the Angle of Attack signals, notice that once speed is established, the offset between the left and right channels remains nearly constant, and the higher frequency content is nearly identical. This suggests the problem was not mechanical.
Also note that the bad AoA reading introduces errors in the altitude and airspeed readings. This is because the static pressure is incorrectly adjusted for AoA for the channel with the erroneous AoA reading.
@Victor,
That FDR trace image is incredible!
It must have been an absolutely terrible few minutes.
A couple of things I don’t understand – what does the trace for “Flap Handle Position” indicate? That they took off with flaps up? Then lowered, then the raised, then lowered them for the rest of the flight? Or is it inverted? I presume so, but even so, the flaps positions seem weird.
I also notice that the Stick Shaker Left went off before they even left the ground, accordinging to the Air / Ground trace, and that the Master Caution went off following the first change in the “Flap Handle Position”.
It seems to me that the crew tried to reverse virtually every move of “Trim Automatic” with a “Trim Manual” moments later, until close to the end when the Auto Trim won out. Also that, when the “Flap Handle Position” was up, there was less fighting over trim.
My question is, was there a bad AoA signal? They appear to match to me, i.e, both went up and down at the same times, once flight was established. To me, the telling thing is that the speed traces diverge during the takeoff roll, and that the Left Stick Shaker went off at that time – exactly when the speed traces start to diverge, but while they are clearly still on the ground.
As I see it, rightly or wrongly, it appears that the software set the “Zero Points” for both AOA sensors before they had even started to operate, and before there were any valid readings from either of them. That would expain why it “thought” there was an AOA error, because it asssumed the random, pre-flight resting positions where valid starting positions, which they clearly need not be.
This is clear from the start of the AOA traces, at which time, the Left AOA sensor was sitting high and the Right was sitting Low. You can see that the traces both move towards each other during the roll, then simply follow each other for the rest of the flight, but the computed air speed traces show consistent differences until the final dive, when the air speed goes high and altitude goes low.
To me, the fact that the Left Stick Shaker only stopped for a brief few seconds near the end of the first dive shows that the Stick Shaker Signal was erroneous for most of the flight, as the plane seems to have experienced just about every possible flight condition during those few minutes, but the software controlling the Stick Shaker signal was “almost never satisfied”.
To me, it looks like the logic is utterly screwed, as if, in at least two places, the data is upside down.
For example, the Stick Shaker signal could be inverted, On when it should be Off and vice versa, and the Flap Handle Position likewise.
Sorry to be long-winded – the consequence of being a land-lubber, I suppose.
Thinking more about those AOA signals. I’m sure that is what is going on, and why the MAX ever got off the ground in the first place.
As I understand AOA sensors, they typically consist of a rotating vane on an arm, on the side of the aircraft outside the cockpit. They simply align with the airflow, and send a signal indicating their position.
During development and testing, no doubt the AOA sensors were all new and relatively stiff to move, due to new seals and bearings.
Later, after a bit of use (and warm Indonesian & Ethiopian air), they would tend to loosen up.
While still new, they would tend to stay in whatever position they were in at the end of the previous flight, probably both nearly horizontal. So, resetting the zero points while the plane was still stationary would probably work “okay”. Good enough to get by, anyway.
However, after loosening up, this would not be reliable. For example, parked beside a gate, the tail is facing the taxiway. Another plane gets pushback, turns and heads out, sending a blast of jet exhaust over one side of the parked MAX 8. This acts backwards over the AOA sensor on the exposed side, and pushes it to its full extreme position, either up or down, depending on the eddies, the wind, locations of parked service vehicles and whatever.
So, one sensor is now at full extreme, and the other could equally be anywhere, middle, down or up. If the software isn’t designed to deal with this…
During “testing” this may never have happened so never showed up, and the awful thing passed and got airborne. Yuck!
@oddball: The AoA errors look like bit errors, which suggest something is not working correctly in the chain of digital processing, be it electronic or software. I doubt the problem is mechanical.
I expect that the AoA sensor is designed with a slight torsional spring load which keeps the vane locked against a stop until aerodynamic forces align it with the airstream. I don’t know whether or not the low speed discrepancies are significant. However, once the vane aligns with the airstream, the offset between the two readings remains constant.
If you accept that the readings should track at all speeds, it looks as though large motions are of opposite sign, but small motions are of the same sign, as if the higher order bits are complemented on the bad channel, but the lower order bits are correct. And if there is a problem like this, why isn’t it seen on all B737 MAXes?
My wild guess is a software glitch in an A/D routine.
Sorry but I can’t resist!
Addendum to Boeing 737 MAX 8 Operations Manual:
Immediately before takeoff:
Both pilots, open your side windows and stick your heads out.
Make sure Left and Right AOA sensor vanes are horizontal.
If not, use broom handle with wire hook to move vane to horizontal position. If it drops back down, wedge in horizontal position with a freshly chewed lump of chewing gum at the back end of the vane. This will shrink and drop off at high altitude. Refer to cabin crew for gum.
Warning: Do not attempt to take off with both AOA vanes wedged with gum.
@Victor
However, once the vane aligns with the airstream, the offset between the two readings remains constant.
Yes, clearly, they are both tracking perfectly in flight, but for some reason, the left one is greatly offset from the right. It could be for either reason – yours or mine – but what we need is to see the traces from the moment of Power On. The traces show relatively minor changes in value for what must have been significant changes in AOA, so I don’t know how that offset occurred. It is interesting that they very nearly meet at the end of the trace, but who knows what happened to them in that instant. One went fully up, the other fully down? Maybe this was how they started out?
Judging by the Left Stick Shaker, the sofware thought the Left AOA was too high, which aligns with the trace, but equally clearly, the Left side was way out of calibration.
If they had swapped control sides, would that have altered the way the Trim system responded?
Uhhh… (self-answer)
but who knows what happened to them in that instant
Power voltages -> 0, so signal voltages -> 0. (Are they analog or digital?)
But FDR internal power holds up and continues recording a little longer due to internal storage capacitors?
Enough, later…
@Victor,
Shortly after the release of the JT610 DFDR trace I managed to acquire a higher resolution version, and came to the conclusion that the RH AoA vane after the A/D conversion had a differential of plus 21.6°. Knowing that it was impossible to fit the vane incorrectly, the probable difference was a factor of 16 in A/D conversion. The small difference of < 1° from the expected 22.5° could be attributed to roll angle / relative airflow.
On the other-hand, I don't know what coupling method is used in detecting the vane shaft angle; possibly 3 phase synchronization.
@oddball
RE: ‘A couple of things I don’t understand – what does the trace for “Flap Handle Position” indicate? That they took off with flaps up? Then lowered, then the raised, then lowered them for the rest of the flight? Or is it inverted?’
The trace is ‘inverted’ for want of a better description, ie a positive signal indicates the flaps are extended. I suspect Flap 5 was selected for take-off. The flaps were then retracted in stages, to Flap 1 and then Flap 0. Shortly after the flaps were retracted, they were extended to Flap 1 and then Flap 5, before being retracted a second time.
If you have a look at the ‘TRIM AUTOMATIC’ trace, you can see the MCAS nose down trim commands (ie the longer duration pulses) began as soon as the flaps were retracted the first time. They ceased for a short time when the flaps were re-extended and re-started when the flaps were retracted the second time. That is consistent with the MCAS, which is not active when the flaps are extended.
@oddball
@Victor
It is not uncommon to see aircraft AOA vanes sitting at all sorts of odd angles when the aircraft is parked on the ground. The vanes then align with the airflow when the aircraft accelerates during take-off. These things have been around a long time and, as Victor mentioned, they are normally very reliable.
The problem could very well be software related, as Victor also suggested. It would be interesting to find out if there are any differences in the ADIRU mod states between different batches of aircraft in the 737 MAX fleet.
Sorry guys! This thing has got me wound up.
Never paid attention to it before, but does anyone know what the scale on the RHS of the AOA traces indicates? Is the central divider supposed to indicate an AOA of 0°, and wouldn’t you expect 0° on both during the takeoff roll? If nothing else, they should both read the same during the roll, and if they don’t, shouldn’t it be flagged and the takeoff aborted?
If both points are true, then it looks to me as if the LH AOA trace is about 4 times more above 0 than the RH trace is below 0.
In other words, they are both wrong, with the LH one much more so.
It seems to me the AOA is now a very critical item of flight instrumentation. Failure to correctly calibrate them at the start could account for these crashes (and others), given they can blow about freely when stationary on the ground, and the whole problem (In the MAX case) could simply be caused by a programmer who doesn’t know about AOAs, and simply called the “Reset/Calibrate” routine while still at the airbridge, instead of at a certain speed during the roll.
This strikes me as a clear design deficiency, because of the inability to calibrate before the roll. Maybe some do, I don’t know, but I think all AOAs should contain calibration actuators, that return them to zero position, then to specified points, maybe +/- 75%, at power on (while stationary), just like a pilot tests his flight controls. If the readings are not within spec, then a Faulty AOA is immediately indicated. Not much good finding out 6 months later, but this has happened before – TWA843 (1992). And so simple a fix.
@TBill
Bill, it will be very interesting to see how this plays out for both Boeing and the FAA. On the basis that you can put a line through deliberate malicious intent this whole MCAS mess will come down to yet another confluence of those two enemies of safety; a failure of imagination and the normalisation of deviance. Those two do not operate in a vacuum. Nor do they just get together one night and make Rumsfeldian ‘stuff’ happen.
It is going to take a very high level inquiry or a criminal investigation or both to get to the bottom of the this. In terms of the former, I see that Congressman DeFazio, chairman of the House Transportation and Infrastructure Committee, said he would hold hearings. In terms of the latter, there’s talk of a grand jury. That will all take time though.
At the heart of the certification issue is ‘Organisation Designation Authorisation’. Another of those ‘good idea poorly implemented’ things.
@Andrew
It would be interesting to find out if there are any differences in the ADIRU mod states between different batches of aircraft in the 737 MAX fleet.
A very high level comparison between the two accident aircraft;
Lion Air 610. PK-LQP. LN:7058
First flight date: 30/07/2018
Ethiopian 302. ET-AVJ. LN:7243
First flight date: 30/10/2018
So, the accident aircraft were built within 3 months of each other. While LSN is a better indication of production run placement than MSN, it’s still not ‘perfect’. Based on Boeing’s production rates there were probably 150 or so airplanes built in that three month period.
@Oddball: “they should both read the same during the roll”
not working below60 knots
@Victor: “This suggests the problem was not mechanical. […] The AoA errors look like bit errors […] if there is a problem like this, why isn’t it seen on all B737 MAXes?”
I was about to ask you the same question. Wouldn’t bit errors affect more aircraft than just LNI610? Barry Carlson mentioned, that it would be impossible to fit the AoA vane incorrectly. But this would explain why only this flight was affected. The FDR graph looks as though one vane was mounted with an offset, although I read that if you tried fitting the sensor offset by 20°, the attachment screws wouldn’t pick up on the captive nuts. But didn’t the maintenance crew remove (and then refit or replace) the AoA sensor prior to the fateful flight? I think I vaguely remember something to that effect.
Maintenance Lapse Identified as Initial Problem Leading to Lion Air Crash
« Crash investigators have concluded preliminarily that improper calibration of an airspeed [AoA?] sensor during maintenance touched off the sequence of events that led to October’s fatal Lion Air jetliner crash in Indonesia […] The suspected maintenance lapse was the initial misstep that ended with the months-old Boeing Co. 737 MAX aircraft plunging into the Java Sea, killing all 189 people on board. Two days before […] mechanics installed but failed to properly calibrate a replacement airspeed sensor called an angle-of-attack indicator. Based on information downloaded from the flight-data recorder, last month’s interim report revealed a constant 20° difference between signals from the AoA sensor on the captain’s side—which had been replaced—and those from the co-pilot’s-side sensor. »
@Peter Norton: We’re all guessing based on the limited facts at hand. The AoA is a reliable sensor. For JT610, likely it was factory-installed before it was replaced by maintenance. For ET302, likely it was factory-installed. The Reuters story said the behavior of the bad AoA sensor was the same for ET302 as it was for JT610. These assumptions lead me to doubt the problems are related to how the AoA sensor was installed or maintained.
Peter Lemme also considered a “bad bit” as a possibility for the AoA sensor problems on the B737 MAX, similar to what I hypothesized.
@Peter Norton,
not working below 60 knots
Many thanks for your comment and link. Obviously, I’m not fully up with the play, so that was very helpful. Yes, I didn’t expect the AOA vanes to move reliably until they reached a decent airspeed. This is just one of the problems…
… mechanics installed but failed to properly calibrate a replacement airspeed sensor called an angle-of-attack indicator.
Seriously!? You’re not kidding me? Is this REALLY the state of the art? Surely not!?
I can go down to any old Auto Parts store and by myself an ‘Any Brand’ after market engine tachometer (rev counter) for my 4, 6 or 8 cylinder car, and fit it to just about ‘Any Brand’ of car, and expect two things: 1. It will work, and 2: It will be accurate to within a few percent.
Yet a brand new, spare aviation part, for a specific model of plane, needs to be “calibrated” when it is installed, and, not having been “calibrated” can produce an error of 20°? To put that in context, the total swing of an AOA sensor must be no more than about 60°, so this represents an error of 33%? Can you elaborate, please?
Also, if one sensor was replaced, why? Was it also “reading” a 20° error, and the fault was not in the sensor at all?
What I can say now, assuming everything you guys are telling me is true, is that I am horrified. I am in utter disbelief. I think I never want to fly again!
To me, the idea that, in 2019, a new, modern, recently (re-)designed aircraft – no, a commercial airliner – capable of carrying more than 20 passengers, can be designed and built so utterly badly, and sold to be relied on by the flightless, unsuspecting, fare-paying public to transport them at high altitude through the air, is just appalling.
The fact that this fault could come down to something as pathetic as a “bad bit” in a digital data path is unbelievable, to me at least.
Now that I have had time to “process” some of what I’ve been told about how the AOA system apparently operates, I’m disgusted. From the DFDR traces, there was apparently a very plain and obvious, major fault with the AOA system, right from Power On. If I have this correct, there are only two AOA sensors, and one of them was completely “out of whack” from the word go, AND YET, this out of whack sensor was being relied upon by a major flight control system, to repeatedly and continually countermand the pilots’ control inputs. Sorry, just appalling.
I’ve worked in electronics for most of my career. I have some idea about its strengths and weaknesses. I know what amazingly cunning things you can do with it, and I know just how extremely fragile it is. Silicon chips are delicate, for several reasons. First, the transistors and other components built on them are microscopic, and second, silicon melts at fairly low temperatures. It’s highly “fry-able” and easy to “blow up”. Yes, things have come a very long way since I started, and in part that’s what makes this so unbelievable.
One of the most unbelievable aspects of the modern aviation industry is that, at the most critical moments, so much is left to human pilots to try to figure out, under extreme duress, with insufficient time. The crash of AF447 is just one example. That “should never have happened.” Lion Air “should never have happened.” Ethiopian almost certainly should never have happened either.
Putting AF447 aside for now as a completely different issue, the Lion Air flight should never have even got off the ground. It should never have even been allowed to commence its takeoff roll.
And, most importantly, it should not have been the pilot’s decision to make. Nor should it have been the maintenance crew’s decision. On the ground, the plane was perfectly safe. In the air, it was simply an accident about to happen (not even “waiting to happen”). It was almost inevitable.
And the decision about whether or not the plane could take off should have been made by the designer and manufacturer – Boeing, in this case.
How? Very simple. Electronic smarts. Designed in.
Let’s digress a little. I don’t know how long front loading washing machines have been around, but it’s a long time. I once had dealings with a big commercial unit that was so old it had no electronics in it. [FWIW, timing was achieved by several “Crouzet” style, geared-motor switches.] Yet, despite being almost antique, it was capable of multiple different wash cycles, controlled by a motor-driven plastic “punch card” system. You just inserted a different card in the slot, pressed Start and off it went. When it was ready, that is. Even though it had no electronics, the entire machine would not start at all if the front door was not properly closed. It had a simple, electric interlock, based on some clever mechanical bits and a micro-switch. And what is the worst that could have happened? A flood over the floor, and the washing not getting done. Obviously, a flood was sufficiently unacceptable that the mere possibility of one was deemed sufficient to “withhold service”. The interlock switch was built-in, to eliminate that possibility, and had complete authority. All without any transistors whatsoever. Even more than that, when the bowl was full of water, another interlock preventing the door from being opened.
Not so, it seems, with modern commercial airliners. Yep, modern airplanes have redundant systems… So what!? When one of two sensors making up a vital redundant system is plainly faulty, the plane is still able to take off – despite not really being able to fly.
The definition of redundancy is “the inclusion of extra components which are not strictly necessary to functioning, in case of failure in other components.”
However, when one of two has already failed, there is no redundancy, and for a critical system like this, the plane should not fly. Especially when one of the supposedly redundant components is not even recognised as faulty. (The next question should be, can the failed component actually be switched out? And can it be done, mid-flight? But that is not my point. The first is that there was no recognition of a fault. Nor safety system to report and diagnose or control it. Let alone a notion of how to deal with it.)
However, the modern jet engine is FADEC-controlled. Those impressive-looking throttle levers are now really just big, electronic “volume controls”, connected to some electrical wires.
So, while still on the ground, it would be trivial for the Aircraft Safety Monitoring & Control System to say, “UNFIT TO FLY”, and prevent a pilot from applying anything more than taxiing power, or achieving anything higher than slow taxi speed. This would require a bit of intelligent design, but if an ancient non-transistor washing machine can be designed to be safe, so can a jet plane.
I welcome any comments.
Oops: “…store and buy myself…”
good points, Victor
@TBill. regarding WPT2 timestamp and the mean speed from there to beginning of Kota Bharu trace. There’s a discrepancy between my response above and my previous estimate last year which I’ll need to resolve. The previous estimate had within 1s match and speed ~457 (if memory serves) back to start of KB. The one above has 7 second difference and 451 knots. Of course both are “slow” so the conclusion isn’t fundamentally different. However, I’d like to avoid unexplained discrepancies and will try and track that one down. As you say, there’s an issue with working out the timestamps of WPT1 and WPT2 in the SIR.
An interesting new twist in the Lion Air 610 crash.
‘As the Lion Air crew fought to control their diving Boeing 737 Max 8 jet, they got help from an unexpected source: an off-duty pilot who happened to be riding in the cockpit.
That extra pilot, who was seated in the cockpit jumpseat, correctly diagnosed the problem and told the crew how to disable a malfunctioning flight-control system and save the plane, according to two people familiar with Indonesia’s investigation.
https://www.smh.com.au/business/companies/pilot-who-hitched-a-ride-saved-boeing-737-max-a-day-before-it-crashed-20190320-p515sq.html
The CVR for that incident flight, JT43, would make very interesting listening.
@PaulS
fyi Gysbreght’s recent analysis suggests MH370 was flying without A/P from the turnaround to beyond KB. He is somewhat agnostic on the U-turn itsef but it tentatively looks like a >30% bank.
I am thinking, if A/P is OFF, that could be because the pilot was trying to turn off all normal L/R Gen and L/R Backup Gen and L/R XFER buses, whereas that would turn off SATCOM and voice and data recorders, not sure about O2 masks. In other words, loss of A/P may support the intentional depressure hypothesis.
Tbill. Can you remember how Gysbrecht arrived at that conclusion? I see nothing in my analysis to indicate conclusively one way or another that the aircraft was on autopilot. What I do see is evidence that it was under control and flying a pretty steady course, albeit with subtle course changes along the way.
@PaulS
Gysbreght’s analysis is posted on JW last couple days, he and I have been discussing on the side. If you need me to, I can copy and paste to my Google Docs and/or Twitter for your access.
As for my comments on aircraft power settings, I am a new user of the more rigorous PMDG FSX flight sim model that Victor uses. My main current interest there is fiddling with the electrical configs, but I realize PMDG may not be totally correct either. I still also use the older PSS777 FS9 for some things.
@Mick Gilbert:
RE: Non-revenue pilot in the cockpit jumpseat prevented crash.
This makes the perfect case for a 3-pilot-cockpit, like in the old days,
while zeitgeist goes in the opposite direction (towards a 1-pilot-cockpit or even 0-pilot-cockpit) …
Any chance the LNI43 CVR content will be released you think (provided the direct relevance for LNI610 proves true) ?
@Tbill. I don’t frequent the “other place”.
For those who would like to believe that the military radar should have been able to accurately paint the path around the IGARI turn and the turnback, please do some trigonometry and establish what radar azimuth and range resolution is required to do this on a 4s sweep periodicity. Unless someone can tell me that at 200+NM range a military radar can obtain azimuth resolution substantially better than 0.01 degrees then by my estimation the the radar COULD NOT HAVE DETECTED the IGARI turn or the start of the turnback on a sweep-to-sweep basis. At best it is going to require multiple sweeps to detect that a change of target heading has occurred. Ergo, the finer features of the military “painting” of the turnback should not be taken literally at and to suggest otherwise is ridiculous.
http://nymag.com/intelligencer/2019/03/atlas-air-the-boeing-crash-no-one-is-talking-about.html
Has Jeff been reading this thread?
Lion
https://www.abc.net.au/news/2019-03-21/lion-air-pilots-were-consulting-handbook-when-plane-crashed/10922820
https://www.nytimes.com/2019/03/20/world/asia/lion-air-crash-boeing.html
Reuters: Exclusive: Lion Air pilots scoured handbook in minutes before crash – sources
RE: “Near the end, the captain asked the co-pilot to fly while he consulted the manual for a solution.”
The FDR data shows the point where the captain handed over control to the co-pilot, as indicated by the sudden increase in the CCFORCE_PITCHCWSFOREIGN trace, which shows the force applied to the co-pilot’s control column. Until that point, the captain had managed to maintain control by opposing the MCAS nose-down trim commands with nose-up trim commands. The nose-up trim commands became sporadic and of much shorter duration after control was handed over to the co-pilot and, as a result, the stabiliser began moving nose down, until it reached the nose-down limit. The CCFORCE_PITCHCWSLOCAL trace shows that, towards the end, the captain also tried to raise the nose by pulling back on the control column, but by that time the aircraft was already in a steep descent and there was probably nothing that could have been done to save the aircraft.
It remains unclear why the pilots of JT610 did not think to use the STAB TRIM CUTOUT switches to de-activate the electric stabiliser trim, despite well over a dozen apparently uncommanded applications of nose-down trim. If they had completed that action while they still had control of the aircraft, they could have used the manual trim system to trim the stabiliser and maintain control, as did the previous crew. However, it was far too late for such action by the time the stabiliser had moved towards the nose-down limit, because the manual trim system is slow to operate and, in extreme situations, the air loads can preclude its use unless the elevators are first unloaded.
@Peter Norton
G’day Peter,
Re: This makes the perfect case for a 3-pilot-cockpit, like in the old days
Mmm … maybe, maybe not. What tends to be forgotten about the 3-person crew days (the third person was usually a flight engineer, not a pilot) was that all three had full time jobs back then.
I suspect what happened on the JT43 flight was more a case of there being a third block of cognitive bandwidth to apply to the problem. If that was the case that third block of cognitive bandwidth was largely untroubled by having to fly the aeroplane. That means it’s not likely to have been degraded by task saturation and it was less likely to have become fixated. Lastly, just by virtue of the physical layout of the flight deck, said third block of cognitive bandwidth was positioned quite nicely to not only take in the whole picture but also to observe the trim wheels.
That’s why the transcript would be useful. I’m sure that the Human Factors folk are all over it because the crew interactions are likely to provide a good guide of the thought processes that were at work.
Re: ‘Any chance the LNI43 CVR content will be released you think ‘
Hard to say. Annex 13 is quite specific about the non-disclosure of records such as CVR audio and transcripts. They are meant to be included in the investigation report ‘… only when pertinent to the analysis of the accident or incident. Parts of the records not relevant to the analysis shall not be disclosed.‘.
However, as the Indonesian KNKT appears to have somewhat a somewhat porous approach to confidential information management we may well get the transcript via unofficial channels.
And now,
FBI joining criminal investigation into certification of Boeing 737 MAX
https://www.seattletimes.com/business/boeing-aerospace/fbi-joining-criminal-investigation-into-certification-of-boeing-737-max/
@Mick Gilbert: Independent of whether it was wise to outsource some of the certification efforts to Boeing, if the FBI determines that Boeing deliberately misrepresented the design and performance of MCAS, there will be serious legal repercussions.
@Peter Norton
@Mick Gilbert
RE: “…the third person was usually a flight engineer, not a pilot…”
While many airlines certainly had professional flight engineers, airlines in the US often used a third pilot in the flight engineer role. That said, Mick’s thoughts about a third pilot are relevant. A third or fourth set of eyes in the cockpit makes a huge difference in an emergency and has influenced the outcome of several high profile incidents/accidents, such as UA232 and QF32.
However, it comes down to a question of airline economics. While extra eyes can make a difference, we’ve reached the stage where serious emergencies don’t occur very often. Modern airliners are designed to be operated by two pilots and no airline would employ an extra pilot on every flight ‘just in case’, unless the regulators impose such a condition. I can’t see that happening.
@Mick
Re: ‘Any chance the LNI43 CVR content will be released you think‘
I am surprised if CVR content is saved?
@TBill
Ah, yes, good point. I was thinking about the recording capability of the FDR rather than the CVR.
Does the pre-flight VOICE RECORDER test ‘reset the clock’ on the 2 hour recording duration or does it just test that the system is functional? If it’s the latter, depending on taxi amd shutdown times, there’s an outside chance that the crew reaction to the MCAS event on JT43 might have been retained.
@TBill
@Mick Gilbert
RE: “Does the pre-flight VOICE RECORDER test ‘reset the clock’ on the 2 hour recording duration or does it just test that the system is functional?”
The CVR test only checks the recording function, it does not ‘reset the clock’. The CVRs on Boeing aircraft typically record continuously any time power is applied to the aircraft, so it’s likely that any JT43 data was wiped.
@Andrew
Thanks for that clarification.
@TBill
@Peter Norton
Well, you can rule a line through that then. It would have been very interesting and perhaps instructive to compare the JT43 and JT610 crew interactions.
https://nypost.com/2019/03/21/pilots-who-fly-for-amazon-were-worried-about-boeing-jet-weeks-before-texas-crash/
https://www.nytimes.com/2019/03/20/world/africa/ethiopian-airlines-boeing.html
Better story. Previous had a paywall.
https://www.cbc.ca/news/world/ethiopian-airlines-captain-untrained-simulator-1.5065501
https://www.africanews.com/2019/03/21/ethiopian-airlines-crash-all-you-need-to-know/
Airlineratings.com:
WHY ARE THE INVESTIGATORS WITHHOLDING VITAL CLUES INTO 737 MAX CRASHES?
CRASH EXPERT GREG FEITH SLAMS CRITICS OF 737 MAX CERTIFICATION PROCESS
https://www.abc.net.au/news/2019-03-22/boeing-plans-to-reverse-optional-safety-feature-on-737-max-fleet/10928066
A light! Yeah, like that’s gonna fix it. What a PR disaster!
People are gonna say, “346 lives for the sake of 2 lights?”
@oddball
A light!
It’s not even that! The AOA DISAGREE alert is simply those two words appearing on the Primary Flight Display. Enabling the option would be just a code change I would think.
I’d love to know what Boeing were charging for that ‘feature’ when it was an option.
@Andrew
Oops Sulley got on the wrong side of Feith. There are a lot of things I would like to suggest to Boeing based on MH370, but I would not go to far with it unless I though I had Feith on board.
AOPA article on the MAX by Richard McSpadden here: http://bit.ly/2UQAlei
Another AOPA article on the MAX: http://bit.ly/2HBDOut
@ALSM
I’d sic Feith on those opinions too
@Mick Gilbert,
I’d love to know what Boeing were charging for that ‘feature’ when it was an option.
#MeToo! As before, I’m appalled by all of this. Just goes to show, (as per the earlier articles on the changes since McDD took over), Boeing would now do almost anything for a buck. So sad.
Now, it’s clearly revealed that you (the fare-paying “punter”) have no idea whether you are flying on the “cattle-truck” version or the “mixed livestock” version, unless you somehow know the particular airline’s ordered options list.
If their reputation isn’t trashed yet, I guess it shows that Boeing’s risk management boys know their market much too well!
@airlandseaman,
Yeah, I saw that article too.
[https://www.aopa.org/news-and-media/all-news/2019/march/20/congressman-concerned-about-foreign-pilot-training]
I’m not surprised they found some “good honest politician” to say that, but it’s very easy to say. Easy to blame the pilots.
To me, the big issue is that the pilots knew (okay, thought) they were flying the plane manually (Ahh, Autopilot off), so might not understand that they were fighting faulty automation, since they hadn’t been properly informed about the MCAS (Might Crash Anytime Soon) system, and didn’t know that it is handled in the same (unbelievably primitive) way as runaway trim.
The MCAS system was obviously “fighting back” so this was not a typical runaway trim situation, and I’m not surprised that they didn’t know what the hell to do about it.
I also saw the Boeing video advert somewhere (not sure where now – you can guess), but it’s both quite stunning and extremely unfortunate. It shows a MAX taking off and flying directly up towards the camera. It really looks for a few moments as if the plane is rising vertically, but of course it wouldn’t be able to because MCAS would be forcing it into a dive!
Oh, the irony!
I doubt that an airline decides whether or not to display the AoA reading based only on the price of that option. The Pitch Limit Indicator (PLI) and the airspeed tape already display the stall margin in the PFD, in addition to the stick shaker warning of impending stall. Historically, the AoA sensor has been used in military aircraft, but only more recently in commercial aircraft.
If an airline does not select the option to display AoA, the indication of AoA sensor disagreement might be confusing, so it is not surprising that there is no indication.
Here is an excellent article from Boeing that discusses the use of AoA indication in commercial aircraft.
@Victor,
Interesting and informative Boeing article, thanks. It doesn’t seem to be dated, includes the 777 but doesn’t mention the 787, so it must have been written a while ago, but as it says, it is most useful at lower speeds… When most crashes happen, I think.
In the case of the MAX, the fact that one incorrect AoA datastream can bring the plane down seems reckless design to me. If it’s that critical, than AOA DISAGEE should be compulsory. And it’s not like they haven’t had time to get some updated firmware written.
What’s more the wording is ambiguous. Disagree, with what? It should say AoAs DISAGREE.
I see from a quick Google that people are catching on. Slowly…
Interestingly, TWA843 that crashed in an aborted takeoff in 1992 was an L-1011 which had AoA sensors, and the FO/PF’s sensor had an intermittent fault which triggered the chain of events leading directly to the accident. Basically, the PF freaked out…
There are also design issues relating to the position of the 787 AoAs wrt the front door: http://www.boeing.com/assets/pdf/commercial/airports/faqs/787_aoa_sensor.pdf
All a bit cavalier, it seems to me.
I’m definitely changing my attitude towards Airbus.
@oddball
A mandatory AOA DISAGREE indication is likely to be one of a series of ‘fixes’ for the problem. Others are likely to include a limit on the MCAS pitch trim authority and dual AOA data agreement before MCAS is activated.
My understanding is the AOA DISAGREE indication was not previously made available unless the AOA indication option was installed and that it was only intended to indicate a disagreement between the AOA indications on the Captain’s and First Officer’s PFDs. As Victor mentioned, AOA indication is not widely used in commercial aircraft and most airline pilots are not trained in its use; stall margin information is provided by other means. Consequently, many airlines do not bother specifying the AOA indication feature due to the extra cost. Nevertheless, the AOA DISAGREEMENT indication might improve the crew’s situational awareness if they experience unusual airspeed & altitude indications and other anomalous aircraft behaviour caused by an AOA data problem.
I’m not convinced that MCAS’s use of AOA data from a single sensor was necessarily ‘reckless design’. However, it does seem that Boeing’s safety analysis failed to adequately consider the ramifications of spurious data. The details are unknown, but the analysis might have concluded:
a. the likelihood of such a failure was remote, given the historic reliability of mechanical AOA vanes; and
b. if MCAS were activated due to spurious data, the pilots would act in accordance with the long established procedures for a pitch trim runaway, ie deactivate the trim system via the STAB TRIM CUTOUT switches.
The analysis might have missed the human factors aspects of such a scenario, where other indications such as the spurious stall warning and air data disagreement might confuse some pilots.
Like it or not, MCAS was required for certification of the 737 MAX and that’s not likely to change. There are obviously technical issues that need to be sorted to reduce the risk of a recurrence; however, I believe that Rep. Sam Graves also has some valid points about pilot training.
The airline industry is under considerable pressure to train pilots at minimum cost and that pressure is likely to increase in the coming decades. The global airliner fleet is forecast to double in size over the next 20 years, spurring a demand for around 790,000 new pilots (Boeing Pilot Outlook 2018). The minimum hours requirement for airline co-pilots has already plummeted in some parts of the world, and in some countries a co-pilot can occupy the right-hand seat of a complex, highly automated airliner with as little as 240 hours flying experience. That’s a far cry from the past, when pilots would hone their skills flying small aircraft for several thousand hours before being considered for employment by an airline.
We don’t know if experience was a factor in the Ethiopian accident, but the co-pilot of that aircraft had only 350 flying hours under his belt (initially reported as 200 hours). The Captain had around 8,000 hours, but he was a graduate of the Ethiopian Aviation Academy and was the airline’s youngest captain. It’s likely that he also joined Ethiopian with the bare minimum flying hours. Similarly, the Captain and First Officer of the Lion Air aircraft were experienced on paper, with 6,028 hours and 5,174 hours respectively. However, the majority of those hours were on the B737 and both pilots only had around 800 hours on other types. It seems likely they joined Lion Air with minimal experience.
Perhaps I’m a dinosaur, but I believe the first couple of thousand hours of a pilot’s flying experience are vital for building the foundations for good handling and problem solving skills. In my opinion the airline world, which tends to focus its training efforts on meeting the minimum regulatory requirements at the minimum possible cost, is not the best place for junior pilots to cut their teeth.
RE: The fact that this fault could come down to something as pathetic as a “bad bit” in a digital data path is unbelievable, to me at least.
If bad software does turn out to be a factor in these accidents, then it won’t be the first time it’s happened and most likely won’t be the last. Try reading the ATSB’s report of the MH124 incident that occurred back in 2005 (https://www.atsb.gov.au/media/24550/aair200503722_001.pdf). And if you think that Airbus is immune from these problems, think again. Try reading the ATSB’s report of the QF72 incident that occurred in 2008 (https://www.atsb.gov.au/media/3532398/ao2008070.pdf).
My apologies for the length of this post – rant over!
@Andrew
To paraphrase Mick Dundee, ‘You call that a rant?‘
All very relevant points, well made.
On MCAS activation and AOA ‘agreement’, there may well have been an issue with the tolerance for normally observed L and R AOA disagreement exceeding the trigger point for MCAS activation.
We know that in normal operations depending on bank and yaw you will see different ‘valid’ AOA readings between the L and R vanes. I think that currently you need to see 10° disagreement to trigger the AOA DISAGREE alert.
At what sort of AOA would you expect to see the B737 wing stall?
On the topic of Boeing assuming that a flight crew faced with errant MCAS AND trim would action it as a Runaway Stabilizer, well, perhaps they didn’t model that as well as they could have.
You’ve got to wonder if they took into account the fact that the bad AOA data that triggered errant MCAS inputs would have also triggered a number of other problems such IAS DISAGREE and ALT DISAGREE. Both of those are annunciated so flight crew attention would be drawn to them first. Then there’s stick shaker activation, hardly missable and subsequently very distracting. And then in the background almost we’ve got MCAS winding in trim, essentially unannunciated apart from trim wheel noise which is now being masked by the stick shaker.
I have been canvassing as many current and former B737 pilots as I can of late (including a couple of ex-RAAFies). To a man they’ve all said the same thing – in the circumstances faced by the Lion Air crews, identifying the runaway would not have been as straightforward as some (including Boeing) suggest.
When it comes to training:
a. Runaway stab is such a rare event in real life that exposure to it in sim training is commensurately infrequent (once every three years).
b. Given the potential severity of the outcome, runaway stab is a memory item that is reviewed six monthly in terms of presentation, remedial actions and underlying causes.
c. On the occasions when runaway stab is refreshed in the sim, its presentation is ‘uncomplicated’. That is, it is rarely ever presented with other non-normal events. And I say ‘rarely’ to be conservative, no one that I have spoken to has ever had Runaway Stabilizer presented with any other concurrent event.
So, you’d have to ask, would any of the previous infrequently trained simulations of runaway stab have served as memorably useful examples of what actually confronted the Lion Air flight crews?
I should add that everyone I have spoken to has said that they would have gotten to the STAB TRIM CUTOUT switches ‘eventually’ if faced with repeated uncommanded AND trimming.
I’ve also been looking into the other topic you touched on, flight crew training. I won’t go into the whole thing here but anyone interested should look into ‘multi-crew pilot licencing‘ (MPL).
For short reads, both the International Federation of Air Line Pilots’ Associations and the European Cockpit Association have published papers on it. For a longer, more detailed read there is a very good paper on MPL by Sweden’s Lund University’s School of Aviation (Rickard Wikander and Dr. Nicklas Dahlström). Dahlström is pretty well known as Emirates’ safety, training and human factors guru.
Airlines currently using MPL are mainly European and South East Asian low cost carriers such as Flybe, Air Asia, Tiger, Air Berlin, Norwegian Air Shuttle, China Eastern, Xiamen, Air China, Easyjet, Dragon Air and Fly Nikki. The more mainstream carriers also using MPL are Ethiopian, Thai Airways and Qatar. The list is not necessarily complete. They are now all on my ‘Must Avoid’ list.
@Mick Gilbert
RE: “At what sort of AOA would you expect to see the B737 wing stall?”
I don’t know the stalling angle of the B737, but most airfoils stall when the AOA exceeds about 15°.
RE: “…in the circumstances faced by the Lion Air crews, identifying the runaway would not have been as straightforward as some (including Boeing) suggest. “
I agree it probably wouldn’t be immediately obvious, but nevertheless the pilot flying had to apply a significant amount of nose up trim on multiple occasions (I counted about eighteen), during a period when the aircraft’s airspeed was more or less constant. The way I see it, that should have been a trigger that something odd was happening with the trim, even with all the other distractions. If the trim is constantly running away (and that does not mean constantly running!), the obvious solution is to invoke the runaway stabiliser checklist. However, as I mentioned in a previous post, that action would need to be completed while the aircraft was still under control. If the stabiliser has already reached the nose down limit, then it’s unlikely the crew would have time to manually wind the trim back to a more reasonable setting.
For those green thumbs in the northern hemisphere looking to fertilise those fruit trees and vegetable patches, a little something from The Australian’s MH370 guru (and helper) for you:
MH370’s co-pilot ‘tried to use mobile in mid-flight’
EXCLUSIVE
By KRISTIN SHORTEN and EAN HIGGINS
An expert review of evidence from a secret MH370 report suggests the flight’s first officer may have tried to use his mobile phone mid-flight, reinforcing the theory the captain hijacked his own aircraft after locking the co-pilot out of the cockpit.
Minutes before the Boeing 777 was lost from radar on March 8, 2014, a mobile telephone registered to the aircraft’s co-pilot, Fariq Abdul Hamid, was detected by a telecommunications tower at Bandar Baru Farlim Penang.
And the co-pilot’s family was never told.
Speaking for the first time, Fariq’s father, Ab Hamid Bin Md Daud, told The Weekend Australian that Malaysian authorities had not informed him of his son’s mobile phone detection.
“No. I don’t know about that,” he said from his Selangor home. “That’s beyond my information.”
A Malaysia police investigation report into the disappearance of Flight MH370 — completed in May 2014 but kept secret — revealed that Telco Celcom had detected a mobile phone number, registered to Fariq on March 8, 2014, at 1.52:27am, Malaysian time.
“MH370 co-pilot’s mobile phone was reported as detected in Celcom’s mobile network in Penang by Sector 2 of BBFARLIM2 Base Station,” the secret report said. “Based on the recorded flight path of MH370 obtained from PDRM, it is noted that MH370 was flying in the coverage area of Sector 2 BBFARLIM2 Base Station at 1.52:59am … which is close to the time it was detected by the BBFARLIM2 Base Station.”
Mike Keane, the former chief pilot of Britain’s largest airline, EasyJet; said the mobile phone either remained on from takeoff or was switched back on midflight to make an emergency call.
Like most professionals in the aviation business, he believes Captain Zaharie Shah hijacked his own aircraft in a complex act of mass murder-suicide.
Mr Keane reckons Zaharie would have asked his “compliant” first officer to go to the cabin — for a concocted reason — before locking the cockpit door, isolating himself with an oxygen supply and depressurising the aircraft.
“The first officer would have been skilled in responding to depressurisation due to regular training,” he said. “If Fariq had his mobile phone with him, he would have grabbed an oxygen bottle before taking his phone off flight mode or switching it on.
“If someone was going to make a transmission with the phone, it’s likely to be the crew because they are trained to get oxygen on as quickly as possible.”
After failing to establish communication, the phone would have remained on.
Matthew Sorell, senior lecturer in telecommunications at the University of Adelaide and adjunct professor of digital forensics at the Tallinn University of Technology, confirmed the mobile phone appeared to have already been switched on before the plane approached Penang.
Dr Sorell, who has extensive operational experience in forensic analysis of mobile phone network records, said the mobile phone connection happened at the edge of the coverage cell, indicating the handset was performing a “new location area update”.
“This means the phone was on, and responded automatically when it detected the cell signal over Penang,” he said. “That ping occurs about 28 seconds after entering new coverage space, which is what would be expected in the case of a location based update.”
The elevated, high-powered base station that detected Fariq’s phone is built to provide wide-area rural coverage stretching 32km over mountainous terrain.
When a local newspaper first reported details of the phone detection in April 2014, Malaysian authorities called for the publication to be “severely punished” for printing a “bare-faced lie” and engaging in “gutter journalism”.
The confidential police report from May 2014, later leaked online, confirmed Malaysian authorities knew about Fariq’s phone detection by April 24 of that year.
Despite this, Malaysia made no mention of it in its Factual Information Safety Investigation report released in March 2015.
Note that that was an ‘EXCLUSIVE’!
It is important to distinguish between a bad AoA sensor and bad AoA values that become an input to software algorithms downstream. The Rosemount AoA sensor was replaced prior to JT43. But that did not fix the problems. After JT43, before JT610, the engineer flushed the static and pitot lines, and cleand an electrical connector, but that also had no effect on the problem. The same left AoA bias (+19.0 degrees) was observed on JT43 and JT610. This suggests the AoA sensor was not the source of the problem. Instead, it is more likely the sensor was good, but the Signal Conditioning Module (converts analog sensor outputs to digital values) was defective. Hopefully investigators are looking into this explanation.
@Mick
Of course our thoughts are with the Nok at this 5th anniversary of the loss of MH370.
Two elements of the MH370 article you cite are (1) NoK understanding of the data, and (2) technical elements of the cell phone call.
I was a bit shocked when a Chinese NoK at the 5th anniv. was profiled by the press, he said he knows (mistakenly) that the Transponder cannot be turned off without a sending a (distress) signal, so therefore he knows for sure that the aircraft was not hikacked in this manner. He was said to be un-official leader of the Chinese NoK, and apparently the only attendee from the Chinese NoK.
Technically, I was recently noticing the cell phone connect at 17:52 seems to happen due south of Penang during an unexplained gap in the Butterworth primary radar data. I notice on Captio’s air traffic replay video that there were a number of flights flew right over Penang a little before MH370 got there.
Technically, it is impossible that the station connected to Hamid’s cellphone, if we consider the plane being at FL350 and flying at Mach 0,84 as estimated by Victor in his former post “M370 flying around Penang”.
You can read about tests by the RMP according the connectivity of cellphones in flying planes at different altitudes in the leaked RMP report.
Although, in case MH370 was below FL 200 at that time, connectivity could have been possible. But what about the other 238 phones?, there are always people who forget to set their mobiles off. Even if pax were already incapacitated, their phones should have locked.
@Gerald: We’ve discussed this before. Independent of whether it is possible to complete a call, it is possible for a cell phone to register on a cell phone tower at cruise altitude. I’ve experienced this myself. As for the other passengers, we have no evidence that the cell phone numbers of the passengers were checked for registrations on cell towers. In fact, we know that some of the NOK were never asked about the cell phone numbers of the passengers.
@TBill
‘I was a bit shocked when a Chinese NoK at the 5th anniv. was profiled by the press, he said he knows (mistakenly) that the Transponder cannot be turned off without a sending a (distress) signal …’
G’day Bill, it sounds like that NoK is confusing the transponder with the ELT.
@Mick Gilbert: He could be referring to an ACARS message when the transponder is turned off. If there was a transponder failure, it’s possible that would occur if ACARS was operating.
Gerald: Re: “Technically, it is impossible that the station connected …”. As Victor noted, that statement is not true. It is not only possible, it happened.
Connections at FL350 are easy if the plane is in range and flying on a track orthogonal to the LOS path to the base station (when the Doppler is near zero). See for example: http://bit.ly/2DRZjo9
@Gerald,
Technically, it is impossible that the station connected to Hamid’s cellphone
May I beg to differ, please?
The article reports:
“The elevated, high-powered base station that detected Fariq’s phone is built to provide wide-area rural coverage stretching 32km over mountainous terrain.”
I agree, it would be very unlikely to connect to active (passenger) cellphones within a metal-skinned plane cabin at 10+km altitude, unless those cellphones were being held up against cabin windows with direct line-of-sight to the tower, for the purpose of acquiring a cellphone signal.
Under my scenario, only FAH would have had reason to be attempting to do that, which would explain both apparent facts (i.e. His, no others). That he might have had his cellphone with him at that point is interesting, though young people do tend to be magnetically attached to their phones.
Did the leaked report confirm that phones were held up to windows during testing? How many passenger phones would have had the relevant (Malaysia, Penang area) SIMs installed is another question.
Oops, didn’t refresh before posting.
Afterthought:
There could be little doubt that many other cellphones (airborne or not) might have connected to that cell tower at the relevant times, but if the SIMs were not registered to a known person, they could not be included or excluded, so would have to be ignored.
@Mick
Dr. Sorell must have had access to the raw base station data dump. His assertion that Hamid’s phone was on when it accessed the Penang base station is based on the signature difference between a VLR (visitor location register) update and a “turn on”.
As far as the possibility of a connection. There is little doubt. As ALSM pointed out, Doppler is near zero when line of sight to the base station is near 90 degrees to the direction of travel.
@DennisW
G’day Dennis,
Re: ‘Dr. Sorell must have had access to the raw base station data dump.‘
Well, you’d hope so. If he’s simply commenting on what was contained in the SKMM analysis then it’s nothing we haven’t heard before.
Unsurprisingly though, his ‘finding’ most assuredly does not support the headline.
Hello DennisW,
Addictive, hey!?
Another afterthought:
Hamid is reported to have lived in Shah Alam, outside KL.
Does anyone know if his cellphone plan had roaming (to Penang) enabled?
Maybe that’s why there was no call – though Emergency Calls should still have worked. Maybe he didn’t think of that. Hypoxia does that to you, apparently.
As I understand it, SMS/Text Messaging was originally only intended as a Telco In-house Engineering Tool, and operates even when the voice channels don’t have sufficient signal. Anytime you are trapped in a hijacked airliner, remember that. Compose (and address) your Emergency Message in case you get a connection, then send it ASAP if you do! You may only get a few seconds.
Media reports are circulating that the Ethiopian stabilizer jackscrew wreckage was found in the full nose down position.
@Pilatus
It would be more accurate to say ‘have been‘ circulating.
Reports of the stabilzer jack screw being found in full nose down position started doing the rounds about 9 days ago. That discovery is believed to have been what prompted the FAA to fall in behind every other jurisdiction and ground the MAX.
The jack screw evidence doesn’t necessarily implicate MCAS. Given that the early stages of ET302’s flight were not inconsistent with improper configuration, it may well be that the stab was trimmed full nose down before take-off.
As the Zen Master said, ‘We’ll see.’
Other news: Pilots transitioned on iPads etc!?
https://www.aviationcv.com/aviation-blog/2019/shocking-facts-boeing-737max-crash
https://edition.cnn.com/2019/03/22/us/max-8-boeing-self-administered-courses-lion-air-ethiopian-airlines-intl/index.html
Also: THAT video, ‘vertical’ action starts at 16 seconds. I guess it’s edited. Or shot from a drone/chopper with a very good telephoto lens.
https://youtu.be/1XEsSRqnOwc
Some cool background scenery. Nice music. Throwing some pretty high-rate climbs and turns. @Andrew – how’s the flying look? The engines look a bit disproportionate to me.
And you can see the RHS AOA sensor right at the end: 2:43. It’s drooping slightly. (As one commenter said somewhere, they double as hard landing indicators.) All a little ironic, really.
Shame they didn’t spend a bit more on the MCAS design & implementation.
@oddball
You can see the ‘chase’ helicopter at various points in the video. As stated in the credits at the end: “Flown by Boeing test pilots…Do not attempt.”
It might come as a surprise to some, but classroom ‘chalk and talk’ has gone the way of the dodo for airline pilot training. CBT is used pretty much exclusively these days and iPads are simply another platform on which ground training courses are hosted. Clearly it was remiss of Boeing not to have included a comprehensive briefing on MCAS in the differences course; however, it seems this particular failure and its consequences were not very well understood before the two accidents. The 737 MAX simulators probably weren’t programmed to simulate the specific failure, so additional simulator training would not have achieved anything. I assume that will change in due course.
As for Neil Hansford’s comment “aviation regulators should require ground school, at least 20 hours in a simulator, and a series of check rides to establish proficiency in the new aircraft”; what utter crap.
@Andrew,
@Mick Gilbert,
Here’s to more ‘rants’! Well done to both of you.
I’m going to attempt to reply without becoming prolix, which for me is quite a challenge. I’ll start with Andrew, and see how that turns out.
I stand by my earlier choice of reckless. I don’t think it’s excessive. There are various dictionary definitions, for example:
“Acting or done with a lack of care or caution; careless or irresponsible.”
That said, of course, it’s largely in the eye of the beholder, but as before, I’m fairly horrified by some of the design standards apparent in the aviation industry. I used the word cavalier earlier, and I really think it fits. In the case of MCAS, I’m firmly sticking with reckless.
First, I think it’s reckless of Boeing to have designed (or at least implemented) such a seriously dangerous automated system:
a) without thoroughly informing and explaining it to pilots;
b) without writing up a detailed description of it in the manual;
c) and regardless of (a) & (b), expected pilots to be able to urgently understand what was going on when it failed, and handle the failure appropriately before everyone gets killed;
d) relying on just one sensor and data path, apparently with no redundancy, and with no simple, immediately recognisable system of indicating/detecting its failure;
e) having a second AOA sensor and data stream available, but not supplying it to the MCAS system, or using it to prevent this outcome.
f) and not including any “self-checking” into the MCAS system, to establish if other systems support the action it wants to take;
g) misleading the FAA about it;
h) knowing what it did but failing to ‘fess up after the Lion Air crash.
I’m sure I could go on… but I think the list above and 2 suspiciously similar crashes and 346 deaths in <5 months all contribute to the suggestion of recklessness.
As Victor said above,
The Pitch Limit Indicator (PLI) and the airspeed tape already display the stall margin in the PFD, in addition to the stick shaker warning of impending stall.
Addressing the stick shaker first: it too was acting erroneously, indicating an impending stall when apparently there never was, likely doubling the pilot’s confusion…
Surely, PLI & Airspeed data could also have gone to the MCAS system, so that it could have recognised that “something was wrong” with what it was ‘thinking’. However, as it was implemented, there was absolutely no cross checking whatsoever, despite there being ample opportunities to implement some. Even pilot and co-pilot cross-check one another, despite their much higher intelligence and ability to “rethink” scenarios.
The MCAS system apparently had no cross-checking of any kind built in. All in all, I call that reckless, but that’s me.
These crashes appear to mirror in some way the crashes of AF447 and TWA843 [and no doubt plenty of others], where a sensor has failed without any warning (even though on all the specified occasions, intelligible warnings could have been given), and control of the plane has suddenly been thrust into the hands of an unprepared human pilot, who sadly, failed to cope with a problem that the previous control system also could not resolve.
The shock alone of suddenly being thrown a dangerous, unknown problem is probably enough to startle most pilots and reduce the clarity of their thoughts, and with all the technology and sophistication currently available, that just seems so completely unnecessary.
Eeeh. Enough for now, but I’d like to address some of the other points later.
@airlandseaman: Thanks for the info. Fact is the cell was registered, on the other hand RMP stated in that report that there was no connection possible in the Celcom net above 8000ft. Obviously they did simulations. That is by the way my experience in hundrets of flights.
This is an important status of the flight, because it would mean the plane was flying way below FL350 or even FL447, which was the height in the link you sent me. Numbers differ nearly 10k, seems not very accurate to me.
Gerald: First, I don’t believe the…”RMP stated in that report that there was no connection possible…”. Reference?
The cellphone tests described in the RMP report only demonstrated that those in charge of the tests did a poor job of coming up with a test plan, and implementing it. Flying a King Air at 24,000 feet was pretty much a waste of money.
Anyway, many people have made and received cellphone calls from aircraft, even at FL400 over Iceland. As my paper demonstrated, the link margin at 17:52 was sufficient for a cell connection to have been made, and one was in fact recorded by the operator. It is no coincidence that the connection occurred close to the time the Doppler went through zero.
As for the altitude, the connection was possible over a wide range of altitudes. This means we can’t use the fact of the connection as an altitude discriminator. What we do know is that the altitude at KB was ~40,000 feet and the ground speed was nearly constant (~530 kts) between KB and Penang. Moreover, the TAS (ground speed adjusted for estimated tail wind component) remained nearly constant from KB past Penang out to at least 18:02, and probably to 18:22 (if you believe the Hotel Radar data). At such a high speed, it is likely MH370 remained at a high altitude.
@ALSM
I am thinking your (very good) essay mentions FL350 as possible upper limit, but I am not sure I undertsand that sentence fully. You wrote that cell phone essay in 2017, we now have new primary radar data that seems to corroborate high altitude for MH370 over Malaysia, and maybe FL450 is cell phone upper limit.
Any new thinking on why there are gaps in the Butterworth primary radar trace? Is it possible that the radar operators have a way to exclude very high altitude targets? I am thinking there might be flight rules for Malaysia such that FL400+ might not be an expected altitude.
@Gerald: The statements you cite from the RMP report (and the extracts from that report used in the Safety Investigation Report) referred to the ability to make call connections. That didn’t occur on MH370. Rather, there was a registration of the cell phone on the tower.
@Victor, @airlandseaman: I accept your experiences, but please accept mine, too. As I stated, I never ever had a cellphone that showed me I was booked in at that altitudes. Ok, I understand your point, as there is the possibility that Cell Stations had detected my phone but nevertheless my phone wasn’t locked in.
In the RMP report, they looked after Cell Stations that were capable of detecting phones in planes flying by. That had obviously happened with Hamid’s phone. The reports states that “a flight reconstruction exercise has been conducted in order to investigate the capabillities of Celcoms base stations, in particular BBFARLIM2 base station to detect mobile phones and while in flight. However, BBFARLIM2 base station was not one of the base stations detected during the reconstructions”. Furtherdown in the summary the report says”Celcom and Digi could only provide higher possibillities of connection below 8000ft.
By the way isn’t it a happy coincedence that MH370 flew by in that 90 degree angle where Doppler is near zero and Flight Levels don’t bother?
@Gerald
Any flyby will produce a zero Doppler instance – a line going past a point. The rectangular cellular antenna has numerous sidelobes besides the main lobe (see “vertical” picture below). I calculate that the first sidelobe is about 35,000′ (geometric) at 30NM. There is still considerable power (and sensitivity) in the first sidelobe. There is no way to know if a phone registered (did a VLR update) without a cell site dump. A VLR update is very different (as Victor points out) than making a call.
I don’t find it odd at all that a registration occurred at 35,000 to 43,000′
https://photos.app.goo.gl/mW3ZiufNEPF7ZBfm7
Sorell is quoted in the Shorten/Higgins article to say “The elevated, high-powered base station that detected Fariq’s phone is built to provide wide-area rural coverage stretching 32km over mountainous terrain.”
Bollocks!
The BBFARLIM (Bandar Baru Air Itam/Farlim) base transceiver station is sited on the roof of a retail building (N5.388266º E100.282668º) in an urban area located in a valley, presumably to ensure full coverage within that urbanised valley.
At 35,000ft there is no impediment for LoS between 9M-MRO’s track and the BTS site. Previously, we have discussed how the BTS antenna design produces multiple high gain “lobes” in elevation. There is nothing mysterious about that BTS enabling the location based service chatter with Hamid’s phone.
@Don
Yep…
https://photos.app.goo.gl/X66zPdXqsY3pFcoSA
@Don,
@DennisW
… is built to provide wide-area rural coverage stretching 32km over mountainous terrain.”
Bollocks!
I don’t know what kind of base station is installed down there, but having been “built to provide …” is not necessarily negated by where it happens to be installed. Sorrell may well be entirely correct, irrespective of who is quoting him. It is “elevated”, albeit only a few metres. If the logs show that it connected, it probably connected (recognising that logs can be doctored, like anything else.)
The […] high-powered base station …
probably shouldn’t be located so close to an obviously much frequented public (and private) area, but this is SE Asia. Damn, reception is good around there!
@Gerald: How would you know if your cell phone registered on a tower? I am aware only because on international flights, the telecom companies in some countries greet incoming guests with a text message. Certainly, there were other registrations where I received no notification. As for the part of the RMP report that you cite, those particular experiments were testing for connections, not registrations.
@oddball
So long as there are no dead birds on the street, things are cool. Worrying about stuff like that is very Mellennial.
When I lived in the Bay Area the military early warning radar on Mt. Umunhum would cause a noticeable “zzztttt” in my stereo system on every rotation. I am apparently no worse for the experience.
https://photos.app.goo.gl/AfYgkBhW3zSUUQoZ9
@Gerald: Let’s suppose your assertions are correct. The radar data shows the groundspeed of MH370 exceeding 500 knots near Penang. Do you really think that speed was reached at an altitude less than 8,000 ft? That would imply an indicated airspeed of over 450 knots. For the B777-200ER, Vmo = 330 knots. At this speed, certainly the plane would have been severely damaged, which is not consistent with flying in a fuel efficient configuration for the next 6 hours.
@oddball
RE: “I stand by my earlier choice of reckless.”
Boeing could certainly be accused of negligence in this case, but I think reckless is a step too far. There’s a fine line between the two, but reckless also implies ‘impetuous’, which I don’t believe is true.
RE: “Surely, PLI & Airspeed data could also have gone to the MCAS system, so that it could have recognised that “something was wrong” with what it was ‘thinking’.”
It seems obvious now that MCAS’ reliance on a single source of AOA data was wrong and that some kind of error detection was warranted. However, PLI and airspeed data comparison are not the answer. The PLI uses AOA data to calculate the difference between the aircraft’s current pitch attitude and the attitude at which the stall warning AOA will be exceeded, so it’s not an independent check. Airspeed is not always a reliable cross-check, because the aircraft will always stall when the critical AOA is exceeded, regardless of airspeed. I think the simplest solution would be a cross-check between the two AOA sensors.
RE:“These crashes appear to mirror in some way the crashes of AF447 and TWA843 [and no doubt plenty of others], where a sensor has failed without any warning (even though on all the specified occasions, intelligible warnings could have been given), and control of the plane has suddenly been thrust into the hands of an unprepared human pilot, who sadly, failed to cope with a problem that the previous control system also could not resolve.”
There will always be situations where pilots need to fall back on basic flying skills, no matter how good the technology. It could be argued that modern technology has made us complacent and that we are now far too reliant on automated systems at the expense of those basic skills. It’s a sad fact that many pilots are ‘afraid’ to turn off the automatics and manually fly an old-fashioned visual approach because they are too used to flying from A to B with the autopilot coupled from 200 ft after take-off until 200 ft before landing. Many of us believe the regulators and airlines need to step up efforts to ensure that pilots retain the basic skills that might just save the day when faced with an unusual emergency.
@DennisW,
So long as there are no dead birds on the street, things are cool.
Frankly, I’m not so sure about that. Dead birds are powerful evidence! What else dies…?
I used to live on a hill near (<2km from) a famous landmark 'high tower' that was (& still is) bristling with antennae of many kinds. The tower was built lower down, so we were more in line with the 'business end' than people who loved underneath. When we noticed that:
1: our sleep quality noticeably deteriorated after a few years,
2: after 2 episodes of me working on the roof for a couple of days, then being immediately hit by serious illnesses lasting about 2 weeks each;
I called up the local Radio Inspectorate. Spoke with a very helpful chap, who assured me that it was highly unlikely the signal strengths, even in our situation, were "above limits". Said he could come check, but his experience was that it would almost certainly prove to be legal.
However, he qualified his comments thus: "That doesn't mean it's safe."
So, I built myself a simple, wide-band RF detector. I found huge variations, just walking about inside the house. There was a large peak, right beside our bed ;-((
After that, we decided to move 20km away and out of LOS.
The difference was utterly remarkable. Very noticeable, and quite literally overnight. From my point of view "everything improved" following that move.
The truth about high energy radio transmissions is not public knowledge. But on (some?) Navy ships, they paint Do Not Cross lines and No Go zones near their radio antennae. Can't imagine why they would do that… (What is the safe amount, and how does time affect it?)
Worrying about stuff like that is very Mellennial.
Oh, how I wish!
… military early warning radar … I am apparently no worse for the experience.
Are you quite sure? How would you know, really? What caused your stroke(s)? Gradual blood vessel cell or immune system deterioration? Contributed to by RF absorption? How can you know?
Sure, my story is anecdotal. But I now sleep like a baby again, and I’m happy with my perceptions. A Uni Student I know claims that her recent tests show that plants do not thrive on freshly microwaved (then cooled) water.
Remember the days when smoking was “not harmful”? Have you actually read the small print warnings about your cellphone? I think they say “No closer than 1cm from the body.” Carry it in your pocket?
Just like with Boeing, it’s always about the money.
@oddball
I was just teasing you. It is probably a good thing to be concerned. Unfortunately there is little hard data on what constitutes a risk from long wavelenght radiation.
Even living near AC power lines exposes you to low frequency radiation on a continuous basis. A person probably is more at risk of mental problems worrying about it than physical problems from the radiation itself. Certainly we are exposed to all sorts of radiation in the last half century and in the coming half century. We live on a “bright” planet right now – radio, TV, cellular, satellites,… As Sagan pointed out, our planet will become “dark” as our technology matures to use “contained” radiation for all of our devices.
@oddball
As an aside, Sagan befriended me, and we shared a couple of drinks. Then it became obvious that he wanted a couple GPS clocks to synchronize his long baseline SETI array (which I gladly donated). He was a really nice guy, however.
@oddball
Comment by ‘Ian W’ on PPRuNe:
“Systems in all modern aircraft will eventually hand the bag of bolts to the pilot if they cannot make sense of what is happening or there is some occurrence they have not been programmed to respond to. This is because it is cheaper to develop systems that deal with the monotonous tasks and hand non-routine/non-nominal to the pilots (you call it a trick in the safety case book, it is in fact standard practice). It is now becoming obvious as you state above that the assumption that the pilot can handle things is not a safe assumption. For this reason systems are being programmed that are capable of handling the non-routine that the pilots can no longer be expected to handle. These are expensive systems to create as they are safety critical and the certification is long and expensive. However, flight crew are expensive too – so more and more aircraft systems are being designed that handle the majority of non-nominal cases. These systems are counter productive in that the flight crew now get even less hands on time and when they do get it their lack of currency shows – so back around the loop building software that will cope with more non-nominal events.
Eventually, the probability of the pilot being needed AND being capable of solving the problems will pass a point where the safety case can be met more successfully by automation. That point is closer than people would think. As soon as that point is reached AND the lifecycle costs of generating and flying operationally with the certified software is less than the cost of employing pilots, autonomous aircraft will become more widespread than they are now.”
@Andrew
Maybe I have expressed this before here, if so I apologize. My retired career is a medic (I wanted to give something back to the community I live in). During my training the instructor would ask “what were you thinking when you did such and such a thing”? Trick question. No matter your answer, the instructor would say “we are not training you to think. We are training you to follow a script.”
The instructor is right. In emergencies (EMT or aircraft or anything else) you don’t have time to think. You fall back on your training. Even MD’s in the ER.
@DennisW
I agree, up to a point. The problem being that every emergency is different and aircraft manufacturers (or whoever) can’t produce ‘scripts’ that cover every conceivable scenario. The following statement can be found in every Boeing FCTM:
“Because of the highly infrequent nature of these occurrences, it is not practical or possible to create definitive flight crew NNCs to cover all events.”
Pilots and others do need to fall back on their training during an emergency, but there comes a point where they might need to think outside the box to safely recover the situation. Unfortunately, the airline training system produces too many ‘cookie cutter’ pilots who have trouble handling things when something unusual happens and they don’t have a script to follow. The biggest problem is they become so engrossed in the problem they forget to FLY THE AIRCRAFT.
@Andrew
Good point. In my case, I don’t have the training to think outside the box. I know my equipment backwards and forwards, and how to use it, and the “script”. Beyond that I am headed to jail or a lawsuit. My “scope of practice” is tightly defined and limited. I dont feel nervous at all when the pager goes off. I know the boundary conditions.
A different situation than facing being splattered in a crash. 🙂
@ALSM. You said that because the AoA left vs right disparity between JT43 and JT 610 was about the same this, “..suggests the AoA sensor was not the source of the problem was not the cause of the problem”.
There was no documented serious down-trim problem before the left AoA sensor was changed prior to those flights though in both those instances that was encountered. Hence I do not follow why for that reason you think the sensor (or its calibration) may not be the problem’s source.
Had there been a disparity like that in the flight immediately before the sensor change, that would suggest it was not the cause subsequently but there is no record of that: at least that has been published.
Yet there may be more to this. There had been speed and altitude indication problems reported after an earlier flight of the day of JT43 and amongst others a “Stall Warning System L” message was evident, together with “AOA SIGNAL FAIL”. The same messages were apparent after a following flight the same day.
The left AoA sensor then was changed with serious down trim first being recorded in the immediately subsequent flight, JT43.
But given those stall warning messages it appears likely there had been left stick-shaking in these flights, unentered in the maintenance log, as was the case after JT 43.
Other defect entries varied in number and description for these flights but in character there was a enough continuity to suggest that those to do with speed, altitude and trim had a common cause. Despite the correlation between the AoA sensor change and the down trim which led to the crash on 28th, it is even possible, if unlikely, that the down-trim had been encountered in those earlier flights too and had been overcome and left unlogged as with JT 43. If so, that would suggest the causation was from elsewhere.
(It seems quite possible also that there were like stall warning and AoA warning messages recorded during JT 43 though because of the incomplete log entries the consequent testing after that flight did not disclose them.)
I do hope that there is investigation into the completeness of the defect write-up and maintenance undertaken that is thorough, methodical and impartial in both this and the Ethiopian crashes, and includes comprehensive questioning of flight and maintenance personnel involved with prior flights.
@Victor, I became interested in that report simply because they did test flights in order to check the possibillity of Hamids registration. I’m not an English native speaker, so maybe I misinterpreted a sentence but in the report it is clearly stated that they did these flights in order to know if base stations were capable of detecting cellphones. That is what the cited words in my understanding mean. And they did it especially for the mentioned Celcom base station BBFARLIM2. In my view this is interesting because it is contrary to your findings.
You are right that the speed would have been to high for this altitude but I remember the 9/11 planes flew at speeds too high in the attacks on the Twin Towers and they didn’t brake up. A test flight with a B777 on the flight path was never done, so it would be easy to check it out if this particular Celcom base station is capable of detecting the phone on the high and fast flying plane. And again, only Hamids phone was detected which in my view is special.
But I dont want to bother you any longer with it. Thanks for the answers to all.
@Andrew, @DennisW,
Eeee! So many points, so little time!
Negligent or reckless, I don’t much mind. The main thing to my mind is “seriously substandard”, but then, I’m a passenger, not a plane vendor, airline or pilot.
On that point, I think we have all been grossly short-changed, for decades. The standards are much lower than the need to be, or should be. I don’t have time tonight to discuss that in detail, but hope to do so soon.
@oddball
RE: “On that point, I think we have all been grossly short-changed, for decades. The standards are much lower than the need to be, or should be.”
Time to quit the histrionics and get a grip on reality? Airline safety has improved dramatically over the last 50 years. According to one analysis, the number of fatal accidents per million flights decreased 16-fold during the period 1970-2018, while fatalities per trillion revenue passenger kilometres decreased 54-fold over the same period (https://theblogbyjavier.com/2019/01/02/aviation-safety-evolution-2018-update/). Aviation safety is by no means perfect and these recent accidents have highlighted a serious issue that needs to be solved, but let’s not forget that airline travel is still extremely safe and far safer than any other mode of transport.
Gerald: Re: “…I became interested in that report simply because they did test flights …”
As noted above, those test flights were a waste of time and money. The “test plan” made no engineering sense. Way too crude. They did not have qualified people planning and doing the tests. Some people just flew around with a hand full of the wrong phones in the wrong aircraft at the wrong speed and wrong altitude concluded that nothing could be concluded because the tests they did were not consistent with the MH370 path and most likely altitude range.
If I had been involved, they would have conducted the tests using an aircraft capable of flying up to 40,000 feet. They would have made multiple passes at incremental altitudes along the known path. It would have been equipped with the right test equipment, not just phones (antennas inside and outside the skin, calibrated receiver and transmitter, spectrum analyser, recorders, etc.)
In so many ways, the sloppy effort on the cell phone questions was consistent with the search and investigation as a whole. Another missed opportunity.
@Andrew:
Time to quit the histrionics and get a grip on reality?
Ooooh! Fighting, insulting talk. I wanted to address some earlier points, but this takes ‘the cake’ (precedence).
The converse of that might well be: “Time to get heads out of clouds and face reality?”
Yes, I accept that airline safety has improved markedly since the days of Richard, Wilbur and Orville, but I believe it has plateaued in recent years, if not started slipping backwards, taking Boeing’s recent contributions into account. It’s pointless quoting damned lies and statistics like this: “According to one analysis, the number of fatal accidents per million flights decreased 16-fold during the period 1970-2018” if in the recent period, accidents have ‘sky rocketed’, to employ a little histrionics. Those “long term trend” statistics allow for smugness and complacency, and reduce the pressure on the throat.
As a perfectionistic type, I can tell you that the first 80% is the easy bit. If we want to bring the commercial aviation industry crash rate down further, we have to really start perfecting, and I see no sign of that happening.
I have been trying to hypothesise the most likely cause(s) of the recent MAX crashes, and I’m going to really stick my neck out here, just for the hell of it.
I could be right, or I could be wrong, but I’m going to “fly with it”:
Coca Cola.
Or fruit juice. Or tea, or coffee, or soda water. Or urine.
And I’m gonna say that the design of the typical, lower cost AoA sensor is pathetic.
You have quoted Victor as saying AoAs are very reliable. Truly, I beg to differ.
I would also contradict some earlier comments, quoting one of the reports you very helpfully referred me to:
https://www.atsb.gov.au/media/3532398/ao2008070.pdf
On page (xvi):
” AOA is a critically important flight parameter, and full-authority flight control systems such as those equipping A330/A340 aircraft require accurate AOA data to function properly. ”
From an electronics point of few, the standard design is hopelessly archaic, it’s crude, it’s primitive, it’s flawed. That old, original, antique design still in common use today should be banned from commercial aviation. (If you want to continue improving the safety stats.)
But I’m not going to explain myself further at this point. Let the fun begin.
Let me just point out some facts:
https://www.boeing.com/commercial/aeromagazine/aero_05/textonly/m01txt.html
https://flightsafety.org/asw-article/galley-leak-douses-747s-electronics/ – the first story.
https://www.aviationtoday.com/2006/05/01/safety-water-and-electrons-never-a-good-mix/
https://www.pprune.org/tech-log/533135-b767-300er-avionics-bay.html
As we know, the MAX is a redesign. We know it’s a competitive industry. We can assume more corners have been cut. I don’t know how the Max crash investigators would ever be able to identify an electrically conductive contaminant as the precipitating cause of those crashes, but that’s my current hypothesis.
I might explain the electronics theory later, or others might offer their explanations. But those planes were both a few months old. Spillages will have happened… And maybe the carriers in question were not so concerned with cleaning them up. But it shouldn’t matter a damn. And maybe that’s the reality.
@David,
“(It seems quite possible also that there were like stall warning and AoA warning messages recorded during JT 43 though because of the incomplete log entries the consequent testing after that flight did not disclose them.)”
Possibly the JT43 crew didn’t understand the problem they had encountered, and this clouded the way they wrote it up in the maintenance log. May be a lack of descriptive English didn’t help the cause either.
On the other hand, the apparent failure of maintenance to physically check the the vane position with the A/D output before changing the vane out, resulted in the flawed assumption that vane was faulty. The final nail in the coffin was to fall into the same trap on replacing the vane.
@oddball: Comments with 5 or more links are automatically held and must manually approved. This is to prevent spam.
@Barry Carlson. “Possibly the JT43 crew didn’t understand the problem they had encountered, and this clouded the way they wrote it up in the maintenance log.”
Could well be. They wrote up a more complete version for other purposes separately but even that seemed to misunderstand.
However, both concealed the potential seriousness of the down trim. My first reaction was that to have done otherwise would expose their decision to continue the flight. I think still that amongst other things, having declared a PAN twice they owed more to the record, to the maintenance people and to their successors and their passengers than their maintenance log entries in particular. After all they had received a briefing devoted to the sensor replacement by maintenance before that flight.
Other thoughts. They arrived late. Conceivably they did brief maintenance orally or were at least available to do that before departing for home though maybe not. Aside from the sensor replacement briefing there was the extensive history of problems with this aircraft that they (and maintenance) should have been aware of, as should have been the subsequent crew.
Then there was the limited time available to maintenance before the next flight to investigate what was written up, to address that and look into the history and its implications, in the small hours and with engineering advice available limited at the least.
While there may be investigation of human factors and systematic failures in the lead up to the MCAS behaviour on the final flight and pilot reaction to it, in looking into prevention of repetition of the accident more generally I think that the disclosure and handling of the relevant evidence of aircraft defects that was available should be examined by the investigation carefully, not so much to attribute blame as to identify procedural and organisational weaknesses from which equally important lessons may be learned.
We have heard nothing of the history of the Ethiopian aircraft and that should be relevant also.
@Victor,
Comments with 5 or more links…
Cool, many thanks.
@DennisW
That’s it, on the Grain Loaf roof.
@oddball wrote “I don’t know what kind of base station is installed down there“. No, but the MCMC database that provided the information to locate the BTS site does specify its transmit power.
Shorten & Higgins’s assertion about “the elevated, high-powered base station that detected Fariq’s phone” is simply misleading. It is neither elevated nor high powered. Sloppy reporting on the part of Higgins who recently had a book published on the subject.
@DennisW,
Yeah, I saw the photo before. But I was presuming that Higgins & co were at least quoting Sorrell correctly. My bad? Surely, on a multi-storey rooftop qualifies as ‘elevated’?
@Andrew,
Sorry, both barrels there… ;-(
@David,
“We have heard nothing of the history of the Ethiopian aircraft and that should be relevant also.”
I’ve seen reports that the HS jack-screw was found in the full ND position. The circumstances surrounding how it got there will be derived from what is on the recorders, and that is probably dissimilar to JT43, possibly runaway ND trim on the HS. If that is the case, MCAS is ‘off the hook’, though its insidious non validated air-data / ADIRU cross check operation is not.
Mind you, someone wasn’t ‘watching the shop’ as the aircraft exceeded Vmo, not something that would be of any assistance if manual NU trim was being applied – when a huge reduction in airspeed would have unloaded the stabilizer with its most likely NU elevators.
@oddball
No sweat and I didn’t mean to cause offence. Nevertheless, I don’t believe the state of the airline industry is quite as parlous as you have implied. There have been blips in the accident rate throughout history, but the long term trend has been down. It’s not surprising the rate has plateaued in recent times, given that it’s already so low. Further gains will not be easily achieved, but that doesn’t mean the industry isn’t trying! The two 737 MAX accidents seem to indicate a problem with the aircraft design and possibly with the certification process. I am confident those problems will be resolved, the same way similar problems have been resolved in the past.
RE: “You have quoted Victor as saying AoAs are very reliable. Truly, I beg to differ.”
Would you care to explain the basis of your opinion?
RE: “From an electronics point of few, the standard design is hopelessly archaic, it’s crude, it’s primitive, it’s flawed. That old, original, antique design still in common use today should be banned from commercial aviation. (If you want to continue improving the safety stats.)”
Seriously? Thousands and thousands of aircraft have been flying with these vanes every day for at least 50-odd years. How many accidents have occurred that have been attributed to this so-called ‘flawed’ design? If they were as bad as you imply the sky would be raining aircraft, but that’s hardly the case is it?
@Barry Carlson. Yes, I had read similar reports about the jackscrew. Prelim report expected shortly I gather.
RE: LNI610/LNI43
Mick Gilbert: « SMH: “That extra pilot, who was seated in the cockpit jumpseat, correctly diagnosed the problem and told the crew how to disable a malfunctioning flight-control system and save the plane.”
The CVR for that incident flight, JT43, would make very interesting listening. »
What communication methods (other than the report for the maintenance crew which ) are there for pilots to communicate such problems to other crews within the same airline (or even beyond) ?
Being unfamiliar with the reporting system, I assume that by submitting the maintenance report, the LNI43 captain has fulfilled all his duties and it would be entirely up to maintenance to brief the subsequent cockpit crew, but still I imagine it must be a terrible situation for him to think that if he had communicated the problem to his pilot colleagues, so many people would probably still be alive. I am not attributing any blame, I am just imagining how it must feel?
@Peter Norton
@Andrew
Peter, Andrew would be the best person to describe the relevant communications methods for a commander to pass information relating to his flight to both maintenance and ops.
I think your assumption ‘that by submitting the maintenance report, the LNI43 captain has fulfilled all his duties might need to be reviewed. I’m sure that Andrew will convey his views on what should have been reported and through what channels.
My view, for what it is worth, is that there were a host of glaring and serious delinquencies in the way the Captain of JT43 discharged his duties. I’m not quite as charitable as you when it comes to assigning blame on that front.
Inmarsat has been purchased by a consortium of private investment firms for $3.4 billion.
@Peter Norton
The Aircraft Maintenance Log is the primary source of information for pilots regarding defects and any subsequent maintenance action. Consequently, it is very important that pilots write up defects properly, not only for the engineers, but for the pilots who subsequently fly the aircraft.
We know from the Preliminary Report that the JT43 PIC reported the incident through the company’s ‘A-SHOR’ electronic reporting system. However, the Lion Air Safety and Security Directorate’s safety instruction included in the Preliminary Report seems to imply the Chief Pilot on Duty did not raise the reported issues with the airline’s IOCC/MCC. Had he/she done so, the aircraft might have been grounded pending further investigation. At the very least, the pilots who subsequently flew the aircraft might have been briefed about what happened the night before.
The nature of the JT43 incident should also have triggered several other reports by the aircraft commander. The incident should have been classed as ‘serious’ according to the Annex 13 definition, which would have required an immediate report (normally by phone) to the civil aviation regulator and/or accident investigation authority, to be followed up by a mandatory written report within a specified period, usually 24-48 hours. Those reports would normally be submitted to the airline’s safety department in the first instance, which would then notify the relevant government authorities and the airline’s management. The Safety and Security Directorate’s reminder to pilots to send reports as soon as practicable seems to imply the required reports were not submitted in a timely manner.
@Victor
The Inmarsat aquisition is a painful reminder for me of the ARM Holdings acquisition by Japan’s SoftBank in 2016 for $32B. I could have made a 41% gain in a day, but I did not act on the information I was given by insiders. I was afraid of getting pulled into a basement in San Francisco and waterboarded by the SEC.
Inside traders are treated with less respect than Arab terrorists by US authorities. They even tossed “darling” Martha in jail.
@DennisW: You were smart not to act on insider information.
@Victor
🙂 The compliance algorithms now employed by the SEC are deadly. Any large transaction prior to a major value changing event is flagged and scrutinized very carefully. A friend of mine got nailed on the acquisition of LinkedIn by Microsoft. It was very very ugly.
@Andrew
@Peter Norton
Andrew, in your view should the temporary activation of the TAKE-OFF CONFIGURATION warning, the Captain’s stick shaker activation, the high control column forces experienced, the requirement to use the Runaway Stabilizer non-normal checklist, the consequent need to set the STAB TRIM CUTOUT switches to CUTOUT, and having to complete the flight using manual trim have been included in the AFML and A-SHOR write ups?
Were there any other aspects of JT43 that you would have expected to have seen written up?
@Mick Gilbert
Yes, I would expect to see all those things mentioned. The automatic nose down trimming after flap retraction should also have been mentioned.
Where I work, the PIC would also make a note that an Air Safety Report had been raised. That would trigger the engineers to download data from the QAR for use in any subsequent investigation.
I would also have contacted the relevant flight operations duty manager by phone to make sure the problem was promptly communicated to management. This was a serious incident and all relevant parties should have been notified immediately.
@Andrew
Many thanks for those clarifications.
Given The Australian‘s history of misleading or inaccurate reporting of matters relating to MH370, subsequent to the ‘MH370’s co-pilot ‘tried to use mobile in mid-flight’‘ story by Kristen Shorten and Ean Higgins I made contact with Dr Matthew Sorell. Dr Sorell happily provided a number of corrections and clarifications to the way his views were reported in the story.
The very first thing that Dr Sorell highlighted to me was that his view is that there is *no* clear evidence that the First Officer tried to phone, rather that his phone was more likely left on (though he allowed for the possibility of it being turned on or out of flight mode). Dr Sorell emphasised to me that he made that clear to journalist Kristen Shorten.
Ms Shorten has made clear in a subsequent conversation with Dr Sorell that the headline and spin were editorial decisions outside of her control but that her story as written originally made Dr Sorell’s opinion clear.
In the course of our exchanges Dr Sorell also noted the following:
Ms Shorten provided Dr Sorell with a copy of the SKMM folder from the leaked RMP files. The doctor had three hours to skim that and make some comments (he was travelling overseas at the time). Ms Shorten was keen on pushing the line that the FO may have tried to call. While the doctor could not refute that, the evidence as far as he could see really only showed that the FO’s phone was on.
With regards to the reporting of ‘The elevated, high-powered base station that detected Fariq’s phone is built to provide wide-area rural coverage stretching 32km over mountainous terrain.’ in the article, Dr Sorell said that that was ‘his interpretation’ based on the terrain and the nominal 35km/120 degree arc. He noted that antenna would be tilted upwards perhaps a few degrees to cover the high terrain to the south and south-west. That antenna orientation contrasts to that commonly used in an urban area where down-tilt is used to control the coverage distance. He observed that the up-tilt probably facilitated the registration.
Dr Sorell had done some work for Celcom Sdn Bhd in 2000 during their application for a 3G licence. Accordingly, he was aware of some of the coverage peculiarities of the network but noted that that knowledge was now dated.
He noted that the recorded registration of the FO’s phone was most likely a location update indicating the phone had detected that it was in a new area of the network. That occured because Penang is in a different network Location Area to Kuala Lumpur (KL International Airport) where the FO’s phone would have been previously registered.
With regards to the connection Dr Sorell said that it was not clear whether this was a 2G (900MHz GSM, 1800MHz GSM) or 3G (2100MHz WCDMA) connection. He suggested that 900MHz GSM was more likely given the distance, noting that 3G falls back to 2G.
Dr Sorell noted that there is a lot of technical data that might have been obtained from the network and it is not clear from the report whether it was. For example, the raw network data from the local VLR does not appear to have been made available. That might have been because it had expired before the possibility of the analysis was identified. He said that a lot of the parameters aren’t stored for long as they are really only there for stable operation of the network. The doctor noted that in Australia we generally have 7 days to get that sort of data from telcos.
With regards to the RMP connection tests, Dr Sorell stated that the experimental flights seem to be have addressed the wrong question. He noted that the evidence we have is from the network side, whereas the experimentation looked at what the phone would see. He made the point that in order to get a location update over Penang, you would have to take off from outside the location area (eg KLIA). He would have set the experiment up with Celcom working much closer to the antenna end of the network and focusing on the network’s view rather than the phone.
In conclusion, Dr Sorell noted that,
‘There is no evidence that the First Officer attempted to place a call or send a text message, and in fact there is an absence of evidence which would be expected if he had attempted to send a text message.‘
He says that if there is further mobile phone network evidence available that he is able to review, that view may change.
______
Dr Sorell was very helpful and very forthright in our discussion/exchanges.
@Mick
thx
@Andrew: Thanks for the firsthand insights.
@Mick Gilbert: “I’m not quite as charitable as you when it comes to assigning blame on that front.”
I tried to be careful. Privately, I share your thoughts. But I want to refrain from apportioning blame for an issue about which I am not knowledgeable enough and before the investigation report is out. I don’t want to blame individuals in a public forum, which the person in question might happen to read. He might be in a psychologically frail state already.
Does the new cellphone info allow any firm conclusions ?
Hi Andrew,
Sorry for the delay. No major offence taken (wound up is about all), but apology happily accepted.
As time moves on, I’ll try to respond briefly… I loved the humour BTW: (…the sky would be raining aircraft…), and glad to see I’m not the only one given to the odd spot of hyperbole.
Regarding AoA related crashes, you may be in a better position to answer, as, right now, mention AoA and Google offers 737 Max pages. I can only think of a few off the top of my head: TWA843, XL888T, and perhaps a couple of Max crashes, but I’m sure there are plenty more.
Regarding “flawed”, I mean akin to the Merriam-Webster definition: “having a defect or imperfection”, as in ‘flawed diamond” (as most are), or “flawed character” – having a weakness, some way off perfect, rather than rather seriously defective.
My issues with them (apart from them being a critical sensor for some purposes), is that the standard design has no easy means of validation, especially in-flight. Electronically, the output ‘power’ if you like, is lowest at the midpoint of its range (low AoA values) – which in one sense may be a good thing – the closer it gets to ‘disaster’ the higher the output capability, but by then, it’s probably way too late. Anyway, typically being analog devices, apparently mostly with direct potentiometer outputs, they are readily subject to leakage currents and interference, however generated. That said, I can’t readily imagine how any amount of Coca Cola appied to ordinary signal cable connector ends is going to pull the readings that far off. Unless the cable also suffers some kind of defect, which would not be unknown, but not likely. However, Coke dripping into the Signal Conditioner / A-D Convertor module could have just about any effect, depending on all kinds of factors.
May I ask you a question? If I offered you an AoA sensor that self-tested and calibration-checked itself over its full operating range as soon as powered on (on the ground) – yep, swung itself from full up to full down and checked its readings – and which also validated itself routinely in-flight, supplied output data in digital format, and output a clear FAULT signal anytime it failed, as well as logging temporary in-flight validation errors as they occurred, would you still prefer to retain the standard model?
I regard the old design as archaic because this alternative is entirely possible with current technology, and would take us closer to 100% reliability. Even if never 100% as everything fails sooner or later, at least, you would be much closer to 100% reliability in terms of knowing when it failed, unlike now when such random, unannounced failures kill even highly experienced pilots. [XL888T in particular, though they were taking foolish risks, IMO.] My point is, if they had known as soon as the ‘faults’ occurred (the AoA Sensors froze and stopped working – did they really?), they would not have wanted to take those risks and the crash likely would not have happened.
Finally, as you questioned my grip on reality, I’ve thought a bit more. Here’s my cynical view. The aircraft manufacturing industry continues to churn out substandard product where, for example, a major spillage in the cabin could result in leakage into the Avionics Bay and take down the aircraft, simply because the current, legally accepted (Court Awarded) value of human life is just too low. The manufacturers and airlines can afford to “lose a few” as it’s more profitable than paying for far better planes. It’s simply the “Law of Commerce”. Of course, as a pilot, this affects you far more than me. Sure, the Max problem will go away, but not much will really change, sorry to say.
“A Southwest Airlines Boeing 737 Max just made an emergency landing in Florida”
http://www.businessinsider.de/southwest-airlines-boeing-737-max-makes-emergency-landing-florida-2019-3?r=US&IR=T
https://cnn.com/2019/03/26/us/boeing-737-max-emergency-landing/index.html
“During flight simulations recreating the problems with the doomed Lion Air plane, pilots discovered that they had less than 40 seconds to override an automated system on Boeing’s new jets and avert disaster. The pilots tested a crisis situation similar to what investigators suspect went wrong in the Lion Air crash in Indonesia last fall. In the tests, a single sensor failed, triggering software designed to help prevent a stall. Once that happened, the pilots had just moments to disengage the system and avoid an unrecoverable nose dive of the Boeing 737 Max, according to two people involved in the testing in recent days.”
https://www.nytimes.com/2019/03/25/business/boeing-simulation-error.html
@Peter Norton,
“The pilots tested a crisis situation similar to what investigators suspect went wrong in the Lion Air crash in Indonesia last fall.”
These pilots had been briefed and therefore aware of what to expect, and the article highlights the 40 seconds rather than explaining that the accident pilots had to start from scratch to fault find a system that had been “papered over”.
@Peter Norton
@Barry Carlson
The “Pilots Had 40 Seconds to Fix Error” makes for a good headline, but bear in mind the window of opportunity to override MCAS is only 40-seconds if the pilots sit there and do nothing. As it says further down the page:
“If the system starts pushing the plane’s nose down, pilots can reverse the movement via a switch at their thumb, a typical reaction in that situation. In doing so, they can potentially extend the 40-second window, giving them more time to avoid a crash.”
For most pilots, trimming is an instinctive reaction because it has been drummed into them from their very first flying lesson. There wouldn’t be many pilots who would sit there and do nothing while the aircraft was trimming against them. The vast majority would instinctively apply trim in the opposite direction to relieve the control forces, even if they didn’t know what was causing the problem.
@Andrew
Yes, human factors play a large roll I am sure of that. I am not an aircraft pilot, but I have “piloted” just about everything else.
The 737Max situation is reminiscent of an “uncontrollable” state in modern control theory terms – controllability, observability, realizabilty. I alluded to this an earlier post.
An example most of us are familiar with comes from the movie “Top Gun”. As you might recall Maverick finds his F14 in a flat spin (from which there is no way to recover – a factual recreation), and the Goose perishes in the incident.
So it seems with the 737Max. If the right response is not found in a given time frame the aircraft becomes uncontrollable regardless of any inputs available to the pilots. Uncontrollable states have received a lot of attention (many many papers) in last few decades, but it is still a trap that occurs frequently until it is purged after the fact. That seems to be the case here.
@DennisW
@Peter Norton
@Barry Carlson
The following information was posted on PPRuNe this morning by FCeng84, a flight control system design engineer based in Seattle:
“…I offer the following as hopeful a fairly comprehensive description of the MCAS system that has been in the 737MAX fleet to date. Note that this does not reflect any of the changes about to be released. Hopefully Boeing will provide clear detail of those soon.
As always, if you still have questions after reading and trying to absorb the following please ask.
1. MCAS was designed to command airplane nose down stabilizer in response to high AOA up to an authority limit of 2.5 degrees for Mach less than 0.4 with lower authority at higher Mach numbers. If the pilot does not make any pitch trim commands, once AOA goes low MCAS will run the stabilizer in the airplane nose up direction back to the location from which it started.
2. MCAS is activated when all of the following are true:
a. Flaps are up
b. Autopilot is not engaged
c. Sensed AOA is above the MCAS activation AOA threshold
3. Once activated, MCAS will not command more than one increment of airplane nose down stabilizer motion until it has been reset. MCAS will be reset by either:
a. Pilot pitch trim command followed by a period of 5 consecutive seconds with no pilot pitch trim command.
– The assumption is made that pilot activation of pitch trim will be closely followed by continued pilot use of pitch trim to return the airplane to a column neutral pitch trim condition. MCAS seeing no further pilot pitch trim for a period of 5 seconds is interpreted as indication that the pilot has achieved column neutral pitch trim.
b. Return (by MCAS) of the stabilizer to its starting position per (1) above.
– Having returned the stabilizer to its pre-MCAS event starting point it is assumed that the airplane is back to a column neutral pitch trim condition.
4. Pilot pitch trim input at any time during the MCAS sequence as described in (1) above will stop MCAS stabilizer motion and end the current MCAS event while immediately moving the stabilizer in the direction of the pilot command.
a. If pilot pitch trim input is issued while MCAS is running the stabilizer airplane nose down, that motion will stop and the stabilizer will immediately move in the direction of the pilot command.
b. If pilot pitch trim input is issued while MCAS is running the stabilizer airplane nose up, that motion will stop and the stabilizer will move in the direction of the pilot command.
c. If pilot pitch trim input is issued after MCAS has completed its airplane nose down motion but prior to MCAS acting to take that motion out (as a result of return to low AOA), the stabilizer will immediately move in the direction of the pilot command.
d. It is assumed that the pilot issuing a pitch trim command is indication that the pilot is taking over the pitch trim task and will return the airplane to a column neutral pitch trim condition.
As a result of 1 through 4 above, given an AOA sensor that is failed so as to give an erroneously high reading (similar to what data appears to indicate occurred during the Lion Air accident flight), the following MCAS related scenarios can occur:
A. MCAS will activate (if flying manually) as soon as the flaps are retracted to up. Note that the stick shaker will have activated as soon as the airplane lifted off the ground regardless of the takeoff flap setting.
B. If the pilot does not make any pitch trim inputs, MCAS will run the stabilizer airplane nose down for one MCAS increment (as much as 2.5 degrees over approximately 10 seconds if Mach is less than 0.4). Without pilot pitch trim input, MCAS will not command further stabilizer motion in either direction. There is plenty of pitch control authority via the elevator using the column to counter the pitch disturbance generated by one MCAS increment of stabilizer motion.
C. If during or after the MCAS stabilizer motion per (A) above the pilot gives a pitch trim command the stabilizer will immediately start moving in the direction of the pilot command.
a. If the pilot pitch trim commands drive that stabilizer back to a column neutral pitch trim condition then the airplane will be back where it started from. In this event, provided sensed AOA is still high, MCAS will activate again once it sees a period of 5 seconds with not pilot pitch trim input. This process will repeat itself with the stabilizer never getting further than one MCAS increment out of trim. It appears that this sequence was repeated 20 or more times by the Lion Air accident flight pilot before he handed control over to his first officer.
b. If the pilot pitch trim commands are activated, but do not drive the stabilizer back to a column neutral pitch trim condition it is possible that successive activation of MCAS triggered by high AOA signal and ineffective pilot pitch trim inputs will lead to the stabilizer moving progressively further in the airplane nose down direction. It appears that this is what took place on the Lion Air accident airplane once the first officer took over control.
As for the reference in media reports this week regarding the crew’s need to intervene within 40 seconds of errant MCAS response to an AOA signal failed high, the following sequence of events would have to occur to so compromise pitch control power in that amount of time:
(a) The flight crew would have to allow a full increment of MCAS airplane nose down stabilizer motion to go in over 10 seconds without interrupting that motion via pilot pitch trim input.
(b) The flight crew would then have to have made a very short pitch trim command that triggered MCAS to reset, but did not re-establish anywhere near a column neutral pitch trim condition.
(c) After a 5 second pause wherein MCAS inferred that no more pilot pitch trim indicated the airplane was back to column neutral pitch trim, the flight crew would have to allow a second full increment of MCAS airplane nose down stabilizer motion to be inserted over another period of 10 seconds. Once again the crew would have to allow this stabilizer motion to go in without interruption via pilot pitch trim command.
(d) Once again, there would have be a repeat of (b) with a short, ineffective pilot pitch trim command.
(e) The final 10 seconds of this proposed 40 second sequence would be allowing another errant MCAS airplane nose down stabilizer motion increment to go in without interruption by pilot pitch trim command.
To summarize, getting in trouble over the course of just 40 seconds requires the crew to not trim when then should and make two very short, ineffective trim inputs following each of the first two MCAS stabilizer motion increments. This represents a worst case scenario.”
https://www.pprune.org/rumours-news/619272-ethiopian-airliner-down-africa-130.html#post10430828
I had previously understood that MCAS would keep adding nose down trim in increments if the AOA indication remained high. However, it seems the system is designed to operate once only, unless it is reset. If the system operates only once, then the resulting trim change is fully controllable through the control column. However, if the pilot uses the electric trim to re-trim the aircraft and the AOA indication remains high, then MCAS will add another increment of nose down trim. If the pilot’s trim inputs are sufficiently each time, the aircraft remains controllable; however, if the trim inputs are insuffficient, the stabiliser incrementally moves towards the nose down limit, as appears to have been the case in JT610.
MH370–IF THE FISH CAN SMELL IT SO CAN WE.
[NOTE: This is an abbreviated summary of a paper I have posted at:
htps://www.dropbox.com/s/fu3ey9ud4fq0njv/MH370–IF%20THE%20FISH%20CAN%20SMELL%20IT%20SO%20CAN%20WE.docx?dl=0
Abstract: An accelerator mass spectrometer (AMS), has a sensitivity of 1/10^15 = 1g/km^3. I estimate the production rate of aluminum alloy solutes for the MH370 site at the present time to be ~2.1kg/day. Deep ocean currents convey such solutes somewhat unidirectionally, and higher solute densities limit upward spreading. A typical current flow of 5cm/s will carry the solute 4.3km in one day, and reasonable assumptions indicate that during that time the solute would be confined to a volume of ~6.6km^3, thus producing a solute density of 325g/km^3 = 325/10^15,clearly within the working range of an AMS. ROVs, searching 2km abreast at 8km/hr, could complete a 10^5km^2 search in 48 days requiring only 4,300 readings.
Might such sensitivity be sufficient to find the MH370 signature via upwells in the Indian Ocean Gyro? One snag here is that Al and Fe tend to have unusually high densities in gyros, mostly due to atmospheric inputs (3). A far better choice would be the I.O gyro’s aptly named garbage patch, which seems to vacuum-up samples of everything that’s going around the neighborhood. Deep searches might be best.
The most certain choice would be the slow deep water currents driven by thermohaline circulations and thus by density gradients. Note that thermohaline currents produce sedimentary deposits called contourites and turbidites, and if any can be found near an MH370 hotspot that has been in growth recently, they might well be worth checking out. Nepheloid layers and turbidity currents might also be considered.
We can identify the MH370 water-analysis signature by taking readings at existing Boeing debris fields which have been in the deep ocean for a time comparable to that of MH370. We can then attempt to use the signature to “rediscover” the wreckage from some distance away, by searching for it at locations where the signature is borne away by seabed current flows. If the distance at which the signature can be detected is sufficient to make water analysis a worthwhile search tool, then we may have a remarkably fast and economic method of doing a closeup search.
I believe the best tool for the job is an AMS. They can measure 1/10^15 = 1g/km^3. This sensitivity is normally used to determine the isotopic composition of elements, but has also been used for measuring mineral content in the oceans, unfortunately they are not exactly portable, so the water samples (micro-sized) would have to be sent to the surface in batches.
However it might be worthwhile for the ROVs to pack laser-induced breakdown spectroscopy devices (LIBS). These can analyze every element in a solid, liquid, or gas. The optical power is 1W; readout is “available in seconds”; bandwidth is i.r to u.v; and accuracy is <10% (Wiki). Unfortunately, they have a sensitivity of “only” 1ppm = 1g/tonne, but are available in a handheld point-and-shoot format, and might provide some pointers as to whether a particular area is ‘hot’ while AMS results are pending. An artificial intelligence provided with all available data from existing Boeing debris sites could search for similarities. An up and running system like Watson might be available.
Please refer to the full paper for all calculations. The 777-200 contains 95,095kg of Al alloys, which I estimate to have a total surface area of 4,522m2 (assuming a thickness of 3.6mm for the skin, and 15mm for the remainder).
Test samples of Al alloys placed in deep seawater have shown a corrosion rate of ~0.064mm/yr, not counting severe losses from pitting and crevices etc. Since the debris alloys apparently experienced a high energy ocean entry, I feel justified in increasing the 0.064 mm loss by a factor of 20 = 1.28mm/yr for uncovered alloys. Note that the previously uncounted pitting etc losses would be very severe in a debris field, and would form on impact, instead of over a period of months, as in the case of the test alloys.
The MH370 debris photos show items that were in seawater for between 16 and 34 months. They indicate the remarkable endurance of the paint, fiber, and honeycombs etc which protected the aircraft’s surfaces, but it is now 60 months since this tragic loss, and the dissolution rate of the site must surely have an exponential component, I therefore think it reasonable to assume that, at the present time, the above coverings have only a 95% corrosion protection efficiency, and we accordingly reduce the previous loss rate of 1.28mm/yr to 0.064mm/yr = (0.064×10^-3)x4522 = 0.289m^3/yr = (0.289×2712) = 784kg/yr = 2.15kg/day.
Deep ocean currents are constantly–one might say perpetually—driven by density gradients caused by temperature and salinity changes. This is a real plus because the flow will drive the solutes at least somewhat to one side of the debris field avoiding a 360 dissipation. The speed of such currents are usually 1-10cm/s. Call it 5, and suppose a current is sweeping across the MH370 site, and carrying off the newly emerging solute of particulate and dissolved Al alloys. It will move or meander 4.3km in 24 hours. Any solutes caught in a descending seabed current will most likely be kept in the stream by turbulence, while their higher density (2.7g/cm3) will limit how far they can rise above the seabed, I therefore assumed that 15 degrees for vertical solvent dispersion.
Regarding horizontal dispersion, I could find nothing in the literature to advise me, so I carried out some tests with a colorant at a local river and concluded that a fanout of 25 degrees either side would be a reasonable figure. It follows that by the time the solute has travelled 4.3km it has fanned out 4.03km horizontally, and 1,16 km vertically. This yields a volume of 6.6km3. It follows that the above 2.15kg of solute has a density of (2.15×10^3)/6.6 = 325g/km3) = 325/10^15, which an AMS with a proven sensitivity of 1/10^15 would clearly have no difficulty reading.
Keep in mind that all these assumptions can be fully tested using existing Boeing debris fields before any big-time commitments are made.
One reason why I developed these ideas is because I can see just how much exhaustive and dedicated work has been put into finding hotspots by interpreting satellite exchanges that last barely a second; analyzing drift patterns subject to chaos; and trying to understand the machinations of a sickened mind that nearly 240 deceased people had thought to be the guarantor of their safety. I think it is time to look for simpler solutions, and If mine doesn’t pan-out, I believe someone else’s will.
©Neville Macaulife, March 26, 2019,
nevillema@aolDOTcom
@DennisW
RE: “Yes, human factors play a large roll I am sure of that. I am not an aircraft pilot, but I have “piloted” just about everything else.”
Human factors is a fascinating subject and it’s obviously very difficult to predict how humans will react to a given scenario. It might be the case that Boeing’s safety analysis assumed that pilots would instinctively trim in the event of a failure and keep the aircraft under control. The analysis might have failed to adequately consider that some pilots might become overwhelmed by the associated failures (ie stick shaker, ALT/IAS disagree, etc) and might fail to input sufficient trim to offset the MCAS inputs. Let’s hope the investigation brings to light the thinking behind the original safety analysis used to certify MCAS.
@Neville,
Great work! I hope it gets tried out. I think it has a high chance of success, depending perhaps on the reliability of the sample position estimation system – GPS etc not available down there!
Another idea I thought of would be to train dolphins, but I guess they cannot swim to the depths required. And I have no idea if they can sense aluminium ions anyway.
Regarding the survival of surface coatings etc, it’s probably better to look at the debris from crashes like the Lion Air 737 or Altas Air 767, as it is hypothesised that the largely intact pieces (flaperon etc) from MH370 detached before impact, during a high speed final descent, so are likely not representative of the rest of the wreckage.
@Peter Norton said: Does the new cellphone info allow any firm conclusions ?
What new information is there?
@oddball
RE: ”Regarding AoA related crashes, you may be in a better position to answer, as, right now, mention AoA and Google offers 737 Max pages. I can only think of a few off the top of my head: TWA843, XL888T, and perhaps a couple of Max crashes, but I’m sure there are plenty more.”
There have not been ‘plenty more’ accidents where a faulty AOA vane was found to be a factor. I searched several databases and only found the accidents you mentioned, plus a handful of incidents over a thirty-year period, one of them still under investigation.
Are AOA sensors perfect? No, of course not. They can fail just like any other mechanical device, but the statistics show the failure rate is very low.
RE: ”May I ask you a question? If I offered you an AoA sensor that self-tested and calibration-checked itself over its full operating range as soon as powered on (on the ground) – yep, swung itself from full up to full down and checked its readings – and which also validated itself routinely in-flight, supplied output data in digital format, and output a clear FAULT signal anytime it failed, as well as logging temporary in-flight validation errors as they occurred, would you still prefer to retain the standard model?”
How much is it going to cost me, including certification? Such a sensor would be more expensive than existing sensors and certification alone would cost a bomb. The expense probably wouldn’t be justified, given the low failure rate of existing sensors. Is it worth spending a lot of money on something with a very small marginal benefit? When resources are limited, the money would be far better spent on other programs that would have a much greater safety benefit.
RE: ”The aircraft manufacturing industry continues to churn out substandard product where, for example, a major spillage in the cabin could result in leakage into the Avionics Bay and take down the aircraft…”
Again, where’s your justification for such a statement? I assume you’re referring to the Qantas B747 incident that occurred during descent into Bangkok over 10 years ago. The incident was investigated and a number of safety actions were implemented to prevent a recurrence, including an FAA airworthiness directive requiring improved water protection on certain models of B747 aircraft.
Some bedtime reading:
The Economics of Safety
Let’s not forget that the more complex devices get, the more prone to failure they are.
Once software is in the mix, it gets even worse.
I would take a simpler, proven system over a highly complex one (disregarding the cost factor) any day of the week.
@ArthurC
Thanks – good point.
@ArthurC
Hey, I am a techie that got paid a lot to make complicated stuff. I never worried complexity, uncontrollable states, or SW bugs (SW always has bugs). You are scaring me. 🙂
Not sure if we are allowed to comment on the 737 Max here. I haven’t been reading recent posts so apologies @Victor if you prefer at this stage to keep this blog confined to MH370.
https://www.seattletimes.com/business/boeing-aerospace/a-lack-of-redundancies-on-737-max-system-has-baffled-even-those-who-worked-on-the-jet/?utm_source=twitter&utm_medium=social&utm_campaign=article_inset_1.1
@all
Way off topic, but the best read I have ever encountered on the climate change and energy generation issue. Please give it a careful read. Very worthwhile.
https://www.manhattan-institute.org/green-energy-revolution-near-impossible?utm_source=CCNet+Newsletter&utm_campaign=69fd5b83af-EMAIL_CAMPAIGN_2019_03_27_02_25&utm_medium=email&utm_term=0_fe4b2f45ef-69fd5b83af-36465589
@Julia
we are allowed to comment on the 737 Max here Absolutely. Lately, it’s been little else.
And this (your link) is an astounding story. We had pretty much figured that out here already, but now it’s widely published, Boeing’s reputation much be in ‘descending’ in flames:
“A single point of failure is an absolute no-no,” said one former Boeing engineer who worked on the MAX, who requested anonymity>/i>
It would be VERY interesting to know how this decision came to be made inside Boeing. If you want scary, Dennis…
@Dennis,
A thought provoking article, thanks.
The green driven ideology masters in may part of the globe have implemented the cancellation of hydro carbon extraction with an end date 25 years from now. Hopefully they will be disabused of their impetuous decision long before the lights go out!
@ArthurC
I would take a simpler, proven system over a highly complex one (disregarding the cost factor) any day of the week.
I have a very nice, healthy 4-legged donkey for sale. As a concession to technology, it has recently been shod.
Happy to take your modern 4-wheeled automobile in exchange.
@DennisW
One of my maxims is “sellers gotta sell”. Applies to those developing wind, solar, marine power generation systems, electric cars: if they built ’em, they gotta sell ’em. Mostly, the sellers are overhyping it. Just as the notion of personal UAVs is pervading the aerospace industry.
It’s my casual observation that the US has been behind the curve on exploitation of ‘renewable’ energy for electricity. This site shows the mix of generating sources providing electricity within the UK. CCGT (combined cycle gas turbine) produces the largest proportion but wind is growing. A recent conversation suggested that an additional 12GW of ‘renewable’ production would be necessary to power a ‘national fleet’ of electric automobiles.
The UK and other European countries are continuing to deploy larger offshore windfarms. Here in Belfast, the building dock at Harland & Wolff (yes, the Titanic constructor) is presently employed as a fabrication site for jacket foundations for wind turbine platforms allowing them to be sited in deeper offshore waters up to 55m. Similar construction to jacket leg oil production platforms.
I do agree that renewables won’t replace carbon based energy (and other) products but developing alternatives does provide new opportunities. Some of the engineering innovations used in offshore wind farm construction are fantastic (more opportunities).
\
The Seattle Times implies that three AOA sensors are required for redundancy management, however, that’s not strictly true. Airbus aircraft do have three AOA sensors, but even Boeing’s latest types, the B777 and B787, only have two. The B777 and B787 both use ‘calculated’ AOA, derived from ADIRU outputs, for redundancy management.
The Seattle Times article implies that three AOA sensors are required for redundancy management, however, that’s not strictly true. Airbus aircraft do have three AOA sensors, but even Boeing’s latest types, the B777 and B787, only have two. The B777 and B787 both use ‘calculated’ AOA, derived from ADIRU outputs, for redundancy management.
@Don
Cool site. Thx.
I had completely forgotten that the UK used 50Hz power.
@Don
Speaking of power, mine went down at the ranch about 3 hours ago. Power company website has not updated the cause or the restoration time. I may have to fire up a generator here before it gets dark.
At least I am not at my beach place where I have the only generator any where in the immediate neighborhood. When power goes down there, neighbors show up with an empty wine glass and sit around my fire until the power gets restored.
@Andrew
I’ll accept your results, that AoA-related crashes to date are few. I just believe that any crash avoided by improved technology ought to be considered when the costs are added up. How much does one crash cost, at the end of the day? Enormous amounts of money. The ones caused by such avoidable failures get me the most. And how many crashes are ‘enough’?
The loss of the TWA843 L-1011 in 1992 (despite no deaths) might well have been enough to supply much improved AOA sensors to all new large passenger aircraft for the following 10 years, for free. Then, the loss of the AirNZ A320 in 2008 could have kept the ball rolling. As I’ve said about finding MH370, I think we need to start thinking differently.
Sure, maybe AoA sensors are not the first priority item, but what’s on your Top Ten list to improve?
How much is it going to cost me, including certification?
Good question. The electronic components are a minor part of the costs. These days, they are cheap, if you stick to standard, high-volume items, ideally MIL-spec. The main expense no doubt lies in the mechanical parts – the vane (casting?), shaft, seals, bearings, housing (cast?), de-icing components. All these parts would be similar in a new, technology upgraded version, so those costs would also be similar.
The certification is another story. I don’t know, but whatever it costs. Interesting point – how did the certification of the MCAS system occur?
Again, where’s your justification for such a statement? (substandard product)
I guess you didn’t read the stories I linked in my earlier, moderation-delayed post. I won’t repeat the same mistake, so here are a few snippets:
Boeing item (Of course, they avoid self-criticism):
“Moisture-related problems … include water dripping onto passengers, electrical equipment failures… ”
Flight Safety story – galley-leak-douses-747s-electronics – this is the one you mention.
Aviation Today:
“Water seeping into the electronics and equipment (E&E) bay–causing terminal contactors to short out–has led to seven nearly identical electrical fires ”
pprune: b767-300er-avionics-bay water penetration, including (despite the earlier 747 incident):
“Indeed I believe the SHZ isn’t on all aircraft, never seen a Tech news briefing for the 747, I believe it’s prominently[sic] aimed at the 737.”
Most of these stories are relatively old, so let’s look at the very latest designs:
Airbus A350: This should scare the pants of most people who know anything about Lithium battery fires. Just LOOK where they have mounted the batteries – in the open, right in the middle of God knows what other electronics. Sure, they have installed a single “vent pipe” to serve both batteries in each pair, but the Li battery fires I have seen (videos) involving the much, much smaller batteries found in laptops still incinerate the laptop as part of the show.
Boeing B787: Boeing has used a notoriously unsuitable (maximum power density, high risk) model of Lithium-ion battery for the 787. I don’t know where the full article I read about it is now, but when I find it, I’ll post it. Meanwhile, there are these:
https://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems
https://www.nytimes.com/2014/12/02/business/report-on-boeing-787-dreamliner-batteries-assigns-some-blame-for-flaws.html
Boeing’s solution? As I recall it – build a stainless steel box around them, with a vent to the outside of the plane. So, when your batteries explode and you lose DC Power and deploy the RAT, hope that the explosion didn’t take out other critical wiring or equipment.
[Rant on]
I wouldn’t allow these installations in my house (would have to go in a shed outside), but they are good enough to fly through the sky. Yay!! But their adoption has nothing whatsoever to do with safety, and everything to do with making an extra dime. Any aircraft accident resulting from a Lithium battery failure will be an avoidable accident, because the technology is not necessary.
Recently, I saw a Security Camera video (taken within last 2 months), showing an electric bicycle battery going critical. The battery was about the length and 1/3rd cross-section of a loaf of bread. Just a low cost, low power density battery, but the burning was INTENSE, something did go bang and flared up, and the smoke filled one level of the underground parking area. Fortunately, all concrete construction meant no spread of fire.
I look forward to the day they launch concrete airliners!
[Rant Off]
@DennisW
It looks like an interesting read, however, after a first scan this article to me appears as rather politically coloured. I agree we need realism in the energy discussion, however the question is if this article provides it. I don’t know the “Manhattan institute” very well, perhaps a neutral local observer can provide some background?
Omitted the Airbus A350 Link.
It’s a guide for firefighters. Must be a new, airborne fire truck out there…
https://www.airbus.com/content/dam/corporate-topics/publications/backgrounders/techdata/general-information/Airbus-Commercial-Aircraft-A350-XWB-Lithium-batteries-guide-for-firefighter.pdf
@oddball
Regarding Li-ion batteries, you might be interested to know that Airbus has recently gone back to Ni-Cad batteries on the A350 for a variety of reasons, including revised certification requirements, logistical constraints on the shipment of spare batteries, and operator feedback over the complex maintenance and handling procedures for Li-ion batteries. Those factors (particularly the revised certification requirements) negate the technology and weight benefits that drove the initial Li-ion battery design. Newly delivered A350s all have Ni-Cad batteries and older aircraft are being retro-fitted.
Top Global Safety Issues
@Niels
The article merely reports what I have determined on my own. The combination of solar+wind+batteries is a non-starter.
@oddball
Re: ‘These days, they are cheap, if you stick to standard, high-volume items, ideally MIL-spec.‘
As someone with first hand experience of both military and civilian-commercial procurement practices I can tell you that ‘cheap‘ and ‘MIL-SPEC‘ are antithetical.
And to the extent that you are looking at building a better mousetrap, failures, problems and oversights relating to the pitot-static system have killed way more people than AoA-related issues.
@Don
I do agree that renewables won’t replace carbon based energy (and other) products but developing alternatives does provide new opportunities. Some of the engineering innovations used in offshore wind farm construction are fantastic (more opportunities).
I have looked pretty hard at the technologies involved in the wind, solar, and battery areas. The political climate is such that these areas are going to get funding (politicians are not the sharpest tools in the drawer), and there might be an opportunity to capitalize on it in the short term. Being risk averse, I concluded that it is better to focus on things that are actually practical, and have a future independent of any peripheral benefits.
Quite an interesting podcast discussion about flight deck automation and the false activation of protection modes as thy relate to the JT610 and ET302 accidents is available here:
https://www.ainonline.com/podcast/air-transport/2019-03-26/episode-19-flight-deck-automation-after-indonesia-and-ethiopia-ains-tales-flight-deck-podcast
The discussion includes some excerpts from an interview with Qantas Captain Kevin Sullivan (he was the Captain on QF72, the A330 that decided to go into business for itself back in October 2008).
There’s some interesting discussion around 26:30 – 33:30 mins about some of the factors that impact the effectiveness of simulator training.
In separate discussions I’ve recently had with B737 pilots from the two major Australian airlines they also spoke about the
Victor Iannello: “What new information is there?”
I am referring to all the information surfacing in the last couple of weeks regarding the FAH’s cellphone connection. There were some news articles and infos posted here in the comments. I lost track/oversight of what is/was reliable/factual. The sourcing for this topic is very confusing.
My impression was that nothing of what transpired recently permits any conclusion (other than FAH’s cellphone was ON when the plane passed Penang). I wanted to ask if I missed something.
Apologies, a bit of premature posting there.
Continuing on …
In separate discussions I’ve recently had with senior B737 pilots from the two major Australian airlines they also spoke about the fact that as training has moved to having an evidence-based focus rather than being tick-and-flick, historically very infrequent emergencies that are not mandatory items simply do not get sim time. And one of those historically very infrequent emergencies that is not a mandatory item is Runaway Stabilizer. While the immediate actions for Runaway Stabilizer are memory items (and are reviewed once every three years), prior to JT610 it simply didn’t figure as important enough to commit sim time to.
On the other hand, unreliable airspeed events were getting attention in training. IAS Disagree and ALT Disagree had received considerable training over the last few years due to a number of loss of control accidents associated with IAS Disagree. It was also a failure that apparently was often poorly handled in the sim, which increased its importance in the evidence-based training world.
So there was potentially a bit of a disconnect developing between Boeing and the airlines. Boeing were thinking that if MCAS does activate improperly the pilots will catch it because it will look like an event that they are trained for. The airlines, not knowing anything about MCAS, were proceeding along the lines that Runaway Stabilizer was such an extraordinarily rare occurence that we can ‘deprioritize’ in terms of sim training.
The poor old piggy-in-the-middle on the disconnect is the pilot. When faced with an event with multiple presentations – stick shaker, IAS and ALT DISAGREEs, uncommanded trim – it does not require a stretch of imagination to understand that one of those presentations might get mistakenly deprioritised or misinterpreted or both. Moreso, when the crew was ‘primed’ by the AFML and A-SHOR write ups for IAS and ALT DISAGREE accompanied by the trim running the wrong way.
@ Oddball
Thanks for your kind words on my water analysis search paper, it’s always nice to be appreciated, and, of course, you can always throw money.
It’s too bad the dolphins can’t go deep, maybe there’s a weird creature somewhere that we could train with the scent of another Boeing site, but what possible incentive could we give it? Nice idea about a water analysis at the Lion site by the way.
Do you think it possible that MH370 could have broken up in the air? If so, do you have any ideas how that would affect the size of the debris field?
Hi Neville,
Do you think it possible that MH370 could have broken up in the air?
I can’t speak authoritatively for others here, but I believe the general consensus is that the plane probably hit the water at high speed, high enough to cause some parts to break loose before the impact. I’m sure someone will correct me if necessary.
The early breakup parts would have then slowed down due to tumbling or other motions, impacted the water at much lower speeds and remained largely intact, whereas the rest of the plane is imagined to have disintegrated in a similar manner to Lion Air, Atlas Air and various other high speed crashes into water.
I don’t know what the maximum Vmo is at sealevel, or how much it can be exceeded before breakup begins, but I don’t believe it’s particularly high. As the air density increases, the maximum safe speed decreases.
My personal thinking on the size of (a) the debris pieces, and (b) the size of the debris field is, (a) probably much smaller than those of AF447, and (b) over a much larger area than AF447 (due to the smaller fragment size, and the potentially greater depth to the seabed). My view is that the pieces will be more bent and shredded than those of 447, so I would expect much of the surface coatings to be severely damaged as well. The rate of corrosion may be much higher in consequence.
@Andrew,
Airbus has recently gone back to Ni-Cad batteries on the A350
Thanks, didn’t know that, but commend their decision. Li-ion batteries are so finicky and fragile as well as prone to self-immolation.
Wonder why Boeing is so stubborn? Huh!! Maybe they are reckless! 😉
.
@Mick Gilbert
failures, problems and oversights relating to the pitot-static system have killed way more people than AoA-related issues
Would it be difficult to suggest what the main failures are – human error or system / component failure? After AF447, I devised a method for indicating blocked or restricted pitot tubes and static ports, but I’m guessing that problem is in the same league as AoA failures?
@oddball
Would it be difficult to suggest what the main failures are – human error or system / component failure?l
No. Typically the physical impairment of the device (mainly the pitot tube but sometimes the static port) by a blockage, generally by a naturally occurring mechanism (ice, water or insect infestation) but sometimes through human error (failure to remove covers), followed by improper handing of the event by the flight crew.
Ever since Henri Pitot stuck a piece of L-shape pipe in the Seine in the 1700s ‘stuff’ has been getting into the necessarily open end of the tube and blocking it up.
The Birgenair flight 301 crash is often cited as a ‘typical’ unreliable airspeed event due to pitot-static system issues that was subsequently poorly handled. The FAA compiled a short list of similar accidents here:
https://lessonslearned.faa.gov/ll_main.cfm?TabID=3&LLID=76&LLTypeID=14
Instead of citing Air Florida flight 90 I think that I would have included Austral Líneas Aéreas flight 2553.
@oddball
RE: “Wonder why Boeing is so stubborn? Huh!! Maybe they are reckless!”
It’s not a case of Boeing being stubborn (or reckless). The B787 has much greater electrical loads than the A350 (B787 is ‘all electric’, A350 is not) and it needs batteries that can deliver a large amount of power in a short period of time. I’m no expert, but my understanding is that NiCad batteries can’t meet that requirement without a huge weight penalty and a massive re-design of the electrical system. The B787 was already subject to more stringent battery containment requirements, so it is not affected by the new FAA airworthiness standards.
The A350, on the other hand, was designed with much lower capacity Li-ion batteries than the B787, but Airbus got cold feet after the B787 problems and the first A350s were delivered with NiCad batteries. They switched over to Li-ion batteries for subsequent deliveries, but have now gone back to NiCads for the reasons I outlined in my earlier post.
@Mick Gilbert
You can add last year’s MH134 out of Brisbane to that list. A massive stuff-up by all concerned, it seems. Fortunately, the aircraft landed safely.
@Peter Norton: Despite what Ean Higgins would like you to believe, there was no new information regarding the cell phone data. The First Officer’s phone registered on a tower on Penang Island as MH370 flew south of the island. It’s possible that that registration occurred at cruise altitude. The cell phone registration is another confirmation that the targets detected by primary radar were indeed MH370. We’ve known this for years now.
@DennisW, RE energy
There are indeed no simple solutions looking at the (future) global energy demand. However, it is important to acknowledge the progress made in energy transition in some European countries like Germany and Denmark.
Especially the energy buffering challenge is a tough one and not easy to solve through batteries. I guess that’s one reason why hydrogen as an energy carrier is still in the picture.
Neville: Re: “Do you think it possible that MH370 could have broken up in the air? If so, do you have any ideas how that would affect the size of the debris field?”
I think there is evidence in plain sight that 9M_MRO may have shed some external hardware on the way down (flap segment and flaperon). However, if that did occur, it would not change the size of the primary debris field unless the plane broke up into many pieces at high altitude. And even then, the large heavy pieces would still be detectable by an AUV.
@Niels
Especially the energy buffering challenge is a tough one and not easy to solve through batteries. I guess that’s one reason why hydrogen as an energy carrier is still in the picture.
At room temperature and pressure, hydrogen takes up to 3,000 times the volume of gasoline containing an equivalent amount of energy. Compressing or liquifying hydrogen takes a lot energy, is a materials challenge, and reduces the energy of the stored hydrogen.
Basically hydrogen is in the “last gasp” category of the greenies. In the UK storage in underground caves has been proposed. 🙂
As far as recognizing the efforts of Denmark and Germany, I am in the “yellow vest” category. I even ordered one from Amazon to wear when I visit my liberal college professor daughter and her friends.
In any case, this is my last post on this subject. I don’t want to further dilute Victor’s blog.
@Niels said: However, it is important to acknowledge the progress made in energy transition in some European countries like Germany and Denmark.
Progress would depend on what the objectives are. If the objectives are low cost, abundance, and self-reliance, Germany fails miserably.
@Andrew
Many thanks for your several comments. Regarding:
The B787 has much greater electrical loads than the A350 (B787 is ‘all electric’, A350 is not) and it needs batteries that can deliver a large amount of power in a short period of time.
This is very interesting. Li-ion is certainly capable of achieving that, and Yes, Ni-Cd is much less capable, size for size, but NiMH is still ok. I have since found this document:
https://www.boeing.com/commercial/aeromagazine/articles/qtr_4_07/AERO_Q407_article2.pdf
which provides a very useful overview of the 787 hybrid system. Even more interesting, if not telling, is that the word ‘battery’ appears just once in the text, and once in one of the diagrams. ‘Batteries’ does not appear at all. I am right in thinking that only the APU and Right engine can be started from the battery? It’s easy to understand why the 787 development ran so far over time and over budget.
My impression is that Boeing has tried to kill too many birds with one stone by using just one ‘battery’. I think Toyota’s Prius design is much superior. They use two batteries. A small, standard 12V deep cycle SLA battery to run all the control systems and to power things up, and a large Traction battery, which is Ni-MH in all the earlier models. (Some of the later models use Li-ion.) In earlier models, the traction battery is 200V, and this is used for engine starting, as well as motive power. Once powered up, the 200V battery constantly supplies power via a DC-DC convertor to charge the 12V battery and supply 12V power for headlights, wipers, window motors etc, etc. Using 200V or higher for engine starting makes huge sense, due to the much greater efficiencies, and lower current demands. It also means the battery cables can be much smaller and lighter, and the current capacity of the battery so much less. The Prius has no standard belt-driven alternator, and has a 3-phase AC VSD controlled electric air conditioner compressor (so the A/C continues even in traffic jams with the IC engine stopped) as well as two, 3-phase PMSMs [Permanent Magnet Synchronous Motors] as part of the drive train. Later Priuses also have an electric engine coolant pump, which makes good sense in an engine that is continually stopping and starting.
The Toyota Traction Battery ECU is religious about protecting the big battery, which is why they last so long without problems. In the US, they are guaranteed for 8 or 10 years, depending on state.
The downside is that (due to less stringent protections) the much lower cost 12V battery is neglected and abused, and does wear out much faster as a result.
My question is: what happens in a B787 when the Li-ion batteries “Chernobyl” mid-flight? I guess CBs trip, to isolate the batteries and at least stop adding fuel to the fire, but surely that leaves the DC bus in a precarious if not perilous position. Batteries are very useful as power smoothing devices, supplying current to sudden large load demands while the various controllers and voltage regulators respond to the sudden change in load. Apparently no battery meltdowns have crippled a 787 so far, but surely, a combination of some other fault and no battery is going to create mid-air mayhem sooner or later?
Thanks also for the addition of MH134 to Mick’s list. I have some research to do.
@Mick Gilbert
Many thanks for your very helpful response and link. I have some work to do, but this is useful. Once again, I am amazed at the seeming lack of innovation by the aviation industry, when it comes to improving on things which repeatedly cause mayhem, catastrophe and death.
I have some very simple answers to some of the problems reported, but want to see if I can refine them to cover more of the other possibilities.
P.S. @Mick or anyone,
Could you please supply me to some insightful references as to the existing designs of [I]AS hardware, and especially, the sensors, and info on Static port hardware design and operation?
Wow, Victor; low cost and abundance. In this era? An unexpected reaction to be honest. I immediately get the association with fueling up in the US where you would get a gallon of petrol for the price of a liter here. Interesting, I’m trying to understand.
https://www.express.co.uk/news/world/1106062/mh370-news-plane-shot-down-two-reasons-spt
@Niels
Wow, Victor; low cost and abundance. In this era?
We tend to ignore the inflation adjustment relative to pricing (of all things). A gallon of gas in the US costs less today than it did in 1978.
https://www.usinflationcalculator.com/gasoline-prices-adjusted-for-inflation/
When I first started driving you could buy gas for $0.25 a gallon.
@oddball
If you want to get a sense of the historical development of the device see patents US1620633A, US1971534A, US2042700A and US2179500A.
For an understanding of the device in its near-to-current amd current configuration see patents like EP3264103A1, US4096744A and US8060334B1.
@ALSM
It is odd that Wattrelos mentions the Inmarsat data relative to defining a path through seven countries (that claim not to have seen the plane) yet fails to explain how the same data supports the notion that the plane flew until fuel exhaustion.
Basically, the guy makes no sense at all.
@oddball
RE: ”I am right in thinking that only the APU and Right engine can be started from the battery?”
The B787 has two primary batteries: a main battery and an APU battery. If no other power sources (external power or an engine-driven generator) are available, the APU battery is used to start the APU, assisted by the main battery. As it states in the article you linked, ”the power source for engine starting may be the APU generators, engine-driven generators on the opposite side engine, or two forward 115V AC ground power sources. The aft external power receptacles may be used for a faster start, if desired.”
The main battery also provides power for the following:
– Electrical power up on the ground.
– Maintenance operations, including refuelling and towing.
– Backup power for electrical braking and in-flight standby power for the Captain’s flight instruments and essential avionics (prior to RAT deployment).
Further information on the mitigations to reduce the risk of Li-ion battery fires on the B787 can be found in the following article:
Boeing Says Dreamliner Battery Redesign Eliminates Chance of Fire
Note the comment:
The battery itself will be installed inside a stainless steel box with walls one-eighth of an inch thick. Contrary to what has been said in recent weeks, Sinnett told reporters the box is not simply designed to contain a fire, it prevents one from starting. “This enclosure keeps us from ever having a fire to begin with”, he said, referring to the newly designed container. He said there is not a sufficient amount of oxygen to “contribute to combustion” should the battery overheat or experience a short circuit. During six weeks of testing, he said, engineers used external heaters to intentionally overheat the battery in an attempt to induce a short. When the cells subsequently vented hot electrolyte as designed, engineers tried without success to ignite the vented gasses. Even after pumping additional oxygen into the box failed to ignite the mixture for more than an instant.
“There was a small amount of combustion for 200 milliseconds and it went out again,” Sinnett said.
RE: ” It’s easy to understand why the 787 development ran so far over time and over budget.”
Many people believe that Boeing bit off more than it could chew with the B787 because the aircraft’s systems are such a radical departure from previous designs. See what happens when you get ‘innovative’?
RE: ”My question is: what happens in a B787 when the Li-ion batteries “Chernobyl” mid-flight? I guess CBs trip, to isolate the batteries and at least stop adding fuel to the fire, but surely that leaves the DC bus in a precarious if not perilous position.”
I don’t know the details, but I assume an overheated battery would be automatically isolated from the electrical system. The aircraft has a huge amount of power generation redundancy, with six generators (two on each engine plus two on the APU) and multiple power converters. During certification, Boeing demonstrated the aircraft could fly for at least 330 minutes on one engine with only one generator operating. The main battery does not need to be connected to the DC electrical system for that system to remain operative.
787 Electrical System
RE: ” Once again, I am amazed at the seeming lack of innovation by the aviation industry, when it comes to improving on things which repeatedly cause mayhem, catastrophe and death.”
The aviation industry has some exceedingly clever people working on these and other issues every day. Have you stopped to consider that perhaps these problems are not as easily solved as you might imagine? Adding further complexity to a system runs the risk of introducing latent problems that will one day bite someone on the ass (or worse). Sometimes it’s a case of sticking with a proven technology (‘better the devil you know’) together with mitigations to reduce the risk caused by an equipment failure.
@Andrew
The theme of your post is definitely correct and appreciated.
It reminds me of a true incident invoving car navigation. Ferrari via Magneti Marelli installed high end navigation systems using our GPS receivers. Ferrari users complained of long cold starts in normal use.
We spend hundreds of hours testing every software release, but the Ferrari issue escaped us. It turns out that Italian drivers frequently turn off their ignitions approaching a red or yellow traffic signal to save gas. The depowered GPS receiver thought it was traveling at 80+ km/hr when it was re-energized. It was looking for satellites with an incorrect Doppler shift on power-up. How can anyone anticipate and test for a problem like that? Absolutely crazy.
Engineers are not evil or opposed to innovation. Sometime events in the field are not anticipated.
@DennisW
Basically, the guy makes no sense at all.
MIL-Spec is to Cheap as Extreme Suffering is to Sanity?
Not sure why Mike posted that one. It’s the “Express”. Just go to the Home page and search on aliens…
@Andrew
The Magneti Marreli problem described above was back in the day when we used an 8 bit 6502 in our receivers. Now-a-days with 32 bit processers and hundreds/thousands of correlators it is a non-issue. Time moves on, but we still have bugs, and weird unanticipated field issues. 🙁
Thanks – damn humans!
@DennisW,
Ahhh! The 6502. That’s going back, but I remember it. The cheapest, nastiest 8-bit CPU on the market at the time. Used IP filched from Motorola. Those were the days. As I remember, even the specs stated that it had 0 guaranteed input noise margin, which meant it was extra cheap to make because the reject rate was much lower. It was used in the Commodore VIC-20, and lots and lots of video arcade game boards. I remember particularly because the VIC-20 had a clock driver design fault – which, in that case, was not entirely the 6502’s fault.
@Andrew,
I understand that some of my comments criticising the aviation industry to which you belong are problematic. I’m sorry about that, but I feel some of the points I make are quite relevant, and in some cases just ought to be explored. I’m happy to debate these issues, as I believe it’s beneficial in the long run, and I hope we can stay on good terms. Warren Buffet promotes contrarianism, and I’m sorry if I’m also contrary. It’s my nature, nothing to do with Buffet, and it’s often not a popular position to take, but I still believe it’s a good thing to do. I’ve been called a Devil’s Advocate before, and not unhappy with that. Sometimes, I’m wrong, but I’ll do my best to keep that to a minimum.
The B787 has two primary batteries
I stand corrected. Thank you. That is good, as the failure of a single main battery would probably make a mid-air black start impossible, unless it has a very powerful RAT generator.
Boeing Says Dreamliner Battery Redesign Eliminates Chance of Fire
I’m not convinced that this is not just a lot of spin. Boeing says… Not an independent authority. Boeing was an early adopter, and all too often, being at the “bleeding edge” is not a great advantage. Anyway, I believe the 1/4 inch thick stainless steel box(es) weigh 85kgs apiece, and eliminate the weight advantage of the batteries in the first place, but sometimes, a design mistake cannot be corrected without a total redesign. Undoubtedly the next version will be better!
I’m also completely unconvinced that the original battery fires are now rendered impossible (as they claim), because it’s the energy stored in the batteries that creates the heat when it is suddenly released in a confined space. As another article I read on the subject concluded, “We don’t call them ‘charged’ for no reason.”
Reminds me of the “Terminator” movie, when Arnie tosses one of his now unstable fuel cells out the window, just in time. Tightly stored energy suddenly released creates an explosion.
See what happens when you get ‘innovative’?
As you rightly say, the 787 was “such a radical departure from previous designs.” I think it’s true to say they tried to redesign almost everything, and underestimated the task. But good on them. The sad thing is, they don’t seem to have learned so much, judging by the MAX.
Anyway, the innovations I propose are not nearly so huge. One small thing at a time, develop it, test it, put it through hell, then assess how it did. In fact, what I would prefer is to fit one new and two old in a double-redundant system and see how the people who use them like it.
The aviation industry has some exceedingly clever people working on these and other issues every day.
I’ll respond to this another day.
Have you stopped to consider that perhaps these problems are not as easily solved as you might imagine?
Yes. I have. Will take a look at the acknowledged IAS and ALT issues and come back with more thoughts. And questions. But I already know there are some simple things that could be changed.
@Barry Carlson. Another thought about whether it was the AoA (defect or set-up) or data processing was what led to the Lion crash, as I alluded to earlier it is quite possible that left stick shaking was left unreported not just during the flight before that but also flights before that. It is also possible that action was taken in those, unreported or unmentioned in the preliminary report, which successfully halted MCAS intervention.
Besides the record from the immediately previous flight there may have been data recorded in those earlier that was recovered from the recorder after the crash.
Since the AoA sensor that was replaced should be available for examination and defect proving/disproving it is quite possible that there is a ready answer to whether that was as the cause of the speed, altitude and AoA disparities.
@David,
In respect of ET320, the AoA vanes are likely to be bits of broken, bent and shredded metal – as is the rest of the aircraft, with the HS jack-screw and the DFDR / CVR only surviving because of their design strength and aft location.
In respect of JT610, elsewhere I have said. “IF the vane had been changed out after displaying the same problem on JT43, then the accident flight JT610 wouldn’t have had the same error.
The offset IMO is a downstream A/D problem, that wasn’t picked up probably because there was no comparison made between AoA vane physical position and A/D output prior to and after changing the vane.”
The ET320 situation is speculation, but the problem may have started with
with a blocked pitot that wasn’t identified during the take-off roll. The rapid increase in speed to exceed Vmo could be related. The aircraft must have been in clean configuration, allowing MCAS to become involved at some stage.
Ethiopian crash news:
https://arstechnica.com/information-technology/2019/03/initial-findings-put-boeings-software-at-center-of-ethiopian-737-crash/
Boeing: “We have uncovered nothing that concerns us in any of those areas…” (Spin??? Read: …because we already knew about it.) Actually, this appears to me to be an own goal by Boeing. The rest of the world can see that there is a serious problem, but Boeing says it’s not concerned.
https://www.aerotime.aero/clement.charpentreau/22512-ethiopian-737-max-the-mcas-was-activated-before-the-crash
Plus the NYT is in on it, and has an interactive graphical depiction:
https://www.nytimes.com/interactive/2019/03/29/business/boeing-737-max-8-flaws.html
And story:
https://www.nytimes.com/2019/03/29/business/boeing-737-max-crash.html
“It appears US and European regulators were aware at least two years before the first 737 Max crash that the method for controlling the plane’s nose angle might not work in certain conditions.”
https://www.theguardian.com/world/2019/mar/29/investigators-believe-anti-stall-activated-in-ethiopian-737-max-report-us-regulators-lawsuit-boeing
@oddball
Re: “It appears US and European regulators were aware at least two years before the first 737 Max crash that the method for controlling the plane’s nose angle might not work in certain conditions.”
I think that you’ll find that relates to the long known fact that the electric trim motor will not trim the stabilizer all the way to the full ANU and AND stops. Only manual trim (that is the ye olde hand-cranked trim wheel) can take the stab all the way to the stops. It’s not really relevant to the MCAS problem.
It seems that the media has got its interns busy trawling for any document that mention ‘B737’ and ‘trim’.
Crikey Mike! 😉
That’s not the same thing at all. Trust the media.
@Barry Carlson. “The offset IMO is a downstream A/D problem, that wasn’t picked up probably because there was no comparison made between AoA vane physical position and A/D output prior to and after changing the vane.”
Yes opportunity missed. It would be worth confirming the replaced left AoA sensor was not defective all the same I think.
Apparently there was no test to confirm blockage to be the cause of airspeed problems of “IAS and ALT disagree shown after take off”, as recorded after the aircraft’s penultimate flight, prior to flushing the left pitot and static air data modules.
Maintenance must have been aware that the left was reading higher from testing after earlier flights though had there been blockage of either pitot or static in the left system I would have expected the left IAS to have read less than the right after take off, not more.
@David,
“Maintenance must have been aware that the left was reading higher from testing after earlier flights though had there been blockage of either pitot or static in the left system I would have expected the left IAS to have read less than the right after take off, not more.”
The AoA data modifies the IAS, not the other way round.
I have a hard time with the notion of a fault in the processing electronics. That stuff is pretty reliable except perhaps for the angle to digit conversion. We delivered tens of thousands of car nav systems and I can’t recall a single gyro failure. Then again, I can’t recall much of anything (and don’t really care).
@Barry Carlson
The AoA data modifies the IAS, not the other way round.
Isn’t IAS what comes from the Pitot/Static system, and is Indicated AS, not Calibrated (“Calculated”) AS, which also includes the relevant AoA correction? In some more advanced implementations, the AoA is also ‘adjusted’, and I think IAS is one of the factors. Of course, 19 or 20 degrees is way outside any conceivable AoA ‘correction’.
@DennisW,
That stuff is pretty reliable …
except for when it fails, gets conductive contaminants dribbled over it, suffers lightning or static electricity damage, power supply (DC rail) spikes and over voltages, power supply output faults including noise, instability and under or over voltage, individual component failure and drift, capacitor leakage, short or open circuit, dry joints, resistor burnout, semiconductor failure, temperature sensitivity, you name it! Almost any of these can be caused (or permitted) by poor design, poor manufacturing (outsourced to ???) or inadequate testing.
Remember a few years ago the “bulging [electrolytic] capacitor” saga the killed thousands and thousand of computer motherboards? Nowadays, you can buy fake USB Memory sticks, that only save some of the data, maybe for a while… Maybe they simply got a bad (or faked) batch of components in the build.
@oddball
Yeah, we had a few of those issues. Funniest was “Pro Shot” – A GPS system we delivered for the golf industry – cart mounted to give you exact distance to the hole. Kids would pessure wash the carts and cause damage to the antennas (BTW antennas is the proper plural. Antennae is reserved for insects.) The damaged carts would oscillate and become known as “death carts”. They would bring down other carts and the differential base station at the clubhouse.
I don’t miss any of that crap including the free rounds of golf at nice country clubs. Not my kind of people.
@oddball,
Static Port pressure needs to be adjusted at a high AoA to correct the IAS. A faulty AoA will impact on the IAS and likewise the CAS.
In the case of JT610, the LH CAS was about 20kts more than the RH CAS as of lift off, and on occasions was even greater. The JT610 Preliminary Report has a suitable graphic.
@Barry Carlson
RE: “In the case of JT610, the LH CAS was about 20kts more than the RH CAS…”
I beg to differ; the Preliminary Report shows the left CAS was LESS than the right CAS. Similarly, the left altimeter was indicating less than the right.
@Andrew,
RE: “.. the Preliminary Report shows the left CAS was LESS than the right CAS”
Thanks, my mistake. I was looking at the LH AoA (red) and when writing it up forgot the LH CAS was green. The point being that IAS/CAS have a dependency on AoA, and the Pitot – Static Port differential decreases as the AoA increases.
@Andrew, I agree, having looked again.
What maintenance had to go on before this flight was the defect description,”IAS and ALT Disagree shown after take off” and recent write-ups of similar defects, with descriptions of consequent attempts at their resolution.
Presumably it was from the result of earlier tests that he identified the left as likely culprit, since the defect description does not say.
A partially blocked left static would lead to the left IAS trailing during a climb and a trailing barometric altitude also.
The maintenance signatory, again presumably, would be unaware that recorded data showed that the altitude and speed disparity in the cruise had remained roughly constant, that being was inconsistent with that fault. He might well assume that the left AoA was not the cause having been replaced and its installation tested; and since earlier tests had not resolved the issue in his mind there would be no gain in repeating them.
That scenario does not explain why he would flush the pitot system, a blockage of which would not cause the altitude mismatch, though that might have been a standard task called up by a generic defect listed in the IFIM.
He does not record testing for confirmation of a blockage before his flushing, which would have disabused him of that being the cause.
@David
RE: “That scenario does not explain why he would flush the pitot system, a blockage of which would not cause the altitude mismatch, though that might have been a standard task called up by a generic defect listed in the IFIM.”
My guess is that flushing the pitot ADM is a standard procedure in the IFIM for an IAS DISAGREE fault. The engineers might have flushed the left ADM because of the previous history, as you mentioned, or perhaps the aircraft’s Onboard Maintenance Function pointed them in that direction. I don’t know if the OMF is able to determine which side was causing the problem.
The maintenance write ups don’t show any additional troubleshooting, nor do they show any indication the IAS and ALT DISAGREE faults might have been related to the previously reported problems. Perhaps they treated the IAS/ALT DISAGREE and FEEL DIFF PRESS faults as isolated events and simply followed the IFIM procedures for those faults, thinking they were unrelated to the previous problems. I haven’t seen any mention of Lion Air contacting Boeing for advice.
@DennisW,
BTW antennas is the proper plural. Antennae is reserved for insects.
Well, I never knew that, but you are right. That said, it seems like the reason is only that RF Enginerrs can’t spell for doodoo. If you have nothing better to do, have a read of this:
https://www.rfvenue.com/blog/2016/03/02/technical-grammar-police-antennas-or-antennae
It’s interesting at least. Seems to me, Radio has stolen ‘antenna’ from wind-powered shipping, and they also took ‘mast’ but not ‘yard(arm)’.
As for GPS for golf carts! I was beginning to suspect you must have lived a protected electronics life, but Death Carts… Interesting story. Can be hard to foresee what abuses people are going to subject your clever creations to. Are you sure the GPS wasn’t so they could find their way back to the 19th?
@Mick Gilbert
“…see patents…
Many thanks, a great suggestion. Been trawling Google Patents, plenty of ideas there, some, quite insane! Haven’t yet found the measuring hardware of a pitot/static Airspeed measuring system, but presumably I’m searching by the wrong terms. Any suggestions?
Are you able to advise if there is a “rule book” for the design of IAS and ALT instruments, please? Things that you either must or must not do, for example, or laws that must be complied with?
@oddball: I don’t mind if the conversation drifts from MH370 as it helps us all to better understand aviation systems. However, designing new pitot-static sensing systems is getting a bit far from our mission, especially since doing this correctly for an airliner could require CFD analysis for transonic flows.
@Victor,
Fair enough! Does it help if I say my intention is not to develop any new pitot-static system, but merely to understand better how they currently work? My whole purpose in doing so is to work out better ways of preventing, detecting and correcting or circumventing Air Data system faults (including Air Speed, Altimeter, AoA & Stall warning systems), both prior to takeoff, and while in the air. As Mick has said, pitot-static system faults are responsible for significant numbers of incidents, crashes and deaths. To my mind, there is much room for improvement, though I agree, that doesn’t appear to be relevant to MH370.
Anyway, CFD Analysis of transonic flows is way outside my knowledge and interest.
My previous question to Mick relates to the possibility of altering the way pieces of existing pitot-static systems connect, the possibility of adding or altering things, and whether there are rules around that. No point investing time in considering what is disallowed. 😉
@oddball: For many reasons, this is not the appropriate forum for redesigning pitot-static systems for airliners.
@Mick Gilbert re 3/28 Post on 737 Stabilizer Runaway
Thank you for the information regarding runaway trim. It seemed reasonable to me to expect the pilots to just use the toggle switch to permanently turn off the trim motor. I assumed they trained for this and memorized the response.
Boeing clearly made errors in the design of MCAS, lack of disclosure in documents, and lack of specific training for MCAS failures – IMO all contributing factors to the crash of JT610 and ET302.
But I believed the primary cause was pilot error. I assumed runaway trim response was supposed to be practiced and memorized. It is unconscionable that an experienced 737 pilot would not know how to turn off the power to the trim motor. If the motor engages the trim wheel can overpower it and reverse the stabilizer and throwing the toggle switch disconnects it completely. You would think this would be embedded in the pilots brain. You would also think that a pilot would intentionally disengage the trim motor and use the manual trim wheel from time to time just to reinforce the use of manual versus automatic trim.
To me this seems like driving a car using cruise control and getting confused about how to stop before hitting the car ahead and not remembering to use the brakes. Just disconnect the trim motor using the toggle and manually trim using the big trim wheel!
@Hank, if I may?
To me this seems like driving a car using cruise control and getting confused about how to stop before hitting the car ahead and not remembering to use the brakes.
Using your analogy, it seems to me, they were trying to “use the brakes” but the cruise control would not disconnect. (Okay, in a car, the brakes are necessarily more powerful than the engine, so push hard enough and it will stop, but clearly, in the case of MCAS, the opposite is true. MCAS wins…)
From my point of view, if you are driving a car (say a Tesla) knowing that you have NOT activated the Driver Assist (self-driving system) – you are in “Standard Manual Control mode” (so you think, and believe) – when the car suddenly starts to jerk to the left (say, you are in the US). Naturally you respond with the steering wheel control, and are now firmly focussed on fighting to keep on course by repeatedly correcting it back to the right. The natural reaction is to imagine that there’s suddenly a major steering problem. The natural response is to stop the car. Not so easy in a plane.
You didn’t turn “this function” on, so how DO you turn it off? It’s undeclared automation, gone bad. First, you would have to recognise that the problem WAS the automation. But when you can’t grasp why this is happening… It wasn’t the same symptoms as runaway trim – the “thing” was fighting back.
Expecting the pilots to “pick up on this” when it suddenly happens is now proven to be an unreasonable expectation by Boeing.
This should be a big lesson to us all, as automation becomes a bigger part of our lives. The cross-over period is the most dangerous!
@Andrew. “I haven’t seen any mention of Lion Air contacting Boeing for advice.”
Or of involvement/supervision by the Chief Pilot with defect write-up standards, Chief Engineer with difficult diagnoses/persistent problems and both with aircraft release and acceptance standards.
@oddball
You’re making my point. The pilots are becoming button pushers and do not understand the basics of their airplane.
A 737 pilot is expected to understand how the horizontal stabilizer operates using the single electric trim motor and the manual trim wheels and the various failure modes. The electric motor is used by the trim buttons on both control yokes to move the jack screw. The autopilot (and MCAS) also can provide a signal to the electric motor. The large mechanical trim wheel can stall and override the electric motors and the pilots can place the stabilizer in any position. The pilots can turn off the trim buttons and the autopilot (MCAS) from operating the motor by using two toggle switches on the center console.
Runaway trim is not just a single hard-over motor command. It could be any anomalous operation of the trim system. It should be second nature for a pilot to just disengage the motor using the toggle if there is any concern over trim operation. The aircraft is fully operable using manual trim.
These pilots did not understand the very basics. They should not have been caught up trying to figure out why the motor keeps starting. Just turn it off! They somehow forgot or never learned how to just turn it off.
I agree about the automation problem. They forgot the basics of how the pitch trim system operates and never used the off switch. Very poor training on basic operation of the 737. On 610 the motor engages 20 times and the pilots never think to just turn it off – really poor understanding of the basic aircraft – bad training of basics and simulation of basic failures.
After all of the discussion about 610, how could the 302 pilots not have memorized the toggle switch and immediately disengaged. But maybe 302 is a different problem.
@Hank
People will form whatever view as to the cause(s) of the JT610 and ET302 accidents as suits them. I’m not interested in a prolonged exchange regarding the should haves, could haves amd would haves that may or may not apply in these cases. What I will say is that Boeing seemed to adopt a philosophy that ‘while our systems may occasionally fail that’s okay because pilots don’t‘. I’d argue that’s a questionable philosophy under even ideal conditions.
Frankly, rather than simply banging on about what’s ‘unconscionable‘ some consideration might be given to why, if the solution was ostensibly so blazingly apparent, did two crews fail to grasp it for such an extended period of time. In one case it took a third crew member about 7 minutes to comprehend and remedy the problem and in the other case, absent the luxury of a third person, it wasn’t spotted at all.
I’ve spent a fair bit of time over the past few weeks discussing this with former and current B737 pilots – all of them high hours, some ex-RAAF, all Captains and one a 10 year B737 pilot and Behavioural Studies/Human Factors graduate to boot. Virtually to a person, they have all said the same thing – it is simply not as straightforward as many commentators, Boeing in particular, would have you think.
Starting with the notion that Runaway Stabilizer is a memory item. Yes, it is. And prior to JT610 it was reviewed orally once every three years. It was rarely practiced in the sim (and I say ‘rarely’ to be conservative and allow for cases beyond the experience of the people I’ve spoken to because in their experience it was never practiced in any of their six monthly sim checks). Training these days tends to be evidence based and the overwhelming evidence with regards to Runaway Stabilizer is that it is such an extraordinarily rare event on the B737 that it did not logically require practising.
So then you’ve got initial type training where there is a Runaway Stabilizer exercise in the sim. Its presentation, however, is always uncomplicated. In training, it is never accompanied by concurrent failures.
So, you might well ask, would that previous simulation experience of an uncomplicated runaway stab, subsequently only infrequently refreshed orally, have served as a memorably useful example given what actually confronted the Lion Air crews?
The Human Factors fellow, currently a B737 Captain, had this to say,
‘Recognising the problem is not as simple as a runaway stab, because the system does not induce a continued runaway. It winds in trim, then stops, which is different to a runaway stab. Indeed, it is not a runaway stab, it is a different problem induced by the new MCAS on the Max that Boeing didn’t think needed to be highlighted to pilots, or even trained for at all. The runaway stab memory checklist fixes the problem, but only because it disables the electric trim system completely which almost fixes it by coincidence. It is not a Boeing procedure designed to combat a feral MCAS. I think Boeing will come up with such a procedure as a result of the accidents.‘
Take it or leave it, it would appear that he might be right on the last point. Reporting of the recent Boeing engagement with operator and flight crew representatives in the US suggests that Boeing will indeed be releasing a revised QRH featuring a new non-normal checklist to address erroneous MCAS activation.
On the topic of unconscionable behaviour, what I am keen to understand is whether Boeing actually simulated an erroneous MCAS activation, complete with all the accompanying concurrent failures, activations and alerts, with a suitably ‘naive’ flight crew. Boeing must surely have understood the possible failures that could trigger MCAS erroneously; did they ever recreate those scenarios and test their assumption that ‘the crew will catch this’?
Article in the WSJ:
U.S., Ethiopian Investigators Tussle Over 737 MAX Crash Probe
Tension over access to and interpretation of data comes ahead of a preliminary report on what happened to the Boeing plane
Tension is simmering between U.S. and Ethiopian officials as investigators prepare to release in the coming days an interim report about the Boeing Co. 737 MAX jetliner that nose-dived after takeoff from Addis Ababa on March 10, according to people from both countries.
U.S. investigators, according to people familiar with their thinking, have privately complained that Ethiopian authorities have been slow to provide data retrieved from the black-box recorders of Ethiopian Airlines Flight 302, which went down minutes into a flight to Nairobi, killing all 157 people on board.
American air-safety officials also have described what they view as an aloof attitude among the Ethiopians toward other investigators and say the Ethiopians have provided often limited access to relevant crash information, these people said.
A spokesman for the Ethiopian transport minister didn’t respond to requests for comment Sunday. Ethiopians involved in the probe, for their part, have chafed at what they see as American efforts to exert control over the preliminary report, according to other people familiar with the investigation.
The behind-the-scenes maneuvering, according to people from both countries, has impeded but not prevented the international investigators from working together.
The preliminary crash report, according to people briefed on the details, is expected to say that data analyzed so far indicates the Ethiopian accident bears important similarities to the crash of a Lion Air 737 MAX plane that went down in Indonesia less than five months earlier, including activation of an automated stall-prevention system and related features.
Boeing is in the process of rolling out a software fix and enhanced training related to the automated feature, called MCAS.
Publicly, U.S. officials have expressed satisfaction with the sharing of information. Last Wednesday, Robert Sumwalt, chairman of the National Transportation Safety Board, which is leading U.S. participation in the probe, told a Senate subcommittee his experts have gotten the data they need.
On Sunday, a Boeing spokesman said: “We have great respect for the Ethiopian government. As a party to the investigation, we’re following all international protocols and conduct all our work through” the U.S. safety board.
From the outset, though, Ethiopian officials have kept tight control of the probe, carefully guarding the recorder data and pushing back at what they view as efforts by Boeing investigators to influence and speed up release of the preliminary report on the crash, according to people familiar with the matter.
The Boeing spokesman said it was “absolutely not true” that the company’s investigators are trying to influence or speed up the preliminary report.
Safety experts have also tussled over the interpretation of certain data and their presentation in the report, according to people from both countries.
Ethiopian officials asked the French aviation accident investigation bureau BEA, which downloaded data from the black boxes, to permanently delete that information from its servers once it had been transmitted to Ethiopian authorities. The BEA has confirmed complying with the request.
Frequently, probes of airline crashes that occur outside the U.S. in which American investigators play a role prompt friction and outright disagreements between U.S. government and industry experts and local investigators leading the probes.
In the case of Ethiopia, the tension is exacerbated by the country’s limited staff and experience investigating major airliner crashes, according to industry and safety experts tracking the probe.
Officials in Addis Ababa, for their part, are still smarting from the results of an investigation into the deadly 2010 crash of an Ethiopian Airlines plane shortly after takeoff from Beirut. That probe, led by Lebanese authorities, found that the airline’s pilots failed to respond adequately to stormy weather during the aircraft’s ascent. Ethiopia at the time disagreed with the findings of the investigation, attributing the crash to bad weather.
“With this investigation, we are the ones who are in charge,” the chief of Ethiopia’s civil aviation authority, Col. Wosenyeleh Hunegnaw, said in a March 20 interview.
Another potential point of friction, according to some people familiar with the details, is the role played by experts from state-owned Ethiopian Airlines, which also faces scrutiny in the probe. The airline’s engineers have been providing technical support to officials from Ethiopia’s transport ministry.
MAX Notes
The fact that AOA vanes are now so heavily integrated into the flight control systems, has changed their status from a “secondary sensor”, to a “primary sensor”. They are now just as vital “in the system” as the pitot and the static.
As such, the existing design criteria of AOA vanes, and more particularly, the AOA “system(s)”, is the central, fundamental issue here.
This is basic airworthiness (or otherwise) system design, 101-Alpha for dummy’s, it is a “system integrity” issue.
They are way too simple, they are “stand alone” sensors, providing a “non-check-able” input, [not just “non-cross-checking” (left to right)], but not check-able at all (as currently implemented).
Consider existing normal takeoff procedure.
After “brakes release”, the takeoff roll proceeds, power is set, trimmed, etc.
At (say, 60 knots), PM calls “speed alive”, (PF glances down at his, yes alive).
At (say, 80 knots), PM calls “eighty”, (PF glances down, yep – 80 – left/right agree – cross-checked, all good, continue).
At (say, 110 knots) PM calls “V1”, (PF thinks “fly” – we go).
At (say, 120 knots) PM calls “rotate” (i.e Vr), (PF eases back, establish initial pitch angle).
Aircraft lifts off (Vlof – let’s say 130 knots) and the air/ground logic senses WOW status change, and goes from ground to air.
Aircraft is now climbing and accelerating.
PM monitors ASI, VSI and ALT.
ASI is increasing, ALT is increasing.
But now, the previously ZERO VSI, is reading a few hundred feet per minute climb.
This “new” data, taken with ALT increasing, causes PM thought logic to confirm climb, and he/she calls “Positive Rate” (meaning a positive rate of climb is confirmed).
PF then calls “gear up”.
And so the climb-out proceeds.
Note, that AOA, does not figure in any existing normal commercial jet operations procedure today, whether fitted, and/or displayed, or not.
Now, in the case of PK-LQP, (LionAir JT610) it did not go as normal.
If you look at the data traces (in the graphic linked above {from the JT610 Preliminary Report}), you can see a number of distinct and disturbing events “during” the takeoff roll.
I will use “x-axis” pixels as markers except as noted.
Pixel 246 = “Brakes release” (beginning of ground speed trace).
Pixel 252 = “AOA alive” – neither known, displayed, or called. (look closely – magnify it).
Two things happen. The Left (CPT) AOA begins to “decrease”, and the Right AOA (FO) AOA begins to “increase”.
This is the first clue. You would expect, that as speed increases, the AOA vanes would align to the relative airflow, from whatever their initial position was, at “brakes release”.
“Normally”, as I understand it, AOA vanes are balanced to be physically at “zero”, with no airflow. But, they are normally extremely low friction devices, and thus very sensitive to any force applied to them, whether it be by hand, by wind gusts, or by normal airflow when the aircraft is in motion. So, they could have been in “any” position at the beginning of the ground roll.
Now, the “AOA zero” line on the graphic is at “y-axis” pixel 434.
If you look closely, you can see that from x axis pixel 252, the right AOA comes alive, and steps up at x axis pixel 258, but note that the right ASI comes alive between those two events, at pixel 256.
This tells us that the AOA data comes into the FMC before the air speed data does.
The right AOA steps up again to its final position prior to eventual rotation.
But, during this time, the Left AOA has first moved “down” at pixel 252, then down again at pixel 258, and then surprisingly, stepped slightly up again, at pixel 265. This is very odd behaviour, and I can’t explain it. Can anyone else ?
From pixel 265 onwards, both AOA are steady, but vastly different.
The right AOA looks “normal”, but the left AOA is obviously too high, and obviously invalid.
The next event of the takeoff roll is at pixel 286.
Simultaneously, both AOA’s begin to rise by the same amounts.
It is logically evident that this is the point of rotation (Vr).
What is alarming, is that simultaneously (at pixel 286) the Left CPT stick shaker activates immediately.
The aircraft is still on the ground.
The nose wheel has lifted off with the pitch up, but the main landing gear wheels are still firmly on the ground.
The aircraft does not lift off until pixel 290 (air ground trace).
Also note that both the left and right speeds were “apparently” in close agreement during the takeoff roll, but began to diverge significantly at stick shaker activation, ie, at pitch up.
A clue perhaps ?
Why did the Left CPT stick shaker activate at rotation, and the Right FO’s stick shaker not activate (indeed it never did at all) ?
To see a clue, as to “a possible “why””, we need to jump forward, to where it ceased, and then reactivated itself.
Pixel 424 is where the stick shaker stopped.
So, the question is, why did it stop ?
Immediately prior, there had been a manual “up” trim input (which immediately followed an automatic “down” trim input).
That pilot trim input had only countered about one third of the preceding automatic down trim as shown on the “pitch trim position” trace. The pitch trim remained substantially “down”.
Interestingly, these events coincided with “both” AOA’s reducing, every so little, but reduce they did.
The right AOA was near zero, but the left AOA was still very high (by the same absolute margin from rotation), so presumably, that tiny Left AOA reduction “might” have been crossing the threshold of shaker activation, but “iff” it was, then that does not gell with the rest of the trace, so what else was happening ?
Go down to the speed and altitude traces.
When the stick shaker stopped, (pixel 424) the aircraft was both diving and accelerating.
Altitude was decreasing, airspeed was increasing, and ground speed was increasing.
One might assume (unwisely) that the airspeed was now high enough (at the AOA at that instant) to satisfy the stick shaker logic.
The flap lever had also just been moved from UP to Flaps 1.
In the brief interval that the stick shaker was off (between pixel 424 and pixel 440) the following occurred:
(a) The aircraft reached it’s highest air and ground speeds (before the fatal dive).
(b) The aircraft bottomed out of it’s dive, and commenced to climb.
(c) The flap lever was moved to flaps 5.
(d) The automatic pitch trim inserted another “down input”, and:-
(e) The pilot initiated another manual “up input”, (which began to move the stabiliser back up a bit towards zero), and both he and it was “still doing so”, at pixel 440, when the stick shaker reactivated.
At this point, “the aircraft was “effectively” out of pilot control”, because “it was not performing / responding to pilot expectations”.
Now, let us return to the point of indicated speed divergence.
It is interesting to note, that from rotation on wards, the Left CPT speed and ALT’s are consistently lower than the Right FO’s, and the ALT difference, in particular, appears excessive, i.e. non normal.
Therefore, I would be looking for a possible “static” issue, since the static is used for both airspeed and altitude.
If the sensed static pressure is higher than true static pressure, then the altitude will be reading lower than it should be, and the difference between the dynamic (ram) pressure in the pitot tube, and sensed static pressure, will be less, so the indicated airspeed will also be less than it should be.
One obvious possibility, is a fault in the Static CPT Left Air Data Module (which was not changed or checked from the previous flight) feeding corrupt data to the CPT Left ADIRU.
A second obvious possibility, is a fault in the CPT Left ADIRU itself (which also was not changed or checked from the previous flight).
However, if either were the case, then why was the speed difference only evident AFTER ROTATION, and not before, during the ground roll ? If it was due to some digital data issue, “corrupt bits” if you will, you would expect it to have been detectable from the trace as soon as we had “speed alive”, if there was sufficient granularity in the graphic to detect it. The graphic is not good, but I doubt it is there.
When you rotate the nose x degrees nose up, with the main wheels still rolling on the ground, you are changing the streamlines flowing down the fuselage from the nose, quite a bit. Commensurate with that, there is a change in the pressure field on the skin of the fuselage. These changes are known and are “calculated in” as corrections, based on the sensed AOA. In this case, we know that the Left CPT AOA sensor was sending false data, so those programmed corrections to the sensed static pressure would be erroneous, no doubt right from when “AOA alive” began sending that data to the computers.
With that in mind, and considering that the AOA issues were “supposedly” resolved after the previous flight, and noting the difficulties experienced on the aircraft’s previous flight, it raises (in my mind) a third, perhaps unlikely, but possible, prospect, of another issue entirely. What if there was some slight, perhaps not even obviously noticeable, left side external damage, in the area of the CPT static port, that could have been inflicted on the ground, prior to the flight the night before ?
Considering that the pitot tubes and AOA vanes are forward of door L1, and the statics are (I think) well behind door L1, maintenance staff would not have had any reason to have examined them, and any minor damage may not have even been detected by whoever may have done it, let alone noticed in a hasty walk-around.
The 737 Classics have combined pitot / static probes. The 737NG’s have separate statics, behind doors L1 and R1. Since those statics do not exist on the classics, and since the MAX was very new to the airline (both airlines), ground staff might not have been as vigilant as they need to be in this area, especially if they had been working on classics for years. Body – robot programming – is a powerful thing.
Thus, it could be, that a very minor “ramp rash” event, could be the common denominator in both disasters.
I don’t know if the statics on the Max are the same as on the NG’s, but look at this, for consideration.
We need a third switch on the pedestal.
MCAS on / off, (as well as the two existing trim switches).
I won’t even consider getting on a MAX, until it is fitted, and operable.
The very act of conceiving of, indeed the very act of proceeding to the implementation of, a system like MCAS, based on a single AOA imput, is a fundamental system design “brain fart” of the highest order. I am astounded that so many “smart engineers”, could not foresee the precipice looming before them, and pull the plug on it, as “a VERY bad idea”, right at the beginning !! They (AOA vanes) should not (in their current form) have ANY “COMMAND” AUTHORITY over flight controls whatsoever.
Regardless of what the geeks will say, my view, is that “An aircraft that is not Pilot-Worthy, is not Air-Worthy, period”.
Missing link from:-
“I don’t know if the statics on the Max are the same as on the NG’s, but look at this, for consideration.”
https://www.faa.gov/air_traffic/separation_standards/ase/2016_Event/documents/2.5_B737_Design_Differences.pdf
I always loved the centre line refuelling probe on the EA6B.
http://www.aiirsource.com/wp/wp-content/uploads/2015/08/ea-6b-prowler-takes-off-in-alask-1280×768.jpg
Perhaps airliners need to have a similar probe fitted, but use it for the Pitot, Static, and AOA vanes. They could be illuminated as well, so you could see them both day and night. Might have helped with AF447 as well ………..
@Mick Gilbert
Thanks for the detailed response. I am disappointed in the 737 simulator training and the low expectations for the pilot knowledge of the basic 737 flight controls. The pilot needs to know how to electrically disengage the trim motor and fly using only the manual trim wheels. It is easy to do during a simulator session. It is easy to do during a revenue flight just to know the aircraft. With all of these pilots it amazes me that the first response to an unexpected trim down event was not to just turn the motor off. And as you note it took the jump seat pilot some time to remember the switch.
Boeing MCAS design is poor and not putting it in the manual and providing training is highly suspect. But the basic 737 training and expectations of pilot knowledge of the flight controls by airlines seems very poor. From what you say about three year reminders this is poor. Just because a runaway is rare is not a good reason to not train the pilots to know how to immediately disengage the trim motor. It would be easy on a check flight for one pilot to hold the trim button while the other disengages the motor using the toggle switch.
Thanks for the information.
@Ventus45
I agree with a lot of what you say about the status of the AoA sensors – hence my earlier raves.
But, during this time, the Left AOA has first moved “down” at pixel 252, then down again at pixel 258, and then surprisingly, stepped slightly up again, at pixel 265. This is very odd behaviour, and I can’t explain it. Can anyone else ?
Maybe. I noticed that too, on my earlier examination, but concluded it was most likely “stiction – release – move – stiction – release – overshoot”, before returning to the proper position, as the airspeed ramped up, providing more impetus to the second (overshoot) move. Possibly indicates good vane design – stable at proper operating speed, but who knows? The right sensor seems to be much freer moving and settles to its ground roll position sooner than the left one, but that makes sense too, if the left one had just been replaced. The right takes two bites at it, the left three.
@Victor
“Ethiopian officials asked the French aviation accident investigation bureau BEA, which downloaded data from the black boxes, to permanently delete that information from its servers once it had been transmitted to Ethiopian authorities. The BEA has confirmed complying with the request”
Has this been confirmed? I find this extraordinary.
@DennisW or anyone who knows:
Reverting to MH370 issues for the moment, can I ask a couple of questions?
1. Where can I find the latest / most accepted MH370 Satellite Handshake data calculation results, please? I’m after the speed and distance numbers at the relevant times, derived from the BFO & BTO data, if that’s an answerable question.
2. On the B777, do all ‘permanently’ hinged doors accessible from the passenger cabin open outwards and forwards – and therefore would be impossible to open more than a small amount, at cruising (or any flight) speed (with or without cabin pressurization)?
@oddball
(1) Best place to start is probably Google Earth and you can put the ping rings visually on there, and then you can use the ruler function to see distances. Speed we do not know, but if you guess a flight path through the Arcs, then you know distance and time, and then you can calculate the speed needed for a given flight path. Simon Hardy’s YouTube flight path videos are instructive even if we do not agree with his flight path.
https://www.youtube.com/watch?v=JjC59H6QLdA
(2) My understanding is (a) there is a small bottom cargo bay door that could in theory be opened but trying to parachute out would probably be fatal, and (b) at some lower altitude around 15,000 to 20,000-ft the cockpit windows can be opened e.g. as a smoke removal emergency procedure.
@oddball,
A number of the IG have created very sophisticated path models which incorporate all the BTO and BFO calculations. Speed and distance are the unknowns. If we knew those we would be able to pinpoint precisely where MH370 crossed the 7th arc.
Two of the models are available here:
http://www.aqqa.org/models
http://www.aqqa.org/godfrey-model
@TBill
@Brian Anderson
Many thanks to you both. That will keep me quiet(er) for a while.
TBill,
For clarification, I wasn’t thinking of escaping from the plane. I imagine that would require at least a rear belly cargo door, and even then, would probably be very dicey. I’m back to my “think like ZAS might” mode, FWIW! I’ll rule out using any of the doors then.
It was just an ‘out there’ idea, but I think altogether too impractical to contemplate, while wearing a mask and carrying an Emergency Oxygen cylinder but planning to stay alive to the end. I think I’ll let Occam’s Razor loose on that one.
@Julia,
“has confirmed complying with ”
Yes, initially, I was a little horrified to see that too.
But hopefully, the F A _ I B is smart enough to figure this one out. Fortunately, the request was (apparently) quite specific and easily complied with. If you follow me ?
Hmmm
https://www.ft.com/content/a2b6c6ec-54bd-11e9-91f9-b6515a54c5b1 (Possible paywall)
“The US aviation regulator said it expected to receive a final version of the update in the “coming weeks”. Boeing had previously said it would submit its software fix by the end of March.”
Alt: https://www.smh.com.au/business/companies/additional-work-boeing-needs-more-time-for-737-max-software-fix-20190402-p519vn.html
And this again. Maybe it is true?
https://www.smh.com.au/world/north-america/regulators-knew-before-crashes-737-max-trim-control-could-be-confusing-20190401-p519k5.html
Ehhh! Please ignore this comment: “Maybe it is true?” It’s out of context, as explained earlier by Mick Gilbert: http://mh370.radiantphysics.com/2019/03/03/mh370-family-member-give-us-the-truth/#comment-22666
A couple of interesting articles from Aviation Week (free registration required to view):
Opinion: Redefining The Path Forward For Pilot-Automation Interaction
Airbus Takes Aim At Inconsistent Pilot Training Quality
Re: MH370 Flaperon / Flap trailing edge damage
At least one theorist believes that the trailing edge damage to the flap & flaperon found after a year or so in the sea is evidence of a soft landing on the ocean, claiming it shows these surfaces were deployed, and that water impacting the lower edges caused the ragged fracturing and loss of material.
Is there any information anywhere which details the supposedly fractured edges, to confirm that the loss of material was not caused by salt water corrosion? (Some photos seem to show fracturing of paint, running away from the edge, making physical fracturing seem more likely.)
Does anyone know what metal the flaperon trailing edge skin was made of? Not pure aluminium, I’m sure. Alloy, including, magnesium? Or something else? Aluminium would bend first, leaving at least some sign of bending even it it later tore off, but the damage appears to be by brittle fracturing. Even Magnesium alloy car wheels bend before they break.
I noticed in particular, in one of the simulation videos, that the flaperon is directly behind the engine, so that, when deployed, the lower (aft when stowed) edge in particular would tend to pick up a lot more soot and other combustion byproducts than the forward surface. Turbulence would probably cause both aftward faces to get a coating.
I know from experience that certain materials greatly accelerate corrosion in some metals. For example, you are not supposed to mark plain galvanised steel roofing “iron” with a graphite pencil, for exactly that reason. Similarly, simply allowing rain water runoff from a “zinc-alum” coated roof onto a galvanised roof with quickly destroy the galvanised roof. Equally, rusty water from exposed steel components will quickly cause pitting and holes in aluminium sheeting.
Could chemically accelerated corrosion be responsible for the loss of trailing edge metal?
As noted by David in another thread (http://mh370.radiantphysics.com/2018/05/16/sixty-minutes-australia-story-on-mh370-is-a-sensation/#comment-15813), engine detachment (upon impact, I presume) could also account for the flaperon damage, but that would seem to require a low speed impact with (presumably) the flaperon down, but does the damage appear consist with that possibility?
Atlas Air crash
Despite the source, the story seems reasonably well balanced:
https://www.wsws.org/en/articles/2019/04/02/amaz-a02.html
Wrong on one point, but forgivable.
YouTube: Pilots talk to KING 5 about 737 Max fix
https://www.youtube.com/watch?v=yIwPivRgJxk
Bloomberg:
Faulty 737 Sensor in Lion Air Crash Linked to U.S. Repairer
http://nymag.com/intelligencer/2019/03/is-the-boeing-737-max-worth-saving.html
Interesting comments from Jack Webb about the Piper Cheyenne and its SAS.
And the 737’s design & development history. Gloomy.
Faulty 737 Sensor in Lion Air Crash Linked to U.S. Repairer
What’s the bet – Returned NFF?
https://www.wsj.com/articles/ethiopian-airlines-pilots-initially-followed-boeings-required-emergency-steps-to-disable-737-max-system-11554263276
@David
“The pilots on Ethiopian Airlines Flight 302 initially reacted to the emergency by shutting off power to electric motors driven by the automated system, these people said, but then appear to have re-engaged the system to cope with a persistent steep nose-down angle. It wasn’t immediately clear why the pilots turned the automated system back on instead of continuing to follow Boeing’s standard emergency checklist, but government and industry officials said the likely reason would have been because manual controls to raise the nose didn’t achieve the desired results.”
The manual trim is quite slow to operate and it takes a lot of manual winding of the trim wheels to change the stabiliser position. As previously mentioned, in some situations the crew might first need to offload the elevators to unload the stabiliser and allow manual trim. If the aircraft had already developed a steep nose down attitude before the electric stab trim was deactivated, the crew might not have been able to quickly raise the nose. They might then have been tempted to restore the electric trim, which would obviously have restored MCAS.
If MCAS goes astray, I believe the pilots would first need to use the electric trim to trim the aircraft for level(ish) flight and then immediately deactivate it via the cutout switches. Recovery might not be possible if the aircraft has already developed a low nose attitude before the trim is deactivated.
@Andrew. Yes as you did mention previously, that sounds very likely.
Even so the stabiliser jack was reportedly found in the full nose down position. If so, they may not have even got to the manual trim.
Also, having restored auto trim they should have been able to trim nose up quickly, and even if not quickly enough the jack should have been off its stops.
Yet perhaps their natural response at that time was to pull maximum up stick.
@David
I guess it depends on how long they persisted with manual trim attempts before the electric trim was restored. They might also have deactivated it a second time before the crash. Hopefully we’ll learn more about the crew’s actions once the preliminary report is released.
@David
Further to my previous comment, if the crew only used very short electric trim inputs (‘blips’), as occurred at the end of the Lion Air flight, the MCAS trim inputs would have been greater and the stabiliser would have progressively moved to the nose down stop. At lower speeds, MCAS moves the stabiliser 2.5° each time, at 0.27°/sec. I don’t know what trim rate is available via the electric trim switches, but the pilot would certainly need to hold the trim switches for several seconds at a time to move the stabiliser 2.5° in the opposite direction to MCAS.
@oddball
RE: “And the 737’s design & development history. “
The 737 MAX is not ‘unstable’, as implied by the Intelligencer article. The airworthiness regulations dictate that the stick force a pilot applies to the control column must progressively increase as the angle-of-attack increases, making it less likely for a pilot to inadvertently stall the aircraft. The 737 MAX did not meet that requirement during certification testing because of the lift generated by the engine nacelles at high angles of attack. My understanding is the stick force reduced slightly at high angles of attack, which necessitated an artificial stability augmentation system to ensure the aircraft met the regulations. That does NOT mean the aircraft is unstable without stability augmentation.
@oddball
Re: Flaperon trailing edge
The MH370 saga is characterized by many differences of opinion within the overall larger community of independent investigators and book writers. The proposed cause of the flaperon trailing edge damage is one of the more contentious areas of disagreement.
From Reuters. Don’t miss the statement in bold at the end.
Now, the investigation has turned toward how MCAS was initially disabled by pilots following a checklist procedure, but then appeared to start working again repeatedly before the jet plunged to the ground, the two sources said.
Boeing issued guidelines to pilots on how to disable the anti-stall system after the Indonesian crash, reminding pilots to use cut-out switches in the console to shut off the system in the event of problems.
Cockpit procedures call for pilots to leave the MCAS system off for the rest of the flight once it has been disengaged.
The Wall Street Journal reported earlier that the pilots had initially followed Boeing’s emergency procedures but later deviated from them as they tried to regain control of the plane.
Disabling the system does not shut down the MCAS system completely but severs an electrical link between the software’s attempts to give orders to push the plane lower and the actual controls, a person familiar with the aircraft system said. Investigators are studying whether there are any conditions under which MCAS could re-activate itself automatically, without the pilots intentionally reversing the cut-out maneuver.
Leeham News:
ET302 used the Cut-Out switches to stop MCAS
@Andrew: I was advised by somebody close to the investigation that the trim was cutout during the descent and crash of ET302, which was the basis of my presenting a hypothetical case in a previous comment. That scenario might have been what actually occurred, and is now getting more attention in the media.
@Andrew,
That does NOT mean the aircraft is unstable without stability augmentation.
Are you saying this quote from the Intelligencer article is false?
“Because the FAA deemed the 737 Max too unstable to be used as a passenger aircraft, Boeing came up with an automated system…”
@oddball,
The flaperon skin is not metal. The skin is carbon fibre. Note how the fracture is primarily along the row of fasteners attaching the skin to the rear spar. Very possibly aeroelastic flutter during increasingly fast final spiral dive into the ocean caused the damage.
@Victor
I agree. You might have already seen that Peter Lemme has picked up on it too:
Trim Cutout with Severe Out-of-Trim Stabilizer can be difficult to recover
correction . . aerodynamic flutter, not aeroelastic.
@Andrew: Peter Lemme was issued a subpoena by a grand jury, as you can see in this Twitter thread. This is moving very fast.
https://twitter.com/AirlineFlyer/status/1112936433583566848
@Andrew
The 737 MAX is not ‘unstable’, as implied by the Intelligencer article.
At the rsik of beating on the same horse, I agree that the 737 Max is not “unstable”, but it might be “uncontrollable” which is a more severe condition IMO. An unstable system might be perfectly controllable, but it can take lot of skill and effort. A good example is riding a motorcycle in the sand. The front wheel sink has the effect of reducing the “trail” of the wheel and producing oscillatory feedback (we have all experienced this effect with a defective shopping cart :-)). Skilled riders live with it, don’t panic, and win races like Paris to Dakar.
In the case of the Max there are indications that perhaps a combination of circumstances can result in an uncontrollable state – that is a state where the pilots have few or no available means of recovery.
@TBill,
Thanks – didn’t know the extent of the disagreement, but can now see the basis for it. Also did a bit of reading on “the other channel” as I think it’s known.
.
@Brian Anderson,
The flaperon skin is not metal.
Ahhh! That’s a great help, thanks. It eliminates a lot of potential questions. I like the sound of aerodynamic flutter! 😉
But it seems both options remain open. I’ll give it some more thought.
In the meantime, can I ask you a couple of questions, please?
Regarding flutter, I guess that all testing, and presumably the design calculations, were based on fuel in the wing tanks. This would affect oscillation frequency and transmission characteristics, significantly I guess, compared with tanks that are “bone dry”? I guess empty wings might themselves flutter if the speed is high enough? Is it possible that the wings and the flaperon got into a resonance which first broke off the trailing edge then ultimately shook the flaperon off its hinges? (I note from elsewhere a guesstimated flaperon flutter frequency and life of 22Hz x 10^4 cycles (requires 7.5 minutes), which seems too long for a normal disintegration.)
Secondly, if a pilot put the flamed out plane into a vertical dive from 40,000 ft starting at say M0.7, what would the terminal velocity be at sealevel? [I recall reading about a German fighter plane (M-109?) during WWII that bit the dirt of Mother England so hard that the crankshaft concertinaed, so it must have been fairly quick.] Would the 777 wings stay on? (Wing disintegration might make the flaperon detachment ‘fit’ easier, but would the broken off wings certainly sink?)
Oh, another question occurs – could the RAT handle that speed, or would it disintegrate sooner?
Hi DennisW,
Can’t stay away! Same, same…
I say “too unstable” means not just unstable, but unacceptably unstable, from the FAA’s POV. It’s all starting to get ‘quite interesting’.
[Comments here are closed. Please continue the discussion under the new post.]