Lion Air flight JT610, with 181 passengers and 8 crew, was climbing out of Jakarta on a flight to Pangkal Pinang (Indonesia) when control was lost at around 5,000 ft. Soon after, the Boeing 737-MAX 8 aircraft crashed into the Java Sea northeast of Jakarta. Although we don’t know the cause of the crash, there were some anomalies noted on the previous flight related to sensor disagreements for speed and altitude which required maintenance. Some suspect that these previous issues might have been related to the crash. Luckily, the flight data recorder (FDR), commonly known as a “black box”, was recovered, and the approximate location is known for the cockpit voice recorder (CVR), the other “black box”, so there is a good probability that the cause of the crash can be determined.
Investigators are now claiming they have recovered 69 hours of data from the FDR, which would be sufficient to analyze JT610 as well as the preceding flight which had the anomalous behavior.
The last ADS-B data that we have from Flightradar24 has the aircraft at an altitude of 425 ft, a groundspeed of about 360 knots, and a descent rate of 30,976 fpm. That translates to an approximate true airspeed of 472 knots and a descent angle of about 40 deg. That suggests the aircraft impacted the sea with very high energy. Similarly, the final BFO values for MH370 suggest a downward acceleration of about 0.7g over 8 seconds, reaching a descent rate of about 15,000 fpm. Unless a pilot was at the controls and skillfully recovered from this descent, MH370 also impacted the sea with high energy. Therefore, the debris produced from the JT610 crash gives us some indication of the types of debris probably produced from the crash of MH370.
Indonesia’s National Search and Rescue Agency (BASARNAS) is in charge of the rescue and recovery operation for JT610, which is in water about 100 feet deep, with efforts reportedly hampered by strong underwater currents and limited visibility. Already one volunteer diver has lost his life while recovering body parts.
The video at the top shows floating debris for JT610. If the objects shown are truly representative of the main field of floating debris, it is evidence that a high speed impact produces only small floating parts spread over a fairly limited area. Now admittedly, a B777 is considerably larger than a B737, and the floating debris field should be easier to find. However, the surface search for MH370 in the Southern Indian Ocean (SIO) from the air began weeks after the disappearance, and the dispersive effects of waves and currents in the SIO are strong. The combination of a dispersed field and small parts might explain the failure for the air search to detect floating objects along the 7th arc. The small size of the floating parts might also explain why satellite images along the 7th arc have not spotted aircraft debris.
Despite the likelihood of small floating debris, the underwater searchers for MH370 expect to find a fairly substantial debris field (bigger than 100 m) and substantial, distinguishable objects such as the landing gear and engines, consistent with the debris field of Air France 447. This is also consistent with the parts of JT610 that have already been found on the seabed. For instance, the picture below shows an engine and part of the landing gear of JT610.
To locate parts on the seabed, BASARNAS is using a combination of technologies, such as multi-beam echo sounders (MBES), side-scan sonar (SSS), magnetometers, and remotely-operated vehicles (ROV). The SSS technology has been the workhorse for the subsea search of MH370, used in both the towed vehicles and the underwater drones.
The video below shows divers helping to retrieve debris from the seabed.
The debris recovered from the crash of JT610 helps explain why no MH370 floating debris was spotted by air and by satellite along the 7th arc, and why we remain hopeful that it will be detected on the seabed with sonar sensors once the correct search area is selected.
Update on November 13, 2018
Here’s a Wall Street Journal story that discusses the stall-protection system that likely led to the crash of JT610.
Boeing Withheld Information on 737 Model, According to Safety Experts and Others
Data related to a new flight-control feature suspected of playing a role in crash in Indonesia
By Andy Pasztor and Andrew Tangel
Nov. 12, 2018 11:16 p.m. ET
Boeing Co. withheld information about potential hazards associated with a new flight-control feature suspected of playing a role in last month’s fatal Lion Air jet crash, according to safety experts involved in the investigation, as well as midlevel FAA officials and airline pilots.
The automated stall-prevention system on Boeing 737 MAX 8 and MAX 9 models—intended to help cockpit crews avoid mistakenly raising a plane’s nose dangerously high—under unusual conditions can push it down unexpectedly and so strongly that flight crews can’t pull it back up. Such a scenario, Boeing told airlines in a world-wide safety bulletin roughly a week after the accident, can result in a steep dive or crash—even if pilots are manually flying the jetliner and don’t expect flight-control computers to kick in.
That warning came as a surprise to many pilots who fly the latest models for U.S carriers. Safety experts involved in and tracking the investigation said that at U.S. carriers, neither airline managers nor pilots had been told such a system had been added to the latest 737 variant—and therefore aviators typically weren’t prepared to cope with the possible risks.
“It’s pretty asinine for them to put a system on an airplane and not tell the pilots who are operating the airplane, especially when it deals with flight controls,” said Capt. Mike Michaelis, chairman of the safety committee for the Allied Pilots Association, which represents about 15,000 American Airlines pilots. “Why weren’t they trained on it?”
One Federal Aviation Administration manager familiar with the details said the new flight-control systems weren’t highlighted in any training materials or during lengthy discussions between carriers and regulators about phasing in the latest 737 derivatives.
Boeing declined to immediately answer specific questions Monday. “We are taking every measure to fully understand all aspects of this incident, working closely with the investigating team and all regulatory authorities involved,” the company said in a statement. “We are confident in the safety of the 737 MAX.”
On Monday, an FAA statement reiterated that the agency had mandated flight manual changes to emphasize proper pilot responses to the new flight-control systems. “The FAA will take further action if findings from the accident investigation warrant,” the statement noted, but declined to comment further.
Boeing marketed the MAX 8 partly by telling customers it wouldn’t need pilots to undergo additional simulator training beyond that already required for older versions, according to industry and government officials. One high-ranking Boeing official said the company had decided against disclosing more details to cockpit crews due to concerns about inundating average pilots with too much information—and significantly more technical data—than they needed or could digest.
Minutes after takeoff from Jakarta in good weather, Lion Air Flight 610 experienced problems with airspeed indicators and a related system that feeds data to computers about the angle of the nose. The crash killed all 189 people on board.
Investigators haven’t described the precise sequence of events that caused the twin-engine jet to plummet into the Java Sea at a steep angle and high speed. But Indonesian authorities already have called for stepped-up pilot training and suggested they are delving into design issues. In the U.S. at least, substantial training changes will have to wait until new flight simulators are delivered to carriers.
The focus of the probe is shifting away from its early emphasis on individual system malfunctions and suspected pilot mistakes, according to people tracking developments.
Instead, these people said, U.S. and Indonesian crash investigators increasingly are delving into the way the MAX 8’s automated flight-control systems interact with each other, and how rigorously the FAA and Boeing analyzed potential hazards in the event some of them malfunction and feed incorrect or unreliable data to the plane’s computers. Swiftly turning off the automated feature is the solution in such cases.
Earlier 737 versions have different stall-protection systems, that don’t automatically drive down the nose even when other functions of the plane’s autopilot are turned off.
Yet operation of those older systems was highlighted in training over the years, and pilots had to memorize steps to counteract potentially dangerous unintended consequences. MAX 8 training materials don’t include a requirement to memorize the steps to turn off the stall-protection system.
Stepped-up scrutiny of the latest 737 MAX features applies to more than 200 of the models that have been delivered to customers around the world, including Southwest Airlines , American Airlines and United Airlines. Boeing’s 737 factory near Seattle currently churns out 52 planes a month.
“We’re pissed that Boeing didn’t tell the companies and the pilots didn’t get notice obviously, as well,” said Capt. Jon Weaks, president of Southwest Airlines Co.’s pilot union. “But what we need now is…to make sure there is nothing else Boeing has not told the companies or the pilots.”
Like Mr. Weaks, some FAA managers and industry officials aren’t satisfied with what they contend is Boeing’s belated candor.
Boeing is working on a software fix, according to industry and government officials, that would likely mitigate risks. On Saturday, the company went further than before in spelling out dangers pilots can face if they misinterpret or respond too slowly to counter automated commands.
In a message sent to all 737 operators, and reviewed by The Wall Street Journal, the Chicago plane maker explained in painstaking detail the engineering principles and operational parameters behind the latest automation.
That message was more detailed than the bulletin Boeing voluntarily issued earlier, alerting pilots about the potential hazard—and touching off debate over the stall-prevention system’s design. Within hours, the FAA followed up with its emergency directive mandating changes in flight manuals.
Such interim efforts “are very appropriate in the near term to increase pilot awareness,” said John Cox, a former 737 pilot and ex-crash investigator for North America’s largest pilots union who now consults on safety for carriers and business aviation.
Boeing’s latest communications with airlines prompted American’s union to alert its members. “This is the first description you, as 737 pilots, have seen,” the union pointedly told pilots in a memo, referring to the 737 MAX stall-prevention system. Noting the system wasn’t mentioned in American Airlines’ or Boeing manuals, the union memo added: “It will be soon.”
The ultimate way to counteract dangerous automated nose-down commands is basically the same for old and new systems, though checklists and procedures for the 737 MAX 8 entail more steps and take more time. Investigators and safety experts are convinced that as the emergency worsened, the Lion Air crew had barely seconds in which they could have diagnosed the problem and taken action to save the aircraft.
Shortly before the plane crashed, according to local Indonesian media reports, one of the pilots told air-traffic controllers about difficulties controlling the plane.
Thanks for this post on JT610, Victor. The 69 hrs of FDR information will likely help them understand what caused this crash. But regardless of the cause, the surface and ocean floor debris fields are providing valuable insight into what a high energy impact looks like, with implications for MH370.
@airlandseaman: Agreed.
For reference, this story contains seabed photos of AF447 as released by the BEA. The condition of the landing gear and engine is similar to JT610.
@Victor Iannello,
The small diameter of the engine hulk has me thinking it might be the APU rather than a main engine.
The very small sizes of floating debris also makes me think the Pemba flap and the flaperon came off in the air. There don’t seem to be any intact flight control structures left floating in this crash, and maybe not for MH370.
@Victor
Please find attached a link to a Google Earth map of the final track marked in red, the location of the 2 flight recorders marked R1 (recovered) and R2 (located) and the 3 boats currently on site marked with a B.
https://www.dropbox.com/s/yqlwji4g9g556em/JT610%20Crash%20Site.png?dl=0
@Victor
I should have said the 3 boats on site recorded by Marine Traffic.
There is a much larger number of boats on site, which are not sending satellite position updates.
@DrB
This 737 MAX was powered by a CFM LEAP-1B engine, its LP fan has 18 carbon composite fan blades. The hub, facing the camera in Victor’s still image, has 18 slots and other close up images show remnants of the carbon composite blade roots still in the hub. Even the compressor casing, forward of the combustors, is torn away.
Definitely an engine, not APU.
@DrB: I doubt it is an APU. A single stage centrifugal compressor and a two-stage axial turbine would be more typical of an APU, such as the Honeywell 131-9D. In the photo above, multiple axial stages (each with its own disk) and what looks like two spools is apparent.
Yes, I agree that flight control surfaces might have separated from MH370 before impact.
@Richard Godfrey: Thank you. The FDR and CVR were right where you’d expect them to be.
@Victor,
Yes, I agree that flight control surfaces might have separated from MH370 before impact.
I am aggressively skeptical of that hypothesis, as well as the dive followed by a glide scenario. The French were fairly clear on water damage relative to the flaperon trailing edge. How else would you explain it except flutter which was not mentioned in the French report?
The two week interval relative to the SIO search is huge.
> Victor Iannello: “sensor disagreements for speed and altitude on the previous flight”
I have a bad feeling that we see a repeat of AF447 and QZ8501 with an unsuccessful stall recovery and an unreliable airspeed condition as in AF447.
Although possibly unrelated to JT610, I am still bewildered every time I am reminded of the many lessons-not-learned and parallels between AF447 and QZ8501, for example the dual side-stick input and the exact same linguistic misunderstanding between the pilots:
« The example of miscommunication between the pilots was when the plane was in a critical stalling condition, the co-pilot misunderstood the captain’s command “pull down”; instead of pushing the airplane’s nose down […], he pulled the stick back […]. Because the captain was also pushing the stick forward and because Airbus has a dual-input system, the two stick inputs cancelled each other out, which led to the plane remaining in a stall condition until the end of the black box recording. (See the similar side-stick control issue in the Air France Flight 447 accident.) » (wiki)
@Victor,
Is there a way to gain access to the satellite data (if any) of JT610 to see whether high-energy impact would result in negative BFO values like the -2 value with MH370?
@TBill
@Victor
RE: “I take it a B777 does not have a STS system, but a 737MAX does? Perhaps due to higher power engines relative to the size of the aircraft.”
The B777 FBW flight control system has a speed stability augmentation function within the primary flight computers. The B737 MAX has a conventional flight control system; only the spoilers are FBW. Consequently, it has a separate speed stability augmentation system, known as the Speed Trim System or STS.
The B737 STS is designed to improve the aircraft’s manual handling characteristics under certain flight conditions (low gross weight, aft centre of gravity, high thrust). It does so by changing the incidence of the tailplane, which increases the control column force and tends to restore the aircraft back to its trimmed speed. The STS ensures the pilot must apply a significant control column force to increase or decrease speed by changing the pitch attitude.
@DrB
RE: “The small diameter of the engine hulk has me thinking it might be the APU rather than a main engine.”
As Victor and Don have already mentioned, the photo is definitely an engine. The engine core is quite small once the fan, cowling and ancillary bits are stripped away, as you can see in the following photo of a LEAP 1B engine core under assembly:
https://www.aero-mag.com/wp-content/uploads/2017/08/234234234234234234-e1504174772170.jpg
@haxi: I doubt it. JT610 would have to have a terminal with the same Doppler pre-compensation algorithm, and there would have to be a SATCOM transmission at the time of the descent.
Reuters is reporting that JT610 had faulty airspeed indication.
@Andrew
Interesting that 737 MAX is not FBW.
JT610 would not have needed satcom for that short, local flight. Even it it did, the AES would not have been transmitting much (if anything after wheels up) during a 13 minute flight.
Bobby: Re: “The very small sizes of floating debris also makes me think the [MH370] Pemba flap and the flaperon came off in the air. ”
The only 610 photo I’ve seen so far that comes close to a flaperon or flap segment is here: http://bit.ly/2PEQN1V It looks like it might be a wingtip. What ever it is, it is the largest piece of the wing (or tail) I have seen that is not related to the landing gears or engine. I think we will learn a lot more from JT610 about the implications for MH370. But the preliminary photos offer more evidence that the Pemba flap and the flaperon did separate prior to impact.
Dennis: The French analysis was flawed in several ways. They speculated that the flaperon probably did not separate in the air based on a critical assumption. They assumed that if the flaperon separated in the air, it would descend in a stable, leading edge (LE) down attitude, reaching a very high speed and crash into the water LE down, causing much more damage to the LE. They provided no data or information to back up this claim. The simple fact is that a relatively flat object will tend to fall like a leaf, not the way the French assumed. Time to toss some more models out the door at 1000 feet.
@Mike
I have no opinion on how a flaperon separated in flight would fall. Your leaf analogy sounds plausible to me. My issue with the flaperon is the trailing edge damage. I can’t conceive of how it could have occured except by flutter or contact with the water while still attached to the wing. You would think the French analysts could identify flutter damage versus water contact damage.
@Victor
Re: Lion Air
I see some articles saying the Lion Air ELT was recovered, but I have not heard if the ELT signal was heard, which we would say probably not for this type of crash.
@TBill
RE: “Interesting that 737 MAX is not FBW.”
The 737 MAX is simply an incremental update, designed to keep the aircraft competitive with the A320 NEO in terms of efficiency. The major changes include advanced, fuel efficient engines; aerodynamic tweaks to decrease fuel burn and FBW spoilers to reduce weight. I suspect that a full FBW flight control system would have been too expensive and taken too long to develop.
@DennisW Re: “I can’t conceive of how it could have occured except by flutter or contact with the water while still attached to the wing.”
You can see similar damage here without water contact and no mention of flutter:
http://code7700.com/accident_china_airlines_006.htm
(I hope I never get a flight with those guys driving. Basic mistake – trust your instruments, not your inner ear.)
@Andrew. In the 777 the autopilot disengages on loss of transfer bus power. It was conventional wisdom on blogs that this was because of pitot tube heat loss, a consequence of that, immediately after which airspeed data could be trusted no longer.
A couple of months ago I believe you said you had found that what prompted A/P disengagement, while still due to possible input data corruption, was more complex than just this pitot heat loss, though without giving details.
My (loose) speculation is that the BFOs could be affected by whatever the cause of the unreliable data is, for 2 reasons. First the assumed 1 min for the SDU to warm up after APU auto-start on engine run-down may be shorter than restoration of reliable data to it generally. Second, if pitot tube heating still has a part in this, a question is whether after a minute’s cooling while the APU comes on line, heating time of a minute while the SDU comes on line will be sufficient.
I note that there is no pitot tube temperature sensor to say when its output can be considered reliable or not. In other words SDU BITE might not test for integrity of all data.
Any comments please?
@TBill
Yes, recovery of a piece of debris, identifiable as the ELT, has been reported. The colour of the ELT may have attracted the attention of a diver or ROV pilot searching for the CVR. The recorders and the ELT are located at the rear of the fuselage.
On the day of the accident, BASARNAS did confirm that no transmission had been received by their SARSAT terminal.
@David
The position and attitude data requried by the AES is sourced from the ADIRU, but the inertial reference part, not the air data psrt of that system.
@Don Thompson. My thanks for your patience. I know you have expounded on this before.
What underlies my interest is why pilots are automatically denied the autopilot in a double flameout until the APU fires up or an engine relights and gets back above idle. Powering it by DC or standby AC would leave it engaged unless deselected by deliberate switching or control movement. A pilot might be busy with other things.
A possible reason for not doing that, relying on the same ADIRU data that the SDU/AES does, is that it is not ‘good’ enough. That leads to my query as to what the SDU BITE will accept as good enough.
@David: The SDU relies on latitude, longitude, groundspeed, track, pitch, bank, and heading to steer the antenna and pre-compensate for Doppler shift. The SDU doesn’t care about air data. On the other hand, stability enhancement and envelope protection need air data. Based on this, it’s no surprise that with the loss of full capability of air data, the flight control mode degrades from NORMAL to SECONDARY, and envelope protection and the autopilot are lost, while the SDU functions in the usual fashion.
@Victor. Fair enough. Thank you.
> TBill says:
> @Peter Norton: Thank you I will give it a try when I get a chance…not sure if that
> will work when I have an aircraft flying in flight sim. I guess I can toggle back and forth.
Please let me know when you have tried.
@David
RE: ‘A couple of months ago I believe you said you had found that what prompted A/P disengagement, while still due to possible input data corruption, was more complex than just this pitot heat loss, though without giving details.’
I did give details! On 25 August, I commented:
‘The loss of power to both AC transfer buses would have caused the loss of a number of systems and sensors that are required for the operation of the PFCS in normal mode. Consequently, the PFCS would have automatically reverted to secondary mode, resulting in the loss of the AP and TAC, etc. In the past it was thought that the mode reversion was caused by the loss of pitot heat. However, recent advice indicates the reversion is caused by the loss of other sensors required by the PFCS. The loss of pitot heat would only cause a mode reversion if the system detected invalid air data.’
On 26 August, you asked:
‘Are the transfer buses the source of power for the “other sensors” or are the main buses? Any more on which they are?’
I replied:
‘I don’t have a comprehensive list, but my understanding is that they are mostly position sensors associated with actuators controlled by the L2 ACE. The L2 ACE is only powered by the L 28V DC bus, which is normally supplied by the L AC transfer bus (via the L TRU).’
In short, the loss of pitot heat alone does not cause reversion to SECONDARY mode unless the air data actually becomes invalid. The reversion to SECONDARY mode is caused by the immediate loss of several other sensors that provide data required by the PFCS. However, as Don and Victor have already mentioned, the data required by the SDU is not affected.
@Andrew. Thanks for that refresher.
15 demerits to me.
Regarding JT610, Geoffrey Thomas is reporting that sources within Lion Air say the aircraft’s tech log shows a record of a problem with “elevator feel and control” on the last flight the day before the tragedy. This is in addition to false airspeed indications.
It would seem that those two problems are related. For instance, an incorrect airspeed input to the STS might cause incorrect trim and incorrect elevator feel, making it harder to manually control pitch.
@Victor
If STS comes on when A/P is off, and A/P is off due to bad airspeed data, it does not really make total sense that STS would use the same bad airspeed data. But it does sound like something could be wrong with STS system, or pitch/elevator controls. Igf you are heading for water surface, might as well try to pull off a Sully-style dicth, unless it was more like Air Alaska with no control of flight surfaces.
@Victor
You stated in a comment on the previous post “I am not seeing an obvious way to use the drift data to discriminate impact latitude along the 7th arc.”
Please find links below to 3 annotated drift maps from various start latitudes of around 22°S, 26°S and 31°S.
All 3 take 477 days ± 8 days from the 7th Arc to Madagascar. All 3 end up at a latitude of around 18.8°S ± 2.3° on Madagascar.
All 3 follow a similar transoceanic track, following the start phase:
https://www.dropbox.com/s/gpa4xft9kcudgd3/Drift%20Map%2021.9666S%20103.5739E%2021.1447S%2048.4794E%20477d%20Annotated.png?dl=0
https://www.dropbox.com/s/nb1k6de5irl56hn/Drift%20Map%2025.6655S%2099.6084E%2018.2956S%2049.4172E%20484d%20Annotated.png?dl=0
https://www.dropbox.com/s/qx3hjw2j8ulctdy/Drift%20Map%2030.7332S%2097.5208E%2017.1433S%2049.5997E%20469d%20Annotated.png?dl=0
I can appreciate the reason for your statement above. I think we need a much broader based statistical analysis from the simulated drift models to be able to draw any conclusions from the drift analysis. However, the drift models must include all the likely or confirmed MH370 discoveries made so far, from Mossel Bay, South Africa to Pemba, Tanzania. The northern bias in David Griffin’s model, almost excludes the southern most find at Mossel Bay, South Africa and makes you wonder how Pemba, Tanzania was the only discovery north of Madagascar.
@Richard G: Yes, looking at it from 40,000 ft…for a broad range of impact latitudes, a lot of debris is predicted to land in Madagascar. A lot of debris was found in Madagascar. It was also the best searched shore in Eastern Africa. Beyond that, we are trying to make sense of what seem like outliers.
@Victor,@Richard,
I don’t believe it is necessary to consider a broad range of latitudes, or do any more work on the drift analytics. Richards’ work has shown (to my satisfation) that latitudes North of 20S are very unlikely based on the debris we have identified so far (including outliers). We have searched +/-25km of the 7th arc from 38S to 25S. All that is left is 25S to 20S at +/-25km. I have shown that there is greater than an 80% probability of finding the wreckage with an underwater search of this area. A conclusion I can now safely put in the “martingale” category. Richard has already done the “heavy lifting”.
There is the issue of reconciliation with the group advocating a wider search width. I have no interesting in that reconciliation, but you are a peacemaker. Those people are not going to be quieted by additional drift analytics. My advice for smart people would be to focus on the search width so that a convincing case can be made for why and how a future should be conducted.
@DennisW: I’m not trying to reach a consensus, which will never occur. I am trying to give everybody an opportunity to make their case to maximize our collective knowledge.
@TBill: The A/P might have been manually disengaged, not automatically because bad air data was detected. But that doesn’t explain why the pilots were not able to set pitch and power and stabilize the plane. With faulty “elevator feel” and/or runaway trim, that task might be more difficult than we realize. They might have also had to deal with faulty stall warnings, which would be loud and very disconcerting. We’ll know soon enough.
@Victor
My definition of reality – things that people universally experience the same way. A flat earth was once a reality like dark matter today. Reality should not be confused with truth or speculation (which dominates posts here).
@VictorI, RichardG
I’m wondering if there are ways to better validate the “Godfrey” and the “Griffin” drift models, by experimental data. To check for a possible “bias” and to check how well the dispersion of a cluster of objects would be captured.
Could this be done based on historic drifter data, or would a specific experiment be needed. For example, what would we learn if 20 undrogued drifters would be released beginning of March 2019 from 32S and 20 from 24S on the 7th arc and followed in time (and compared to the models).
@Niels: The only variation between Richard G’s model and the historical drifters would be due to annual variations, as the historical drifters define the spatial and temporal drift fields.
@Richard G: Here’s a fundamental question: When you are using multiple historic drifters to calculate the drift velocities, do you average the speed and direction separately, or do you average the velocity vectors? I suspect you average the velocity vectors, i.e., velocity components.
@All,
Drift modeling, unfortunately, is relying on historical and/or after the fact drifter buoy data, which IMO isn’t a compelling methodology in determining a specific drift scenario. Thousands of theoretical ducks left to their own devices will go whichever way the air/water interface pushes them, and it doesn’t take long before they have spread far and wide. Drifter buoys behave in a similar fashion, but we don’t have thousands of them – just a few.
In short, the actual sea level at any given time is subject to the prevailing atmospheric pressure and the surface wind friction caused by the differential isobaric pressure. The air/water interface surface current so created will be modified by any existing subsurface currents, up-wellings etc. due to temperature inclines, and often this disturbance can turn into a gyre. Overall, the conditions being experienced at any point in time are extremely fluid (no pun intended) and due to the nature of the beast, basically impossible to pin down, let alone quantify after the fact.
On top of the previously mentioned conundrum, is the difficulty in estimating the performance of assorted pieces of floating debris in respect of how each item reacts to the affects of Stokes drift and additional leeway due to windage. Errors made in assumptions for the aforesaid become accumulative, and over 100’s of days small ones become large.
Essentially, every drifter buoy and/or piece of floating debris could announce to the world, “Know me well, for I shall pass this way only once.”
Having said the above, I respect the efforts that have been and are currently being made to determine from whence the debris that has been identified as from MH370 actually originated.
@VictorI
Yes, so for the “Godfrey” model the experimental validation would need to cover several years to get a feel for the annual variations.
A first indication for these variations (however less convincing than obtained from experimental data), could perhaps be obtained by running the “Griffin” model several times for different starting years.
@Victor
RE: “It would seem that those two problems are related. For instance, an incorrect airspeed input to the STS might cause incorrect trim and incorrect elevator feel, making it harder to manually control pitch.”
The leaked maintenance log page I referred to earlier indeed shows the ‘FEEL DIFF PRESS’ light illuminated during the previous flight. A malfunctioning elevator feel system might make pitch control more difficult, as you mentioned, and that could make an unreliable airspeed event harder to manage. However, the B737 elevator feel system uses a dedicated pitot system for dynamic pressure sensing, with pitot tubes mounted either side of the vertical stabiliser. That system is independent of the pitot-static system used to derive airspeed, so the two problems might not be related. Either way, it seems the aircraft had some significant gremlins that were not adequately resolved before the accident flight.
Bloomberg article on JT610 here: https://bloom.bg/2qwPBjb
@airlandseaman: That’s not good. It sounds as though they are converging on a bad AoA sensor.
@all
Confessions to make here.
I have never had a pilots license, but have flown quite a lot. My proprety did not have a long enough straigt-away, so you had to run around in a circle a few times to gain speed before take-off. Landing was OK, but you had to drop it in pretty quickly.
When I read about AF447 or JT610 I can only shake my head (no disrespect, Andrew). Good grief, fly the f’ing airplane. What is the problem with pilots these days?
I have the same opinion about ABS, particularly on motorcycles of which I am an affectionado, and have raced them for over two decades. I have some 15 of them, none newer than 2009 simply because non-ABS is no longer an option. If I want a computer controlling some portion of my life, I will elect not to participate in that portion (and I am really good with computers).
@DennisW
RE: “When I read about AF447 or JT610 I can only shake my head (no disrespect, Andrew). Good grief, fly the f’ing airplane. What is the problem with pilots these days?”
No offence taken; seasoned pilots have been warning about that kind of thing for donkey’s years. Automation is a fabulous tool that has improved safety in many areas, but that has occurred at the expense of good old-fashioned stick and rudder piloting skills. Many (most?) airline pilots today barely get enough hands-on flying to remain proficient, let alone improve their skills, especially those that fly long-haul. Some airlines insist their pilots make the maximum use of the automation by engaging the autopilot immediately after take-off and only disengaging it shortly before landing. That’s all very well and good, except when something goes wrong and the pilot suddenly needs to fall back on his or her manual flying skills. The problem is exacerbated by the increasing number of low-time pilots that are moving into the right hand seat at many airlines, particularly the low-cost carriers. I fear it will only get worse if the forecast global pilot shortage starts to bite and cockpit experience levels plummet.
Thx Andrew,
I regretted the post almost the moment I made it.
I really want to do and encourage intelligent things going forward. IMO, that is to continue North on the 7th arc at the +/-25km width.
Sorry to be boring and sorry Victor, I have nothing else to contribute here.
More on JT610:
https://www.seattletimes.com/business/boeing-aerospace/boeing-to-warn-737-max-operators-of-a-potential-instrument-failure-that-could-cause-the-jet-to-nose-dive/
https://theaircurrent.com/aviation-safety/boeing-nearing-737-max-fleet-bulletin-on-aoa-warning-after-lion-air-crash/
Erroneous angle of attack data causing the aircraft to trim nose down, together with spurious stall warning and airspeed disagreement. Wow…
@Victor
You asked “When you are using multiple historic drifters to calculate the drift velocities, do you average the speed and direction separately, or do you average the velocity vectors? I suspect you average the velocity vectors, i.e., velocity components.”
When calculating each day a new drift speed and direction, there might be up to 20 drifters within the 1° of latitude and longitude spatial granularity and 1 month temporal/seasonal granularity. Each drifter will be moving with a different speed in a different direction and changing speed and changing direction all the time within the artificial bin created by the granularity definition.
If I would take the average speed and average direction separately, it would distort the result giving an average point to point trajectory within the artificial bin. This would make drift simulations significantly faster than actual drifters. Drifters do not travel at constant speeds in constant directions, not even for a short time frame. An average point to point speed and direction is misleading. Of course the raw GDP data is only every 6 hours, so I do not know what goes on in between successive data points.
In my view, you have to average the velocity vectors within the artificial bin created by the granularity definition. I did quite some testing comparing actual drifters to the simulator results and within the constraints listed below, I was satisfied with the results.
The simulator is obviously not perfect. (1) I am averaging a small number of 6 hourly data points for each new calculation. (2) I am averaging data points between the years 2000 and 2018, not just for the years between 2014 and 2016, when the MH370 floating debris was actually in passage. (3) I am averaging only 280 undrogued drifter data sets. (4) I do not account for a storm passing through the simulator track. (5) The average drifter data will reflect storms that particular drifters encountered, although this tends to get averaged out.
@Andrew: On the bright side, whatever issues there are should be quickly identified and resolved. Clearly, Boeing has liability. It will be interesting to see, after the final report is written, whether there is a determination that pilot error contributed to the crash.
———–
DennisW: “@Donald, Being the gatekeeper of the whacko category I inform you that you are IN.”
DennisW: “@TBill, I think you are full of shit.”
———–
@Victor: Sorry, but why do you tolerate such language on your blog ?
@Niu Yunu: I try to encourage respectful behavior, but I also don’t apply a heavy hand until the language or accusations become a distraction to the discussion. I sometimes get accused of both too much and too little moderation.
Andrew: Given a full down elevator command from the new 727 trim system(s), how much stick pressure would be necessary to over ride the trim? Is it even possible?
Faced with a sudden, unwelcome full down elevator trim situation…probably some negative Gs, multiple alerts, and other bad jumbi going on… how long do you think it would take the average commercial pilot to pull the right CBs or switches to regain manual control?
@Niu Yunu
My interpretation was that I had won that debate.
MH370-Possible Reasons for Intentional Descent at End of Flight
@Victor: Thank you for the feedback. I understand. I just wondered why nobody said anything. I’m certainly just oversensitive. Sorry.
@TBill: best riposte 🙂
JT610 final seconds: http://bit.ly/2F7mbCj
The previous JT610 linked plots had some scale color errors, corrected here: http://bit.ly/2PdUITW
@All,
The link below gives an update to my drift results for beachings in the Southern Indian Ocean west of 65°E from various start latitudes near the 7th Arc in a similar format to David Griffin’s Fig. 5a:
https://www.dropbox.com/s/bjdh6wonx2a7yzg/Drift%20Analysis%20Results%20West%20of%2065E%2007%20Nov%202018.pdf?dl=0
There were 155 beachings out of a total of 190 simulator runs. 35 simulator runs ended up in mid-ocean gyres or heading out into the Southern Atlantic Ocean having rounded South Africa.
The link below gives the list of beachings in excel form, including the days spent in transit for each simulator run:
https://www.dropbox.com/s/bwjn3zm5ig0angk/Beaching%20Locations%2007Nov2018.xlsx?dl=0
@ALSM. Thanks for the JT610 plot.
The 23:31:45.4 7500 ft/min roc looks spurious, particularly noting instantaneous acceleration to 9000 ft/min rod.
David: I agree that it looks spurious. FR24 confirmed several spurious “transmission errors” in the previous flight’s ADS-B data set. Remember, the transponder modulation is a form of amplitude pulse modulation, which is more susceptible to transmission interference and error than more robust coded digital modulation schemes, like PSK.
@ALSM
RE: ”Andrew: Given a full down elevator command from the new 727 trim system(s), how much stick pressure would be necessary to over ride the trim? Is it even possible?”
A lot. I doubt it would be recoverable at high speed.
”Faced with a sudden, unwelcome full down elevator trim situation…probably some negative Gs, multiple alerts, and other bad jumbi going on… how long do you think it would take the average commercial pilot to pull the right CBs or switches to regain manual control?”
It shouldn’t take long, provided the pilot realises what’s happening. I suspect that was made more difficult in this case because of the stall indications and IAS disagreement. The pilot could have momentarily stopped the runaway STS by using the control column trim switches to trim nose up. However, the runaway STS would have started trimming nose down again 5 seconds after the pilot released the trim switches. The longer term fix is to select the STAB TRIM CUTOUT switches to CUTOUT to shut down the electric trim system, as recommended by Boeing in its latest FCOM bulletin. The cutout switches are located on the centre pedestal, within easy reach of both pilots. On the 737, the pilot could then manually trim the stabiliser using the stabiliser trim wheel, also located on the centre pedestal.
Boeing FCOM bulletin:
https://pbs.twimg.com/media/DrbMs-VVsAA9NgB.jpg:large
FAA Emergency Airworthiness Directive:
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/83ec7f95f3e5bfbd8625833e0070a070/$FILE/2018-23-51_Emergency.pdf
The Seattle Times:
Scrutiny in Lion Air 737 crash turns to automated systems that command plane’s pitch
@Andrew: Thank you for the links.
“the AOA sensor can […] cause the jet to enter an aggressive dive”¹
Is this as bad as it reads or am I over-reacting ?
———-
Dominic Gates: “If the automatic trim system is fed false angle of attack (AOA) measurements, it will go awry. If the sensor tells the system the AOA is too high, the automatic system begins moving the tail to point the nose down. Even when the pilot corrects that by pulling the column […] the system will begin to pitch the nose down again.”²
Boeing FCOM bulletin: “… can occur during manual flight only”
• I’m surprised that even when supposedly flying “manually”, there is so much automation that can prevail over the manual inputs – even when applied with force – and force your plane into the ground.
———-
John Cox (former pilot and chief executive of aviation consultancy Safety Operating Systems): “On no other 737 is there a system based on the angle of attack that will move the (horizontal tail) trim. That is unique to the MAX. I was surprised that a single angle of attack indicator could cause the activation of this system.”²
AD: “if an erroneously high single angle of attack (AOA) sensor input is received by the flight control system, there is a potential for repeated nose-down trim commands of the horizontal stabilizer. This condition, if not addressed, could cause the flight crew to have difficulty controlling the airplane, and lead to excessive nose-down attitude, significant altitude loss, and possible impact with terrain.”
• What happened to redundancy ?
• And why is there no failsafe to do NOTHING in case of AOA sensor disagreement ?
———-
Boeing FCOM bulletin: “Initially, higher control forces may be needed to overcome any stabilizer nose down trim already applied.”
ALSM: “Given a full down elevator command from the new 727 trim system(s), how much stick pressure would be necessary to over ride the trim? Is it even possible?”
Andrew: “A lot. I doubt it would be recoverable at high speed.”
• Then why is this advised by Boeing ?
———-
ALSM: “Faced with a sudden, unwelcome full down elevator trim situation…probably some negative Gs, multiple alerts, and other bad jumbi going on”
Seattle Times: « Cox said he considers the MAX safe and would fly on one tomorrow without hesitation. […] Bjorn Ferhm, a former jet-fighter pilot and an aeronautical engineer […] believes the MAX is as safe as any 737. »²
Victor Iannello: “Clearly, Boeing has liability.”
• How is this “safe”, if from onset of the problem you have a mere ~10 seconds to identify the problem and hit both stab trim cutout switches, or your plane is beyond recovery and lost ? (And in these few seconds all hell breaks loose in terms of warnings, see the 9 items on p.2 of the bulletin, which makes calm thinking next to impossible.) This doesn’t read very safe to me:
« the sensor may feed false information about this angle to the flight computer, which in turn triggers other errors. With the sensor falsely indicating that the nose is too high, when it isn’t, it causes an automatic system response that “trims” the horizontal tail of the plane to [put] the plane’s nose down. At the same time, it causes an indicator of the minimum speed to tell the pilot that the plane is near a stall, which also causes the pilot’s control column to shake as a warning. And the airspeed indicators on both sides of the flight deck disagree. The pilots can use extra force to correct the nose down trim, but the failure condition repeats itself, so that the nose-down push begins again 10 seconds after correcting. “If the nose is trimmed down on an aircraft, it becomes difficult for the crew to hold it,” said the person briefed on Boeing’s bulletin. “The nose is turning itself down and they are having to fight it. It takes a lot of effort to keep it from diving. Especially if you have a crew that’s confused and doesn’t know what’s going on.” […] Pilots are typically trained on how to handle a runaway trim situation, said the person briefed on the Boeing bulletin, but that’s with everything else working as it should. In this case, the control-column shaking, the stall warning and the air-speed-indicator disagreement all combine to create confusion and keep the pilots very busy. »³
—
¹ theaircurrent.com
² Seattle Times
³ Seattle Times
@Peter Norton
RE: “• I’m surprised that even when supposedly flying “manually”, there is so much automation that can prevail over the manual inputs – even when applied with force – and force your plane into the ground.”
The STS helps with speed stability and is also part of the stall protection system. If a high AoA is detected, the STS is designed to trim the stabiliser nose down to increase the amount of rearward force the pilot must apply to further increase the AoA.
“• What happened to redundancy ?
• And why is there no failsafe to do NOTHING in case of AOA sensor disagreement ?”
I don’t know. According to John Cox, the AoA input to the STS is a new feature that was introduced with the 737 MAX. The investigation might explore the basis for its certification by the FAA.
“• Then why is this advised by Boeing ?”
Because INITIALLY the pilot would be able to overcome the nose down trim by applying more force on the control column. Applying rearward force on the control column is only one of the steps that is needed to contain the failure.
“• How is this “safe”, if from onset of the problem you have a mere ~10 seconds to identify the problem and hit both stab trim cutout switches, or your plane is beyond recovery and lost ? “
The system doesn’t trim fully nose down in the first 10 seconds; it’s not that fast. However, if the pilot doesn’t do anything, the system will keep putting in more nose down trim until it reaches the nose down limit. Cox believes the aircraft is ‘safe’ because: “Countering the problem, if it arises in flight, should require only a standard pilot procedure — one that was newly emphasized by Boeing in its safety bulletin Tuesday.”
@Andrew: thank you
Andrew: “The system doesn’t trim fully nose down in the first 10 seconds; it’s not that fast.”
How much time does the crew have to react?
I.e.how long would you say it takes from the onset of the problem (first STS trim down) to full nose down trim (which I assume unrecoverable at this flight level) ?
Andrew: “The investigation might explore the basis for its certification by the FAA.”
Hopefully. It seems kind of a self-certification:
“If the accident investigation ultimately were to find fault with Boeing’s design of the nose pitch control system, it would raise questions about the safety-certification process, much of which is delegated by the FAA to Boeing itself. Boeing on Wednesday declined to comment.” (Seattle Times)
Personally, as a pilot, what is your thought about what we are reading here?
• “I am not afraid/worried, because countering the problem requires only standard pilot procedure.”
or more like
• “This is creepy. Can lead to a really dangerous situation and urgently requires a software update.”
?
Planes plummeting is getting a habit …
https://www.google.de/amp/s/www.bbc.co.uk/news/amp/uk-46137445
@Peter Norton: We need more facts and a better understanding of Boeing’s design philosophy. It might be that if one AoA sensor indicates stall, and the other does not, the designers believed that automated protection against stall has higher priority than protection against an unplanned descent, as it would be easier for the crew to recover. After the AF447 crash, I think both designers and crew put a large emphasis on the avoidance of stall when sensors disagree.
@Andrew @all
Re: Lion Air
Did the pilots ever have have a chance to turn the AutoPilot on, or did the problem prevent that?
While we are talking automated systems, the new system I want if is possible is logic to prevent aircraft diving into terrain.
Regarding instrumentation, in industry we often use 3oo5 (3 out of 5 voting) for temperature readings required for automated emergency shutdown.
@TBill
Multiple sensors are a good thing, but the methodology of sensor fusion is complex.
How did you combine the outputs of your five temperature sensors? Average? Something more complex such as picking the average of the three sensors having the smallest variance from the ensemble mean? I could go on and on…
Darwin’s boat, the HMS Beagle, had 22 chronometers on board during the 2nd voyage. It is not known how Fitzroy combined the chronometer readings, but over the five years of the second voyage the time determined by the Beagle was in error by 33 seconds (8.5nm error). An amazing achievement considering the technology at the time, and the environment on board the Beagle. (Fitzroy was said to be dissappointed).
Sorry for the distraction, but sensor fusion, Kalman filtering,…are pet topics of mine.
@All,
So it would seem that the STS, unless it is isolated by the ‘Stab cutout’ switches could keep applying more and more incremental nose down trim. The pilots would have to pull back more and more putting great strain on the Stab screw jack. By the sudden dive at the end I suspect it finally gave way.
What do you think?
@All,
Below is a link to an academic paper by Casner et al. 2013 entitled “The retention of manual flying skills in the automated cockpit”.
Given 3 different problems in a simulator, the results were:
(1) 98% of pilots verbalised there was a problem.
(2) 75% of pilots cross-checked other instruments.
(3) 69% of pilots deviated from the flight path (altitude, heading, approached stall).
(4) 77% of pilots diagnosed the problem.
It appears that pilots retain their basic manual flying skills, even when they are not used that much. However, only 13% of pilots, at least sometimes, spend time with the flight director, autopilot, and flight director all off, to keep their skills sharp.
It appears that pilots lose their cognitive skills as a result of cockpit automation. More frequent and serious problems were observed, when a failure was introduced in the simulation. In the event of a failure, 69% of pilots deviated from the planned flight path.
Eventually, 77% of pilots diagnosed the problem, but the question is whether the deviation from flight path had already taken too long, before diagnosis and remediation occurred.
The stated purpose of cockpit automation is to afford pilots more time to concentrate on following the progress of the flight. The study shows that pilots spend 20% of their time during automated flight thinking about other things, whereas it is less than 7% of their time during manual flight when using instruments.
https://www.dropbox.com/s/3np40ntawtjopvf/The%20retention%20of%20manual%20flying%20skills%20in%20the%20automated%20cockpit.pdf?dl=0
@All,
The link below gives an update to my drift results for beachings on mainland Africa west of 42°E from various start latitudes near the 7th Arc in a similar format to David Griffin’s Fig. 5b:
https://www.dropbox.com/s/0b5b27vmka0y3d6/Drift%20Analysis%20Results%20West%20of%2042E%2008%20Nov%202018.pdf?dl=0
Out of a total of 190 simulator runs, 78 beachings were on mainland Africa, 73 beachings on Madagascar and 38 simulator runs ended up in mid-ocean gyres or heading out into the Southern Atlantic Ocean having rounded South Africa.
The link below gives an update to my drift results for beachings in the Southern Indian Ocean west of 65°E from various start latitudes near the 7th Arc in a similar format to David Griffin’s Fig. 5a (many thanks to @DrB who spotted a mistake in yesterday’s comment, where I had included 3 particles as beachings that ended mid-ocean):
https://www.dropbox.com/s/bjdh6wonx2a7yzg/Drift%20Analysis%20Results%20West%20of%2065E%2007%20Nov%202018.pdf?dl=0
> TBill: @Andrew @all
> Did the pilots ever have have a chance to turn the AutoPilot on, or did the problem prevent that?
I read the Boeing bulletin as saying as long as AOA data is erroneous, A/P is not available (p.2, abridged cit.):
« pilots are reminded that an erroneous AOA can cause some or all of the following indications and effects:
• inability to engage A/P
• automatic disengagement of A/P
• AOA DISAGREE alert »
Sounds intuitive to me, since A/P always disengages in case of insufficient required data to fly on.
But if so, why would Boeing make a point pointing out that this “AOA failure condition can occur during manual flight only” (p.1, emphasis NOT mine), when you end up flying manually either way due to A/P disengagement ?
Victor Iannello: “It might be that if one AoA sensor indicates stall, and the other does not, the designers believed that automated protection against stall has higher priority than protection against an unplanned descent, as it would be easier for the crew to recover.”
At low altitude?
If AOA disagree after takeoff, design a dive?
Victor Iannello: “After the AF447 crash, I think both designers and crew put a large emphasis on the avoidance of stall when sensors disagree.”
If the dive is a design intention rather than a malfunction, the emphasis might have to return to avoidance of terrain.
@Peter Norton: I don’t know. A stall at low altitude is also very bad. As I said, we have to better understand the design criteria.
@Peter Norton
RE: “How much time does the crew have to react?
I.e.how long would you say it takes from the onset of the problem (first STS trim down) to full nose down trim (which I assume unrecoverable at this flight level) ?”
The STS uses the autopilot stabiliser trim, which has a range of motion of 0.05 to 14.5 units. My understanding is that with flaps retracted, the system trims at the low speed rate of 0.2 units/sec. The time it would take to reach the nose down limit obviously depends on the position of the stabiliser at the onset of the problem, but let’s say it starts at around 5 units. At 0.2 units/sec, it would take about 25 secs to trim fully nose down, assuming continuous operation. However, the Boeing FCOM Bulletin states that the pitch trim system trims the stabiliser nose down ‘in increments lasting up to 10 seconds’, which suggests that it won’t trim continuously to the nose down limit.
RE: “Personally, as a pilot, what is your thought about what we are reading here?
• “I am not afraid/worried, because countering the problem requires only standard pilot procedure.”
or more like
• “This is creepy. Can lead to a really dangerous situation and urgently requires a software update.”
?”
I think it’s a problem that needs to be investigated and a fix found to prevent it happening again; however, you can put me in the first category – ‘I am not afraid/worried’. I don’t think it’s so serious that it requires grounding of the MAX fleet. I believe the steps taken by Boeing and the FAA to alert pilots to the problem and the existing procedures that should be used to deal with it are appropriate. There are plenty of things that can go wrong with an aircraft that could have catastrophic consequences if not handled correctly. The key is to make sure that pilots have the necessary information and training to deal with such problems.
@TBill
RE: “Did the pilots ever have have a chance to turn the AutoPilot on, or did the problem prevent that?”
At this point, we don’t know. As @Peter Norton mentioned, the problem might have prevented them engaging the autopilot, or caused the autopilot to disengage if it was already engaged.
RE: Regarding instrumentation, in industry we often use 3oo5 (3 out of 5 voting) for temperature readings required for automated emergency shutdown.”
It sounds as though the stall protection system on the MAX only requires one of the two AoA vanes to detect a high AoA. Going to 2oo2 might have unintended consequences that make the system less safe in terms of stall protection. Let’s say the aircraft has a high AoA that is not detected by one of the AoA vanes. In a 2oo2 system the stall protection would not activate. I doubt that would get past the regulators!
@Tim
RE: “So it would seem that the STS, unless it is isolated by the ‘Stab cutout’ switches could keep applying more and more incremental nose down trim. The pilots would have to pull back more and more putting great strain on the Stab screw jack. By the sudden dive at the end I suspect it finally gave way.”
That might be the case. The ADS-B data suggests that something catastrophic might have occurred in the last few seconds. Perhaps we’ll know more when the Indonesians release their preliminary report.
@Richard Godfrey
RE: “Below is a link to an academic paper by Casner et al. 2013 entitled “The retention of manual flying skills in the automated cockpit”.”
Thanks for posting the paper; I am guilty of oversimplifying the skills retention problem in my earlier post. I think Casner et al are correct in that it’s the pilot’s cognitive skills that deteriorate, which leaves the pilot with little spare capacity to process other problems when confronted with a manual flying task.
Andrew wrote “you can put me in the first category – ‘I am not afraid/worried […]’.”
I concur with Andrew’s view.
It would be wrong to think that onset of the condition described by the FAA’s AD and considered to have led to the loss of PK-LQP was somehow insidious: the disparity in L & R ADIRU data (IAS/AOA DISAGREE flags) would result in a Master Caution alert and, if the stabiliser trim did ‘run away’, the sustained spinning of the trim wheels on either side of the throttle quadrant would have been unmissable. The standby attitude display, separate from the main L & R flight deck displays, provides a third instrument reference.
Like PK-AKC/QZ8501, PK-LQP appears to have suffered from an interrmittent technical problem that persisted over a number of previous sectors and was not resolved by maintenance. The LCC business model relies on minimising time on the ground, maximising airframe utilisation. NTSC and the Indonesian regulator must ensure that maintenance is given primacy for serious serviceability issues, and that ‘tested/no fault found’ is not an acceptable practice.
@Don
I totally disagree with you and Andrew which is unusual.
For Boeing to describe a procedural work around for what is obviously a design defect is unforgivable IMO. It is reminiscent of the Toyota unintended acceleration problem (which killed 89 people and injured 52 people). Fix the problem! Toyota did not send a notice to Lexus owners instructing them to put the car in neutral, turn off the ignition, and apply the brakes. Toyota did end up paying $1.2B in financial penalties because they knew the source of the problem, which was rare, and they continued to manufacture defective vehicles.
IMO, the 737 MAX should be taken out of service until the issue is properly corrected and verified to be corrected. Boeing should be held liable for the damages sustained because of the problem.
Sure, taking the plane out of service will cause a lot of pain to Boeing’s customers. That is just the way it should be.
@Don Thompson,
… and that ‘tested/no fault found’ is not an acceptable practice.
I take from that an implication to consider other dependencies that may have conspired in giving the pilots reason for writing up the fault being dealt with, should also be investigated, and they be noted along with the result(s) of any testing signed off too.
@DennisW
As far as 3oo5 readings for automated emergency action, we are looking for temp runaways, so we are not too concerned about the average. We are just looking for sky high temperature readings. But an open thermocouple can throw a bad high reading, so it needs to be more than one data point.
@DennisW
RE: “IMO, the 737 MAX should be taken out of service until the issue is properly corrected and verified to be corrected. Boeing should be held liable for the damages sustained because of the problem.”
I suspect we’ll have to agree to disagree on that point. For the record, I was not advocating that Boeing publish a work around procedure and leave it that. I said ‘…it’s a problem that needs to be investigated and a fix found to prevent it happening again’. Do I think the fleet needs to be grounded in the interim? No. At this point in the investigation we don’t know exactly what happened, or if the crew’s action (or inaction) contributed in any way. There are perfectly good procedures for dealing with an errant stabiliser trim that have been around for a very long time – flip the cut-out switches, fly the damn aircraft and trim manually.
Many years ago I had an incident shortly after take-off in a Falcon 900. The aircraft’s stall protection system activated when we retracted the slats & flaps, resulting in lots of warning noises in the cockpit and the outboard slats continuously cycling in and out. Confusing at first, but it was obvious that we were nowhere near a stall condition, so we simply extended the slats & flaps (which stopped the warnings) and came back and landed. We admittedly did not have a runaway trim problem, but we did what we were trained to do and FLEW THE AIRCRAFT. It turned out that our problem was caused by a faulty AoA vane that had taken in some water after the aircraft was parked overnight in heavy rain.
@Andrew
Yes, it is OK to disagree, and I do see your point of view. My issue is based more on protocol than the specifics related to this incident.
Yes the new B737max’s should be grounded until the problems are corrected
The work around aren’t proven to prevent another crash.
@Victor Iannello: I concur. Although I also sympathize with DennisW RE:Toyota.
@Don Thompson: RE “unmissable, not insidious”: I think nobody contended that. I see the opposite problem: a situation where you get overwhelmed with the aural and visual errors listed on p.2 of the Boeing bulletin.
• You have a stall warning/stick shaker.
• You have uncommanded, hard to fight nose down trim.
• maybe even a third type of error we don’t know yet
I imagine the situation to be quite confusing. Are you stalling? (In which case the nose down trim would be helpful.) Or is the automatic trim system going rogue? Or is something else going on (in addition)? Which errors/instruments do you trust?
Reading the last paragraph here, I could see how it would be difficult to handle the situation.
@Andrew: Thank you for the provided timing.
> @Andrew: “the Boeing FCOM Bulletin states that the pitch trim system trims the
> stabiliser nose down ‘in increments lasting up to 10 seconds’, which suggests that it
> won’t trim continuously to the nose down limit.”
You mean after 10 seconds it makes a pause and continues later on?
How long would that pause take ?
Within the context of the described scenario and countermeasures, I had interpreted this information as “[only] if the pilot fights back the nose down trim for 10 seconds using the electric stabilizer trim switches, the trim system stops, but will restart 5 seconds after releasing the switches, [otherwise it will trim continuously to the nose down limit]”.
@Peter Norton
RE: “You mean after 10 seconds it makes a pause and continues later on?
How long would that pause take ?”
I’ve never flown the B737, but that’s how I interpret the FCOM Bulletin, which states:
‘In the event of erroneous AOA data, the pitch trim system can trim the stabilizer nose down in increments lasting up to 10 seconds. The nose down stabilizer trim movement can be stopped and reversed with the use of the electric stabilizer trim switches but may restart 5 seconds after the electric stabilizer trim switches are released…It it possible for the stabilizer to reach the nose down limit unless the system inputs are counteracted completely by pilot trim inputs and both STAB TRIM CUTOUT switches are moved to CUTOUT.’
I don’t know how long it would pause between the 10 second increments. My understanding is that the STS stops immediately if the pilot uses the electric trim switches, but restarts 5 seconds after they are released.
@Peter Norton
RE: “I imagine the situation to be quite confusing. Are you stalling? (In which case the nose down trim would be helpful.) Or is the automatic trim system going rogue? Or is something else going on (in addition)? Which errors/instruments do you trust?”
Yes, it certainly would be quite confusing. That’s where pilots need to be disciplined and quickly assess if the aircraft is still flying and which instruments are correct. If the aircraft has the correct pitch attitude and the correct thrust, then it is unlikely to be stalled if it was flying normally immediately before the warning occurred. The pilots can easily check which airspeed indications are correct by cross-checking the indications on their PFDs with the standby airspeed indicator.
@Andrew:
>> Peter Norton: “You mean after 10 seconds it makes a pause and continues later on?
>> How long would that pause take ?”
>
> Andrew: “I’ve never flown the B737, but that’s how I interpret the FCOM Bulletin,
> which states: […]
> I don’t know how long it would pause between the 10 second increments.
> My understanding is that the STS stops immediately if the pilot uses the electric trim
> switches, but restarts 5 seconds after they are released.”
I know, I have read the Bulletin, but I don’t find it overly logical that if the pilot does not “fight back”, the STS stops itself after 10s and takes a pause, possibly longer than the 5s pause it grants WHEN the pilot does “fights back” …
> Andrew: “That’s where pilots need to be disciplined and quickly assess if the
> aircraft is still flying and which instruments are correct. If the aircraft has the
> correct pitch attitude and the correct thrust, then it is unlikely to be stalled if it
> was flying normally immediately before the warning occurred.”
FR24 data suggests JT610 had not been flying normally but at varying altitude before the crash, possibly due to the crew fighting the trim system in intervals.
> Andrew: “The pilots can easily check which airspeed indications are correct by
> cross-checking the indications on their PFDs with the standby airspeed indicator.”
According to Skybrary“the standby airspeed indicator […] will not provide reliable information if the fault is within the pitot static system”. This may not have been the case for JT610, but AF447 sent an ACARS message at 02:10 (4 min before final transmission) indicating a fault in the pitot-static system.
> Andrew: “Yes, it certainly would be quite confusing.”
Even more so when you have to tune out that a few hundred people will die if you fail to stop whatever is occurring within probably less than 60s. It’s hard to think under that pressure.
> Brian Anderson: “aircraft can be flown quite safely without any airspeed indication.
> The standard procedure is to set the pitch [angle] to the appropriate value, and
> set the power levers to the appropriate position, then if everything else is OK the
> aircraft will fly straight and level.”
>
> Andrew: “Absolutely. A well trained, competent pilot should be able to fly and land
> the aircraft quite safely with an unreliable speed indication. The procedures are
> well defined and the required pitch attitude/thrust tables are readily available in
> the pilot’s QRH.”
I wonder why there is such stark disagreement among professional pilots. In the aftermath of the AF447 crash, Bruno Sinatti, president of Alter, Air France’s third-biggest pilots’ union, said: “Piloting becomes very difficult, near impossible, without reliable speed data”.
@Andrew
The AOA DISAGREE alert is only if the AOA indicator option is installed.
Do we know whether this option was installed on PK-LQP?
@Peter Norton
RE: “FR24 data suggests JT610 had not been flying normally but at varying altitude before the crash, possibly due to the crew fighting the trim system in intervals.”
Of course the aircraft wasn’t flying normally before it crashed, but it looks to me as though the aircraft climbed out pretty much normally until it reached an altitude just below 2,000 ft, which might be when the problems started.
RE: “According to Skybrary“the standby airspeed indicator […] will not provide reliable information if the fault is within the pitot static system”. This may not have been the case for JT610, but AF447 sent an ACARS message at 02:10 (4 min before final transmission) indicating a fault in the pitot-static system.”
Large airline aircraft (including the 737 MAX) typically have three independent pitot-static systems; one for the Capt, one for the FO and another for the standby instruments. A failure in one system should not affect the other systems.
Pitot probe icing, as occurred in AF447, is one of the few things that can affect all three pitot-static systems. In the AF447 accident, the ADR1 (ie Capt) airspeed data was only invalid for 29 seconds before it recovered, while the ADR3 (ISIS or standby) data was invalid for about one minute. It’s not known how long the ADR2 data was invalid, because it wasn’t recorded on the FDR, but it probably recovered at about the same time. Consequently, the pilots of AF447 probably had valid airspeed data on all their instruments within about one minute of the first indication of a problem. If they had done nothing more than maintain the aircraft’s attitude and thrust setting, it’s very likely that 228 people would not have lost their lives.
RE: “Even more so when you have to tune out that a few hundred people will die if you fail to stop whatever is occurring within probably less than 60s. It’s hard to think under that pressure.”
It might sound callous, but pilots don’t spend their time fretting about the hundreds of people sitting behind; they are more concerned with keeping the aircraft safe. If it’s safe, then by extension everyone on board (including the pilots!) will be safe.
RE: “I wonder why there is such stark disagreement among professional pilots. In the aftermath of the AF447 crash, Bruno Sinatti, president of Alter, Air France’s third-biggest pilots’ union, said: ‘Piloting becomes very difficult, near impossible, without reliable speed data’.”
Well he would say that, wouldn’t he? Piloting does become very difficult, near impossible, without reliable speed data if the aircraft isn’t flown correctly. That’s why there is now far greater emphasis on unreliable airspeed (UAS) procedures during training. We regularly practice UAS procedures in the simulator and I can assure you the aircraft can be safely flown and landed without airspeed data. A number of years ago there was an incident involving a B747-400 at the airline where I work. The aircraft was on its first flight after heavy maintenance and lost all airspeed information shortly after take-off. That crew followed the procedures and landed the aircraft quite safely.
@Richard Godfrey
RE: “Do we know whether this option was installed on PK-LQP?”
I haven’t seen anything official, but I did read a report that said the aircraft did not have the AOA indicator option installed.
@David @Andrew. I’d like to circle back to the issue of AP disengagement at end of flight.
Originally, we had understood that loss of pitot heat was the trigger, moreover that it was loss of power to pitot heat and not drop in temperature. From Andrew & David’s earlier exchange “the loss of pitot heat alone does not cause reversion to SECONDARY mode unless the air data actually becomes invalid”. Question: other than icing conditions, is there any reason to expect the air data to become invalid? If icing conditions are unlikely until you reach cloud / vapour below (say) FL200, would you not expect air data to remain valid as long as the aircraft is at altitude?
Second, Andrew mentioned that “..recent advice indicates the reversion is caused by the loss of other sensors required by the PFCS.” and that “my understanding is that they are mostly position sensors associated with actuators controlled by the L2 ACE. The L2 ACE is only powered by the L28V DC bus, which is normally supplied by the L AC transfer bus.” Question: In event of loss of power after flameout, are these circuits among those that failover to power from hot battery?
If those actuator sensors do receive backup battery power and airspeed data will not go bad at altitude even without pitot heat, then I don’t see that we have good reason to expect near-immediate loss of AP and reversion to SECONDARY at flameout. That in turn opens the door to possible un-manned controlled flight: whether an unpowered “glide” of sorts or powered flight with left engine still providing thrust but not electrical power under “alternate electrical configuration”
In considering these possibilities, please suspend belief (if you can) in traditional interpretation of the final BFOs.
https://www.thetimes.co.uk/edition/world/lion-air-boeing-737-safety-alert-after-crash-mb0mglzbc
Today’s The Times.
> Andrew: “pilots need to […] quickly assess if the aircraft is still flying and which
> instruments are correct. If the aircraft has the correct pitch attitude and the correct
> thrust, then it is unlikely to be stalled if it was flying normally immediately before the
> warning occurred.”
>
> Peter: “FR24 data suggests JT610 had not been flying normally but
> at varying altitude before the crash, possibly due to the crew fighting the trim system
> in intervals.”
>
> Andrew: “Of course the aircraft wasn’t flying normally before it crashed, but it looks
> to me as though the aircraft climbed out pretty much normally until it reached an
> altitude just below 2,000 ft, which might be when the problems started.”
What I was trying to say is that AF447 was, as you described, “flying normally immediately before the warning occured”. On JT610, however, starting at 23:22 (~1min into the flight) until the crash at 23:32 there were many ups and downs, which could have been disorientating and unsettling, given that the trim system possibly developed a life of its own. This in combination with all the alarms going off and the stick shaker might have created an overall situation in which a stall wasn’t dismissable out of hand. Plus the nose down trim would also be consistent with a stall.
I could see why one could be confused and have doubts in this situation.
@Paul Smithson
RE: ”Question: other than icing conditions, is there any reason to expect the air data to become invalid? If icing conditions are unlikely until you reach cloud / vapour below (say) FL200, would you not expect air data to remain valid as long as the aircraft is at altitude?”
The air data should remain valid unless the aircraft encounters icing conditions. That is not very likely at high altitude.
RE: ”Question: In event of loss of power after flameout, are these circuits among those that failover to power from hot battery?”
No.
RE: ”I don’t see that we have good reason to expect near-immediate loss of AP and reversion to SECONDARY at flameout.”
The PFCS does revert to SECONDARY when AC power is lost at flameout. The only question was why that occurrs.
@Andrew. Thanks for the quick response. “The PFCS does revert to SECONDARY when AC power is lost at flameout”. How do we know that definitively?
@Andrew
I am sure that you are a disciplined and well trained pilot.
I am sure that your colleagues are disciplined and well trained pilots.
It is the others that I am concerned about, especially when experiencing a “wow” situation and having a short time to diagnose and remediate the situation.
To quote you, two days ago, “Erroneous angle of attack data causing the aircraft to trim nose down, together with spurious stall warning and airspeed disagreement. Wow…”
Why is the AOA DISAGREE indicator an option?
Surely it should be mandatory, if a system such as the STS relies on a single AOA sensor input.
@Paul Smithson asked: “The PFCS does revert to SECONDARY when AC power is lost at flameout”. How do we know that definitively?
Boeing has confirmed that the loss of both IDGs and backup generators would cause a flight control degradation to SECONDARY because some critical data, such as total air temperature, would be lost.
@Victor. OK, I’ll take that (reversion to secondary and loss of AP) as read, then. I’d also like to probe the assumption that in secondary mode without
manual input the aircraft will quickly become unstable. From what I can see online, control surfaces are still automatically adjusted without pilot input to keep the plane in equilibrium, albeit in a slightly cruder manner and without envelope protection.
“Secondary mode Boeing Secondary mode is somewhat similar to the Airbus Alternate Law. When the PFCs can not support Normal mode operation due to internal faults or to loss of information from other aircraft systems, they automatically revert to Secondary mode. Reversion to Secondary mode results in the loss of the autopilot and the pilots must control the aircraft manually. The ACEs still receive pilot control inputs and send the appropriate signals to the PFCs. However, due to the degraded mode of operation, the PFCs use “simplified” computations to generate the flight control surface commands. These commands are sent back to the ACEs from whence they are sent to the flight control surfaces in the same manner as during Normal mode operations.
Aircraft handling qualities are affected by the simplified computations or PFC control laws that are utilised in Secondary mode. While all flight control surfaces remain operative, the elevator and rudder are more sensitive at some airspeeds. The following functions are inoperative or degraded during Secondary mode operations:
autopilot
auto speedbrakes
envelope protection
gust suppression
tail strike protection
thrust asymmetry compensation
yaw damping
@Paul Smithson
Our company test pilots have also confirmed the above behaviour. They regularly simulate the complete loss of AC electrics during maintenance test flights, to check the RAT auto deployment and APU auto start.
@Andrew. Thanks. By “the above behaviour” I’m assuming you are referring to the reversion to secondary mode and AP drop-out. What do your simulation tests reveal about the stability of the aircraft without AC electrics, AP disengaged, control mode secondary and no pilot inputs?
@Richard Godfrey
Thank you. My ranting was not meant to imply that every UAS event will have a happy ending. Some pilots clearly continue to be caught unawares, especially when confronted with other problems. Nevertheless, it is possible to fly the aircraft safely without airspeed information.
I don’t know why the AOA DISAGREE caution is not available without the AOA indication option.
@Paul Smithson: You are asking about what the “simulation tests reveal about the stability of the aircraft without AC electrics, AP disengaged, control mode secondary and no pilot inputs?”
This is what Boeing attempted to answer by conducting the end-of-flight simulations. From a previous post:
If we consider that the end-of-flight Boeing simulations were representative of the actual conditions of MH370, we have three possibilities:
1. If the flight was uncontrolled after fuel exhaustion, and if we ignore the final BFO values, the plane impacted no farther than about 15 NM from the 7th arc.
2. If the flight was uncontrolled after fuel exhaustion, and if the descent rates suggested by the final BFO values are valid, then the aircraft impacted no more than about 8 NM from the 7th arc.
3. If the flight was controlled after fuel exhaustion, an efficient, stable glide starting at about 40,000 ft could have achieved a distance of 120+ NM from the 7th arc.
@Victor. Fair enough. Do you happen to know what would happen if the aircraft had earlier dropped into secondary and AP disengaged due to left side power issues BUT AP was manually re-engaged at that earlier point? Does it drop out afresh at final flameout of does the earlier manual re-engagement “latch” it into an ON condition?
@Paul Smithson: I’m not sure I understand your question, but each time both transfer busses simultaneously lose power, the flight control degrades to SECONDARY, and the mode can only transition to NORMAL if the power returns to a transfer bus AND the PRIMARY FLIGHT COMPUTERS switch is cycled to DISC and to AUTO.
@Paul Smithson
RE: ”By “the above behaviour” I’m assuming you are referring to the reversion to secondary mode and AP drop-out. What do your simulation tests reveal about the stability of the aircraft without AC electrics, AP disengaged, control mode secondary and no pilot inputs?”
Yes. In my experience in the simulator, the aircraft rolls to the right and descends.
@Andrew
You stated “I don’t know why the AOA DISAGREE caution is not available without the AOA indication option.”
Fair enough! You are not an employee of Boeing in charge of their sales tactics.
My question was poorly worded, my apologies.
What I should have asked was:
“As a pilot, familiar with Boeing aircraft, do you agree, that if a system such as the STS relies on a single AOA sensor input, that it should be mandatory to install the AOA indication option, so that in the event that one of the AOA sensors fails, the pilot is given an alert that AOA DISAGREE and can quickly diagnose the problem?”
I think it is bad practice that Boeing offer the AOA indication as an option. It should be mandatory.
Having worked on the design of aircraft systems, where a stringent single and double failure analysis has to be performed, I would regard this as a design (or at least a commercial) failure from Boeing and potentially a case of gross negligence.
> Richard Godfrey says:
> @Andrew, I am sure that you are a disciplined and well trained pilot.
> I am sure that your colleagues are disciplined and well trained pilots.
> It is the others that I am concerned about, especially when experiencing a “wow”
> situation and having a short time to diagnose and remediate the situation.
> To quote you, two days ago, “Erroneous angle of attack data causing the aircraft to
> trim nose down, together with spurious stall warning and airspeed disagreement. Wow…”
I didn’t state that because I found it obvious, but now that it’s there, I want to add for the record, that this is also where I was coming from.
I also agree with Richard Godfrey on the comment directly above. It seems slightly weird to offer essential security features as options.
This seems to indicate that OI will be not be extending the search for ARA San Juan beyond the contracted 60 actual search days.
https://pbs.twimg.com/media/Drl4SOkXcAElWiu.jpg
The part in heavy type:-
“nos maniferaron que el buque no retornara a puerto alguno en Argentina una vez finalizados los 60 dias operativos y que seremos trasbordados a un buque de la armada”
Appears to translate (google) as:
“they made sure that the ship did not return to any port in Argentina once the 60 days were over and that we will be transferred to a navy ship”
Ocean Infinity will be ending their initial 60-day search phase for ARA San Juan on 16 November. Then Seabed Constructor will sail directly to South Africa for refurbishment. The Argentine Government has extended their contract for 120 calendar days, from ~ 16 November until mid-April 2019. Ocean Infinity plans to return in February and perform a second 60-day search for ARA San Juan. It is unlikely any MH370 search could be performed by OI this (southern) summer, even if funding were to become available.
@Richard Godfrey
RE: “As a pilot, familiar with Boeing aircraft, do you agree, that if a system such as the STS relies on a single AOA sensor input, that it should be mandatory to install the AOA indication option, so that in the event that one of the AOA sensors fails, the pilot is given an alert that AOA DISAGREE and can quickly diagnose the problem?””
Yes, I agree. It seems that AOA input to the STS is a new feature of the 737 MAX. I am surprised that the AOA DISAGREE caution is an option, given that the system appears to require a ‘stall’ indication from only one AOA vane to activate the stall protection. I don’t know the logic behind the certification of this new feature and I hope that aspect is covered by the accident investigation. Perhaps we’ll see a recommendation that the AOA DISAGREE caution be made mandatory, or perhaps the FAA will do so of its own accord. We might also see a requirement for other modifications, which might include removal of the AOA input to the STS if it is found to be a major problem. Time will tell.
Of interest, a Transavia B737-800 experienced a very similar problem with a faulty AOA vane earlier this year. That aircraft was fitted with the AOA indication/DISAGREE option. The crew of that aircraft safely returned to the departure airfield, but they did not have to contend with the STS problems that seem to have occurred in the Lion Air accident, as the aircraft was not a MAX variant. The Transavia incident is still under investigation by the French BEA.
https://www.aeroinside.com/item/11033/transavia-france-b738-at-paris-on-feb-8th-2018-ias-aoa-and-alt-disagree
http://www.avherald.com/h?article=4b4f3b2b&opt=0
https://www.bea.aero/en/investigation-reports/notified-events/detail/event/alarme-sonde-dincidence-defaillante-en-montee-initiale-demi-tour/
@DrB
It is unlikely any MH370 search could be performed by OI this (southern) summer, even if funding were to become available.
There will never be another search for MH370.
@DennisW,
You said: “There will never be another search for MH370.”
I think there will be, but it won’t be government funded, and it won’t happen soon. At some point OI will have competitors who might want to best OI’s null result. It’s also possible that OI will find ARA San Juan in the near term and recoup their investment in that effort, in which case OI might then decide to go back and look for MH370 if they felt there was a reasonable chance of success within the scope of a new search that they could afford.
@Andrew: Why do you suppose that AoA is an option and not standard? My guess is that some companies might believe the information is superfluous and confusing since the PFD already displays the stall margin via the speed barber pole and via the pitch limit indicator (PLI).
If the AoA is not indicated, the logic for not displaying AOA DISAGREE might be that because there are not multiple AoA indications to interpret, there is no need to warn about disagreement. Instead, there is a warning that the indicated speeds do not agree.
But as discussed, this also makes it harder to diagnose the runaway STS condition when of the two AoA sensors disagree.
It will be interesting to learn of Boeing’s design criteria, and whether there will be changes to displays and/or functionality.
@Victor Iannello
RE: “Why do you suppose that AoA is an option and not standard? My guess is that some companies might believe the information is superfluous and confusing since the PFD already displays the stall margin via the speed barber pole and via the pitch limit indicator (PLI).”
I think the main reason is simply because dedicated AOA indicators have not been used previously in many commercial aircraft, even though military fast jet aircraft have had them for years. Consequently, most commercial pilots have never been trained how to use them and some companies see them as superfluous when other instruments provide an indirect indication of the aircraft’s AOA. I guess it all comes down to the airline’s perception of cost vs benefit.
The following article from Boeing’s AERO magazine discusses the use of AOA indicators in commercial aircraft:
http://www.boeing.com/commercial/aeromagazine/aero_12/aoa.pdf
RE: “If the AoA is not indicated, the logic for not displaying AOA DISAGREE might be that because there are not multiple AoA indications to interpret, there is no need to warn about disagreement. Instead, there is a warning that the indicated speeds do not agree.”
That’s probably correct. It will be interesting to see if there’s a change of thinking given this accident and the potential impact of a faulty AOA vane on the control of the 737 MAX aircraft.
The following is a presentation by the late Captain Warren Vanderburgh about control malfunctions and flight instrument anomalies, copied from the JT610 thread on PPRuNe. It’s about 20 years old, but still very relevant today:
https://youtu.be/WfNBmZy1Yuc
@Victor,
You asked “Why do you suppose that AoA is an option and not standard?”
What I said yesterday in my comment at 5:26 am was “The AOA DISAGREE alert is only if the AOA indicator option is installed.”
The Boeing FCOM states “Additionally pilots are reminded that an erroneous AOA can cause some or all of the following indications or effects:
…
AOA DISAGREE alert (if the AOA indicator option is installed)
…”
Please see the Boeing FCOM bulletin:
https://pbs.twimg.com/media/DrbMs-VVsAA9NgB.jpg:large
@Andrew
Many thanks for your thoughtful and informative reply to my question regarding the AOA indicator option.
http://mh370.radiantphysics.com/2018/11/04/crash-debris-from-lion-air-jt610-provides-clues-about-mh370/#comment-19891
@Andrew, @Victor,
The Boeing AERO magazine article Andrew posted is very informative on the subject of a separate AOA indicator.
I understand why the AOA indicator or gauge on the Primary Flight Display (PFD) is an option, when you already have Stick Shaker (stall warning), Pitch Limit Indicator (AOA margin to stall warning) and Speed Tape Indicator (airspeed relative to speed limits).
I appreciate Victor’s point that an erroneous AOA can cause up to 9 indications or effects, but I think of these the AOA DISAGREE alert is the most helpful in quickly diagnosing the problem.
Therefore, I do not understand why Boeing only present the AOA DISAGREE alert if the AOA indicator option is installed. As Andrew says, that may be one outcome of the Lion Air accident investigation, to change the AOA DISAGREE alert to mandatory, whether or not the additional AOA indicator option on the PFD is installed.
@Victor
My apologies, I misinterpreted your question to Andrew: “Why do you suppose that AoA is an option and not standard?”
On first reading I had understood – what evidence do you have that the AoA indicator is an option and not standard?
On second reading I had understood – why do you think Boeing offers the AoA indicator as an option and not standard?
@DennisW said: There will never be another search for MH370.
It comes down to whether the value proposition for the search changes. That requires either a reduction in the cost to search per unit area, or new knowledge or insight to limit the search area. On this blog, we’ve focused on the latter, arguably with no success. The former is not likely to occur for some years, and will require step change in technology the way OI’s underwater drones were a step change compared to the towfish.
@Victor
Yes. Another factor is the value associated with finding the wreckage. I don’t believe anyone who might write a check believes it was a aircraft failure issue, hence nothing to be learned in that domain. FDR will likely show the plane was flown to location where it was found. CVR will likely be blank. What is the driver for finding the wreckage? Some people will probably say closure for the NOK.
The answers to this mystery lie in Kuala Lumpur IMO.
@DennisW: So how do we advance the ball forward? Or do we just give up?
@Victor,
I honestly feel we have a better handle on the aircraft location than ever before. Richard’s drift work puts a very reasonable limit of 20S on the 7th arc. If we can convince ourselves that +/- 25nm is also reasonable, that combination may prove attractive to OI or a similar entreprenuer.
I have no other thoughts on your question.
@DennisW: I can make the case that we have the best chance to find the plane by searching at a width of +/-25NM to the north of 25S latitude. If there were no pilot inputs after 19:41, that’s where the plane is. If there were pilot inputs after 19:41, the search width might increase to +/-125 NM, the latitude range along the 7th arc would be large, and the search becomes impractical using current technology, in my opinion.
So, how do we convince ourselves that there were no pilot inputs after 19:41?
@Victor
The BFO values at 00:19:XX have me convinced there were no pilot inputs at or after that time. There is nothing to suggest otherwise, and supporting data (no IFE log-in) that the plane plane came down shortly after 00:19:37. The APU shutdown is a fabrication (it is possible) to suggest a pull out and glide.
If the above is true the previous search up to 25S at +/-25nm can be deemed valid subject only to a failure to detect the wreckage (I give that a very generous 10% probability, weighted by the 13 out of 18 degrees searched). 18 degrees being the range of latitude from 38S to 20S I am proposing.
Richard’s work has convinced me that a terminus North of 20S is very unlikely. Based on this logic it is more than 80% probable that the wrechage is located between 25S and 20S latitude on the 7th arc, and within +/- 25nm of the arc.
I have presented all the above in previous posts. There has been almost zero feedback except from the dive followed by glide enthusiasts who weigh in with the possible APU shut down. Sure, they could be right. More likely they just want to stir their pot. I can think of no way to make the dive only scenario any more compelling than it is (and it is pretty damn compelling, IMO).
@All,
Victor posted a flight path ending further north on the 7th Arc at 21.9666°S, back in June 2018.
http://mh370.radiantphysics.com/2018/06/08/an-mh370-flight-path-ending-further-north-on-7th-arc/
I have now completed the drift analysis centred on a possible MH370 end point at 21.9666°S 103.5739°E.
The results are shown in the 3 links below (overview, table and 25 simulation runs):
https://www.dropbox.com/s/3ygmt7ycx8ukpvk/Array%20End%20Points%20Victor.pdf?dl=0
https://www.dropbox.com/s/54y0hrjjoesw5em/Array%2021.9666S%20103.5739E%20100%20NM.xlsx?dl=0
https://www.dropbox.com/sh/ij76gp2bp2orjwq/AADaLrPQUchZ2SmFK1ihOdFNa?dl=0
Comparing the new results with those previously published, using a simple scoring system, gives the following:
End point at 31.6°S scores 7.
End point at 24.0°S scores 37.
End point at 21.9666°S scores 25.
With an uplift of the Flaperon speed to Reunion of 15%, gives the following:
End point at 31.6°S scores 7.
End point at 24.0°S scores 35.
End point at 21.9666°S scores 21.
With an uplift of the Flaperon speed to Reunion of 30%, gives the following:
End point at 31.6°S scores 23.
End point at 24.0°S scores 10.
End point at 21.9666°S scores 13.
The data to beachings on mainland Africa, demonstrates bifurcation around Madagascar from an end point near the 7th Arc at 24.0°S and 21.9666°S, but not from 31.6°S.
The drift angle for the Flaperon to Reunion based on theoretical calculations by Pengam was 18° or 28° left of wind depending on orientation. David Griffin’s empirical analysis showed a drift angle left of wind up to 30° and typically between 10° and 20°. The drift angle from the 7th Arc to Reunion from an end point at 31.6°S was on average 36.5° left of wind, for 24.0°S was on average 29.7° left of wind and from 21.9666°S was on average 33.1°S left of wind from the simulation runs.
I conclude that a MH370 end point between 25°S and 20°S near the 7th Arc, in an area not yet searched, fits with the drift analysis. I do not exclude an MH370 end point at 31.6°S near the 7th Arc, but this area has already been searched.
@Dennis
I agree with you that there is a high probability that MH370 will be found between 25°S and 20°S within ±25 NM of the 7th Arc.
The rate of descent analysis from the BFO data at 00:19:29 and 00:19:37 UTC shows an accelerating high speed dive in excess of 15,000 fpm. Both the Boeing simulations and the tragic accident of JT610 show that this rate of descent can develop in under 10 seconds and within 30 seconds of impact (much shorter for JT610 as the aircraft had only reached an altitude of maximum 5,475 feet).
For those interested in JT610, the following was allegedly released to its members by the Allied Pilots Association, which represents the pilots of American Airlines. The information allegedly came from Boeing. I can’t confirm its authenticity.
“MCAS (Maneuvering Characteristics Augmentation System) is implemented on the 737 MAX to enhance pitch characteristics with flaps UP and at elevated angles of attack. The MCAS function commands nose down stabilizer to enhance pitch characteristics during steep turns with elevated load factors and during flaps up flight at airspeeds approaching stall. MCAS is activated without pilot input and only operates in manual, flaps up flight. The system is designed to allow the flight crew to use column trim switch or stabilizer aislestand cutout switches to override MCAS input. The function is commanded by the Flight Control computer using input data from sensors and other airplane systems.
The MCAS function becomes active when the airplane Angle of Attack exceeds a threshold based on airspeed and altitude. Stabilizer incremental commands are limited to 2.5 degrees and are provided at a rate of 0.27 degrees per second. The magnitude of the stabilizer input is lower at high Mach number and greater at low Mach numbers. The function is reset once angle of attack falls below the Angle of Attack threshold or if manual stabilizer commands are provided by the flight crew. If the original elevated AOA condition persists, the MCAS function commands another incremental stabilizer nose down command according to current aircraft Mach number at actuation.”
@Andrew: Very interesting. Assuming it’s true, what is your take on it?
@Peter Norton
I don’t have much to add except that the MCAS on the 737 MAX seems to operate similarly to the STS found on the older variants, except that it has an AOA input and only operates when the flaps are UP. That might explain why the ADS-B data seems to show the aircraft’s flight path only became ‘wobbly’ after it reached an altitude just below 2,000 ft, which is about where the flaps would have been retracted.
@Andrew
The concerning passage in that alleged APA memo was the bit that followed the MCAS description;
This is the first description you, as 737 pilots, have seen. It is not in the AA 737 Flight Manual Part 2, nor is there a description in the Boeing FCOM. It will be soon.
If true, that’s somewhat astounding I would think.
> Andrew: “That might explain why the ADS-B data seems to show the
> aircraft’s flight path only became ‘wobbly’ after it reached an
> altitude just below 2,000 ft, which is about where the flaps would
> have been retracted.”
Compare this to the problems on the previous flight(s):
« The previous flight of the accident aircraft, JT043 from Denpasar, showed similar erratic values in altitude and airspeed immediately after takeoff. After 8 minutes the ADS-B reported values stabilized. An unverified tech log item for that flight […] remarked “Airspeed unreliable and alt disagree shown after take off. […] Identified that CAPT instrument was unreliable and handover control to FO.” […] Lion Air did confirm that the aircraft had a “technical problem the previous flight which had been resolved according to procedure”. »¹
This reference was later replaced by:
« The NTSC reported that an airspeed indication anomaly did occur on the accident aircraft’s last 4 flights. »²
—
¹ https://web.archive.org/web/20181029200558/https://aviation-safety.net/database/record.php?id=20181029-0
² https://aviation-safety.net/database/record.php?id=20181029-0
@Richard Godfrey,
You said: “I conclude that a MH370 end point between 25°S and 20°S near the 7th Arc, in an area not yet searched, fits with the drift analysis. I do not exclude an MH370 end point at 31.6°S near the 7th Arc, but this area has already been searched.”
Looking at your predictions near the 7th Arc, I cannot discern any significant, systematic differences between distances of 0 NM, 25 NM and 75 NM (or possibly more). Thus, so far, your drift predictions, with a limited number of trials, do not provide any discrimination of distance from the arc (and that may not even be possible), at least for separations < 75 NM. That said, if you cannot exclude 31.6 S as being an end point of MH370 within 25 NM of the arc, neither can you exclude 75 NM from the arc at 31.6 S. In simple terms, the drift models have not been shown to be capable of determining likely distance (if < 100 NM) from the arc, so they can’t be used to include or exclude end points based on distance from the arc, just, hopefully, based on latitude.
It is important to understand that the debris beachings are generally low in probability, and, according to David Griffin's model, most of the debris never makes landfall in the Indian Ocean (he estimates only 1/3 beaches there). He uses a very large number of trials – 76,200 in fact. That does not inherently improve accuracy, but it certainly improves the precision of his predictions (by a factor of about 20X compared to your recent 199 trials).
As you know, David Griffin’s model predicts different fractions going north and south of Madagascar than your model predicts. The problem is, we can't know from the debris locations what the real probability of landfall is, even in a relative sense, between north and south landfalls. We have only one item (the Pemba flap) that we know traveled north around Madagascar. Was it the only one, or were there many more debris which went to the north but were not found or were found but not reported? In the absence of a systematic search along the entire Africa coastline, I don't think we can conclude much from the number of debris reports, except to say that some went north and some went south. Most hit Madagascar, and a small error in the beaching model can have a large impact on how many pieces go around Madagascar and how many of those pieces beach in Africa. In particular, the rocky beach in the northern shoreline of Madagascar may be particularly difficult to model.
I am in the process of comparing the two drift model predictions in great detail, and I will soon post some results intended to clarify and compare their predictions for a range of crash latitude This includes their geographical distributions, divided into 6 zones, and their predicted drift times compared to debris reports, also segregated into the same 6 zones.
@Peter Norton
I guess it depends on how you define ‘immediately’. The JT43 flight path seems pretty much normal until it reached about 1,500 ft. Again, that’s about the time the flaps would have been retracted:
https://www.flightradar24.com/blog/wp-content/uploads/2018/10/JT43-Alt-Ground-Speed-Vspeed-First-11-Minutes.jpg
@DrB
That said, if you cannot exclude 31.6 S as being an end point of MH370 within 25 NM of the arc, neither can you exclude 75 NM from the arc at 31.6 S.
It is true that the drift analytics cannot exclude distances greater than +/-25nm from the arc, but the weight of other evidence does, IMO. The rate of descent at 00:19:XX strongly suggests an impact near the 7th arc. The lack of an IFE log-in strongly suggests an impact near the 7th arc. There is nothing that supports your point of view. Why do you cling to it?
@Mick Gilbert
RE: “If true, that’s somewhat astounding I would think.”
Yes, it is surprising. However, as I said to you privately, I don’t think it’s necessarily a critical factor in this accident given the similar behaviour of the STS stall protection, minus the AOA input.
The crew of JT610 should have been aware of the previous problems and the maintenance work that had been completed. That history should have been a warning to them of the potential for similar problems to occur on their flight. Having accepted the aircraft, the Captain should have carefully reviewed the ramifications with the FO, together with the likely actions that would be needed if the problem did recur. The CVR, if it’s found, should allow the investigators to determine if that occurred.
@Andrew. “Having accepted the aircraft, the Captain….”
Interesting that. Is that the way with airlines generally? To me it is the ground crew with their access to detailed manuals and, when required, professional engineers, including recourse to others outside the airline, who have prime responsibility for “technical airworthiness” and the clearing of a defect. That could entail local maintenance test flights with a maintenance test pilot and if needed engineers to observe, to confirm the defect has been cleared, before it is released.
Expensive on an airline certainly.
I would expect requirements like that to be regulated, not just left to an airline or indeed a pilot.
@Andrew
The problem existed over several previous flights, and there was little reason to assume that it was remedied by maintenance. The aircraft should have been taken out of service, and 189 people would still be alive.
Sorry, I do not subscribe to your views on how the problem should have been dealt with then or how it should be dealt with now. That aircraft needs to be taken out of service until a fix is implemented and tested.
@David
RE: ‘To me it is the ground crew with their access to detailed manuals and, when required, professional engineers, including recourse to others outside the airline, who have prime responsibility for “technical airworthiness” and the clearing of a defect. That could entail local maintenance test flights with a maintenance test pilot and if needed engineers to observe, to confirm the defect has been cleared, before it is released.’
Yes, of course that’s what should happen before an aircraft is released, although maintenance test flights are rare unless such a requirement is specified in a manual somewhere. However, an aircraft commander is not obliged to accept an aircraft unless he or she is satisfied with the work that has been completed. The commander is obviously not a maintenance expert, but nevertheless it is incumbent upon him or her to review the aircraft’s previous defects and the associated rectification work. If there are ANY doubts, the commander should consult the engineer that released the aircraft.
As I said previously, HAVING ACCEPTED THE AIRCRAFT, a prudent commander would review what might happen if the problem recurs, together with any associated procedures. It’s called THREAT MANAGEMENT.
@DennisW
Stop putting words in my mouth. I DID NOT SAY THE AIRCRAFT SHOULD HAVE CONTINUED IN SERVICE. Given it’s history, it should have been taken out of service until the problem was properly investigated, with the help of Boeing if necessary. However, rightly or wrongly, the aircraft was released for service and the captain accepted it for the flight. Having done so, he should have carefully reviewed what might happen if the problem recurred.
@Andrew. In this case the corrective action was insufficient and the potential seriousness was evident. IMO the aircraft should not have been released once that condition became known, much less in continuation.
Either the regulatory structure which allowed that was flawed or was not applied: for example the training/professional education of those involved (which should also be regulated) was insufficient.
The aircraft designer and certifiers might carry responsibility for the condition but not for the aircraft’s repeated release.
As you say the pilot might have taken sensible precautions under threat management but to me that is under his responsibilty for safe operation of the aircraft not for corrective action being adequate (‘incumbent’ to ‘review’).
Those clearing the aircraft would be responsible for seeing there was a maintenance test flight to check out corrective action has been successful if that is uncertain and the consequences could be serious.
It must be quite clear IMO where such responsibility lies.
@Andrew. I was not commenting on your most 11:39, not having seen your most recent.
Delete the first ‘not’ please.
RE: “As you say the pilot might have taken sensible precautions under threat management but to me that is under his responsibilty for safe operation of the aircraft not for corrective action being adequate (‘incumbent’ to ‘review’).”
To be clear, the commander does not review the corrective action to decide if the work is ‘adequate’. That’s the engineer’s domain, not the commander’s. The commander reviews the maintenance log to ensure that he or she understands what work has been completed and that the defect has either been rectified or deferred under the provisions of the MEL. In doing so, the commander must obviously rely on advice from the dispatching engineer, but can also seek advice from the airline’s engineering management if he or she is not satisfied.
@Andrew. Thanks.
Hey guys,
I was wondering: from the moment MH370 went missing,
how long have the engines kept running? How many hours?
Wall
@Wall: The answer to this question and many more can be found in the Safety Report issued in July 2018.
DennisW says: “@DrB: The rate of descent at 00:19:XX strongly suggests an impact near the 7th arc. The lack of an IFE log-in strongly suggests an impact near the 7th arc. There is nothing that supports your point of view. Why do you cling to it?”
Dennis, you begin to sound more and more like GeRijn who was banned from this forum. Evermore preaching, proselytizing and ad-hominem attacks and less and less sober, factual discussion from you.
DrB already answered here – with his usual scientific rigor – the exact same questions you repeat over and over again.
@DennisW said: The rate of descent at 00:19:XX strongly suggests an impact near the 7th arc.
I’d say the final BFO values are consistent with an impact near the 7th arc.
The following remain possibilities:
1) The APU ran out of fuel before the expected IFE log-on.
2) The pilot arrested the steep descent, glided for some distance, and then entered into a second steep descent.
Of these, (2) seems very unlikely, but that’s just my opinion. How do you eliminate it as a possibility without bias?
@Perfect Storm
DrB’s reply had no reference to anything scientific. He merely suggested that one guess is as good as another. My assertion is that my guess is better than his guess.
@Perfect Storm
Your argument against @Dennis is a touch hypocritical!
“Argumentum ad Infinitum” is something you could accuse many of us of. The number of commenters sticking, come hell or high water, to their pre-conceived ideas is not a small minority.
Unfortunately this has sometimes descended into “Argumentum ad hominem”.
Your examples of @Ge Rijn (100% ad hominem) and @DrB (100% ad infinitum for 31.6S) are poor choices to compare and contrast with @Dennis.
If you can’t take the heat, then get out of the kitchen.
… and “ad infinitum”, MH370 is to be found between 25S and 20S!
😂😳😉
@DennisW, @Richard G: I would have a very difficult time recommending a search area that implies the dive-glide-dive scenario to be true, unless other areas closer to the 7th arc come up empty. So perhaps it’s all a matter of priority. I’ve also made the case that if the dive-glide-dive scenario is true, then the possible range of latitudes for the 7th arc crossing is very difficult to define, because there would be little reason to believe the flight was completely automated after 19:41.
@Victor
I agree with you.
Our priority is to check the search area between 25S and 20S at +/- 25 NM.
If that fails to find MH370, then I agree to give up until a new generation of technology is implemented.
@Victor
How do you eliminate it as a possibility without bias?
You cannot eliminate it as a possibility (remote as it is). You can eliminate it based on the fact that searching wider on the 7th arc is a non-starter. Entertaining DrB’s scenario is the equivalent of giving up and walking away.
Ask yourself instead – what is the best way to proceed now? What is the best use of search resources deployed for a future search? The answer is obvious to me – you follow the path most closely aligned with what we know. At this moment that is also the most “doable” path.
I was (as you well know) totally against starting an underwater search before debris was found based on the Inmarsat data. The Inmarsat data is garbage relative to anything other than the direction South and the rapid descent at the end of the flight. I (and knowledgable colleagues) knew that years ago, most people are just accepting that now. DrB, TBill, and Perfect Storm being notable exceptions.
We have a very manageable area remaining based on the huge amount of work and expense already done and the drift analytics. I am not willing to toss that in the toilet based on alternative remote possibilities. You might even say I feel strongly about it.
@DennisW: Would you be so bold as to state what you believe is the probability of finding the MH370 debris field between 25S and 20S latitudes within +/-25 NM from the 7th arc?
@Victor
The very simplest way to look at it is to assume the debris is in the latitude range of 38S to 20S and within +/-25nm of the arc. Using the Metron AF447 criterion, the probability of finding the wreckage is 90%. The probability of missing it being 10%.
The above does not assign any probability to the debris not being in the area searched. If one assigns a 90% probability (arbitrary at best) to the debris being in the search range, then the probability of finding it in a continued search of 25S to 20S becomes ~80% which is a number I think is very reasonable.
@DennisW: OK. 90% that the impact occurred within 25 NM of the 7th arc, and a 90% detection probability. What is your rationale for limiting the probability of the dive-glide-dive scenario to 10%?
@Victor,
I thought 10% was generous based on:
1> BFO values
2> No IFE log-in
3> Unexplainable choice of flight dyamics
Item 3> is particularly relevant. There is absolutely no reason for the initial dive if a glide was ulimately intended. We have already established that the RAT would do fine with a simple glide from altitude. What could possibly explain a dive-glide-dive choice?
@Victor Iannello,
You said: ” I’ve also made the case that if the dive-glide-dive scenario is true, then the possible range of latitudes for the 7th arc crossing is very difficult to define, because there would be little reason to believe the flight was completely automated after 19:41.”
In my opinion the “little reason” you throw aside would be the pilot flying the aircraft in the normal automated fashion, which was also done from VAMPI onward. I don’t agree that using that method is of low probability from VAMPI until MEFE.
@Victor
There is no historic precedent for an aircraft crash with a dive-glide-dive scenario.
Out of 20,300 incidents in the ASN database, only 23 have suicide as a contributory cause.
We are talking less than 0.1%.
Even if you add the 328 occurrences of missing aircraft (such as MH370) and the 104 occurrences where the cause is undetermined, we only get 2.3%.
Even if you add 44 occurrences of loss of situational awareness, 55 occurrences of alcohol/drug abuse, 3 occurrences of mental problems, you only get to a 2.7% probability.
@DrB: You are seriously mistaken. Your proposed route has the pilot changing from LNAV to a constant magnetic track, and then remaining in that automated navigational mode with no further pilot inputs for 5 hours until fuel exhaustion. To fly that period of time in that particular autopilot mode is not a “normal automated fashion”. To then believe a pilot would enter into dive-glide-dive maneuvers is proposing an absurd series of events. It’s all possible…but I’d consider this sequence to be very low probability.
The only automated mode that would be “normal” over those distances and times would to be following one or more waypoints.
@DrB: You said “the pilot flying the aircraft in the normal automated fashion, which was also done from VAMPI onward”
That’s your belief. What you call fact, I call conjecture. There are many reasons to doubt the Lido Hotel data, including the fact that the Malaysians refuse to officially acknowledge their existence, and during the investigation, they told the Australians the data doesn’t exist. Not to mention that it’s not possible to extrapolate the radar data to the satellite data without introducing a lateral offset maneuver in the 3-minute gap between the two data sets. Those are all excellent reasons for questioning the Lido Hotel data.
@DennisW: I note that Byron Bailey believed an initial high speed descent was necessary for the RAT to produce the required power. He argued it here on this blog. Now, we know that he is mistaken. However, he is a former 777 captain, and his knowledge base might be representative of other 777 captains, so perhaps the MH370 captain had the same mistaken belief.
@Richard G: I’m not sure I understand your point. What scenario do you believe is most likely?
@Victor
My point is that a dive-glide-dive scenario is an extremely low probability.
My rationale is, that there is no historical precedent for a dive-glide-dive scenario in any aircraft crash.
There are plenty of occurrences of a dive.
There are some occurrences of a glide.
But never a dive-glide-dive.
I find such a scenario contrived to try and match certain end points.
In my view we need to search between 25°S and 20°S up to ±25 NM from the 7th Arc.
@Richard Godfrey,
MH370 is unique. You cannot compute its probability.
@DrB
You stated “MH370 is unique. You cannot compute its probability”.
That is “Argumentum ad Absurdum”.
The Aviation Safety Network (ASN) Database contains detailed descriptions of over 20,300 incidents, hijackings and accidents. Each of the 20,300 events are unique. That does not prevent the ASN publishing statistics and computing probabilities.
Of the 14 pilot or hijacker murder suicide events, all were a powered dive into a target building, own home, target airfield and aircraft, mountains, ocean or until a mid air break up. MH370 was an unpowered dive after fuel exhaustion, into the ocean, in a remote location, at over 15,000 fpm, as shown by the BFO data.
The dive-glide-dive scenario is a contrivance to get around the conflict between the BFO data and the negative search within ±25 NM of the 7th Arc.
@Victor,
All oceanographers agree that the most likely location for MH370 debris to beach is on the eastern coast of Madagascar. Out of my 200 recent simulation runs, 66 beach on the eastern coast of Madagascar, which is only 378 NM from Reunion and it takes on average 47.5 days for floating debris to travel from Reunion to Madagascar. The time between Reunion and Madagascar is almost constant, irrespective of the start latitude on the 7th Arc. The arrival time near Reunion, taken from these 66 simulation runs, that eventually beached in Madagascar is shown in the link below:
https://www.dropbox.com/s/qhxxywj0fld8onh/Arrivals%20near%20Reunion%2012Nov2018.pdf?dl=0
The start latitude near the 7th Arc closest to the 508 day trajectory of the flaperon is 24.9°S.
An arrival in the Reunion area 30 days earlier is closest to a start latitude near the 7th Arc at 23.5°S.
Excluding 7 outliers, the start latitude is highly unlikely to be north of 18.8°S or south of 31.8°S.
@RichardG
The arrival time near Reunion you just posted; is that purely based on undrogued drifter data, so roughly excluding possible extra (direct) wind induced drift for the flaperon on top of the Stokes drift?
@Niels
The arrival time in Reunion is based on undrogued drifter data. Additional windage would mean an earlier arrival. As indicated, 30 days earlier would mean a start latitude on the 7th Arc of 23.5S.
@RichardG
Thank you for clarifying. As a rough estimate for the uncertainties: 508 days x 10 cm/s is a lot in distance traveled.
@Niels
I am talking about the Southern Indian Ocean, not Stormy Bay Tasmania.
Even 100 days earlier arrival in Reunion, would mean a start latitude on the 7th Arc at 21S.
I have only claimed, we should search from 25S up to 20S.
I find it interesting, when I say the Flaperon was in Reunion after 400 days, I am criticised that it arrrived far too early.
I find it interesting, when I say the Flaperon was in Reunion after 500 days, I am criticised that I have forgotten windage..
> Richard Godfrey: My point is that a dive-glide-dive scenario is an extremely
> low probability. My rationale is, that there is no historical precedent for
> a dive-glide-dive scenario in any aircraft crash.
There is no historical precedent for MH370. What all theories have in common, is: none of them are based on any precedent. The known part of flight MH370 (until IGARI or 18:22, depending on what you admit as evidence) has no historical precedent either. And yet it occurred.
Why would you demand that the end of an unprecedented event must have precedent ?
It’s not valid to argue that the continuation of an unprecedented event would somehow be of “extremely low probability” because it lacks precedent.
It’s like arguing it would be extremely improbable for a green alien to have yellow eyes, because there is no historic precedent for humans with yellow eyes.
> DrB: MH370 is unique. You cannot compute its probability.
>
> Richard Godfrey: Each of the 20,300 events are unique.
Few of the 20,300 events are completely unique. Most share a common cause with many other flights (cargo fire, birdstrike, midairs, CFIT, fuel exhaustion, spatial disorientation, etc). MH370, on the other hand, seems to be unique on every level.
> Richard Godfrey: Of the 14 pilot or hijacker murder suicide events, all were
> a powered dive into a target building, own home, target airfield and
> aircraft, mountains, ocean or until a mid air break up.
None of them lasted for 7½ hours.
> DennisW: Another factor is the value associated with finding the wreckage. I don’t
> believe anyone who might write a check believes it was a aircraft failure issue,
> hence nothing to be learned in that domain. FDR will likely show the plane was flown
> to location where it was found. CVR will likely be blank. What is the driver for finding
> the wreckage? […] The answers to this mystery lie in Kuala Lumpur IMO.
> DennisW: I view not finding wreckage dissappointing, but not a huge loss. I think the
> CVR will contain no information, and the FDR will show that the plane was flown to
> where it was found (not an aircraft failure).
> What I don’t think the wreckage will provide is the answer to why the plane was
> diverted. Since I am not a fan of the suicide motive, I am sure that answer lies
> elsewhere and may eventually surface.
@Victor:
Is this blog’s mission limited to finding MH370, at which point it would be closed?
Or, in case of DennisW’s scenario, will you all continue to investigate/discuss MH370 in a bid to solve key questions of MH370’s mystery (for example why it was diverted, as Dennis said) ?
@Peter Norton
You stated: “The known part of flight MH370 (until IGARI or 18:22, depending on what you admit as evidence) has no historical precedent either. And yet it occurred.”
The flight route N571 is flown over 100 times each day.
Hijackings, unfortunately have happened all too often.
Pilot murder suicide has also happened several times.
I have not “demanded” anything. YOUR WORD, NOT MINE. Do not put words in my mouth!
Andreas Lubitz considered his plan for the German Wings for longer than 24 hours and the crash was only on the return flight. Why do you think a flight of over 7 hours proves anything unique?
So what is your conclusion, following your tirade?
Are you trying in your strange Argumentum ad Hominem, to prove a dive-glide-dive?
If so, please deliver your rationale.
@RichardG
I think a way forward could be to estimate error margins for the models we are using. This applies to the drift models as well as for the BFO model. At first we will possibly be shocked; next it could help to point out on which aspects of the models we should work to improve accuracies.
For your model I’m not sure if we should put too much effort regarding the flaperon, as it is a single item with rather peculiar wind sensitivity. However, for the low windage items arriving at African / Madagascar shores, I think it is for example interesting to find out what possible errors are introduced by basing the drift model on historic data, as well as by the numerical methods used.
Regarding the BFO model: I have been in brief contact with Ian Holland and he still refers to this “geographic dependency” for the “structured bias”. To me it indicates there is room for improvement in the BFO model that was used by DSTG.
@Peter Norton: The blog will remain open as long as I perceive it is adding value and I have the willingness to continue. It may continue after the aircraft is found. Or it may end before that time. We’ll see.
@Richard Godfrey: I don’t think you have understood my comment. I don’t know how else to explain it. Maybe rereading it without feeling attacked personally might help, because
> Argumentum ad Hominem
there were none
> I have not demanded anything.
Sure. First 3 lines of the posting you were referring to.
> Andreas Lubitz considered his plan for longer than 24 hours
He considered it probably for weeks, months or maybe even years.
The execution took only minutes. Not 7+ hours.
@Victor Iannello:
I didn’t want to inquire about this blog’s lifetime. I understand that this is of course hard to predict and a personal decision. I rather wanted to ask about its mission. Is it to help locate the wreckage or beyond that to solve the mystery?
When DennisW wrote that the wreckage might not tell us enough, it occurred to me that I don’t know the answer to this question. I mean what would happen if, say, tomorrow the wreckage were found? Would the mission be considered accomplished, regardless of what is found or would it depend on what is found?
(By “wreckage” I meant the crash site.)
@Peter Norten
You are continuing your Argument ad hominem.
Now you accuse me of not understanding you (last resort argument). I understood you perfectly.
However, you did not understand me, I asked if you would supply your rationale for a dive-glide-dive scenario.
You failed again to provide your rationale, preferring to continue your personal attack!
No wonder. you want Victor to close his blog.
I rest my case.
> Peter Norton: “The known part of flight MH370 (until IGARI or 18:22, depending on
> what you admit as evidence) has no historical precedent either. And yet it occurred.”
>
> Richard Godfrey: The flight route N571 is flown over 100 times each day.
> Hijackings, unfortunately have happened all too often.
how many of those have “gone dark” (ACARS, XPDR, etc.) ?
Do you really want to contradict that the circumstances of MH370’s disappearance have no historical precedent ?
@Richard Godfrey: I would like to talk MH370, not engage in personal arguments please. I have not “accused” you of anything. You reaction gave me the impression that you didn’t understand my comment and I told you that. That’s all.
> No wonder. you want Victor to close his blog.
Come on, I have never said that in the least. I’m glad it exists.
@Peter Norton: If you look at the top of the page, it says “Helping to Solve the World’s Greatest Aviation Mystery”. If the mystery is solved, or we are not contributing towards solving the mystery, I’ll end it. This blog is not to promote a book, an article in a journal, or a media appearance. On the other hand, I suspect that finding the aircraft will not completely solve the mystery, and will in fact create many new avenues to explore that may be of interest to me and other readers here.
@Victor Iannello: Thanks. I share your point of view and hope you can keep it open as long as possible.
@Peter Norton
I have different theory that I raise from time to time but isn’t generally considered much.
I assume that Z is planning a suicide mission and does not want the aircraft to be easily found. He plans to put the aircraft in the SIO. He plans to burn all of the fuel to minimize a fuel slick after impact. He plans to decouple any post flight simulation by Boeing of range at fuel exhaustion, by periodically performing a wide 360 clearing several times during the flight. He needs reasonable distance, but not maximum distance. The ATSB zones were biased toward long straight flights and intentional holding as not allowed – so ARC 7 most likely position was centered at 38S. With intentional clearing turns the ARC 7 crossing could easily be above 25S.
Z also wants to put the plane underwater with a small debris pattern. I think that this might be best done with a vertical entry at relatively low speed. A dive from cruise altitude, leveling off just above the surface, bleed some speed off, then pull up into a loop with a near vertical entry. This takes daylight to execute. Lots of simulation by Z would be needed to be able to perform the maneuver. There may be other terminal maneuvers that could result in a clean, less than stall speed, vertical entry.
A controlled vertical entry from inverted flight at 100 knots may be a good way to get the bulk of the aircraft wings and fuselage underwater without much surface breakup. If Z planned this including the holding on the way south he has been very successful.
Hank: You have a vivid imagination.
“I think that this [minimum debris] might be best done with a vertical entry at relatively low speed”? Good luck with that maneuver.
@Hank
I assume that Z is planning a suicide mission and does not want the aircraft to be easily found.
I can find nothing that supports a suicide motive. If you have any links to anything anywhere that suggests a suicide motive, please post.
@Hank. The Comoros Island flapless 767 ditching outgcome was marred by interference with the flight crew. Even so it was into little seas and no swell. The fuselage broke in 2 places, there was considerable internal damage and bits came off, including from the wings.
Comparing reports of Silk Air wreckage and photos of Lion Air debris I do not think we should dismiss a flapless ditching.
https://www.youtube.com/watch?v=fbeeMk5xFmo
https://www.youtube.com/watch?v=sgRAc4ZL9KA
@Hank
Sounds like we can safely put you in the active pilot category, with myself and some others.
@Victor
Just had a couple of very smooth 737-800 flights on American. Apparently not the same as the 737-MAX8, but we saw a MAX8 get pushed out of our gate before our aircraft came in there. Distinctive wing tip on the MAX8.
@TBill
So as a member of the active pilot category, what is your suggestion for a continued search?
@TBill Yes, I believe the entire flight profile could have been executed by one experienced pilot.
@DennisW It is feasible for a pilot to perform the flight. The pilot may have had some reason why he destroyed the aircraft which was acceptable to him. So his death may have been consequence and not a primary goal. I loosely used the term suicide rather than just intentional diversion and destruction of the aircraft. One motive may have been to embarrass the Malaysian government by successfully making MH370 disappear.
@airlandseaman The maneuver I described is easily performed at airshow at altitude. This is not unlike the half loop performed by the SEA Q400 by the ground agent where he rolled into loop. If the Q400 guy rolled over at half the altitude he would have been vertical at water entry. The objective is to enter vertically at low speed.
@David The Comoros islands are ditching which almost always go bad. It is common to think of plunging into the sea at high speed in some terminal dive or a flat landing into rough seas. Splat – a mess. Near vertical at less than 100 knots.
The pilot would not know about the Inmarsat arcs so there would be no reason to glide a straight segment beyond flameout. With fuel gone it just makes sense to get down fast and perform the terminal maneuver. A few 360 turns en-route mess up any max range simulation. The circles will bring the arc 7 point north of 25S. Each 360 could move arc 7 crossing by 100 miles.
@Hank
@DennisW The pilot may have had some reason why he destroyed the aircraft which was acceptable to him. So his death may have been consequence and not a primary goal. I loosely used the term suicide rather than just intentional diversion and destruction of the aircraft. One motive may have been to embarrass the Malaysian government by successfully making MH370 disappear.
OK. So you do not have a supported opinion of why the flight was diverted.
@Hank: Thank you for sharing your theory. How would “a few 360 turns en-route” be consistent with BTO/BFO data ?
@Richard Godfrey,
You said: “The arrival time in Reunion is based on undrogued drifter data. Additional windage would mean an earlier arrival. As indicated, 30 days earlier would mean a start latitude on the 7th Arc of 23.5S.”
Actually, the arrival in Reunion is considerably more than 30 days prior to the undrogued drifter prediction if CSIRO’s estimate of speed increase is used. In that case the best latitude to match the Flaperon’s arrival is near 31S.
It is pointless to make two assumptions regarding one debris: (1) one assumption regarding the size of the reporting delay and (2) another assumption regarding the drift speed, just so that a particular crash latitude becomes consistent with the reporting date. We already have an estimate for the Flaperon windage parameters, and I don’t see any justification for assuming a different speed uplift. Let’s use what we have and then see what the reporting delays would have to be in order for any particular crash altitude to become consistent. Then one can decide if those reporting delays are acceptable or not when assessing a particular crash latitude. If you make assumptions regarding both reporting delay and drift speed you can make any latitude appear consistent with the actual arrival. What’s the point in doing that?
You also said: “The Aviation Safety Network (ASN) Database contains detailed descriptions of over 20,300 incidents, hijackings and accidents. Each of the 20,300 events are unique. That does not prevent the ASN publishing statistics and computing probabilities.
Of the 14 pilot or hijacker murder suicide events, all were a powered dive into a target building, own home, target airfield and aircraft, mountains, ocean or until a mid air break up. MH370 was an unpowered dive after fuel exhaustion, into the ocean, in a remote location, at over 15,000 fpm, as shown by the BFO data.”
Thank you for proving my point. MH370 is unique, and it does not fall neatly into any of the existing classes of statistics. What is different about MH370 is the appearance that a primary goal (possibly even “the” primary goal) was to disappear the aircraft. I am unaware of any precedent.
@DrB,@TBill,@Hank,…
Your narratives are consistently lacking a procedural recommendation i.e. what should we do next?? My guess is that is also a characteristic of your careers – presenting analytical summaries for other people who are the decision makers. There are people who speculate on causality. There are people who comment on events. What is needed are people who decide how to proceed. That is the way the world works at the highest levels. We are not highly rewarded for our opinions. We are highly rewarded for what we actually decide do or punished for things we decide to do that turn out poorly.
So at this point I am pretty much discarding posts that lack a procedural recommendation (which has always characterized my own posts). Until recently my recommendation was to do nothing based on the information we had. It turns out that was an intelligent choice. My recommendation now is to search 25S to 20S at +/- 25nm.
Your recommendation??
@DrB
It is pointless to hang on to your theory that MH370 ended up at 31.6°S.
This area has already been searched up to ±25 NM from the 7th Arc.
It is pointless to hang on to your theory of a dive-glide-dive scenario at the end of flight.
You must agree, that this contrivance is clutching at straws in order to make your MH370 end point fit the final BFO data.
It is pointless to hang on to the CSIRO data that shows a clear bias northwards and fails to predict MH370 floating debris arriving in South Africa in the correct timeframe, where 4 items have been found, which are highly likely or almost certainly from MH370.
You must agree, that the CSIRO windage predictions were based on sea trials off the coast of Tasmania and not in the Southern Indian Ocean and there is a mismatch between the theoretical windage calculated by Pengam and the empirical windage shown by Griffin.
My recommendation now, is to search 25°S to 20°S at ±25 NM.
What do you have against that recommendation?
If you disagree with my recommendation, what is your recommendation please?
Richard Godfrey says:
@DrB, @Niu Yunu,
David Griffin changed the scale he was using in recent Fig. 5a and Fig.5b.
On 27th Oct 2018, Fig. 5a looked like this
On 1st Nov 2018, Fig. 5a looked like this
@Richard Godfrey:
Thanks, that clears it up.
Why did the underlying data change so much ?
@Niu Yunu
If you look at the scale on the right of the graphic, David Griffin has changed it:
27 Oct: 100 x #items beaching / #items tracked.
01 Nov: 100 x fraction of items beaching in each latitude bin.
I assume the underlying data has not changed, just the presentation of the data.
Hank: Vertical and low speed are mutually exclusive. Please show your math.
———-
Richard Godfrey: I assume the underlying data has not changed, just the presentation of the data.
———-
I don’t think so, because when compared to 27 Oct, on 1 Nov …
– some squares got colder (e.g. entire row findings:12S)
– while others got warmer (e.g. findings:2S/crash:8S)
@airlandseaman, @Victor Iannello:
I’ve just read that you first came up with the ‘cone of silence’ method. I have missed that when I was away for some weeks. I found a discussion in April/May. Was it ever presented as a paper here?
@Peter Norton: You have included the link to Mike’s results, which includes ground speed calculations performed at various altitudes. To assist those interested in performing their own calculations, at the end of the post on civil radar data, I included a link to an Excel file that converts the PSR data into latitude and longitude as a function of altitude. Using that file, and recognizing the 4-minute boxcar average that Mike used, you should be able to replicate his results.
@All: There is a new WSJ article on the crash of Flight JT610. I have included all the text from the article in the post above. Here are some relevant excerpts:
Boeing marketed the MAX 8 partly by telling customers it wouldn’t need pilots to undergo additional simulator training beyond that already required for older versions, according to industry and government officials. One high-ranking Boeing official said the company had decided against disclosing more details to cockpit crews due to concerns about inundating average pilots with too much information—and significantly more technical data—than they needed or could digest….
The focus of the probe is shifting away from its early emphasis on individual system malfunctions and suspected pilot mistakes, according to people tracking developments.
Instead, these people said, U.S. and Indonesian crash investigators increasingly are delving into the way the MAX 8’s automated flight-control systems interact with each other, and how rigorously the FAA and Boeing analyzed potential hazards in the event some of them malfunction and feed incorrect or unreliable data to the plane’s computers. Swiftly turning off the automated feature is the solution in such cases…
Some changes in flight software, training, and documentation are in order…
@Victor
What a great time to be an attorney.
Boeing has a real mess on their hands. Carriers have to be wondering about the potential liability they face by not taking the aircraft out of service until their pilots receive additional training (when simulators become) available. If I was running a US carrier I would take the plane out of service and sue Boeing for lost revenue and damages associated with unserved customers.
@DennisW
“Your narratives are consistently lacking a procedural recommendation i.e. what should we do next??”
Dennis I am a chem engr so you are correct about analyzing data, and presenting data, but normally there certainly is a specific process design recomendation based on interpretation of the experimental data.
Your question is interesting, because nobody has asked that. Here are my thoughts:
(1) If it was active pilot, that alternative has received much less analytical development of flight paths and flight procedures that criminal intent might have done. Every day I ask myself, is the passive flight truly proven by the data, or is it just a “policy” position to favor that so strongly? I need to realize some investigators may have insider info that I do not have, but the passive alternative is feeling weaker to me, from my vantage point.
(2) Based on Item-1, there is more work needed on the active-pilot option. It is very frustrating when the passive pilot advocates say, for example, the search should be cancelled after 20-25 South +/- 25-nm is searched, because at that point the passive pilot advocates will be completely out of ammo (ideas). It seems like there is zero interest (by passive advocates) in pursuing the active pilot alternate even if that is suggested by the results.
(3) As far as specific search areas, an active pilot might have crashed close to Arc7 between 20-25 South. But I am not overly optimistic. I am thinking there was may have been an active glide. Hank is philosophically correct up until the end of flight, where although the pilot perhpas did not understand BTO/BFO, he may have understood the satellite system has to logon again when turned on, thus telling us he was still flying, and/or needed to get where he was going, for whatever strategy he had in mind.
>>Preliminarily I like the pilot’s simulator path 30S as the Arc7 flyover point. To me that is the only flight path we actually know could have been used. On JW blog it was recently postyed about an unrelated scientific search of Dordrecht Hole/Diamantina Escarpment sea bottom area. So I figure I got one iron in the fire, if that is true.
@DennisW: After this crash and the heightened awareness to the issue, it is unlikely we will see another accident with the same root cause in the near term. I don’t think we’ll see many operators that choose to ground their fleet of MAX 8s. It will be interesting to see how Boeing and airlines choose to remedy the issue, what actions Boeing will take to limit their liability, and what liability, if any, is incurred by Lion Air.
@TBill
Still come up short of a specific recommendation so I will make one based on your postings.
Search centered at 31.5 latitude. Search area 33S to 30S at +/-120nm. I like to use degrees to compare search areas. It is easy and avoids conversion errors. One degree is equivalent to 60nm.
So your area (which I created for you) is 4 degrees wide (+/-120nm) and 3 degrees along the arc. That amounts to about 12 deg^2 of search area. Contrast that with 25S to 20S (5 degrees) and +/- 25nm (5/6 of a degree). That amounts to 25/6 deg^2 ~ 4 deg^2. Quite a large difference.
@Victor
@DennisW: After this crash and the heightened awareness to the issue, it is unlikely we will see another accident with the same root cause in the near term.
I would agree with that, but the liability associated with a Max 8 crash has gone up astronomically. Lion Air can rightfully claim they are blameless, and the victim of misleading marketing by Boeing. That claim can no longer be made by any carrier.
You want to rely on your pilots being told what to do via a Boeing “corrective action” memo which may or may not be complete (since the manufacturer has already engaged in misleading statements), or would you prefer a more prudent course of action (a completed investigation of JT610 and specific training related to that investigation). As a director of a publicly traded airline I would resign if the aircraft was not immediately removed from service in the short term. You cannot put profit associated with flying what amounts to a defective aircraft ahead of the safety of your customers.
@Victor Iannello,
@airlandseaman
Thank you for the references about the CoS method. Here is a short explanation of it by another author. Has one of you written a paper on that subject ?
@Victor
Re: WSJ
If I recall wasn’t it Andy Pasztor (and Joe Ostrower) who broke the early news on MH370 about the satellite pings, before Malaysia admitted to it on 15-March-2004.
@DennisW
Why are you restricting width to 120-nm? Maybe a better preliminary way to think of it is +/-25 nm around Broken Ridge and/or +/-25nm around simulator path. Duncan Steel before he left the debate was recommending quicker search by using grid that does not cover every square inch. Maybe some synergies with other scientific seraches that many be planned.
correction: end should say “other scientific sea bottom searches that may be planned”
@Peter
A lot has been discussed relative to the so-called cone of silence. As usual my own interpretation is different, which resulted in unfounded criticism (which is also usual) by DrB and ALSM. There are more direct ways to interpret what happened.
https://docs.google.com/document/d/14oMdSPFUpV8MF7qM9HCwpyNkwU-Lw54_Iasg9CuoRgE/edit?usp=sharing
@Peter Norton: That paper is an over-simplification because it assumes a symmetric CoS and a fly-over of the radar site. However, not withstanding those simplifications, I see nothing technically incorrect in the paper. If it helps you to understand the method, then use it. I haven’t taken the time to document the method because it is fairly simple geometry, and most readers here are technically adept and don’t need the help. At the request of some of the readers here, I created the spreadsheet so that others can perform similar calculations using the available PSR data. Perhaps Mike has produced some documentation that might assist you.
@TBill: Yes, the WSJ was adamant that satellite communication continued for hours after the transponder went dead. However, the WSJ also contributed to the misunderstanding between SATCOM and ACARS, as well as making false claims about the engines transmitting data. Unfortunately, there are some that continue to cling to those mistakes from early reports as evidence of a cover-up on the part of Inmarsat, Boeing, and Rolls-Royce. So the WSJ contributed to forcing Malaysia to admit that the flight continued for some hours after 17:21, as well as contributing to rumors about that the satellite data that continue today.
@DennisW said: You want to rely on your pilots being told what to do via a Boeing “corrective action” memo which may or may not be complete (since the manufacturer has already engaged in misleading statements), or would you prefer a more prudent course of action (a completed investigation of JT610 and specific training related to that investigation).
I’d want both. They are not mutually exclusive. Effective immediately, MAX-8 pilots need to recognize runaway trim in flaps-up manual flight and be able to take corrective action. (That clackety-clack of the trim disks spinning should be very helpful in diagnosing the problem.)
@Peter Norton
Regarding: “@Hank: Thank you for sharing your theory. How would “a few 360 turns en-route” be consistent with BTO/BFO data ?”
The DTSG particle filter was entirely based on a ghost flight and for that the PDF was centered on arc 7 at 38 S (figure 1.1 in their book). The simulations only allowed turns of up to 180 degrees and back to back 180 degree turns would have been extremely unlikely in all of their route generation.
If BTSG ran the same simulation but required exactly one 15 minute 360 turn to be randomly located in each of the many thousands of generated profiles and weighted using the same BFO/BTO data, this would result in a different PDF.
Notionally a 360 between two arcs (a 15 minute time gap) has the effect of pushing the flight path to the right because there is less effective time to cover the distance and a southeast path is shorter than a southern path for the arc geometry. So IMO if DTSG had run the model with one required 360, the arc 7 pdf would be centered further north. If a simulation was run with two required holding 360s, that would move it even further. The BFO/BTO data would rule out many of the locations for a 360.
The PDF for no 360 (baseline), exactly one 360, and exactly two 360 would be very different, but all of the BTO/BFO information would be used in each case.
My recommendation is the DTSG should rerun their simulation with a requirement for exactly one 360 and compare it to their baseline model.
I expect the new PDF will locate above 25S on arc 7.
@airlandseaman
re: “Hank: Vertical and low speed are mutually exclusive. Please show your math.”
In a steady state model an aircraft descending straight down will accelerate to a high terminal velocity.
If you can descend to just above the water and bleed airspeed and then perform a vertical loop such that the aircraft is pointing down but at zero vertical speed 500 feet above the water, the maximum entry speed would by 180 fps – about 122 MPH – not 600 MPH.
@Hank: That maneuver won’t end well in a B777. But, don’t trust me. Let’s ask @Andrew.
DennisW
re: “Your narratives are consistently lacking a procedural recommendation i.e. what should we do next?? My guess is that is also a characteristic of your careers – presenting analytical summaries for other people who are the decision makers.”
You actually have no idea what my career has been.
If I could I would direct DTSG to perform additional runs of their model to allow for one or more planned 360 turns. I have sent recommendations to them to no avail, during the time that the original searches were ongoing. But I can’t order them to do anything. And I can’t recreate their work and do it myself. I expect the resulting PDF would be above 25 S on arc 7 which others recommend based on drift analyses. I also can’t actually order or fund a new search above 25 S.
@victor
Maybe it can’t be done. But ditching is almost always unsuccessful in rough sea state and without power. My question to an experienced stunt pilot (even with a large aircraft) is how can you put the plane underwater with the least breakup.
@Hank: The recovered debris shows evidence of a high energy impact. This talk about an attempted ditching, whether successful or unsuccessful, doesn’t fit the data. A slow, vertical entry to the water that doesn’t destroy the plane is also not possible.
@DennisW: Here is an interesting video showing a simulated recovery and landing after a trim runaway event on a B737. It is two-person effort, as the PF struggles to exert the required pressure on the column as the PM works the trim wheels to unload the column. The pilot and instructor in the video don’t seem like seasoned pilots (e.g., the instructor seems to say “rudder” when he means “stabilizer”), but the video is helpful nonetheless.
@TBill
Why are you restricting width to 120-nm? Maybe a better preliminary way to think of it is +/-25 nm around Broken Ridge and/or +/-25nm around simulator path. Duncan Steel before he left the debate was recommending quicker search by using grid that does not cover every square inch. Maybe some synergies with other scientific seraches that many be planned.
I put the search thinking (and specifying) into five primary categories. SH1 through SH5.
SH1 – I don’t feel strongly about where to search, but I think the search should continue.
SH2 – The data we have simply does not support the expense of an underwater search. Go home.
SH3 – The search should continue at the following precise location.
SH4 – The search should continue at a precise location, but I dont want to say specifically where that is.
SH5 – The most important thing is to simply get along and be nice.
I put Victor in the SH1 category. DrB and TBill are members of SH4. I was in SH2 until OI finished up. Now I am in SH3. Hank and Perfect Storm are in SH5.
@Peter N
You said:
@Victor Iannello: Thanks. I share your point of view and hope you can keep it open as long as possible.
There is no end to it. A while back I had a Far Side Cartoon dream. It showed a large gathering of people milling about with a drink in one hand and a spreadsheet in the other. Above them was the banner “20th Annual Reunion of MH370 Analysts”
@DennisW said: There is no end to it.
Speak for yourself.
@Hank
It’s interesting to brainstorm intentional grounding techniques for MH370. I have wondered if keeping negative pressure inside the aircraft could help to bring in water upon hitting surface.
But I am currently thinking an unsurvivable, hard, fast flaps-up glide/ditch at 200-250 Ground Speed would split the plane initially into two pieces, and be somewhat consistent with debris appearances. Also pilot can get out of cockpit to manage evidence, by not being present on the flight deck.
Speak for yourself.
🙂 🙂
@ Victor
re: “@Hank: The recovered debris shows evidence of a high energy impact. This talk about an attempted ditching, whether successful or unsuccessful, doesn’t fit the data. A slow, vertical entry to the water that doesn’t destroy the plane is also not possible.”
Without an active pilot the aircraft would end up in a near vertical, spiral dive at over 500 kts. This would be a high energy impact, but you would think the aircraft would just crush at the surface like Lion Air 610. Are you suggesting the debris was from this type of entry?
While I was suggesting a way to have a <150 kts vertical entry, I would be easy to take a 777 to 200 feet, slow to <200 kts, and then nose over to a 45 degree entry. This impact could rip of a flap but maybe the wings and fuselage could go under and not crush at the surface.
Maybe the located debris does indicate a 500 kt+ vertical entry from a terminal spiral dive?
@Victor, DennisW, TBill, others
JT610/PK-LQP
Victor, yes, that’s a helpful video. The first audio alert in the clip at 2m56s, if I recall correctly, is the autopilot disconnect aural warning (I have quite a number of unlogged ‘hours’ flying time in Level D 737 simulators, albeit -300/400/500 series configs).
In that simulator exercise, it is the runaway trim that the pilots react to, not any specific cause that is alerted. The crew ignored the fold-out handle on the trim wheel, used for manual cranking. That feature is a legacy of the 707 and 727 designs.
There are many other clips on YouTube of short, but actual, 737 NG and MAX flights that show the typical, short, bursts of trim wheel operation that would be expected.
Runaway stabiliser trim is a warning in itself that something is wrong. IAS/AoA/ALT DISAGREE annunciations on the PFDs and a MASTER CAUTION horn would also have been expected on PK-LQP if unofficial commentaries about AoA vane failure are correct. The DISAGREE annunications require L-R ADIRU output mismatch above a threshold for >10s before appearing, so I’d expect sustained stab trim operation to have been the initial indication that something was awry.
A number of ‘systems’ will instigate stabiliser trim operation, but disabling the powered trim is the first action (per Boeing’s SB reiterating the non-normal procedure). The cause is a secondary concern.
It’s reported today that a new ‘system’ was implemented on the MAX series, the Maneuver Characteristics Augementation System (MCAS), and its function is not part of pilots’ training material used in preparation for flying the MAX. It would be more correct to describe MCAS as a function that is incorporated,in one of the NG series computers, I expect that MCAS is incorporated in the Flight Control Computer, as per the 737 NG FCOM description for other trim functions, but I haven’t seen it specified. While Mach Trim and Speed Trim are mentioned in the NG series FCOM, as functions, there is no reference to a specific, related, non-normal procedures. At least one national regulatory authority, Brazil, has not required that implementation of MCAS necessitates a procedural or training change for MAX operators transitioning from NG. Certainly, NTSC need to address this in their investigation.
BTW: American Airlines and Delta Airlines specified the optional PFD presentation of AoA for their 737 NG aircraft, AA has continued that requirement on its MAX aircraft.
@TBill – Pasztor and Ostrower were responsible for instigating the incorrect ‘transmitted engine data’ tripe concerning MH370. They should’ve known better, or perhaps the reporting simply reflected how few people really understood the nuances AMS(R)S* and ACARS usage in March 2014. Around that time I talked with a 757 pilot who was emphatic that ACARS was a VHF only thing. I subsequently corresponded with an individual who operated an aircraft tracking website that exploited HFDL to acquire aircraft position, he too was emphatic that his source data was not ACARS messages (but it was!).
[*] Aeronautical Mobile Satellite (Route) Service
@TBill
re: “@Hank It’s interesting to brainstorm intentional grounding techniques for MH370. I have wondered if keeping negative pressure inside the aircraft could help to bring in water upon hitting surface.”
The cabin pressure is always greater than the outside atmosphere. It is like a balloon. The structure is not designed to be a vacuum chamber.
IMO the only way for the pilot to get up and walk around would be after a controlled ditching. Very hard to do with ocean waves and no power without breaking the aircraft. This would have likely left large floating pieces on the surface.
@Victor
@Hank
RE: “That maneuver won’t end well in a B777. But, don’t trust me. Let’s ask @Andrew.”
I agree 100%.
Andrew
How would you fly a 777 into the ocean without power to get it underwater with minimal breakup? The objective is not having a debris field on the surface. You don’t have to survive.
@Don Thompson, @Victor et al
RE: “A number of ‘systems’ will instigate stabiliser trim operation, but disabling the powered trim is the first action (per Boeing’s SB reiterating the non-normal procedure). The cause is a secondary concern.”
I agree with Don’s statement ‘the cause is a secondary concern’ when something goes wrong. Pilots work in a dynamic environment where things change rapidly. In many failure cases, they do not have time to analyse a problem in depth before they need to take action to stabilise the aircraft’s flight path.
In the event of a runaway stabiliser, the NNC has several memory items that should be completed before the electric trim is disabled via the STAB TRIM CUTOUT switches. One of those steps is to ‘Control airplane pitch attitude manually with control column and main electric trim as needed’ (my emphasis). In other words, the pilot should initially use the electric trim to oppose the movement of the stabiliser and help control the pitch attitude. If the runaway continues, the pilot then disables the trim via the STAB TRIM CUTOUT switches. Those items in the NNC are all memory items, which means they must be completed from memory, without reference to the QRH.
For the record, I think the lack of information about the new MCAS function in the 737 MAX FCOM is a gross oversight. As a pilot, I want to know how my aircraft works and I object to decisions that ‘dumb down’ the manuals for the sake of commonality between aircraft variants. However, I wonder if that information would have made any difference to the outcome of JT610. Ultimately, it seems the crew had two main problems to contend with: unreliable air data (IAS/ALT DISAGREE) and a runaway stabiliser. The crew should have handled those two problems according to procedures that were already documented and should have been trained, regardless of what was causing them to occur. The crew of the previous flight seemed to manage the same problems and landed safely. Why was the crew of JT610 not able to do the same?
@Hank
RE: “How would you fly a 777 into the ocean without power to get it underwater with minimal breakup? The objective is not having a debris field on the surface. You don’t have to survive.”
I don’t believe there’s any way a pilot could ‘get [the aircraft] underwater with minimal breakup’. As we’ve seen in the JT610 accident, a high speed (near vertical) impact can produce a limited debris field on the surface. Given that the surface search for MH370 didn’t commence until several weeks after the aircraft disappeared, it’s hardly surprising that nothing was found, especially if the search was in the wrong area.
Hank: I’ve been a pilot (power and glider ratings) for 50 years. I’ve also done my share of aerobatics in gliders.
As Andrew, Victor and I have all said in so many words above, it is impossible to enter the water near vertical at slow speed. These assumptions are mutually exclusive. So let’s dispense with that idea.
The debris fields left by JT610 (-40 degrees at 472 kts) are good examples of what we should expect from MH370. We see only “confetti” (relatively small scraps) on the surface. Heavier than water confetti was also found on the ocean floor. A small number of larger high density pieces were found on the floor (engines, gear, etc.).
We know that all of the MH370 debris found so far was all relatively small, except for the flap segment and flaperon. The evidence suggests that MH370 also entered the water at a very high speed. It is likely the flap segment and flaperon separated in flight after FE, but before main impact.
Peter Norton: Yes, I published several papers on the KB and BW PSR data. Here is an updated copy. Page 11 is a new addition to this paper. http://bit.ly/2QExcw1
@Hank
As other pilots have said, if the intention is to minimise debris, by minimising water entry speed, both horizontally and vertically, dynamic vertical makeovers are definitely NOT the way to do it.
In any case, ditching, if possible, would be the preferred option, either if the intent was possible survival, or minimising structural breakup, or both. Any other option, would result in certain structural destruction, and death.
As a hypothetical, if survival was not a consideration, and you wanted to minimise the size of the debris field above all else, but with minimum physical structural breakup (into water) as well, then Ultimately, the primary goal, in this case only, is to minimise both the horizontal and vertical velocities at impact.
The second is the easiest to achieve, since You can minimise vertical velocity at impact by being as low as possible before departure from controlled flight.
Therefore, said departure has to be contrived to occur, as low as possible, and as slow (horizontally) as possible.
Proceed as follows.
Commence a low level (100 – 200 ft) level run, in level flight, at 1.41VS (which is stall speed at 60 degrees bank, = 2G), with power set to maintain that speed, level.
Slowly, (emphasised) commence turn, slowly increasing bank angle, whilst slowly increasing power as needed, to maintain 1.41Vs, and slowly and continually pull back on the pole as needed, with top rudder input as necessary, to maintain the tightening (wind up) level turn.
This will, if you do it smoothly, eventually get you to 60 degrees of bank, at your desired height, before the aircraft stalls abruptly, (cut engines abruptly at stall by fuel cut off) resulting in forward motion virtually stopping because of the now massive drag at stall, and the aircraft falls, (from your low height) with auto rotation now increasing bank angle towards 90 degrees, perhaps beyond, and the nose will also drop.
This will result in a near vertical impact with very slow horizontal and vertical vectors.
This is was what happened to the B-52 at Fairchild Air Force Base on the 24th June 1994.
This photo shows that one crew member ejected, but he did not survive the fireball.
https://www.armytimes.com/resizer/QNJvjpYuiWdGbZp_vz4RbZyEAUg=/1200×630/filters:quality(100)/arc-anglerfish-arc2-prod-mco.s3.amazonaws.com/public/Y2NUDCBE5JDEDMMNERW24AOSJE.jpg
This photo shows the aircraft attitude at wing tip contact with a power line.
https://media.spokesman.com/picture_story_item_images/FAIRCHILD_CRASH_t1170.jpg?e2225bc5c1a75a1036ca3021fecba2b47792abfe
As you can see, the turn radius was tight.
https://upload.wikimedia.org/wikipedia/commons/7/75/Fairchild_B-52_crash_overview.png
As you can see, the debris field was tightly contained.
http://files.cluster2.hgsitebuilder.com/hostgator26804/image/z2photo.jpg
The USAF report files are here.
https://fairchildhospitalshooting.com/wp-content/uploads/2017/04/2AFD-100510-032Report.compressed.pdf
https://fairchildhospitalshooting.com/wp-content/uploads/2017/04/3AFD-100510-031Statements.compressed.pdf
https://fairchildhospitalshooting.com/wp-content/uploads/2017/04/4AFD-100510-030Statements.compressed.pdf
https://fairchildhospitalshooting.com/wp-content/uploads/2017/04/1AFD-100510-029regulations.compressed.pdf
Video of the incident is here.
https://www.youtube.com/watch?v=pJGMl1-fsbg
@airlandseaman: Thanks for reminding us about the paper, which made a very persuasive case for MH370 flying at a high altitude over Kota Bharu.
@ventus45: You seriously believe a stalled, high-bank turn will result in “minimum physical structural breakup (into water)”, as opposed to skimming the underside of the fuselage, wings, and engine along the water in a very shallow, low-speed ditching?
FAA Launches Probe of Boeing’s Safety Analyses
Hmmmm. So where was the FAA’s oversight in the first place?
@Hank
“The cabin pressure is always greater than the outside atmosphere.”
I believe you can land with low pressure in the aircraft, but not too negative. The aircraft has negative pressure relief valves designed to pop open if the pressure outside exceeds the pressure inside (by about 1 psi if I recall).
I am not suggesting pilot survived the crash. Exit from the cockpit would have to be prior to crashing.
@airlandseaman, @DennisW, @Victor Iannello: many thanks for the links to your papers
@Victor Iannello: I think I can apply the method correctly. It’s just an interesting subject I was eager to read up on.
@Andrew, all
#JT610/PK-LQP
I should’ve taken more time to compose my comment above and not paraphrase (badly) the NNC. I had no intent to contradict it.
The Brazilian ANAC Evaluation Report for the 737-8 lists five system additions to the 737-8 Flight Control Systems:
Fly-by-Wire Spoiler System
Maneuver Load Alleviation
Maneuver Characteristics Augmentation System
Landing Altitude Modifier
Elevator Jam Landing Assist/Direct Lift Control
The report, in Appendix 2, details ‘the minimum differences levels operators must use to conduct differences training, checking and currency of flightcrew members’.
Only Elevator Jam Landing Assist/DLC is deemed to require procedural change and MCAS is deemed as not impacting FLT CHAR (flight characteristics). Yet, MCAS is being conflated with the Lion Air loss.
I agree with Andrew’s demand to “know how my aircraft works”.
The ANAC Evaluation Report provides a list of training topics for review when NTSC complete their report into the loss of PK-LQP
@Don Thompson: I won’t try to apportion blame, but I do think there were many contributing factors, including the pilots’ incomplete understanding of MCAS functionality in manual, flaps-up flight. That said, it would seem the runaway trim condition should have been quickly diagnosed and manually corrected, even without diagnosing the faulty AoA sensor.
@Don
Many thanks for the information regarding the new systems.
5 new systems obviously requires a pilot update.
I fully agree with Andrew and you, that Boeing must inform pilots of such changes.
If the reports are true, that Boeing decided not to overload pilots with too much information about new automation, then it is a sad day for aviation.
@Don Thompson
Don, there’s something extraordinarily odd going on with regards to the MCAS on the MAX.
The November 2016 version of the B737 NG FCOM includes an entry for ‘MCAS – Maneuver Characteristics Augmentation System’ in the Abbreviations table but that is the only mention of that system in that document. There is no mention of the system in the body of the FCOM.
Note that the B737-800 FCOM Abbreviations entry is for a ‘Maneuver Characteristics Augmentation System’; recent Boeing correspondence for the MAX refers to a ‘Maneuvering Characteristics Augmentation System’. There’s no way to say whether they’re the same or not because there was zero detail provided previously and only scant detail provided now.
The document that you might reasonably expect to be a reference when it comes to changes between the B737 NG and the MAX, the FAA’s Flight Standardization Board Report, Boeing 737, Revision 14 makes no mention whatsoever of an MCAS.
And you can’t rely on that Brazilian Agência Nacional de Aviação Civil Operational Evaluation Report to be anything other than what Boeing wrote for them.
At least part of the issue confronting both investigators and, more importantly, operators now is what else don’t they know about the flight systems on the MAX. Boeing decided to plug AoA data into an undocumented flight control system that is activated without pilot input in manual flight and didn’t deem it prudent to make an AoA Disagree caution a standard item on the MAX. One of the questions that immediately comes to mind is whether any of the other systems associated with Stall Identification now use AoA data or use it differently. Along those lines, Captain Dennis Tajer of the Allied Pilots Association is now publicly querying how MCAS interfaces with the Elevator Feel Shift module and the Speed Trim System when dealing with a sensed impeding stall.
MCAS may not have caused JT610 to crash, it may not have even contributed to the crash but, hell’s bells, this is not a good look for Boeing.
@Victor, Richard, Mick, others
#JT610/PK-LQP
Mick, thank you for the reminder pointing to the FAA FSIMS database. The Differences Table presented in FAA’s doc Appendix 3 (2018-10-17) and that in ANAC’s doc Appendix 2 (2018-01-18) differ. FAA doesn’t list MCAS under Flight Controls. I have two copies of 737-800 (NG) FCOMs, only one includes MCAS in the Abbreviations table.
I understand that an AoA DISAGREE alert is common to NG and MAX types, but only certain customers’ aircraft (notably, AAL & DAL) provide the AoA gauge symbol on the PFDs and HUD. I’ll be happy to be corrected if a QRH is to hand that is not AAL or DAL.
Victor, I’m trying to avoid attributing blame, rather, attempting to offer some broader view. MCAS may, or may not, be the source of the stab trim runaway that ensued from the AoA vane sensing error. Like PK-AKC, where a solder dry-joint caused an interrmittent fault, the cause for PK-LQPs loss may even be an LRU manufacturing defect.
Consistent documentation: Boeing seems to have a problem in this regard: the 737-800 vs 737-8 MAX differences tables; the two FCOMs and reference to MCAS; comprehensive explanation for the various avionics systems and their functions.
@all
Confusing terminology above posts we are tallking 737-800, 737-MAX8, 737-NG, 737-8. Recently we flew in a 737-800, which I am thinking is the older generation, due to the older style wing tips, but correct me if wrong.
Before we took the flight I was not sure if 737-800 is the same as 737-8, but I guess not? I was also curious if the safety placard in the PAX seats says 737-MAX8?
@TBill: Wikipedia has a lot of information about the various 737 models. In short, the 737-800 is one of the NG series, along with the -600,-700, and -900. The 737-8 is one of the MAX series, along with the -7,-9, and -10.
Wikipedia probably has more information than Boeing, and you don’t have to kiss ass to get it.
@Victor
David Griffin includes the following graphic in his blog update on 5th November 2018:
https://www.dropbox.com/s/kacixntgho87ixx/David%20Griffin%20Beaching%20Locations%2005Nov2018.png?dl=0
Out of 25,884 modelled low windage non-flaperon beachings, there are zero on the west coast of Madagascar.
David Griffin shows in the same graphic, there are 18 drifters which end up on the west coast of Madagascar.
Out of my 200 simulations, 11 end up on the west coast of Madagascar.
There is something wrong with David Griffin’s drift model.
@Richard G: The west coast of Madagascar and the coast of South Africa have drifter beachings, but no beachings of virtual particles.
So we’re all on the same page, where was the injection point of the virtual particles for this graphic?
@Niu Yunu
My apologies, I may have misled you.
You correctly questioned in your previous comment “Why did the underlying data change so much ?” in David Griffin’s Fig. 5a on his blog.
I incorrectly replied “I assume the underlying data has not changed, just the presentation of the data”, referring to the scale on the right hand side of the graphic, which changed from 27 Oct: “100 x #items beaching / #items tracked” to 01 Nov: “100 x fraction of items beaching in each latitude bin”.
Peter Norton correctly pointed out that the underlying data did change between David Griffin’s post on 27th October 2018 and his subsequent post on 1st November 2018.
Peter stated in a subsequent comment:
“when compared to 27 Oct, on 1 Nov …
– some squares got colder (e.g. entire row findings:12S)
– while others got warmer (e.g. findings:2S/crash:8S)”.
I find it strange that David Griffin changes the underlying data between 27th October 2018 and 1st November 2018, without any reference to this fact in the text of his blog. I can only assume there is a significant change in the underlying data or an error in the published graphics.
@Victor
You asked “where was the injection point of the virtual particles for this graphic?”
The injection of David Griffin’s 76,200 particles was between 8°S and 36°S, near the 7th Arc.
25,884 particles beached according to David Griffin, either on mainland Africa or on the islands in the Southern Indian Ocean like Madagascar and Reunion.
5,026 particles beached on Madagascar and the other islands. 0 on the west coast of Madagascar.
20,858 particles beached on mainland Africa between 0°S and 32°S. 0 on the coast of South Africa, south of 32°S, such as “Roy”, which beached at Mossel Bay (34.093767°S 22.149905°E) or the Right Aileron, which beached at Nautilus Bay (34.220809°S 21.978754°E).
@airlandseaman: Since there continues to be interest in your paper on estimating the altitude of MH370 using the PSR data, I have included a link on the page of selected papers so that it can be more easily found.
@Richard Godfrey, Peter Norton, Niu Yunu
My understanding of the new figs 5 was that the representation has changed such that the sum of each column adds to 100%. This changes the colour distribution as in the old figs 5 the sum of each column can be different.
@Victor
Re your 10:26pm
No, I do not. I am a confirmed “ditcher” and have been from the beginning. I would always ditch, even in mountainous seas, pick a wave crest etc, and pray.
The point is, that an aircraft making a B52 like water entry, would not be “shredded” into millions of tiny pieces like Swissair111, or JT610.
The takeaway from the B52 crash is that the velocities are low, hence “energy” is low (relatively). The video shows that the left wing initially just folds on impact. As the rest of the aircraft hits, it would just be folded, crumpled, and broken, at multiple weak points, into a number of relatively large pieces, which themselves would also be bent, twisted and crumpled for sure, but not shredded, which is the central point here. The fact that the B52’s fuel exploded, hid those facts from view. MH370 was out of fuel, and would not have exploded like the B52 did.
@Andrew @Victor @airlandseaman @Ventus45
Thanks for the feedback on my piloted water entry scenario.
@Ventus45, the B-52 information was interesting, but still looks like a big mess in a small place.
@airlandseaman, I have done a few loops in a Schweizer 1-26. I have a commercial ASEL Instrument certificate but only 700 or so hours and haven’t flown since 1982. I spent my entire working career since 1970 designing and building fly-by-wire control systems and electronic engine controls. My degrees were in aeronautical engineering with flight dynamics focus.
So my weird ideas on terminal aerobatics to achieve a low speed, but steep angle, water entry had some basis in flight dynamics – but maybe not for a heavy aircraft with no power.
I appreciate the feedback and accept that the likely entry was vertical at terminal velocity following a classic spiral dive.
@Richard Godfrey,
You said: “25,884 particles beached according to David Griffin, either on mainland Africa or on the islands in the Southern Indian Ocean like Madagascar and Reunion.
5,026 particles beached on Madagascar and the other islands. 0 on the west coast of Madagascar.
20,858 particles beached on mainland Africa between 0°S and 32°S. 0 on the coast of South Africa, south of 32°S, such as “Roy”, which beached at Mossel Bay (34.093767°S 22.149905°E) or the Right Aileron, which beached at Nautilus Bay (34.220809°S 21.978754°E).”
The correct numbers for David Griffin’s model are as follows:
Assumed crash latitudes are from 7.7S to 36.3S
76,200 = Total # of trials using “non-Flaperon” parameters
50,033 = # Trials which ended in mid-ocean or left the calculation grid (what I call Zone 6)
26,167 = # Beachings in calculation grid
283 = # Beachings to east in Australia (what I call Zone 5)
25,884 = # Beachings to the west in Africa and Nearby Islands
11,148 = # Beachings in Madagascar, Reunion, Mauritius, & Rodrigues (what I call Zone 1)
12,474 = # Beachings in Zone 2 (Northern Africa coastline from 0S to 17.5S)
2,034 = # Beachings in Zone 3 (Central Africa coastline from 17.5S to 27.5S)
228 = # Beachings in Zone 4 (Southern Africa coastline from 27.5S to 35.5S)
Thus, Dr. Griffin’s model actually predicts 228 beachings in Southern Africa (Zone 4), 7 of which (not zero) are between 31.5S and 34.5 S.
He also predicts 178 beachings (not zero) on the west coastline of Madagascar. His plot does not show all the low-probability predictions accurately because it is limited to 100 of the highest probability locations.
@all
I previously posted a link to a WSJ article that stated the FAA has launched a ‘high priority review’ into Boeing’s safety analyses of the B737MAX. The article implied the review was a separate activity to the Lion Air investigation. The FAA has rebutted that story:
https://www.faa.gov/news/updates/?newsId=92268
https://www.nytimes.com/reuters/2018/11/14/business/14reuters-boeing-deliveries-faa.html
@Richard Godfrey,
You said: “It is pointless to hang on to the CSIRO data that shows a clear bias northwards and fails to predict MH370 floating debris arriving in South Africa in the correct timeframe, where 4 items have been found, which are highly likely or almost certainly from MH370.”
Actually Dr. Griffin’s model does predict beachings in Africa as far south as 34.5S and is in good agreement with the timing of the southern Africa debris reports, The agreement is slightly better at 31.6S than at 23S.
I don’t see any major disagreement between Dr. Griffin’s predicted timings and the debris reports.
@Richard Godfrey,
@DennisW,
RG said: “What do you have against that recommendation? If you disagree with my recommendation, what is your recommendation please?”
DennisW had a similar question.
I previously gave my response to that question some weeks age:
http://mh370.radiantphysics.com/2018/10/20/french-investigation-into-mh370-extends-to-us/#comment-19576
I am in the middle of a detailed analysis of Dr. Griffin’s predictions. I’ll report those findings when that process is complete. As of today, the only two conclusions I have drawn are that (1) the area north of 20S crash latitude is very low in probability and (2) discerning distance from the 7th Arc is unlikely to prove possible. The open question remaining is whether drift models can discriminate with some certainty between ~23S and ~31.6S. I don’t yet know if this is possible given the uncertainties in debris reporting delays.
@Don Thompson
Don, regarding the AOA DISAGREE alert on the MAX, the answer is in the wording of both the Boeing FCOM Bulletin and the FAA Emergency AD:
Boeing:
‘… erroneous AOA input can cause some or all of the following indications and effects:
…
AOA DISAGREE alert (if the AoA Indicator option is installed)’
FAA:
‘… erroneous AOA input can cause some or all of the following indications and effects:
…
AOA DISAGREE alert (if the option is installed)’
@Don Thompson
RE: “I should’ve taken more time to compose my comment above and not paraphrase (badly) the NNC. I had no intent to contradict it.”
My comment wasn’t intended as a criticism. I mentioned it to highlight an important difference between the simulated runaway trim in the video that @Victor posted and the JT610 scenario. In the JT610 scenario, it is suspected that bad AOA data caused the MCAS to trim the aircraft nose down. In that scenario, the use of electric trim to oppose the stabiliser motion, as required by the Runaway Stabiliser NNC, would inhibit the MCAS for a short time. That behaviour is exactly the same as the STS inhibit found in earlier models of the B737. In the event of a runaway stabiliser caused by the MCAS or the STS, the pilot should be able to use the electric trim to position the stabiliser at a manageable setting, before using the cutout switches to stop any further stabiliser movement.
@All,
Just a quick note. Yesterday, Chinese NoK members were told that MH370 Investigation Team would officially be dismissed on November 30, and all the related work would then be handed to Malaysia’s Air Accident Investigation Bureau.
The hope to start a new search is really starting to fade…
@Haxi
Yesterday, Chinese NoK members were told that MH370 Investigation Team would officially be dismissed on November 30
And the bad news is?? These people should have been dismissed a long time ago. They are a part of the problem; not a part of the solution.
@DennisW,
The bad news is, Malaysia is secretly turning the Safety Investigation Report into the Final Report.
@Victor
David Griffin has updated the following graphic on his blog as of 15th November 2018 (his Fig. 4b):
https://www.dropbox.com/s/5gngdwwzl0rrhm1/David%20Griffin%20Beaching%20Locations%2015Nov2018.png?dl=0
Out of 25,884 modelled low windage non-flaperon beachings, there are now 4 locations on the west coast of Madagascar shown where items have beached. This was achieved by changing the sampling from 1 out of 50 to 1 out of 10.
A further change that has been made is to distinguish undrogued drifters in blue from drogued drifters in red.
@DrB
You stated:
“76,200 = Total # of trials using “non-Flaperon” parameters
25,884 = # Beachings to the west in Africa and Nearby Islands”
Thank you for confirming the numbers, I had stated in my previous comment.
David Griffin states on his blog, that the number of beachings in his zone east (45E to 65E, 15S to 25S), which covers Madagascar, Reunion, Mauritius and Rodrigues, was 5026. You state “11,148 = # Beachings in Madagascar, Reunion, Mauritius, & Rodrigues (what I call Zone 1)”. There is a significant discrepancy between what you are reporting and what David Griffin is reporting.
The updated Fig. 4b from David Griffin (published on his blog today), with the higher sampling rate of 1 out of 10, still shows no beachings in South Africa south of 32°S. This is not compatible with “Roy”, which beached at Mossel Bay (34.093767°S 22.149905°E) or the Right Aileron, which beached at Nautilus Bay (34.220809°S 21.978754°E). Even if, as you say, there were only 7 modelled beachings, this should now show up with at least 1 green dot, but there are none.
@Niels,
“My understanding of the new figs 5 was that the representation has changed such that the sum of each column adds to 100%. This changes the colour distribution as in the old figs 5 the sum of each column can be different.”
If your assumption that each column adds to 100% is correct, then the scale depicted is not “100 x fraction of items beaching in each latitude bin”, but should be “100 x fraction of items beaching at each crash latitude”. I understand a latitude bin to mean the intersection of a beaching latitude with a crash latitude. There are 1,015 bins, 35 beaching latitudes, 29 crash latitudes depicted in David Griffin’s Fig. 5a and Fig. 5b. The 25,884 beachings are colour coded across the 1,015 bins in Fig. 5a.
If the bin (8S crash latitude 2S beaching latitude) has now more particles than the bin (9S crash latitude 2S beaching latitude), whereas previously it was the other way around, as Peter Norton pointed out, and your assumption is correct, then there was not an even distribution of the 76,200 start particles across the 29 start or crash latitudes.
I still think there is an error in the graphics or the underlying data changed between 27th October and 1st November.
David Griffin has not published a list of modelled beachings, so I am unable to analyse this anomaly further.
@Niels
CORRECTION: “100 x fraction of items beaching at each crash latitude” should read “100 x fraction of items beaching from each crash latitude”
@Mick,
Thank you for the correction, I’ve been reviewing so many documents as I attempt to clarify differences in instrumentation between type variants (and even within a particular model).
@Andrew,
Noted, but I did exclude that the crew would be expeceted to immediately counter the automated stab trim command with an opposing demand from the yoke mounted switches, before disabling the trim wheel drive.
Managing crew training across mixed fleets with nuanced variants of base aircraft series must be a challenge. FlightGlobal’s 2018 simulator census lists only six specific 737 MAX series simulators, Boeing Flight Services operate one at their Singapore training centre and another at their Shanghai centre. The other four are in North America and Europe. Lion Air operates three 737-900ER Level D FFS and a 737 integrated procedures FTD. I recall that some 737-300/400/500 simulators could represent EFIS and non-EFIS aircraft by a quick swap-out of instrument panels & a software reload. At first glance, that idea seems feasible so as to create a dual purpose NG and MAX simulator but differences extend across other areas of the overhead panel and the aisle stand.
@Haxi, all
It’s worth reminding that a Malaysian Air Accident Investigation Bureau was the proper body to pursue an investigation into the loss of 9M-MRO.
However, Malaysia’s AAIB didn’t exist in 2014 despite an outstanding recommendation from ICAO that states should create an investigation body that is independent of the industry’s regulator.
The Malaysian ICAO Annex 13 Safety Investigation Team for MH370 was a contrivance of Najib Razak’s cabinet.
For my part, that lack of conformance to ICAO’s recommended structure has sustained my scepticism that the MIA13SITfMH370 could ever deliver a transparent and comprehensive outcome.
@Don Thompson
Thank you I believe this above is important background.
Also seems to me in the USA, NTSB will bring in FBI if the cause of the accident appears to possibly criminal/nefarious intent (eg; TWA800). My understanding NTSB wanted to bring in FBI for EgyptAir 990 but ICAO rules apparently gave Egypt right of refusal, which Egypt did refuse FBI involvement.
Needless to say, in the final analysis, TWA800 cause was fuel tank issue, not nefarious.
@Don Thompson said: For my part, that lack of conformance to ICAO’s recommended structure has sustained my scepticism that the MIA13SITfMH370 could ever deliver a transparent and comprehensive outcome.
That’s part of the problem. But don’t forget that the criminal investigation was in the domain of the Royal Malaysian Police (RMP), which has a history of conducting politically-influenced investigations and issuing reports that whitewash crimes. Based on the leaked RMP report on MH370, we know that a comprehensive and competent criminal investigation was never performed by Malaysia, and likely never will be. Based on recent press reports, I also have little hope for the French investigation, as the investigators seem to be following scenarios with very low-probability.
Some interesting background information re the 737 MAX MCAS:
https://leehamnews.com/2018/11/14/boeings-automatic-trim-for-the-737-max-was-not-disclosed-to-the-pilots/
@Andrew
Yes, Boeing’s “bulletins” after the JT610 event were described by Boeing as “confirming” operating instructions. The APA called nuts to that and said the were “enlightening”. Boeing people are lying through their teeth and trying to cover their ass. They deserve to be crucified over this.
@Andrew
My comment a week ago was “I would regard this as a design (or at least a commercial) failure from Boeing and potentially a case of gross negligence.”
http://mh370.radiantphysics.com/2018/11/04/crash-debris-from-lion-air-jt610-provides-clues-about-mh370/#comment-19887
Now we have the facts.
It turns out to be a case of gross negligence against Boeing.
@Andrew
“Some interesting background information re the 737 MAX MCAS:”
Yes interesting article, and I was perhaps on the right track further above when I speculated the MAX STS system was needed due to more powerful engines? though it also has to do with engine placement.
I am holding my political comments on your FAA comments, but yours would not be the first such criticism. You are allowed to comment as a outside U.S. observer.
@TBill wrote “I was perhaps on the right track further above when I speculated the MAX STS”
The 737 Speed Trim System (STS) was first implemented on the Classic series (300/400/500).
In previous comments US-FAA and BR-ANAC documents were provided as examples that described 737-800 vs 737MAX-8 design differences.
FAA: This Design Differences table, from the Boeing 737-800 to the Boeing 737-8, was proposed by Boeing and validated by the FSB on 08/16/2016. It lists the minimum differences levels operators must use to conduct differences training and checking of flightcrew members.
ANAC: This Design Differences tables, from the Boeing 737-800 to the Boeing 737-8, were proposed by The Boeing Company and validated by ANAC.
My earlier comment also noted that the FAA’s Design Differences table did not include MCAS.
Can anyone explain what the regulator’s validation process entails? My experience of regulators, when certifying FFS, was that it was not a rubber stamp process.
@Richard Godfrey,
You said: “There is a significant discrepancy between what you are reporting and what David Griffin is reporting.”
The numbers I posted for each zone are based on the latest full lists of 25,884 beachings for non-flaperon debris to the west (Zones 1-4) and 283 to the east (Zone 5) which I obtained from Dr. Griffin. The number in his blog text may be outdated.
@Don Thompson
RE: ”Can anyone explain what the regulator’s validation process entails? My experience of regulators, when certifying FFS, was that it was not a rubber stamp process.”
The following comment was posted on PPRuNe by a former Boeing propulsion engineer who goes by the name tdracer:
But “Self Certification” is a serious miss-representation of the process. Boeing is “Delegated”, not self certifying. The FAA is intimately involved in the a new Amended Type Certificate (ATC) (which is the case for the MAX). I was a DER or the delegated equivalent AR for nearly 30 years and was quite involved in the certification process.
A new ATC is a long, complicated process, with countless meetings between Boeing and the FAA. There would be a high level ‘Tech Fam’ where Boeing described all the changes planned for the MAX relative to the NG, then a series of specialist meetings where the certification basis is negotiated (this somewhat unique for an ATC (rather than a new TC) and gets into something called the Change Product Rule or CPR – CPR basically says any system that’s changed as part of the new ATC has to step up to the latest regulations and be re-certified, but there are exceptions and these are what get negotiated). Then there would be another set of specialists meetings where the planned changes are discussed in detail, and the FAA would determine which items will be FAA retained and what will be delegated. In the Propulsion world, precious few changes got delegated – although many of the documenting deliverables were delegated (in my case, the FAA would routinely delegated the flight test reports, since the FAA would nearly always participate in the flight test and the ‘report’ was simply my documentation of what they’d already witnessed).
I don’t know what happened with MCAS – I’d be somewhat surprised if MCAS was fully delegated but it’s certainly possible – but to say the FAA was unaware or uninvolved in the certification of MCAS doesn’t reflect the way Boeing and the FAA work.
@DrB
Please get real!
You state currently: “11,148 = # Beachings in Madagascar, Reunion, Mauritius, & Rodrigues (what I call Zone 1)”
Please see your comment dated 14th November 2018: http://mh370.radiantphysics.com/2018/11/04/crash-debris-from-lion-air-jt610-provides-clues-about-mh370/#comment-20051
David Griffin states currently: “5026 modelled dates of debris beaching within 45-65E, 15-25S”
Please see David Griffin’s blog last updated 15th November 2018: http://www.marine.csiro.au/~griffin/MH370/br15_pwent2d/br15_beachdates_east_nonflap_36_08_25.gif
11,148 is not the same as 5,026!
Either you are wrong or David Griffin is wrong!!
@Don Thompson
Re my previous post, I understand tdracer’s comments aren’t specific to the FSB’s validation process, but as you stated, it seems the road to an amended type certificate is far from a ‘rubber stamp process’.
tdracer also posted the following comment:
I’m reasonably sure MCAS was properly certified, with the associated FMEA (Failure Modes and Effects Analysis), and perhaps a SSA (System Safety Assessment) – at least in the Propulsion world FMEAs are not probabilistic (basically shows no single failure is unsafe) and the SSA covers the probabilities for multiple or combinations of failures.
Again, I’m not involved and have no direct knowledge of what happened, but I can guess: Someone did an FMEA of MCAS – determined that the worse case failure was no worse than a stab trim runaway, which has a procedure – and decided it was acceptable. The people that reviewed it (including, in all likelihood, an FAA specialist) didn’t dispute that – not recognizing how bad it might be if an overloaded crew didn’t figure out what was happening.
I’m also reasonably sure there are some 737 flight control types who are pretty sick about it right now. I’ve never had an accident or serious incident attributed to a system that I was responsible for (and I pray that remains the case). But I know how the Lauda investigation affected me and trust me, it wasn’t pretty. I can only imagine how much worse it would be if it was my system…
When it’s all said and done, and a fix is certified and implemented, I have little doubt there will be some retirements and/or resignations among the 737 flight controls ranks – perhaps worse.
I see the lawyers aren’t wasting any time:
https://www.colson.com/colson-hicks-eidson-files-lawsuit-against-boeing-on-behalf-of-plane-crash-victim-aboard-lion-air-flight-610/
@Richard Godfrey,
You said: “Either you are wrong or David Griffin is wrong!!”
You left out a third possibility.
The numbers that David and I posted are both correct. You are comparing apples to oranges.
David’s number, as he says, is from 45-65 E, 15-25 S. This does not include the northern portion of Madagascar.
My Zone 1 number, as I said, is for Madagascar and nearby islands (La Reunion, Mauritius, Rodrigues, Seychelles, Aldabra, and Comoro Islands). It is from 42.5-65.5 E, 2.5-25.5 S and it includes all of Madagascar, resulting in a much larger count of beachings.
For those also following Ocean Infinity’s search for ARA San Juan, they have processed a possible contact near the CTBTO predicted location. In the last several days OI had moved 300 NM north to clear an area called Site 2 where unusual noises were heard 6 days after the implosion event occurred on 15 Nov 2017, one year ago today. Seabed Constructor will return to Site 1 as soon as the last AUV is recovered at Site 2. A ROV will then inspect the contact in 800 m water depth, which is consistent with an implosion occurring near 390 m calculated depth. The low-resolution sonar image can be seen on Twitter by searching #ARASanJuan. It appears to show multiple or mangled debris with an overall length circa 60 m. Seabed Constructor has recently completed a re-inspection of canyons in that area of Site 1, and it was not scheduled to return to Site 1 but to South Africa for refurbishment. The ROV will allow rapid assessment of the contact as possible wreckage of the submarine. I anticipate photographs of the contact will be forthcoming within the next day or two.
@DrB thank you for defining your Zone 1 with Latitude and Longitude ranges.
Up until now you had only stated “Beachings in Madagascar, Reunion, Mauritius, & Rodrigues (what I call Zone 1)”, you had not specified any Latitude or Longitude range, but it now becomes clear you are actually talking about 2.5°S to 25.5°S and 42.5°E to 65.5°E and go 1,390 km further north and 269 km further west than David Griffin (also a little bit further east and south).
David Griffin states “Now consider beaching in the east (Madagascar, Mauritius and Rodrigues) region.”, but is actually only talking about 15.0°S to 25.0°S and 45.0°E to 65.0°E, and as you say cuts off Northern and Southern Madagascar, which is actually from 11.94°S to 25.61°S.
It is sometimes a bit difficult to tell the difference between your Apples called “Beachings in Madagascar, Reunion, Mauritius, & Rodrigues” and David Griffin’s Oranges called “beaching in the east (Madagascar, Mauritius and Rodrigues) region”. Anyway, I am sure you are correct that the Apples are 11,148 beachings and the Oranges are 5,026 beachings.
Out of the 25,884 beachings, 56.9% are on the coast of mainland Africa, 43.1% on Madagascar and the nearby islands.
12,474 (84.6%) beachings are in the northern area, where only 1 item of MH370 debris has been reported.
2,034 (13.8%) beachings are in the central area, where 7 items of MH370 debris have been reported.
228 (1.5%) beachings are in the southern area, where 3 items of MH370 debris have been reported.
The modelled beachings of David Griffin on mainland Africa are skewed compared with the MH370 debris that has been reported.
Out of my recent 200 simulations, 158 beached in Africa and the islands, 50.6% on the coast of mainland Africa, 49.4% on Madagascar and the nearby islands.
26 (32.5%) beachings are in the northern area, where only 1 item of MH370 debris has been reported.
35 (43.8%) beachings are in the central area, where 7 items of MH370 debris have been reported.
19 (23.8%) beachings are in the southern area, where 3 items of MH370 debris have been reported.
The modelled beachings from my simulation on mainland Africa are aligned compared with the MH370 debris that has been reported in the central and southern areas, but misaligned with the northern area.
@RichardG
You wrote:
“Out of my recent 200 simulations, 158 beached in Africa and the islands, 50.6% on the coast of mainland Africa, 49.4% on Madagascar and the nearby islands.
26 (32.5%) beachings are in the northern area, where only 1 item of MH370 debris has been reported.
35 (43.8%) beachings are in the central area, where 7 items of MH370 debris have been reported.
19 (23.8%) beachings are in the southern area, where 3 items of MH370 debris have been reported.
The modelled beachings from my simulation on mainland Africa are aligned compared with the MH370 debris that has been reported in the central and southern areas, but misaligned with the northern area.”
Could you give an indication about the 7th arc latitude(s) for these 200 simulations?
@Niels
You asked “Could you give an indication about the 7th arc latitude(s) for these 200 simulations?”
The range of start latitudes near the 7th Arc is between 10°S and 38°S.
The link below gives a full list of the beachings:
https://www.dropbox.com/s/wmw3h1inp9fl4j9/Beaching%20Locations%2011Nov2018%20200%20Runs.xlsx?dl=0
@RichardG
Interesting, thank you. I was wondering if we could compare the beaching distribution originating from say range S30-S35 with the range S20 – S25. Perhaps the numbers are a bit low, but I think your table is helpful for this.
@DrB said: Seabed Constructor has recently completed a re-inspection of canyons in that area of Site 1…
Can you provide us with the details of how the canyons of Site 1 were initially inspected, i.e., by whom and using what equipment?
@Niels
Below is a link to a .pdf comparing the beaching distribution originating from between 20°S and 25°S and originating between 30°S and 35°S as you proposed:
https://www.dropbox.com/s/l1aoe4jj7k5nold/Beaching%20Map%20-%2020S%20to%2025S%20vs%2030S%20to%2035S.pdf?dl=0
You can flick backwards and forwards between the 2 pages. It is quite revealing.
@RichardG
Great, that’s helpful. I’m now comparing with the map of finds as posted by David Griffin; would it be possible to extend your .pdf with a similar map which shows the find locations?
Another question: do you also have a list of all 200 starting latitudes; were they equally distributed over the whole latitude range?
@Richard
Beaching distribution comparison – compelling, IMO.
@Niels
The Excel I posted only includes the start latitudes of the beachings. I will produce a list of all 200 start latitudes including those that ended mid ocean in a gyre or headed out into the Southern Atlantic Ocean.
I will extend the .pdf as requested.
@Niels
I have included the confirmed or likely MH370 debris locations.
https://www.dropbox.com/s/p68zsaooguiogig/Beaching%20Map%20-%2020S%20to%2025S%20vs%2030S%20to%2035S%20vs%20Debris%20Locations.pdf?dl=0
@NIels
I have included the 200 start locations near the 7th Arc in an updated .pdf.
This comprises:
(1) the 7th Arc between 10°S and 40°S in steps of 0.5°.
(2) the 7th Arc ± 1° of longitude between 15°S and 35°S in steps of 1.0°.
(3) 25 points at ± 50 NM and ± 100 NM around @DrB’s end point at 31.6°S.
(4) 25 points at ± 50 NM and ± 100 NM around my end point at 24.0°S.
(3) 25 points at ± 50 NM and ± 100 NM around @Victor’s end point at 21.9666°S.
Here is a link to the updated .pdf:
https://www.dropbox.com/s/r4yjbeh436bxazx/Beaching%20Map%20-%2020S%20to%2025S%20vs%2030S%20to%2035S%20vs%20Debris%20Locations%20plus%20Start%20Locations.pdf?dl=0
Here is a link to the tabular data:
https://www.dropbox.com/s/0gl8bgv6xxcqosv/Beaching%20Map%20-%2020S%20to%2025S%20vs%2030S%20to%2035S%20vs%20Debris%20Locations%20plus%20Start%20Locations.xlsx?dl=0
Some interesting facts regarding the search for the ARA San Juan:
The Point-of-Interest (POI) that will be investigated by OI’s ROV is centered at (-45.9499,-59.7730). Meanwhile, using the hydro-acoustic data from CTBTO sensors that was collected on Nov 15, 2017, the hot-spot was estimated to be centered at (-46.12,-59.69). That’s a distance of about 20 km.
There was a test explosion on Dec 1, 2017, that was used to calibrate and verify the position estimation model. The position error of the test explosion was 37 km. Therefore, if the POI is indeed the debris field of the submarine, the position error is well within what was expected based on the test explosion.
An interesting description of the hydro-acoustic analysis is presented here.
Whether or not the POI is the debris field of the submarine, we need to better understand why the POI was scanned but was not detected until this last scan, which might have been the second or third scan of this location. There could be important implications on the detection probabilities of MH370.
It appears that the Atlantis, owned by the US Navy and operated by the Woods Hole Oceanographic Institute (WHOI), previously scanned the position of the POI about a year ago.
According to a news release from WHOI, the advanced research vessel arrived in the area at 2 p.m. Nov. 21 and immediately began search operations using the ship’s sophisticated multibeam sonar and underwater communications systems. The multibeam sonar is usually used to map the seafloor, by directing a fan-shape cone of sound waves that reflect off the ocean bottom.
The limitations of MBES could explain why the Atlantis did not detect the debris of the submarine.
Some Malaysian ATC and MAB responses to Safety Investigation Report recommendations.
http://www.mot.gov.my/en
@Andrew
Thank you for the tdracer comments…it is refreshing to have former Boeing person input…I am surprised but pleased he/she is contributing to the discussion. I worked for a company with perhaps similar carefulness with outside communications.
re: Automated Flight Path Destination/Exhaustion (Law of Conservation of [‘Negative’] Energy)
What is the sensitivity of an automated flight path to different fuel load – i.e., where will the plane be by adding/subtracting flight time before fuel exhaustion? Perhaps the ([reported] high speed/altitude) maneuvering before the FMT is simply just to prepare/waste fuel for a subsequent automated flight to an ‘appropriate’ destination.
***[function(fuel range, fixed direction/path, fixed start point) = exhaustion/end point range]
Addendum (‘Variational’ Analysis)
Maybe the ‘best’ pre-programmed/automated flight path is also “the path of the ‘simplest’ [‘robust-est’] descent”, one which is [also] least sensitive to fuel variation.
@Victor Iannello,
The first ARA San Juan search zones covered by OI at Site 1 included the area where the recent POI #24 was found, but this feature was not reported at that time. This area includes the first zones 1-11 which were negatively searched by OI:
https://twitter.com/juanmab/status/1063463166024302597
This second plot shows the new zones (primarily #15) aligned with the canyons in Site 1 which were searched again more recently:
https://twitter.com/Armada_Arg/status/1063546834398912513
More information is available at:
http://www.ara.mil.ar/submarino/sanjuan/partedeprensa132.html
Update on Ocean Infinity & search for ARA San Juan:
The images of the POI #24 are useful in assessing what the MH370 debris field might look like. Here is the best sonar image so far available:
https://twitter.com/DrBobbyUlich/status/1063498396286107648
For scale, the height of this image is about 120 m.
I think there is a good probability the POI #24 is the imploded wreckage of this Thyssen Type 1700 diesel-electric submarine. It is located only 11 NM north of the CTBTO position estimate (which was improved in accuracy after a 100 kg test explosion was carried out about 2 weeks after the implosion event was recorded at HA04 in Crozet Islands and at HA10N/HA10S at Ascension Island). If only we had such data for MH370, but a surface impact of an aircraft does not couple energy efficiently into the SOFAR channel, so any recorded sounds will be faint and very difficult to identify.
In spite of the small radial error (11 NM) from the best estimate of the implosion location, it took OI 60 days of searching to find this POI. This is a lesson that can be applied to the MH370 search.
This latest image shows numerous pieces of high reflectivity, “proud” debris (i.e., rising above the seabed and casting acoustic shadows).
Metallic objects will have a higher acoustic reflectivity than the seabed. Some debris to the left of center suggest the stern section is crushed, with the propeller/screw remaining relatively intact. Part of the rudder and or stern planes may be visible just forward of the propeller. The stern section of the submarine is generally the strongest part because it contains the mechanical drive components.
The largest separate debris may be the sail (conning tower) and associated hull under it. Other large debris may be forward sections of the submarine which were physically separated by the implosion.
I have calculated the implosion depth at 390 m, and the water depth here is 800 m. Supposedly the debris falls straight down after an implosion because forward momentum is lost. This debris field shows a diameter of about 100 m, and this seems reasonable for a roughly 70 m submarine breaking up about 400 m above the seabed.
The implosion potential energy released is equivalent to about 1,900 kg of TNT. Part of that energy tears and crushes the metal structures, and part is radiated in a low-frequency (infrasound) bubble pulse (pressure wave). Since the implosion occurred at a large depth, the infrasound pulse is coupled into the SOFAR channel efficiently, with some of it reflecting off the sloping seabed off the coastline of Argentina (producing detectable echoes). Even at the large distances of the CTBTO listening stations, the sound is fairly loud, the SNR is high, and its frequency can be measured (4.4 Hz). That frequency, plus knowing the hull displacement, allows me to calculate the depth and the energy released.
I expect that, within the next 24 hours, OI will arrive back at Site 1 and position Seabed Constructor directly over this POI. Then she will explore the seabed with a ROV. A few images (both sonar and visible light) from a close range will then answer the question of whether this is the ARA San Juan wreckage. If it is, OI will earn a $7.5M US fee, which will only cover its out-of-pocket costs (estimated at $125,000 US per search day). I do not think OI is obligated to recover the wreckage by their current contract, but I suspect they will try to retrieve a small piece of the wreckage sufficient for identification as ARA San Juan can be made with certainty. They may also conduct a survey of the debris field and collect additional imagery of the debris to assist the Argentine Navy in determining the cause of the loss and in making a decision on recovering all the debris.
Re JT610 and MCAS, even airline pilots can’t agree:
Dispute arises among U.S. pilots on Boeing 737 MAX system linked to Lion Air crash
@Andrew: That’s interesting, although I’m not surprised by the disagreement. The pilots efforts might have been hampered by incomplete knowledge, but they could have overridden the errant automation and recovered if they had followed established procedures. This will all get decided in court someday. In the meantime, I am very curious about how the problem is rectified.
@Victor
I agree. I don’t agree with Insler’s (ALPA – United) view that ‘[pilots] don’t need to know how it works’. Pilots do need a rudimentary understanding of the aircraft systems, especially systems such as MCAS that can have a significant effect on flight control. It will be very interesting to find out what sort of failure analysis was conducted and if the significant adverse effects of an AOA vane failure were appreciated. That said, I agree that long-established procedures should have allowed recovery, if they had been followed correctly.
Given that MCAS was designed to solve a pitch-up problem at high AOA, I doubt that rectification will include significant changes to the system that would require re-certification. I suspect the ‘fix’ will be relegated to pilot training, better documentation and possibly a requirement for the mandatory fitment of the AOA indicator and AOA DISAGREE caution.
Armada Argentina has confirmed that PoI 24 is the wreck of ARA San Juan.
A positive result for Ocean Infinity.
A technical report for the search will make an informed read, why the canyons en-bloc were not searched with sufficient detail until Nov 6th? I’m concerned that advice may have been that the hydroacousitc event occurred on open seafloor, not within a canyon.
Ocean Infinity reportedly has a contractual requirement to document the find. No new imagery is available yet.
Don, how deep are the canyons, if you know? The implosion occurred midway between the surface and the site depth of 800 m.
@Victor, @DrB, @Don,
Here is a link to the Seabed Constructor track from 8th September 2018 until today.
It would appear that Ocean Infinity was only 7 km from where ARA San Juan has been found on day 5 of the search on 13th September 2018.
I also include the track of Seabed Constructor for the second visit to the area where ARA San Juan has been found between 6th – 10th November 2018.
https://www.dropbox.com/s/e32csb0s11jj357/Ocean%20Infinity%20ARA%20San%20Juan%20Search.pdf?dl=0
Here are the .kmz files:
https://www.dropbox.com/s/ypsjfcf6w6kdqkl/San%20Juan%20Argentina%20Sep%20and%20Oct.kmz?dl=0
https://www.dropbox.com/s/0kj0zhvd9lpo58r/San%20Juan%20Argentina%20Nov.kmz?dl=0
Important that the San Juan has finally been found.
I hope that an analysis of this search will give some more insight in the difficulties of scanning in areas containing steep slopes. Trying to think about it more deeply, it seems not easy at all to develop a strategy which is both efficient and effective for such terrain.
@RichardG
Thank you for yesterday postings with the data on drift / beachings from S30-35 and S20-25 starting latitudes. It is interesting data; I’m trying to make sense of what we see.
An additional question that comes forward (to make the picture more complete) is how many of the simulations from both starting regions ended in the Atlantic?
@RichardG
It would be important to find out how many times OI scanned the location of the wreckage and in what direction.
There are some clues, for example on the @juanmab timeline:
https://mobile.twitter.com/juanmab/status/1048231972391342080
However, if possible better to get the overview in a systematic and reliable/direct way.
@DrB,
I have only the bathymetry images to inform the depth of these canyon areas, no raw or processed MBES data yet. My estimate is 400-500m deep. The contour lines are at 50m intervals.
Armada Argentina published OI’s Daily Status Reports (DSR) through to Sep 24th. The last reported AUV dive in Area-01, where the wreck has been found, was recovered on 2018-09-19. On 09-16 the DSR had stated zero data holidays and no limited probability of detection.
Yet, the submarine has been located in Area-01, in a canyon/trench.
OI acted on 2018-11-06 to return and survey all canyon areas, where the wreck was ultimately found. My interpretation of that is either a) advice was given that the canyon areas were not a likely candidate location, or b) exploitation of the AUVs was ineffective (vis-a-vis AUV survey height above seabed and SSS operation – i.e. effective resolution). I have seen comments that Armada Argentina/MoD set a requirement for b), the AUV surveys were undertaken with scan line spacing at 800m and 500m.
Concerning the search for MH370, the ARA San Juan outcome renews concern about the confidence for probability of detection given by Fugro, Phoenix International and OI.
The SSS images published for ‘SUSJ’ PoI 24, now confirmed as the wreck, showed bright targets in an area of radius 30m, the debris field for a 777 is expected to be in the order of 200m x 200m or more*.
[*] the intactistas should be more confident. Rather than scattered ‘confetti’ one could expect larger intact pieces, even sitting vertical and proud of the seafloor, to best reflect as backscatter the ultrasound pulses.
@Don Thompson: I don’t understand why OI would get advice that canyons were not likely to contain the debris field. The acoustic event was generated by an implosion as the submarine was descending. The acoustic event could have been generated before the wreckage entered the canyon.
I think it is possible that OI knew that the canyons were not previously scanned at the ideal resolution, but chose to cover as much seabed as possible, leaving the most challenging (and slowest) areas for last. Assuming that the probability per unit of seabed area was relatively constant at a given radius from CTBTO’s best estimate location, that would make sense.
@DrB
Great news that the sub was found by OI. Your interpretation of the propeller was quite convincing. You said 24 hours we know, but it was less.
@Victor
Re: Broken Ridge Implications
This gets back to my comment that, although I was satisfied with the time commitment that OI gave to the BR difficult terrain region, we have not really heard anything about how much %/how well they were able to search the BR area. This is one reason why I say the hypothesis that MH370 was intentionally downed in a difficult terrain region is still a valid hypothesis.
@TBill: Independent of whether it was deliberate, it’s possible that MH370’s debris field lies in challenging terrain. We need to better understand whether or not that challenging terrain was adequately covered.
@TBill,
This is one reason why I say the hypothesis that MH370 was intentionally downed in a difficult terrain region is still a valid hypothesis.
Congrats. You just made the whacko category.
@All,
I am still going through the data from Seabed Constructor, but the wreckage location was part of the 2nd AUV sortie from 9th to 11th September 2018 depicted below:
https://www.dropbox.com/s/zo3lpld3mozr3s6/ARA%20San%20Juan%20Initial%20Coverage.pdf?dl=0
This sortie raised the first POI described as a metallic wreck with the same dimensions of the sought contact. It was dismissed as a fishing trawler that was previously reported sunk 330m away.
https://www.dropbox.com/s/mip9uuwsvbl0xwx/ARA%20San%20Juan%20Initial%20POI.png?dl=0
I put together a summary of the Argentine Navy briefing on the first inspection of the ARA San Juan. Photos made by OI using the the ROV from MV Seabed Constructor are included.
https://drive.google.com/file/d/1n8VK4CurKF-OmL8vxQMunnoIfvHeOorA/view?usp=sharing
One Argentine Navy officer was quoted later as saying they don’t have the capability to recover the wreckage at that depth. It is possible that inspection of debris might indicate damage due to fire and/or explosion before the sinking and implosion. Recovery of a substantial portion of the debris would assist in understanding the cause of the sinking and subsequent destruction, and there will be pressure to mount a recovery effort.
@DennisW You statement above: November 17, 2018 at 10:09 am
I respect your opinion, therefore I am interested to know how you can be so apparently certain of this? Is it the southern location of BR (conflicts with R. Godrey’s latest drift simulations) or is it the ‘intentionally downed’ factor?
@RichardG
I’ve been looking more in detail in your drift simulation results. I’ve divided the beaching regions into North (north of Tanzania), Tanzania, Mozambique, South-Africa, and East (Madagascar and the islands to the east). To compare I’ve normalized the number of beachings with respect to the total number of starts, and later with respect to the total number of reported finds. Here are the numbers as extracted from your excel file:
S20.0 – S25.0 (74 started, 55 beached):
(E,N,T,M,S): 30, 2, 3, 12, 8
S30.0 -S35.0 (49 started, 36 beached):
(E,N,T,M,S): 25, 0, 0, 9, 2
Focusing on mainland Africa:
Found (RG):
(N, T, M, S): 0, 1, 6, 3
S30 – S35 x 10/11:
(N, T, M, S): 0, 0, 8, 2
S20 – S25 (x 49/74 x 10/16):
(N, T, M, S): 1 , 1, 5, 3
In addition it would be interesting to know the number of simulated items that passed south of Africa into the Atlantic.
@Niels: “In addition it would be interesting to know the number of simulated items that passed south of Africa into the Atlantic” — not really IMO, from what we know of finds on the Indian Ocean side, would we expect ANY finds from this statistical tail from Namibia on north to be reported?
@Shadynuk
The notion that MH370 was intentionally terminated in difficult underwater terrain has absolutely no basis in any fact associated with the MH370 incident. Any notion of a selected terminus is at odds with running out of fuel before terminating. Likewise the notion of a glide to minimize debris. A powered ocean landing would be much preferred for that purpose.
The facts indicate that MH370 came down rapidly at an essentially random location when it ran out of fuel.
[Comments here are closed. Please continue the discussion under the new article.]