Ocean Infinity Proposes New Search for MH370

On Sunday, MH370 family member V.P.R. Nathan presented several slides highlighting Ocean Infinity’s willingness to conduct another subsea search for the debris field of the aircraft. The search area, which may be refined later, extends along the 7th arc from about 33°S to 36°S, and out to about 45 NM (83 km) on either side of the arc. Ocean Infinity also plans to “fill-in” areas that were previously searched that had low quality or missing data due to equipment failures or challenging terrain.

The proposal is broadly consistent with the flight reconstruction and recommended search area that we presented in UGIB 2020 and the subsequent drift study. In fact, the “Last Estimated Position” (LEP) presented in those studies is designated the “IG Hotspot” in the slide. The proposed search area will also incorporate our high priority area due south of the LEP that was missed by the previous searches by the ATSB and Ocean Infinity due to the steeply sloping terrain in that area.

So, will Malaysia accept Ocean Infinity’s offer to conduct another search with the proposed terms of “no-find, no-fee”? At Sunday’s event, Transport Minister Anthony Loke expressed an interest in discussing the new proposal with Ocean Infinity. However, both he and Malaysian Prime Minister Anwar Ibrahim cautioned that a new search would be conducted only if there was “credible new evidence”. So, although we may be seeing progress towards a new search, it is unclear whether or not Malaysia will accept Ocean Infinity’s proposal.

359 Responses to “Ocean Infinity Proposes New Search for MH370”

  1. Viking says:

    @All

    The distribution at 23:14 is extremely skew. It is roughly the upper half of a complete Gaussian distribution without any further truncation, and has an average value close to its smallest value (bizarre), while the distribution at 18:40 is an approximately symmetrically truncated Gaussian as expected during regular flight. The truncation on both sides comes from the temperature-stabilization, which suppresses large excursions with periods above 0.3 seconds (round off, turbulence and navigation effects excluded). A slight top truncation is due to insufficient compensation against small, fast excursions. In previously published plots of integrated BFO error distributions from 20 flights, there is also a long but very low probability tail towards negative deviations. I presume these predominantly come from cold starts in airports (e.g. a cold winter morning in Beijing) or from fast ascents during takeoff.

    @DrB

    Please look in the previous comment block for my reply.

  2. TBill says:

    @Victor
    Interesting to watch search decision process. Loke seemed very well spoken and most encouraging. Strong, decisive, not wishy washy in the least.

    @Viking
    There are two issues with phone call BFO, slight amount of scatter in the 23:14 results, and in both cases it is a different channel so we do not know if the average value should have a different correction factor.

    It is interesting to suggest two phone calls at 1840. The 1840 values are so smooth it tends to suggest steady flight (not descent in progress) but that is very subjective, unproven. The 2314 call is likely in the high winds below 22s so that is one thing, possibly descent in progress if it was a slow descent ~400ft/min (if it was active pilot).

  3. Viking says:

    @TBill

    My analysis is insensitive to different channels unless one of them is hardware damaged, because it only relies on relative values. On the other hand, you are perfectly right about problems with comparing the absolute values.

  4. Viking says:

    @All

    How is such a strange and unusual distribution possible at 23:14? The only realistic possibility is that the SDU operated under conditions outside its specifications. If it were due to events before 18:40 those would have affected data from the first phone call as well, so the unusual conditions occurred due to events after 18:40.

  5. DrB says:

    @Viking,

    1. The truncated trig functions produce sawtooth errors, with peak-to-peak amplitude as much as 5-6 Hz.
    2. Figure F-4 in UGIB (2020) shows a typical waveform.
    3. Sawtooth errors have a flat-top probability density function with a full width equal to the peak-to-peak amplitude of the sawtooth.
    4. It is not possible to reliably determine the shape of the probability density function of this error in one or a few phone calls. There are simply too few samples.
    5. The oven temperature controller has a low bandwidth, and it does not have any frequency feedback, only temperature.
    6. After initial temperature stabilization upon power-up, the contributions of OCXO temperature fluctuations to BFORs in a normal flight environment are negligible. That’s not to say the OCXO frequency does not drift, just that the drift is not due to crystal temperature changes.
    6. The only remarkable thing about the first 2.5 seconds of the 23:14 phone call for MH370 is the very small fluctuation of 1 Hz peak-to-peak. That proves the random “read noise” is quite low.
    7. The observed 6 Hz peak-to-peak range in BFORs at 23:14 is due to other error sources besides read noise, and it is probably dominated by the trig quantization, which in this case has a period of about 20 seconds.

    You said: “It is also important to notice, that it would give more noise, not less as observed @23:14.”

    I would not characterize the 23:14 phone call BFORs as having “less noise” since they have a 6 Hz peak-to-peak variation. The fluctuations in the first 2.5 seconds are observed to be quite small, but over this short period of time the change in the quantization error is generally expected to be less than 1 Hz anyway.

    The DSTG’s empirical probability density function for BFORs is generally gaussian, as one should expect because the convolution of a number of different PDFs always tends to become gaussian. Observing a gaussian shape does not prove that one contributing PDF is not flat-topped.

  6. TBill says:

    @DrB
    For 2314 are you able to throw out some points as being math noise? and thus arrive at a stable value estimate?

  7. Jérôme Chabot says:

    Hi Mr. Iannello,

    Did you hear about Patrick Blelly and Jean-Luc Marchand study ?

    What are your thoughts about this work ?

  8. Peter Norton says:

    @Barry Carlson: This is true. You are right that for OI it’s certainly better to have a contract and rather be safe than sorry. But do you really think there is a chance that if OI finds the plane and announces this breakthrough to the media, that somebody could really come and “snatch” the plane (or parts of it) away ?

    @Victor Iannello
    @Barry Carlson: I have made the same remarks throughout the years, but I still get angry when I hear that Malaysia does not accept a zero(!) risk deal despite claiming to be “happy to reopen … whatever needs to be done must be done”. This is such an outrage. Victor, I know you have said in the past that Malaysia could have good arguments for their stance, but I can’t remember what you specifically mentioned and I still can’t see any really good ones. Why does Malaysia exact “credible new evidence” ON TOP OF a zero-risk-deal ?? In my mind either one is enough. Why both? Why demand anything when Malaysia bears no risk at all? That really beats me.

    It’s a win-win-situation for Malaysia:
    • Either the plane is found … which Malaysia claims to desire, so that would be a win for Malaysia.
    • Or the plane is not found … then Malaysia has received the benefit of a free search and can tell the NOK and the whole world that they have done something, which is certainly a PR win (in addition to the free search).

    So why does Malaysia not accept this zero-risk-deal ?

    They are like “you can work for me doing an incredibly demanding, exhausting, difficult, very costly and maybe even somewhat dangerous job in the Roaring Forties (in case it’s not entirely remotely operated) but you have to pay for that AND on top of that we ask you to present to us evidence that you will find something BEFORE you find it”. This is just nuts.

    Whenever I hear that Malaysia only accepts this zero-risk-deal if “new credible evidence” is presented to them, I can’t help but think that the Malaysian government doesn’t want the plane to be found. I find it hard to think of any other “credible” reason, because
    a) there is absolutely no reason to demand for anything in return for a free search!
    and
    b) it’s so obvious that this hurdle of “new credible evidence” is almost impossible to overcome. First of all: What “new” evidence should all of a sudden emerge 10 years after MH370’s disappearance? The chances of that a very slim given the time that has passed and Malaysia obviously knows this.
    And second of all: Malaysia’s wording is very clever. The word “credible” is very subjective and who is the arbiter of whether this standard is met? Right, Malaysia. So whatever scientific paper is presented to them, they can always argue that it is “not enough” to be sure. After all: You can only be sure if you have located the wreckage site.

    So in fact the Malaysian government demands something almost impossible and traps offers such as OI’s current one into this circular reasoning: “Show me new hard evidence, such as the black boxes, and we allow a search.” But this evidence is what the seabed search tries to find in the first place, therefore this is a demand almost impossible to meet.

    What if no new evidence will ever emergence ? (which is the most likely case given the elapsed time)
    Then Malaysia will never agree to a new search – despite claiming they want to find the plane.

    Sorry for getting emotional, but this stubborn demand for “new credible evidence” really appears like a shabby excuse.

  9. DrB says:

    @TBill,

    There is no available method for selecting certain BFOs circa 23:14 as having greater “reliability”.

    I can imagine two methods for predicting the “true” value:
    (a) simply average all the phone call BFO values, equally weighting all data points, or
    (b) fit a sawtooth by least squares to the BFOs, and use the average value of the sawtooth over the duration of the transmissions as the best representation of the “true” value.

    There is not a large difference between the two methods, but Method (b) might be the best one can do with the information we have in hand.

    In general, one can only apply Method (b) to the phone calls, because those are the only MH370 events with a sufficient number of BFOs in rapid succession to discern the sawtooth amplitude and phase.

  10. Barry Carlson says:

    @Peter Norton wrote:-

    “I have made the same remarks throughout the years, but I still get angry when I hear that Malaysia does not accept a zero(!) risk deal despite claiming to be ‘happy to reopen … whatever needs to be done must be done’.”

    I believe (from my own experiences) that there is a cultural adversion to even accepting that ‘they’ in some way or another may be culpable in the loss of the flight and the souls onboard. In addition, when things do go wrong, there is a distinct tendancy to ‘raise the drawbridge’ and walk away.

    Finally, “we will” needs to be treated with caution, i.e. interpreted as “we might”, and also remember there is no such thing as a “free lunch”!

  11. Victor Iannello says:

    @Jérôme Chabot: They make some assumptions about pilot actions that I think are guesses, and their level of certainty is optimistic. However, their crossing of the 7th arc is not too far from the UGIB 2020 prediction, and their point of impact is within the area that we believe should be searched, so there is little reason to dispute their results.

  12. ventus45 says:

    @Peter Norton, @Barry Carlson

    I basically agree with your sentiment’s gentlemen.

    It was clear to many after only a few weeks that Malaysia did not want it found. I think it is clear that Malaysia still does not want it found, recent chest beating notwithstanding.

    The early dumping of AMSA for Dolan’s ATSB, the ‘driving of the search north’, and the subsequent creation of the JACC (with Houston for PR ‘street cred’ cover), all had a faintly unpleasant odor about it, (to some of us local natives at the time) which seemed to be driven, more by the perceived need not to contradict, annoy or (God forbid) embarrass Malaysia, diplomatically, than with actually getting on with the job of finding the plane. It became a political / media circus.

    The Chinese weren’t impressed either, especially when their IL-76’s were prevented from searching where their own satellites showed target of interest (deep south west end of the search area, plus a bit further). They packed up and went home pretty smartly after that little episode, and their official attitude has been one of ‘studied indifference’ ever since.

    If you go back through contemporary ‘Senate Estimates’ hearings, (some of which are still available on YouTube) you will find that most of the time the dear Senators were asking more about ‘how much is this costing’ than anything else. In fact, they even questioned the ATSB’s choice of Fugro, (since they had ‘representations’ from some ‘aggrieved parties’ who strongly suggested that the ATSB had not selected the best offer that was tendered for the search contract), either on technical grounds, or on financial (best value for money for the Commonwealth) grounds.

    It was in this political climate, that the phrase ‘credible new evidence’ came into being.

    In all probability, it was undoubtedly created by a sly Australian public servant within the Australian Treasury, as a barrier, an impossible hurdle to hurdle, that would give the Government an excuse to stop spending any further money on any further searches.

    The Malaysian Government loved it, and adopted it, as their ‘get out of (further searching) jail card’.

    Money is still the public Malaysian issue.

    In the multiple press conferences and short interviews the other day, the Malaysian Transport Minister kept repeating that any contract proposal had to ‘go to Cabinet’ because of the financial implications.

    Most people mistakenly interpret that to mean the cost of the new search (if it occurs). Such costs would be a mere drop in the bucket, a few tens of millions, nothing more than loose change to a nation.

    But that is only a ruse for the media and the NoK, it is not the real issue at all.

    The real issue is that if the aircraft were to be found, and if the investigation proved that either the Airline or the Captain was culpable, the financial implications would be huge, and the political and diplomatic damage would be substantial.

    I think it is clear that Malaysia never wanted 9M-MRO found, still don’t, and never will, for those reasons.

    Now, that leads into their current problem, how to handle the building calls for ‘another search’.

    At this point, I have to declare my hand clearly, (for those who may not be aware).

    I am embedded in the deliberately piloted flight to the ‘deep south’ camp, specifically, into the GFZ.
    I have never accepted that drift studies of the Flaperon confirm 35 South (give or take two or three).
    I do not have a gut acceptance of WSPR technology either.

    Now, since the Malaysia Government can not afford for MH370 to be found, (for the reasons above), handling calls or a new search becomes an exercise in political damage control for Malaysia, pure and simple, nothing else matters to them.

    In my opinion, the Malaysian Government will only ever ‘reluctantly’ agree to a new search, (for PR brownie points only) in an area that their own information tells them it can’t possibly be, because they must be absolutely certain, in their own minds, that the search will certainly fail, and that OI will end up with egg on their face, yet again, before they sign any new contract.

    They will ‘reluctantly’ sign contracts in the north, but only if they have to, for PR reasons alone.

    Now, hypothetically, consider what would happen if the IG suddenly came out with some miracle reinterpretation of the ISAT data, that re-confirmed the absolute certainty of the initial positions near 38/39/40 South !!

    Would all ‘the pilots’ suddenly get a fair hearing ? All of them are down there, Hardy, Keane, Bailey, and others.

  13. ventus45 says:

    (dropped off last post some how) !

    Would OI consider searching down there ?

    Would Malaysia allow it-or orbid it ?

  14. 370Location says:

    It’s never too late for new evidence to be presented.

    In the past I’ve been supportive of all scientific approaches to help narrow the search zone, and I fully acknowledge all the effort that has been put in over the last decade. I’ve made my points where it seemed necessary, but avoided dismissal of serious theories.

    Allow me again to be the contrarian.

    I’m now releasing a report on barnacle growth that excludes a cold water crash site. The paper was started nearly a year ago based on barnacle growth, but I’ve been distracted. It now incorporates new photo evidence that barnacle growth on the flaperon started AFTER the debris ran aground. Juvenile and adult barnacles are clearly observed to have grown for weeks atop worn off screw heads and abrasions that could not have occurred at sea.

    The report is now on my website:
    Barnacle Growth on MH370 Debris is Consistent with a 7th Arc Crash Site in Tropical Waters

    I don’t mean to thwart search efforts based on old evidence and past assumptions. The search needs to resume at any and all viable candidate sites.

    I’m simply pointing out that the barnacle evidence
    which has previously been dismissed as inconclusive and inconsistent with a cold water crash site is fully explained by a crash at the Java site. The matching acoustic evidence came after the search was suspended, and can also be considered new evidence for a specific location.

    Malaysia has just called for “compelling” new evidence. That seems like a political rather than evidentiary new threshold.

    I can only hope that the Java candidate site with a relatively tiny area of a few square km can help in compelling new search.

  15. Viking says:

    @TBill and @DrB

    WOW, that was a difficult challenge – particularly to answer in a pedagogical way. The short (not pedagogical) answer is that my first reply to DrB is enough. Sorry, it took me a couple of hours to come up with a pedagogical answer. I came up with one when I accidentally looked at my Globus.

    Try to place yourself at roughly 6 times the radius of the earth, over the equator, slightly south of India (analogous to the relevant Inmarsat satellite). Then remember that the classical Doppler shift is only dependent on the projected part of the airplane speed along a straight line of contact. This goes roughly proportional to the third power of the distance along the surface of the earth, and the average (as well as the typical) distance on the route from Beijing to KL is roughly 1.5 times longer than for any solution to the 7th arc in the Indian ocean. Since the speed with which the signal moves along the saw-tooth curve is also roughly proportional to the Doppler effect this means that the BFO value changes at least 3 times more slowly there. In other words, the MH371 data is not representative for what happened during the two attempted phone calls.

    There is only small effect during 1 minute, probably 1-2 Hz. This may explain why the last few points lie slightly higher than my analysis shows, but it is not changing any of my conclusions.

    On the other hand, it does have significant impact for longer time intervals.

  16. Viking says:

    @370Location

    I am looking forward to reading your new paper. It is in good agreement with my own conclusions based on scientific results from DTU Aqua (from research on global warming effects on barnacle survival and growth).

  17. Viking says:

    @All

    For handling the statistical distribution of BFO values, it is necessary to understand the underlying reasons for unusual behavior. In order to obtain a good and stable technical performance at ambient conditions one uses a general layout for control boxes (including the SDU) placing the stabilized oscillator as far as possible from the power supply and the amplifier/microwave-source, producing large and variable amounts of heat, which is a dominant error source for periods below 1 minute. The distance reduces thermal crosstalk, which is essential for good and robust performance. It also introduces a delay in the reference frequency drift (affecting the BFO) compared to the power output (heat-release-time).

  18. TBill says:

    @Victor
    Assuming it was not a fish-that-got-away story, they should probably try to spend a few days finding that wing…it’s a wing and a prayer but it is “new” evidence. Chances are low but if MH370 that could help solve.

  19. Viking says:

    @370Location

    I have now read your paper. I agree with most of what you write, but have a few comments:

    First, I find part of the introduction a bit confusing. I am not saying it is wrong, but some people may take advantage of the way you phrase things, and use this to ignore your work. I say this only to help you.

    Concerning the pure technical content I would like to add that from the scientific publications by DTU Aqua it is clear that all types of barnacles they investigated showed an Arrhenius temperature behavior with the same exponential factor but with 4 (individual for each type) threshold temperatures.

    T1: Minimum survival temperature
    T2: Minimum normal life temperature
    T3: Maximum normal life temperature
    T4: Maximum survival temperature

    Between T2 and T3 they grew according to Arrhenius (of course with individual front factor depending on species and food available)

    Between T1 and T2, and between T3 and T4 they needed time to adapt to uncomfortable conditions (typically 2-4 weeks with no growth). After adaptation, they grew according to Arrhenius again.

    From your paper T2=18degrees, T3=25degrees and T4=34degrees

    This may change some of your conclusions.

  20. Viking says:

    @All

    In addition to the half-Gaussian data distribution, there are three other differences between the data sets. As mentioned above, the 18:40 data consists of two attempted phone calls shortly after each other, while the 23:14 data is from one attempt only. This becomes clear by plotting them in the same figure, showing that the 18:40 set has additional interleaving points shortly after the beginning. Later the two sets have the same time-structure, and both span approximately 1 minute.

    The next difference is that the thermal delay (for heat-transfer from the ‘heat-release end’ to the oscillator) is much longer at 23:14 than at 18:40. This is particularly clear in the beginning, where the BFO value remains practically unchanged for a long period after the amplifier starts sending signals at 23:14 while the BFO values start going up shortly after the amplifier starts at 18:40.

  21. Barry Carlson says:

    @Viking wrote:-

    “… the thermal delay (for heat-transfer from the ‘heat-release end’ to the oscillator) is much longer at 23:14 than at 18:40 etc..”

    The unredacted Inmarsat IOR sat data was analysed by Mike Exner in a post he made on 2017-06-12. His referenced portable document file is to be found at:-

    https://tinyurl.com/6dypr2zz

    In short he found that the Carrier to Noise levels (C/N0) were commonly low at the initial logon by the aircraft on both the IOR and POR satellites.

    When you refer to “amplifiier”, I suspect you mean “transmitter”. The OCXO is unlikely to react to the TX turning on as you suggest. The OCXO is maintained at about +75°C and its power-supply is well regulated. However, if you read onward from the 2017-06-12 post the possibility of the SDU being off for a period until shortly before the 1840 logon is raised, and this will more likely relate directly with your initial BFO errors.

  22. Viking says:

    @All

    Last, the temperature stabilization for the oscillator does not attempt to compensate the heat-transfer at 23:14, giving a dramatically longer settling time (for effective heat dissipation from the oscillator), and a long upper tail for the statistical distribution with absolutely no truncation from the stabilization. This is very unusual, and indicates a serious malfunction of the SDU.

  23. Victor Iannello says:

    @Barry Carlson said: The OCXO is unlikely to react to the TX turning on as you suggest.

    It should also be noted that the SDU and HPA are separate LRUs, and the heat generated by the HPA should have little effect on the stability of the SDU’s oscillator.

  24. Viking says:

    @Barry Carlson

    The analysis by Mike Exner predominantly discussed the authenticity of the data and the C/NO. I agree that there is nothing strange about these things. Everything looks normal.

    When I say amplifier, I include all power consuming (and heat producing) parts, so it would be better to say Transmitter. However later in my analysis it is the amplifier-part which is most important. Sorry for the initial confusion.

    My approach is different from Mike’s. I am looking into the distribution of BFO and power levels as a function of time during the two attemted phone calls. There I found no indication that the fact that the SDU was off for some time prior to 18:25 had measurable effects on the data collected at 18:40. This indicates that the cabin was not particularly cold during the ‘SDU off’ time. The pressure may well have been low prior to 18:25, but that was also back to normal at 18:40.

    During both phone calls the power was falling sharply (roughly 10dB). I am pretty sure this was predominantly due to heating inside the amplifier. I will discuss the details later.

  25. Viking says:

    @Victor Iannello

    It looks like our contributions ‘crossed’, so I saw yours much later.

    It is most likely that the amplification happened in two stages. As far as I remember the most powerfull single-stage amplifier I had in 1990 had 40dB gain and 10W output. With those specifications it had great trouble with overheating causing automatic shut-down and 10 minutes waiting time for cooling. That would be totally unacceptable for the SDU. The correct design would therefore have a preamplifier inside the SDU box (responsible for the thermal crosstalk) followed by the HPA in a separate unit.

    Sorry I forgot that important detail.

    Therefore, please read preamplifier where I initially wrote amplifier or transmitter.

  26. Niels says:

    @Viking
    Follow your motto “The devil is in the detail” a question:
    Is there / will there be a paper (incl. references where possible, and with sufficient technical details) substantiating your findings? I think it is much easier to properly give feedback and have a discussion if there is such a detailed paper instead of a series of slightly descriptive posting.

  27. airlandseaman says:

    @ALL: Regarding the phone call BFO values…As Victor noted above, the OCXO frequency is not affected by the heat from the HPA. The OCXO thermal control system maintains a very constant temperature (whole circuit including the xtal), regardless of the ambient temperature over a wide range (-40C to +55C). For the 1 minute period related to a phone call, the change is absolutely zero.

  28. Niels says:

    @DrB
    I was checking your App. F.3 “BFOR noise measurements” from the “UGIB” paper.
    It states:
    “All BFORs in this plot use the same BFO Bias of 150.0 Hz for prediction, and we have subtracted 16Hz from the MH371 BFOs to compensate for the 16 Hz step reduction applied in the SDU at 16:00:25 (as a result of an automatic frequency calibration procedure) when at the gate prior to MH370 push-back.”

    How did you know this “16 Hz step reduction”, was it explicitly logged or was it somehow extracted?

  29. Victor Iannello says:

    @Niels: We talked about this at length in the 2017-2020 timeframe. The log-on at 16:00 showed a BFO jump of around 16 Hz, which is consistent with information from the ATSB about the bias adjustment from the frequency calibration algorithm.

  30. Niels says:

    @Victor
    Thanks Victor. I remembered the 16 Hz jumps and auto-calibration being discussed but didn’t remember the specific details -> I’ll have a look at the unredacted logs again.

  31. airlandseaman says:

    @Niels: When I was in London Dec 2017, I had a discussion with the guy from Thales about how the AES maintains the OCXO calibration. He was a little vague about the details, but basically, the AES recalibrates the frequency offset from nominal frequency by periodically measuring the L band downlink offset when the plane is on the ground (as it did at 16:00Z). It recalibrates each time at least 26 hrs have passed since the previous ground logon calibration. So it’s not done on an exact schedule.

    Rockwell holds a patent on a method that uses the L band downlink offset to calculate the required uplink offset continuously. That’s why Honeywell cooked up the scheme they use. Note: 16 Hz is ~ 10^-8 * carrier frequency.

  32. DrB says:

    @Viking,

    1. The BFO fluctuations during the MH370 phone calls are consistent with and fully explainable by the quantized trig computations in the SDU of the pre-compensation Doppler shift.

    2. There is no need to hypothesize that rapid BFO changes up to 4-5 Hz occurred over a period of several tens of seconds or less caused by OCXO temperature fluctuations. Nor is this even possible after the power-up transient has settled.

    3. All the BFO-sequence examples I have seen from MH370 and MH371 show the same peak-to-peak amplitude near 5 Hz. This is to be expected when the aircraft is in typical flight, as I have explained previously.

    4. Only the “frequency” of the saw-tooth varies among the calls, depending on the time rate of change of the cosine of the angle between the aircraft velocity vector and the line of sight from the aircraft to the satellite.

    5. In fact, uniquely determining the value of this angle can be done solely from the slope of the measured BFOs between the “steps” occurring when the pre-compensation Doppler changes to a new value. Note that this calculation is independent of any assumed BFO equation or model. In fact, this BFO slope is the time derivative of the ACTUAL Doppler shift.

    6.This change in the ACTUAL Doppler shift (i.e., the 5 Hz sawtooth step amplitude) occurs in the same time as the cosine of the LOS-aircraft angle changes by a fixed increment (i.e., the SDU computational increment). This allows the LOS-aircraft angle to be uniquely determined. However, there is a “mirror symmetry” of routes with the same Doppler shift and therefore the same LOS-aircraft angle, so in general there is a pair of route solutions for each phone call.

    7. This slope technique is a new method of checking the viability of any proposed MH370 route, at least at the times of the phone calls. It won’t tell you BOTH the location and the course (track bearing), but it relates them in a numerical way such that if you assume one, you can find useful limits on the other. So, the combination of a predicted location and a predicted course can be checked for consistency, and this check is significantly more discriminating for the sequence of phone call BFOs than what is possible at those times when only an isolated BFO measurement is made.

  33. Victor Iannello says:

    @DrB: That is VERY clever! During the times when the Doppler pre-compensation is constant due to the discrete steps associated with the trig function, the slope of the BFO is essentially the rate of change of the true Doppler shift.

    I really doubt anybody has considered this before.

    So with that in mind, it would become harder to spoof the BFO with fake satellite inclination parameters so that a northern path has the BFO signature of a southern path, as the slope of the sawtooth would be different for a northern and southern path, even though the BFOs might be very similar.

  34. Niels says:

    @DrB, Victor
    Very interesting idea indeed!
    I just looked at the logs and if the aim is to determine the d(Doppler)/dt around 23:15 can’t you just remove the steps / staircase (and thereby effectively the compensation component). This would allow to fit on all available points for the slope.
    Now the step height would be a (weak) function of the aircraft position -> you get a measured d(Doppler)/dt which strictly speaking slightly depends on aircaft position (through the removed step height). For each path you can calculate the the d(Doppler)/dt, which for given moments in time (and hence known satellite velocities) would depend on aircraft velocities, which is known for each path tested. For each path tested the aircraft position is also known and hence the measured d(Doppler)/dt more accurately. The two can then be compared. Does that make sense?

  35. Niels says:

    @alsm
    Thanks Mike. So the conditions for the calibration to occur are time elapsed > 26 hours and of course being on the ground. In theory I guess it could be multiples of 16 Hz.

  36. Viking says:

    @Niels

    I am considering to make a complete new publication, but as the many comments show it is a complicated matter, and therefore I prefer taking the discussion first.

    @DrB

    I considered using the method you proposed on BFO derivatives (or a similar method using BTO derivatives) already in 2016. At first glance it is an excellent idea. However, after some thinking I realized that the resulting uncertainty is too large. There are a couple of reasons for that. First of all the intrinsic 1Hz resolution limits the precision. Basically you take two large numbers (each with 1Hz resolution) and subtract these. This gives a large relative uncertaity. Secondly, the round-off error (discussed yesterday) severely complicates things, and roughly doubles the uncertainty. Thirdly, the method is potentially very sensitive to height changes.

    @All

    I will reply to your comments very soon (mostly today). I am going to merge some of the comments/replies to avoid repeating too many things.

  37. Viking says:

    @All

    Concerning heat release from a pre-amplifier:

    I agree with your comments on the heat release from the HPA. This one is almost certainly well temperature stabilised (probably military grade) and isolated form the SDU box. However, heat from a preamplifier (e.g. 33dB gain with a few W output) is sufficient to causing thermal crosstalk.

    Just listen to this personal observation: Someone with limited knowledge of HF amplifiers borrowed my 10W device in 1990. He placed it on a plastic chair and pushed it hard to get maximum output. After a few minutes the chair melted (just from the heat coming out of the ‘exhaust’ from the fan), and only the emergency thermal shut-down prevented it from falling on the floor or starting a fire. After this we had to throw the plastic chair in the bin. Fortunately it was a cheap one.

  38. TBill says:

    @Victor
    I still claim B777 BTO/BFO spoofing is impossible. JJW had an expert on a couple weeks ago, who talked about the conditions necessary, including wheels down, changing out memory chips, etc. This spoofing rumor is just conceptual with no proof anyone could do this on a real B777. Let alone have it not be obvious from the sat data logs. Hitchen’s Rule applies that which can be claimed without evidence can be dismissed without evidence.

  39. Victor Iannello says:

    @TBill: Yes, the penetration vector proposed in that episode was ridiculous.

  40. DrB says:

    @Niels,

    You said: “. . . can’t you just remove the steps / staircase (and thereby effectively the compensation component). This would allow to fit on all available points for the slope.”

    Sure. For MH370 at 18:40 there are about 19 steps of about -5.6 Hz and 3.1 seconds each, so its slope is roughly about -106 Hz / 59 seconds = -1.80 Hz/second. Fitting the actual data with the compensation steps removed to see the actual Doppler shift (plus a constant) allows a reliable determination of the slope (and its error) by least squares fitting. Note the slope at 18:40 is negative because the positive Doppler shift (caused by the aircraft moving toward the satellite) is getting smaller with time.

    I will also note that one can “fit” the pre-compensation steps to each BFO data set by adjusting the amplitude, period, and phase so as to minimize the least-squares residuals of the straight-line fit. What this process does is minimize the discontinuities when the steps occur.

    It’s also necessary when finding the Doppler Angle ” (i.e., what I call the angle between the aircraft velocity vector and the line of sight from the aircraft to the actual satellite location) from its sine value that the proper quadrant is chosen. For instance, at 18:40 the Doppler Angle is in the range 0 to 90 degrees, but at 23:14 it is in the range 90 to 180 degrees. The quadrant is chosen based on whether the aircraft track is reducing (0-90 degrees) or increasing the satellite range (90-180 degrees).

    At 23:14 we have 3 steps of roughly -5.6 Hz each about every 21 seconds, so its actual Doppler slope is about -16.8 Hz / 63 seconds = -0.27 Hz/second (7X smaller than at 18:40). At 23:14 the Doppler shift is negative, because the aircraft is moving away from the satellite) but the slope is again negative because the Doppler shift is becoming more negative with time.

    The actual BFO slope is proportional to the time derivative of the cosine (which is therefore minus the sine) of the Doppler Angle, That means at 23:14 the slope is small, so the aircraft is flying less obliquely to the tangent of the “arcs” than it was at 18:40, when it was flying more or less directly toward the sub-satellite location and the magnitude of the BFO slope was much higher.

    You also said: “. . . Does that make sense?”

    Yes. It’s also worth noting that one does not need to know the satellite velocity vector in this slope method, so long as you assume it does not change appreciably during the 1 minute phone call.

  41. DrB says:

    @Viking:

    You said: “. . . the method is potentially very sensitive to height changes.”

    I think you mean the vertical speed. Sure. The vertical speed must either be known or assumed to be constant (and not necessarily zero).

    You also said: “First of all the intrinsic 1Hz resolution limits the precision. Basically you take two large numbers (each with 1Hz resolution) and subtract these. This gives a large relative uncertaity .”

    Over the duration of a call, about a minute, the change in BFO is -106 Hz at 18:40 and -17 Hz at 23:15. It is true that the data are quantized in 1 Hz increments. However, the impact of that quantization is a best-fit line deviation of 1.0 / SQRT(12) = 0.3 Hz per point. So, the quantization error is actually not a limit in the uncertainty of the slope, because it is considerably smaller than the RMS read noise per data point.

    As Niels described, we can simply add the pre-compensation steps to the data and then fit a straight line to the “uncompensated” actual Doppler shift. That will give the slope, and we can then find the uncertainty in the slope from the fitted residuals. That slope uncertainty can then be converted to the uncertainty in the sine value, and that can be converted to the Doppler Angle uncertainty. So, we can solve for the Doppler Angle and have a reliable estimate of its uncertainty for each phone call by “removing” the pre-compensation steps and fitting a straight line by least squares.

  42. Viking says:

    @TBill (and Victor)

    I agree completely. Brute-force BTO/BFO spoofing as described by JW is impossible in the real world, in particular after 9/11 security measures.

    However, a special type of BFO spoofing may in principle be possible using an analogy to methods developed to compromise cryptography. I will discuss it in more detail later.

    I do not believe it was used for MH370.

  43. Viking says:

    @DrB

    I do not see how you arrive at those values for the change in BFO within 1 minute.

  44. Viking says:

    @DrB

    I think you forget that the large change at 18:25 was due to a re-booting effect.

    – and

    I do mean sensitive to vertical speed (not absolute height).

  45. Victor Iannello says:

    @DrB: I said During the times when the Doppler pre-compensation is constant due to the discrete steps associated with the trig function, the slope of the BFO is essentially the rate of change of the true Doppler shift.

    What I said is not exactly true. When the AES pre-compensation is held constant, there will indeed be contributions to the slope of the BFO from changes in the uplink Doppler (L-band), but also changes in the downlink Doppler (C-band) and changes in the EAFC correction. Nonetheless, all of these are quantifiable for a given time and position/velocity vector of the aircraft, so some discrimination of paths should still be possible.

  46. Paul Smithson says:

    It won’t surprise many here if I reiterate that I believe the aircraft will ultimately be discovered at +/ – 39.6 south, on the 7th arc because that is where BTO error optimisation tells us it ought to be. And at the end of the game, I think that most here agree that BTO is the best among an otherwise fuzzy heap of evidence to go on.

  47. Paul Smithson says:

    @Dr B. I’m also intrigued by your sawtooth derivative as a novel analytic method, independent of assumed BFO bias drift or absence thereof. I’ll be happy to submit my path-predicted parameters at phone call times for you to run those numbers.

  48. DrB says:

    @Victor,

    During the duration of the 18:40 and the 23:14 phone calls, the predicted BFOs without the actual Doppler shift change by 0.4 Hz or less when neglecting the SDU quantization effect. Therefore, assuming the sum of all the other terms, except for the actual Doppler shift, is constant is a very good approximation and introduces no material error.

  49. DrB says:

    @Viking,

    You said: “I think you forget that the large change at 18:25 was due to a re-booting effect.”

    No, I didn’t forget about the OCXO transient on warm-up. Six years ago in 2018 I demonstrated the warm-up transient settles out in 3 minutes. So, after 18:28, the transient is gone.

    The 2018 transient analysis is available here.

    Therefore, the warm-up transient is long gone by 18:40 when the first phone call came in.

    You also said: “I do not see how you arrive at those values for the change in BFO within 1 minute.”

    After I get the code running and tested, I will prepare and post some figures to demonstrate the application of the BFO slope method to three phone call events. These will make it clear that the BFOs actually follow a sawtooth waveform within the normal read noise.

  50. DrB says:

    @Paul Smithson,

    You said: “I’ll be happy to submit my path-predicted parameters at phone call times for you to run those numbers.”

    I can do that once I have the bugs out. It would be convenient if your inputs were in the format in my BTO/BFO model available here.

  51. Mick Gilbert says:

    @DrB
    @Victor Iannello

    Gents, I am more than happy to ‘fess up to a bit of a “dog watching TV” moment here regards the recent discussion regarding (and I’ll use Paul’s words here) using the saw tooth derivative as an analytical tool for the phone call BFOs. I’m picking up the palpable excitement and there’s a smattering of words I recognise but that’s followed by that thumping whoosh of most of it passing overhead.

    Any chance of CliffsNotes or “Saw Tooth Derivative as an Analytical Tool for the Phone Call BFOs for Dummies” please?

  52. Peter Norton says:

    @TBill:
    In your comment, what “new evidence” are you referring to ?

    @370Location:
    « Malaysia has just called for “compelling” new evidence. That seems like a political rather than evidentiary new threshold. »
    My feelings exactly.

    @ventus45:
    « The real issue is that if the aircraft were to be found, and if the investigation proved that either the Airline or the Captain was culpable, the financial implications would be huge, and the political and diplomatic damage would be substantial. »
    That might very well be the reason.

    « The Chinese […] when their IL-76’s were prevented from searching where their own satellites showed target of interest (deep south west end of the search area, plus a bit further) »
    I must have missed this or forgotten. I couldn’t find any source for that. Do you have one?

  53. sk999 says:

    Out of curiosity, I took the BFOs from during the two phone calls, fitted a quadratic, and made the following figure:

    https://drive.google.com/file/d/1bQd2mXgAOJSTvNOttvfY_vcg59-BUtM7/view?usp=sharing

    (BFOs from 23:14 have had 140 hz subtracted to fit on the figure, and Delta-UT is UT in hours relative to the average of all UTs during each phone call.)

    A quadratic fit works well. The rms scatter is actually lower for the 23:14 call (0.8 v. 1.1 hz).

    I take no position on the interpretation of these results or what relevance they have to sawtooth quantization.

  54. David says:

    All. Some selected recent media reports:

    – The ‘IG’ opinion finally gets some media attention:
    https://www.9news.com.au/world/mh370-where-is-missing-plane-on-7th-arc-and-will-we-ever-find-malaysian-airlines-boeing-777/e6afa618-dd20-4265-81fd-dc8a62054aaf

    – At least as announced, the Australian support for a new search is limited to “technical information”, neither funding or support to OI being mentioned:
    https://www.foreignminister.gov.au/minister/penny-wong/media-release/mh370-10-years

    – In Oz we haven’t seen the BBC show yet, which might include the gist of the below, but I see in at its 3:45 on that Liverpool Uni will not have concluded its wide study into the merits of WSPR claims until October/November.
    OI might be awaiting that before evincing any enthusiasm for it:
    https://www.youtube.com/watch?v=9SEMSQDO-pg

  55. Victor Iannello says:

    @DrB: Here’s a test case. At 18:40, we have for the UGIB path (assuming my quick calculations are accurate): LLA = (7.5180 deg, 94.5830 deg, 16,300 ft), GS = 337 kn, VS = -1840 fpm. According to my calculations, the rates are: Uplink Doppler = -1.52 Hz/min, Downlink Doppler = 0.48 Hz/min, AES pre-compensation = 1.48 Hz/min, EAFC = -0.17 Hz/min. Therefore, the BFO rate is 0.26 Hz/min with the AES pre-compensation varying. If the AES pre-compensation is held constant, the BFO rate is -1.21 Hz/min, which is less in magnitude than the Uplink Doppler rate (-1.52 Hz/min).

    [These numbers were updated since the original comment was submitted.]

  56. Victor Iannello says:

    @David: I really haven’t tried to promote the UGIB 2020 path and the associated recommended search areas in the media the way many have promoted their paths. In fact, I shun most media contacts because few have the capability and willingness to accurately cover our work. However, I assure you that anybody that is seriously considering re-starting a search is well aware of our work. This blog has always been geared towards technical discussions among informed investigators. The target audiences of the media and the other blogs are much different. That’s part of the reason that extraordinary technical claims go unchallenged.

  57. Victor Iannello says:

    @Mick Gilbert: We know that the BFO varies with time, position vector, and velocity vector. But now we have potentially a new parameter (BFO rate without AES compensation) discovered by Bobby that also varies with time, position vector, and velocity vector. We have this new parameter because the AES compensation is theorized to change in discrete steps, and the BFO rate between discrete steps can be measured. This new parameter is available from the burst of BFO data we have at the time of the phone calls. So, we are exploring whether we can use this data to further constrain the set of hypothetical routes. I’d say the jury is out until we study it further, but it may indeed prove useful.

  58. Kenyon says:

    The link below is a feasibility study for estimating a kinetic energy budget and its potential for generating seismic energy for a (hypothetical) forward fuselage section impacting the seafloor.

    https://www.dropbox.com/scl/fi/n77um4ph01ltwxgll1bn0/MH370-Feasibility-Study-of-Radiated-Seismic-Energy-Generated-from-a-Forward-Fuselage-Section-Rev-0.pdf?rlkey=grgxagcmiel5nuvel67nxjsgm&dl=0

  59. Mick Gilbert says:

    @Victor Iannello

    Thank you for that, Victor.

  60. Niels says:

    @DrB
    First of all:many thanks for your feedback on my posting yesterday.

    Earlier you wrote:
    “This change in the ACTUAL Doppler shift (i.e., the 5 Hz sawtooth step amplitude) occurs in the same time as the cosine of the LOS-aircraft angle changes by a fixed increment (i.e., the SDU computational increment). This allows the LOS-aircraft angle to be uniquely determined”

    How do you actually know that the SDU computes the relevant inner product of vectors this way (using the cos of the LOS-aircraft angle)?
    Based on available TT, GS, Lat, Lon there could be different ways to implement the calculation of the f_comp in a basic processor. For example one could just use add, subtract, multiply and look up tables for sin and cos and calculate using those and avoiding the need to use a divide routine, square roots, or to first solve for an angle.
    Also, thinking about it a bit more, I would just use a spherical earth approximation, and indeed use a stationary satellite position, as they do. But then there could be many different cos and sin’s involved with their discretized look-up tables.

  61. Niels says:

    @DrB
    The “many different cos and sin’s” would typically be sin(lat), cos(lat), sin(lon), cos(lon), sin(track), cos(track) in one possible implementation I have in mind.

  62. Viking says:

    @Niels

    Thanks for making the computational details clear. In light of incomplete information from Inmarsat on their detailed software I just took the statistical approach.

    @Victor Iannello

    Concerning your numbers published on March 8 at 9:19pm.

    Your numbers agree nicely with mine. In my statistical approach this is abbreviated as 1-2 Hz (as I wrote two days ago).

  63. Viking says:

    @DrB

    As a further follow-up on your comments and proposed method, I actually spent some time finding an optimum combination of such methods (including both BFO and BTO) before publishing my first paper. The results are summarized graphically in figure 2 of my paper.

    From this I could conclude one important thing. The final major turn (FMT) happened shorty after 19:41, and it was close to a U-turn (because of the sign change).

  64. Peter Norton says:

    @Victor Iannello: « it would become harder to spoof the BFO with fake satellite inclination parameters so that a northern path has the BFO signature of a southern path, as the slope of the sawtooth would be different for a northern and southern path, even though the BFOs might be very similar. »

    Harder or impossible ?
    Does that mean a northern path can definitely be excluded now based on this ?
    Have you determined if the sawtooth does indeed differ for a northern and southern path ?

  65. Peter Norton says:

    @TBill says: « spoofing […] is just conceptual with no proof anyone could do this on a real B777. Let alone have it not be obvious from the sat data logs. »

    How would spoofing manifest itself obviously in the logs ?

  66. Viking says:

    @Paul Smithson

    You claim using only BTO values the optimum solution is near -39S. This is not correct. First of all, BTO alone does not give a good basis for finding an optimum solution. It basically just defines the 7th arc.

    If one insists using BTO only, there are two ‘solutions’. One is slightly north of your number (near -37S as far as I remember – it takes a lot of mathematical skills to calculate). It is an extremely shallow and broad solution on the limit of mathematical stability. Actually, I think it is not stable.

    The other BTO optimum is near my solution. It is narrow and deeper, but I would not call it good.

    As DennisW once wrote: The problem is underdetermined. More information (than just BTO) is needed. I think DennisW actually claimed the entire problem was underdetermined, but I disagree on that.

  67. Viking says:

    @Peter Norton

    A perfect spoof would be invisible in the log, but it would lead the investigators to wrong conclusions.

    The only ways to identify a spoof are:
    1) In the log, if the spoofer made one or more small mistakes.
    2) Using other information (biofouling, beaching pattern, seismic data, contrails, eyewhitness reports, etc.)

  68. Viking says:

    @All

    I think it is now time to proceed according to my original schedule:

    For the 23:14 data, it looks like the thermal crosstalk-delay increased 3-4 times compared to the 18:40 data. This is particularly clear in the beginning of the data sets. Everything looks normal (in terms of induced noise and delay) at 18:40, but at 23:14 there is practically no noise until much later.

    In addition, the overall re-cooling time (seen later in the data sets) increased roughly 10-15 fold. How is that possible? There are three possibilities according to my experience with similar boxes for controlling semiconductor-lasers or optical detectors:

    1) The SDU was so cold and/or moist that significant amounts of frost or water had condensed on the surface of the frequency-oscillator
    2) The cabin pressure was reduced 3-4 times (to below 0.25 bar)
    3) Somebody had hardware-modified the box.

    We choose to discard option 3, since nobody on board had the necessary technical knowledge, no realistic motive, and certainly not sufficient time (and no adequate equipment because it would not get through security after 9/11) to make such modifications. For a corresponding laser box, it would have taken me around 1 hour. Somebody without daily experience (only general knowledge of electronics) would need one day.

  69. Victor Iannello says:

    Peter Norton asked: Harder or impossible ?

    Work in progress. I’d say the merits of this new approach are far from proven.

  70. Victor Iannello says:

    @Niels said: The “many different cos and sin’s” would typically be sin(lat), cos(lat), sin(lon), cos(lon), sin(track), cos(track) in one possible implementation I have in mind.

    I think that if the waveform observed is truly due to changes in AES pre-compensation in discrete steps, there are other possibilities, such as the finite resolution of the output of the pre-compensation algorithm or the frequency output of the SDU, and not necessarily discrete approximations of the trig functions.

  71. airlandseaman says:

    @Viking: There is no “thermal crosstalk”. We need to ditch that idea. The OCXO frequency is not measurably affected by the heat generated in the HPA (or any other AES component). In fact, the HPA and SDU (which contains the OCXO) are in separate LRUs separated by several inches. The thermal control system used in the OCXO is capable of maintaining a constant circuit temperature over a wide temperature range (-40 to +55C). Over a 1 minute period (or an hour), there is absolutely no possibility that HPA heat could significantly change the OCXO frequency. See a small sample of my OCXO and related files here: https://bit.ly/3It0OJx

  72. Paul Smithson says:

    @Viking I agree that the problem is underconstrained for bto optimisation if you start on arc 2. Because to do that removes all practical latitude discrimination. If you include a requirement to join up with the last known path and no loiter then you do indeed have a BTO optimized solution space. It stretches from roughly 38.5 to 39.8 south. Dstg and IG mark-1 were biased a little north of there (circa 38S) because they sought to optimise BTO & BFO combined.

  73. Peter Norton says:

    @Victor Iannello says: « Work in progress. I’d say the merits of this new approach are far from proven. »

    In my humble opinion it would be very exciting if you could show that the sawtooth differs for a northern and southern path and thereby proving with mathematics alone that only 1 of these 2 paths is possible – completely independently of the found debris which some claim was planted.

    By eliminating these other theories (presented in the Netflix documentary or even on CNN this week highlighting the WSPR theory) it would help focusing the search efforts.

  74. Peter Norton says:

    @Victor:

    I think it would be advisable to redact the private parts of the link posted by @ventus45 in this comment because it reveals his full name and email address.

  75. Victor Iannello says:

    @Peter Norton: OK.

  76. Niels says:

    @Victor
    Besides questions about the exact origin of the saw tooth waveform in the BFO data, I have a bigger worry: By thinking about how a most simple implementation of the pre-compensation calculation based on Lat, Lon, Track and GS as input could look like (and considering that the pre-compensation does not need to be fully accurate for the system to function), I wonder if the eq. 5.9 in the DSTG book exactly represents what is implemented in the hardware. Spheroid vs. elliptical earth model is just one example of possible subtle “shortcuts” in the implementation. Another typical point is how the ac-sat distance (the denominator in eq. 5.9) is exactly taken care of. Remember the “geographic dependency” like in fig. 5.4.

  77. DrB says:

    @Niels,

    You asked: “How do you actually know that the SDU computes the relevant inner product of vectors this way (using the cos of the LOS-aircraft angle)?”

    I don’t know how the SDU computes the pre-compensation Doppler shift. What I do know is that the amplitudes of the saw teeth matching the BFOs in the three phone calls are close to the same value (about 5 Hz). Now, in these particular cases the aircraft speeds are also close to being equal (cruising at high altitude). If the pre-compensation frequency steps are equal in amplitude at about the same aircraft speeds, that means there is a similar quantization in the calculation of the Doppler shift. The Doppler shift is, in its simplest form, equal to (aircraft speed / c) times the carrier frequency times the cosine of the “Doppler Angle” (i.e., the angle between the aircraft velocity vector and the vector from the aircraft to the nominal satellite location). So, if the speeds are the same, the observation that the saw teeth are close to the same amplitude implies that the quantization is equivalent to equal steps in the cosine of the Doppler Angle. I note that, even though the BFO slope (which is proportional to minus the sine of the Doppler Angle) varies by a factor of seven, and thus the Doppler Angles would appear to be quite different in relative value, the step size still looks to be the same amplitude in frequency space. The simplest model of this observed behavior is that, equivalently, there may be steps in the cosine of the Doppler Angle.

    I also note that at 480 knots the maximum uplink Doppler shift is 1,356 Hz. If the cosine of the Doppler Angle were quantized to 8 bits in magnitude, say in a look-up table, the frequency steps would be 1356 / 256 = 5.3 Hz, which is consistent with the visible steps in the BFO data during the phone calls.

    I don’t yet have an explanation for how often the steps occur. This varies from about 3 seconds (at 18:40) to 20 seconds (at 23:14 for MH370 and also in the MH371 event). These step periods don’t seem to match the predicted Doppler slopes. That is, the time it takes for the computed Doppler to change by 5.3 Hz is about 100 seconds, which is much longer than the observed 3-20 seconds between steps in measured BFOs.

    Thus, the calculated Doppler slopes and the observed BFO slopes in between steps are NOT equal. I think that means that the SDU is doing something presently unknown to us that modulates the pre-compensation frequency in 5 Hz steps much more frequently than would be the case with a simple look-up table.

    So, the “BFO Slope Method” is still an unvalidated theory. I can reasonably predict the step amplitude, but not the step rate.

    I wonder why the transmitted frequency has these steps so often? The only explanation I have for the existence of the BFO saw teeth is that the SDU is impressing the saw teeth in the calculated pre-compensation of Doppler shift toward the nominal satellite position.

    Despite the current disagreement in the BFO step frequency, it may eventually be possible to discriminate between a course of 180 degrees at 18:40 with no descent or a westerly course with an ongoing descent. I think this may be possible because the SDU applies no pre-compensation for vertical speed, and this may assist in discriminating routes with a descent. In addition, at 18:40 the Doppler to the nominal satellite location (used to pre-compensate the transmission frequency) and the actual Doppler shift to the satellite are rather different. That circumstance may also help to discriminate between the west and south courses used in the two methods of matching the 18:40 BFOs. First, however, we need an explanation for why the time between BFO steps is so short. Once this is understand, we will then know if we can reliably determine the 18:40 course.

  78. ventus45 says:

    @Peter Norton:
    @Victor:

    Careless of me.
    Thanks both.

  79. TBill says:

    @Peter Norton
    When I said “new evidence” I was referring to the claim by skipper Christopher (Kit) Olver that he snagged what appeared to be a commercial aircraft wing in his trawl net off Robe, South Australia in October 2014—about 6 months after MH370 disappeared.

    I rate it low chance, but worth a small effort if we have location. I am thinking OI has more shallow depth AUV’s that might be used.

  80. Mick Gilbert says:

    @DrB

    Any chance that lateral manoeuvring during a transmission causes the Doppler compensation to be run more frequently than would be the case for straight and level flight?

  81. Niels says:

    @DrB
    Thanks for further clarifications. I think we are more or less on the same page. Yesterday I also found that the slopes observed in the BFO data don’t seem to match the expected d/dt(Doppler) for the 23:14 phone call, being a factor 7 or so off. Assuming the step size is indeed 5-6 Hz (at 23:14 they are at least a couple of Hz in magnitude) this actually means that the steps are not due to the pre-compensation mechanism trying to compensate for the (change in) Doppler shift and having some unknown discretization effect in the calculation. Unless (and @Mick Gilbert asked this) the slope in the BFO data is not what we expect (based on the overall, hours long development of the BFO data). But it would be quite coincidental that a temporal disturbance in the overall BFO trend would (with the BTO and BFO data suggesting something close to straight and level flight) overlap with the phone call attempt. And we also have the discrepancy in the MH371 event.
    So, for the moment I tend to conclude that we are not looking at discretization events originating from the Doppler pre-compensation calculation.

    You mention: “The only explanation I have for the existence of the BFO saw teeth is that the SDU is impressing the saw teeth in the calculated pre-compensation of Doppler shift toward the nominal satellite position.”
    Do you mean with a purpose, or as a “parasitic” side-effect of some process?

  82. 370Location says:

    @Viking:

    Thanks for taking the time to read and comment on my MH370 barnacle growth report.

    I’ve removed a non-technical paragraph of the intro. I suspect that was not the portion you see at issue, and I’m open to other refinement.

    Comparing Arrhenius growth curves related to global warming is interesting. I couldn’t find the particular paper you’re referencing, but I get the gist. It is relating the rate of growth change with temperature. I note in the paper that several sources show faster growth at the warmer end of the range, but that doesn’t change the conclusions. I compare the flaperon drift into tropical winter temperatures with the towing of the oil platform from the equator to NZ in 30 days, with lepas anatifera reaching 52mm. With a 39mm barnacle on the flaperon, that is still conservative evidence that it grew to that size within a month. The reproductive range of 18-25C is important for attachment and initial growth. Variations in that growth rate are less important, and Arrhenius effects on the two paths should be comparable.

    I see a approximate match between the local Reunion waters temp curve starting early-June with the shell growth temperature curve.

    A major finding in the paper is that the flaperon barnacles are growing atop the scouring from beaching. That drastically changes the timeline previously assumed for arrival and discovery of the flaperon, and the rate of growth on the barnacles. A crash site in tropical waters on the 7th Arc now completely explains the barnacle evidence. It also disrupts previous attempts at matching temperatures along a drift path back toward a cold water crash site, or later arrivals predicting a 34S latitude.

  83. 370Location says:

    @Kenyon:

    Thanks for exploring the energy vs seismic detectability for impact of a sinking fuselage fragment with the seabed.

    You appear to compute the momentum using only the estimated weight of the fuselage material, along with 27 cubic meters of seawater. That might be correct for a hollow fuselage sinking without entrained water. As I wrote last year, it doesn’t account for the mass of water contained within a half-sealed fuselage section. The mass of the contained water, plus an additional amount of water dragged along with and behind the debris, could increase the momentum estimate as much as 10x your calculation.

    Regardless, an impulsive sound was detected by dozens of seismometers and hydrophones. It appears to be at seabed depth, yet from a century of cataloged quakes in the immediate area, all were deep in the subduction zone below the Sundha Trench at a depth of 30-90 km.

    Something anomalous happened at that site that doesn’t match geological events. The sound was very loud on hydrophones, but seismically weak. The timing was just as MH370 was sinking near the 7th Arc. The epicenter accuracy is within a few km, and well within the 7th Arc BTO accuracy.

    Seismometers can be exquisitely sensitive. It is about whether local noise near a seismometer masks a more distant event. In some cases cattle or road traffic might dominate. Seismic magnitudes are about the volume of crustal movement, and usually at sub-1Hz frequencies. The detections of the Java event are in the anthropogenic range above 1-2 Hz, usually filtered out of quake analysis.

    Lightning bolt strikes on land are easily detected on nearby seismometers, but the higher frequencies don’t propagate like quakes. The same is seen for the seabed Java event.

    Like not being able to imagine what might create a loud enough implosion to be detectable on distant hydrophones, let’s be cautious about dismissing a seabed impact as detectable by seismometers.

    Fortunately, most of the seismic data is public. Analysis by expert seismologists can validate the depth, polarization, and other parameters that further separate an isotropic event from crustal movement.

  84. Victor Iannello says:

    @Niels: Another possibility is the jumps in BFO are related to the temperature controller of the OCXO. If for instance the heater is ON/OFF with a hysteretic temperature range, there might be a jump when the heater turns on followed by a decay. Differences in the cycling time between 18:40 and 23:14 might be related to the slower temperature decay due to differences in heat transfer rates.

  85. Viking says:

    @airlandsman

    Please read my contributions from the last few days again. I am sorry that I initially used the word amplifier, where I should have written pre-amplifier.

    The point is that the HPA needs a pre-amplifier (inside the SDU box), since it is impossible to have very high gain for HF HPA’s. Particularly for older models.

    The reason for my mistake is that during the last many years I did most work in optics. There it is more easy to have higher gain in HPA’s due to more favorable quantum effects (e.g. in Yb fiber-amplifiers). This also allows much higher wall-plug efficiencies.

  86. Peter Norton says:

    @TBill says:
    « skipper Christopher (Kit) Olver that he snagged what appeared to be a commercial aircraft wing in his trawl net off Robe, South Australia in October 2014—about 6 months after MH370 disappeared. »

    No pictures of this wing ?

  87. Viking says:

    @370Location

    If you wish, I can send you links for the two papers I refer to, but I fear they may be behind pay walls for you. I can send copies directly to you if you send me an email.

    Concerning the details, it quickly becomes complicated. However, one simple thing is the complete absense of species breeding in temperate and/or sub-tropical waters in the biofouling. According to the DTU Aqua research some of this would almost certainly have survived if the airplane came down in the southern Indian Ocean.

    The main message of the research papers is of course good news for marine life in a significantly warmer climate, but our investigation of MH370 can also benefit here.

  88. Peter Norton says:

    @Mick Gilbert says:
    « Any chance that lateral manoeuvring during a transmission causes the Doppler compensation to be run more frequently than would be the case for straight and level flight? »

    Since Jeff Wise’s podcast co-host sometimes meets the Rockwell CEO and can ask him questions about their SDU, I was thinking: Can’t the IG likewise obtain the required information from Thales rather than the hard way through number crunching ?

  89. Viking says:

    @All

    After eliminating option 3 (from yesterday), we can extract more information and decide which of the two initial possibilities is most likely. The magnitude of the crosstalk seems to be unchanged or increasing (remember to compensate for more heat due to two attempts at 18:40). This is ruling out frost or water as the cause, since both would have reduced the magnitude of the crosstalk (they insulate and increase the effective thermal mass at the same time). Therefore, the only possibility is that the cabin pressure was low!

  90. Victor Iannello says:

    Peter Norton said: Since Jeff Wise’s podcast co-host sometimes meets the Rockwell CEO and can ask him questions about their SDU…

    They are confused. The “Rockwell” CEO he is referring to runs Rockwell Automation, based in Milwaukee, which includes the brand Allen-Bradley. The avionics group, designated Rockwell Collins, is based in Cedar Rapids, Iowa, and split off from Rockwell International some years ago (2001).

  91. TBill says:

    @Victor
    Juan Brown informative update on the United max that ran off the runway on landing, looks like speed was too high for the turn at the end, and runway was wet. Juan says having trouble keeping up.

  92. Viking says:

    @All

    The 10-15 fold increase in overall re-cooling time also practically rules out frost (because it would have thawed in the pre-amplifier heat after one minute). Instead it points to a low cabin temperature in addition to low pressure, since such a long re-cooling time means that the effective temperature difference (driving the cooling, since the stabilization-mechanism is unable to cool actively) must be much smaller than usual. Without detailed knowledge of the design of the SDU, we cannot calculate the exact cabin temperature. However, it must have been so low that the heating power from the temperature-stabilizer was permanently at maximum to explain the asymmetric data distribution. This also explains the absence of any signs of active stabilization. That only occurs if the heating power (from the temperature-stabilization) is completely off, or if it is pinned to maximum. It is extremely unlikely that it was completely off. I have never seen that error (except when the user forgot to switch on the whole box), while I have seen practically all other thinkable errors in such stabilizations. More importantly, if the heating were completely off the rest of the data would have been absent or looked very different. Therefore, we can be sure it was pinned to maximum.

  93. TBill says:

    @Peter Norton
    No pics of the purported wing that was cut loose from the fishing net. This has been a “popular” news story out of Oz over couple months ago.

  94. DrB says:

    @Mick Gilbert,

    You said: “Any chance that lateral manoeuvring during a transmission causes the Doppler compensation to be run more frequently than would be the case for straight and level flight?

    I doubt the nominal Doppler frequency calculation is done at a variable rate, but the frequency steps certainly occur at a variable rate. Lateral maneuvering may be one of several possible explanations for the rapid steps observed at 18:40. There may also be a simpler cause.

    So far, the only model we have to explain the saw teeth in the measured BFOs is that the uplink frequency is quantized. It may be that this is not simply a quantization in the calculation of the pre-compensation of the predicted Doppler w.r.t. the nominal satellite location. Suppose the AES uplink frequency controller is ALWAYS quantized with about 5.3 Hz “steps”.

    In this model, the “least significant bit”, or LSB. of the 1646 MHz transmitter frequency is about 5.3 Hz. I also note that the 16 Hz adjustments of the frequency “offset” for 9M-MRO would be 3 bits at 5.3 Hz each.

    It is clear that the AES uplink frequency is digitally controlled by the SDU. Therefore, it must have a LSB of a few Hz. My guess is that it is not 1 Hz, but about 5 Hz. The GES at Perth measures the downlink received frequency with a 1 Hz resolution. However, there is no need for the LSB of the uplink frequency to be as small as 1 Hz. Considering the uncompensated Doppler shifts and the drift of the OCXO, 5 Hz is certainly adequate for proper system operation. Manufacturers don’t usually make their system more capable and more complex and more expensive than what is required to work well. I don’t see any benefit of having the SDU control the uplink frequency with 1 Hz resolution. 5 Hz will do just as well.

    Back to your question, the period of the steps tells us the slope of the SDU-calculated transmitter frequency (assuming we know the amplitude of the least significant frequency step). The more rapidly the steps occur, the higher is the slope of the predicted nominal Doppler that is being pre-compensated. That is the only variable term in the SDU calculation. Remember that the only frequency adjustments made in the SDU are the offset and the Doppler pre-compensation of horizontal speed. There are a number of other terms which affect the BFO, but they are either outside the knowledge in the SDU or purposefully ignored (such as aircraft vertical speed, which is a much smaller contributor to Doppler than is the horizontal speed).

    At 18:40 a standard turn from west to south takes about a minute and reduces the nominal Doppler by 594 Hz. That’s an average slope of 10 Hz/second, which is much too fast to match the 5.3 Hz / 3.0 seconds = 1.8 Hz/s based on the observed saw teeth at 18:40. With no turn, the nominal Doppler slope for a constant-speed west course is only -0.05 Hz/s. So, it seems that something was happening at 18:40 in the horizontal course which was not a constant speed westbound, because the BFO slope in this case is far too small. Neither was it a standard turn to the left (from west to south), because then the nominal Doppler slope is much too large. These bounds indicate the aircraft could make a maneuver which matches the nominal Doppler slope, but I don’t yet know for sure what it might be. Possibly a change in speed? The estimated nominal Doppler slope of -106 Hz/minute (the equivalent of -5.3 Hz in 3.0 seconds) observed in the BFOs between steps can be matched by a smooth deceleration from 480 kts ground speed to 415 kts in one minute while on a westbound course at a constant flight level.

    One flight model which can match both the 18:40 BFO values and the observed step period of 3.0 seconds is a 270 degree course, a linear deceleration from 480 kts GS to 415 kts GS and an ongoing descent with -1800 fpm rate. The predicted BFO, ignoring the quantized transmitter frequency, is steady at 87 Hz. Thus, it is possible to match the BFO data at 18:40, including the steps, by including the ground speed reduction with a straight course and a descent. Because the westerly course is nearly straight at the nominal sub-satellite point, the predicted BFO is insensitive to aircraft speed, and it is virtually the same at 480 kts or 415 kts. However, the slow-down is needed to also match the 3.0 second step period.

    There may be other combinations of maneuvers which match the 18:40 BFOs and steps. In my example solution, we can see that knowing the step period provides additional route information which is especially useful in discerning aircraft speed changes.

    @Niels,

    You said: “So, for the moment I tend to conclude that we are not looking at discretization events originating from the Doppler pre-compensation calculation.”

    Please propose an alternative theory.

    You also said: “Do you mean with a purpose, or as a “parasitic” side-effect of some process?

    As mentioned above, I think the quantization is in the 1646 MHz transmitter frequency. If this is the case, it is certainly purposeful and ever-present for all AES uplink transmissions.

  95. Victor Iannello says:

    @DrB said: Please propose an alternative theory.

    As I stated above, cyclic heating of the OCXO from a hysteretic controller.

  96. Niels says:

    @DrB, Victor
    We could check for a typical OCXO how stable the temperature is controlled and what, for a high quality quartz crystal, this means for frequency stability. I would expect they could do a bit better than 4 ppb for short time scales.
    Perhaps @alsm could help here?
    Also the saw tooth like pattern would be a bit difficult to understand for this case.

    Regarding the uplink frequency: I would think there is a base frequency (the 1.6 something GHz) which is based on multiplying the OCXO clock frequency (through a PLL multiplier?)and which is kept as stable as possible. Relative small shifts for channel select and Doppler pre-compensation are then probably added to the base frequency by mixing (multiplying harmonic signals). I hope again @alsm or others could help and provide more details?

    In general, to understand electronic system behavior and certain artefacts without knowing the circuit lay-out is tricky. There are so many options. Even knowing the circuit lay-out it can be sometimes be tricky to fully understand it..

  97. Victor Iannello says:

    @Niels: Just thinking out loud as what could cause the periodic shift in BFO. If a PID controller is used, the current controller for the heater would be inefficient unless it is PWM, which is of course possible. Maybe likely. But a PWM heater could introduce switching noise into the signal amplification and processing. An approximate saw tooth waveform would occur if the temperature ramp during heating was much higher than the temperature decrease rate when the heater was off.

  98. Niels says:

    @Victor
    PWM is possible and perhaps indeed a saw tooth waveform could be the result. But again I would think the frequency could be stabilized just a bit better then we see.
    I was thinking in the direction of the OCXO frequency multiplication: like a “slip” and relock of a multiplier.

  99. Peter Norton says:

    @Victor Iannello:
    Thanks for the correction concerning Rockwell. The question about Thales still stands though: Doesn’t Thales help with the search for MH370 by providing the IG with the required information about the SDU ?

  100. Peter Norton says:

    Victor Iannello says: « it would become harder to spoof the BFO with fake satellite inclination parameters so that a northern path has the BFO signature of a southern path, as the slope of the sawtooth would be different for a northern and southern path, even though the BFOs might be very similar. »

    @DrB:
    Have you (or Victor) been able to verify this or are you planning to do so ?
    It would be a big achievement and would help focusing the search if you could prove mathematically that a northern path is impossible because the sawtooth doesn’t match.

  101. Mick Gilbert says:

    @DrB

    Thank you for that, Bobby, much appreciated.

  102. airlandseaman says:

    @ALL: I spent a lot of time many years ago trying to track down the exact OCXO data sheet, but never did score. Don helped look for it, but nether of us found the exact data sheet. That said, I’ve had a lot of experience with TCXOs and OCXOs from several vendors over the decades. And I have some FCC type certification test data on the Thales OCXO (freq varied monotonically only 30Hz over -30 to +50C ambient).

    I am confident that the oven controller is an analog (probably PID; at least 2nd order) type controller (not an On-Off modulation or PWM). IOW, the heater is supplied with a continuous DC voltage, controlled by the loop. Therefore, there will be no jumps in the temperature or the frequency due to a “bang-bang” type controller. (Victor is right about PWM. I used bipolar PWM on Peltier thermal control systems for microwave radiometers. Huge noise generator.)

    Also, the electronics are sealed in a hermetic can, so moisture is not a factor.

    I’m not sure about this, but based on the measured L band frequency over the operating temperature range, the oven could be a double oven.

    The photos I have of the OCXO show that it has a massive heatsink to provide a very long thermal TC. A burst of hot air from an adjacent LRU would have no impact on the OCXO temp or frequency.

    I added a couple of files (see FCCID.io-1313881.pdf for more OCXO pics) in the Google Folder here: https://bit.ly/3It0OJx

    Good luck finding documentation:
    Honeywell Frequency Reference Oscillator (OCXO) Assembly 81771-MBE
    Honeywell Frequency Reference Oscillator Schematic 81771-WDME
    Racal part number 81771-MBE

    Finally, I suggest looking at the Rockwell Patent in the Google Folder. It goes into a lot of detail on how the uplink frequency is controlled to cancel Doppler during dynamic conditions (turns, etc.). Honeywell uses a different method, but they have to account for the same dynamic conditions.

  103. Victor Iannello says:

    @All: Today, somebody unsuccessfully attempted to reset the password to this blog site to gain access. The IP address of the attacker is 59.42.120.122, which corresponds to Guangzhou, China, although if a VPN was used, we can’t know the original location.

  104. DrB says:

    @Victor Iannello,

    The first 5 Hz step appears in the 18:40 data set in the interval between two BFO measurement only 0.2 seconds apart. That very narrow time window means the step can’t be produced by any real aircraft maneuver or thermal effect in the OCXO. It must be introduced by software, probably when a slowly varying calculated frequency value trips the next bit of transmitter frequency control, and there is a jump (step) of about 5 Hz.

    @Peter Norton,

    You said: “In my humble opinion it would be very exciting if you could show that the sawtooth differs for a northern and southern path and thereby proving with mathematics alone that only 1 of these 2 paths is possible – completely independently of the found debris which some claim was planted.”

    Unfortunately, no distance-based and Doppler-based data can discriminate between two “mirror image” routes (N and S) with a line of symmetry through the satellite. The ranges, the range rates (i.e., the Doppler shifts), and the second derivatives of the range (i.e., the slopes of the Doppler shifts) are identical, so one cannot tell them apart. In effect, there are always two route solutions to match BTOs and BFOs, as I mentioned recently. When the satellite is over the equator, a North route and a South route are both possible. That does not mean you can’t tell a North and a South route apart, but doing that requires more information than range and range rate. We have this for MH370 from take-off to 18:22 by means of ACARS and radar position reports. So, we know that any route after 18:22 must connect with the pre-18:22 route and be flyable. In UGIB (2020) we showed a feasible route which ended in the SIO. I do not think it is possible to establish a northern route satisfying all the BTOs and BFOs and which seamlessly connects to the pre-18:22 positions, but it’s almost impossible to “prove” this can’t be done. We also know that MH370 crashed in the SIO. Claims of planted MH370 debris seem preposterous to me, as do claims of spoofed Inmarsat data.

  105. Viking says:

    @airlandsman

    Thanks for an excellent description of the performance of the OCXO. Your temperature shift data agree with the official 0.3Hz/degree shifting which I used in my analysis. I do not mind a slightly higher number. That would go from good agreement to Bulls Eye.

    I also played with push-pull systems using Peltier elements. The oldest models were horrible, since they easily went into oscillation (therefore your huge noise). The first commercial one of good quality I met was launched in 1993. Good home built ones were developed around 1989.

  106. Viking says:

    @Victor Iannello

    Unusual with Guangzhou. Most of the official Chinese hackers are from Beijing or Shanghai. Probably it was through VPN or some amateurs. Guangzhou is a large town.

    Good you managed to stop it. Hacking is a large problem these days.

  107. Viking says:

    @All

    What would our best estimate for the temperature at 23:14 be? If we assume a specified operation range of 0-40 °C for the SDU, the temperature would have to be below minus 30 °C, since the stabilization also could not ‘lock’ intermittently after the pre-amplifier had supplied heat for close to a minute.

    Please note the importance of these two conclusions. They rule out any solution in the southern Indian Ocean, and they totally rule out an active pilot during the last 2 hours of the flight, since he would have died as the special oxygen supply in the cockpit ran out. In addition, temperatures below minus 30°C are hard to survive for prolonged time without special clothes.

    The security-video shows none of the pilots brought proper protection. Why does it rule out solutions in the south? The problem is that such solutions no longer fit the BFO values due to the 0.3Hz/°C correction for the SDU and the extremely low temperatures (at 11km height) at those latitudes, while the solution near Christmas Island fits well given the atmospheric temperature at 11km at that latitude.

    @airlandsman

    Did you make tests below minus 30 °C ?

  108. Tim says:

    @All, re cabin temperature.

    Assuming a decompression or open outflow valves the packs could still be on and trying to maintain cabin temperature, pumping in warm air. So the temperature at the SDU in the roof may not be that low.

  109. TBill says:

    @Viking
    Qualitatively working on many proposed flight paths, I do not see any problem with BTO/BFO data for the flight. I do think BFO may have drifted 3-4 units over the flight, but that would be normal drift for the quartz crystal.

    In the active pilot scenario, most likely cabin pressure was restored, perhaps with intermittent bleed air. I don’t know if air flow can be maintained and heated without bleed air, or with less bleed air.

    In any case, the data *looks* rock solid, poss with minor BFO drift. You have the burden of proof to demonstrate something is wrong and show a credible example.

  110. Brian Anderson says:

    Yesterday there was a serious incident with a Boeing 787 flying from Sydney to Auckland. Media in NZ and I think elsewhere in the world too, have been full of it all day.

    The aeroplane was flight LA800, LATAM Airlines, en-route from Sydney to Santiago, with a stopover in Auckland, on Monday 11 March.

    The media reports are very inconsistent. A sudden drop, sudden nose down, pilot reports all gauges going blank, [the unreliable] Geoffrey Thomas repots a sudden upwards movement before the “plunge”. The event lasted about 10 seconds, before the “pilots regained control”.

    About 50 passengers injured with some hospitalised on arrival in Auckland.

    Nothing untoward on FlightAware, or FlightRadar24, that I can see, but of course altitude reports in these apps will not be real time.

    The aeroplane is still in Auckland and the FDR is to be examined.

    It seems that turbulence is not the likely cause.

    It would be nice to get some accurate information.

  111. George G says:

    @Brian Anderson,

    We may have to wait for FDR and (hopefully) CDR analysis. ?

  112. Viking says:

    @TBill

    The slow drift of a few Hz is no problem.

  113. Viking says:

    @Brian Anderson

    I experienced a similar (fortunately much milder) event as we passed Iceland many years ago. As far as I remember it only injured one stewardes (twisted arm or something like that). Many passengers got the coffee thrown in their face.

    However there was a funny detail. Roughly 10 seconds before it happened, I said to the guy next to me that I could feel from the turbulence noise spectrum that something big was coming. Therefore we swallowed our coffee and grapped solid hold of the seat in front. After the event he was impressed – since he was an airline captain himself, and he had not expected it.

    Perhaps a warning system could be developed based on this observation? A few seconds warning could prevent many injuries.

  114. Viking says:

    @All

    In order to understand the complete picture we now have to take a step back and look at the two telephone-call-related data sets again. Apart from extremely different statistical BFO distributions, they actually look very similar. Both last close to one minute, and the time-distribution of data is similar. However, a closer inspection reveals some important differences. For the first data set at 18:40, two attempted phone calls came very fast after each other. To realize this, look at a plot of the first 10% of the time – some data points at 18:40 are practically occurring at the same delay-times as for 23:14, while some interleaving points appear. These additional points are the reason that there were significantly more BFO values at 18:40 than at 23:14 (almost twice as many).

    Now we must remember that each time a BFO value occurs, the SDU pre-amplifier sent out a powerful pulse burst to the HPA and from there via the antenna to the receiving satellite. This produces heat at the ‘heat-release end’ of the SDU box. Therefore, one would expect almost twice as high temperature-rise at 18:40 compared to 23:14. This is clearly not the case as can be seen from the amplifier-power (C/NO). There are similar drops in the power-output due to heating of the pre-amplifier itself. How is that possible? Well, the heat dissipates in two different ways from the pre-amplifier. Normally the dominant dissipation is through the airflow generated by fans in the box. However, this is reduced roughly a factor 3-4 due to reduced pressure (roughly same factor as the increase in the time-delay discussed above), but simultaneously increased slightly due to a larger temperature difference (remember the temperature inside the pre-amplifier is much higher than on its surface – so the total difference only increases slightly). The other way is through the chassis. This is more efficient at low temperature. In practice, it looks like the four contributions (including almost twice the thermal energy at 18:40) effectively canceled each other leaving the power-curves practically identical.

    A conspiracy theorist would probably ask if that was a coincidence or somebody planned everything carefully and told the telephone operator to call twice the first time (at 18:40) to make the data look similar the second time. We are not in favor of conspiracy theories, so therefore we choose to consider it a random event. However, a very unusual one because of the extremely short time (0.8 s) between the two attempts at 18:40. Just try with your mobile phone. If something goes wrong with getting a connection the first time, most people wait 4-8 seconds before trying again. For a fixed net telephone and/or high call-price typically longer. At 18:40, the operator waited less than one second.

  115. TBill says:

    @Victor
    I do not recall if we discussed this short YouTube here, I find it fascinating. It is the account from Butterworth of a USA military jet aircraft advisor when he got to work on 8-March-2014, the jets were surprisingly flying search missions for MH370 over the Malacca Straits, which the advisor did not understand why.

    Believe I may have inferred on Reddit that Malaysia obfuscated that they knew about the radar turnaround at IGARI, and somebody took issue with my wording, suggesting Malaysia did not know. Well, they looks like Malaysia had a strong idea.

    Personal account starts at 2-min mark, before that they are critiquing comedienne Jocelyn Chia.

    https://www.youtube.com/watch?v=xlJBS9yRVpU

  116. flatpack says:

    @Viking

    I think it possible that the second call attempt was actually automatically placed by the ground station in an effortt to improve QoS.

  117. Viking says:

    @TBill

    I have a vague memory that Kate Tee had seen these aircrafts too.

  118. Don Thompson says:

    Viking wrote ‘Now we must remember that each time a BFO value occurs, the SDU pre-amplifier sent out a powerful pulse burst to the HPA and from there via the antenna to the receiving satellite.

    That is quite wrong.

    The C-channels operate as SCPC, single carrier per channel (in each direction). The modulation and transmission of the C-channel carrier is continuous from approx 18:39:55 for the earlier call on channel 3730 and 23:14:00 for the later call on channel 3737 (until the minute long no-answer timeout exprires).

    C channel. Circuit-mode single channel per carrier (SCPC) channel, used in both to-aircraft and from aircraft directions. This channel is time division multiplexed to provide a primary channel for voice or data traffic and a sub-band channel for signalling, supervision and data messages. The use of the channel is controlled by assignment and release signalling at the start and end of each transaction.

    BFO is extracted by the GES channel unit, whether processing an ALOHA or TDMA burst (R or T-channel, resp) or SCPC, as each convolution block is processed. It’s perhaps a misnomer to prefix the SCPC FO with ‘Burst’.

    Regardless, to write ‘the SDU pre-amplifier sent out a powerful pulse burst to the HPA‘ is nonsense. The SDU of the MCS-6000 system doesn’t emit any ‘powerful’ pulse, it generates the IF signal to the RFU which, in turn, upconverts the IF signal to L-band before amplification by the HPA.

  119. Viking says:

    @Don Thompson

    From a system point of view you are probably right about the sequence. However, how do you explain the following details:

    1) The HPA needs a significant input power since its amplification (in dB) is limited to moderate values.

    2) How do you compensate for loss in various components, connectors and cables and still feed the HPA with sufficient power?

    3) How do you account for the significant drop in received power during the one minute duration?

  120. Don Thompson says:

    @TBill,

    Referring to your linked video, Gonky is indeed a former Navy F/A-18 International Instructor Pilot. After leaving the Navy, he flew with the Malaysian Air Force as a Boeing Instructor Pilot. (Per bio).

    His recollections don’t seem strong. However, his comment that aircraft were making search sorties from Butterworth the next day (Sat 8th March) shouldn’t be surprising. The clueless media throng gathered at KL were simply lost, unfamiliar with what they were dealing with, barely able to form one single cogent question.

    From my conversations with people with direct, first hand, involvement it was known to DCA early on the 8th that the turnback had occurred. I have no specific details about when playback of the military air defence radar occurred but DCA’s Area Control and the TUDM/RMAF Regional Air Defence Operations Centre (RADOC) were then co-located in the same building at Subang Airport. I cannot conceive that, following establishment of the RCC on the morning of 8th March, that the DCA Area Control staff and TUDM staff had not initiated some comparison of what their systems had surveilled overnight by accessing recordings.

    Indonesia began search sorties over the Str of Malacca using its unique B737-200 Surveiller aircraft, repositioned to Medan to conduct the sorties. It’s my hypothesis that Ms Tee’s story involved an encounter with an inquisitive Surveiller crew.

    In summary: the Malaysian authorities knew, on Saturday 8th, that the turnback had occurred. Continued search for possible debris in the SCS should not have been surprising: at that time, the turn back may have been considered a consequence of some event that caused debris to fall into the sea. The media throng in KL were unable to divert their attention to what was happening to the west, their reporting was behind the curve. The Malaysian authorities (DCA, MOT, etc) were slow to divulge what was happening, I’d assume that they were attempting to constrain their narrative to what could be attributed to verifiable ‘facts’.

    I’m not excusing anyone then involved but everything now known about that time has emerged in hindsight. Some choose to meld what later emerged with what was in the early days of the saga, errant speculation.

  121. Don Thompson says:

    Viking asked ‘3) How do you account for the significant drop in received power during the one minute duration?

    Because the AES and GES were negotiating optimal transmitted EIRP from the AES at 10 second intervals during the 1 minute period when channels 3730 and 3737 were active. Had the call been established, that repeated optimisation would have continued.

  122. sk999 says:

    R.E. timing on the morning of March 8, according to a press statement of May 1, 2014 from Hishammuddin Hussein, we have the following (all local time):

    7:24 Malaysia Airlines issued its first Media Statement.
    8:30 Review of playback of military radar data
    9:00 Air Force operations room notified
    10:30 Hussein notified, who then notified Razak.
    10:54 Military aircraft sent out.

    The possibility of an air turnback was announced by Hussein at a press conference at 11:30 am the next day.

  123. Don Thompson says:

    @sk999,

    Thank you for that detail. The habit of variously publishing ‘Press Statements’ via Facebook, or Twitter, or mot.gov.my made cataloguing difficult.

    In this case, it was Facebook

  124. Victor Iannello says:

    Don Thompson said: From my conversations with people with direct, first hand, involvement it was known to DCA early on the 8th that the turnback had occurred.

    I had a long conversation with the NTSB representative that was sent to Malaysia to help them analyze the radar data. According to him, the military and the DCA were at odds about where to conduct the search. The DCA favored the South China Sea, where MH370 dropped off SSR. The military favored the Malacca Strait, as their radar data suggested a turnback over the Malaysian peninsula. You might recall the Malaysian military officer who first said there was a turnback, and later retracted his statement and said there was only a possibility of a turnback.

    That same NTSB representative told me that the Indonesian military radar was not turned on. He reviewed the Indonesian radar data, and there were no targets. However, even known traffic was not captured. He thought the radar was turned off at night to save on diesel fuel.

  125. Victor Iannello says:

    @Viking said: The HPA needs a significant input power since its amplification (in dB) is limited to moderate values.

    There is nothing preventing the HPA from having several stages of amplification to achieve whatever gain is required. In fact, some versions of the HPA tout a gain of 60 dB, which means only tens of microwatts of input would be required for an output of tens of watts. I don’t think there would be any correlation between duty factor of the transmitter and the stability of the OCXO, which would be a very poor design.

  126. ventus45 says:

    @Victor

    That same NTSB representative told me that the Indonesian military radar was not turned on. He reviewed the Indonesian radar data, and there were no targets. However, even known traffic was not captured. He thought the radar was turned off at night to save on diesel fuel.

    1. Which Indonesian Radar’s did he get to see:
    (a) PSR’s or SSR’s or Both ?
    (b) Military or Civil or Both ?
    (c) Physical Locations of Radar Heads ?
    (d) Time period examined (start UTC / end UTC)

    2. Re turned off at night, was that generally known, presumed or suspected ‘around the traps’ (in aviation circles).

  127. sk999 says:

    To follow up, this website:

    https://says.com/my/news/malaysia-airlines-flight-mh370-missing

    has many of the early stories. Later on Sunday (Day 2) at 1:54 pm, it was announced that the search had expanded to west of Penanag.

    The story of the “Malaysian military officer” who allegedly retracted a previous statement r.e. the turnback can be found here:

    https://www.gmanetwork.com/news/topstories/world/352163/malaysia-air-force-denies-tracking-missing-jet-to-strait-of-malacca/story/

    It was Daud, and what he actually said was that he had never made any statement in the first place. [The newspaper Berita Harian apparently put words in his mouth.]

  128. Victor Iannello says:

    @ventus45: He was looking at the recordings of military radar data. I assume it was for the Indonesian Air Force’s Radar Unit 231 at Lhokseumawe in Aceh, Northern Sumatra. I can’t recall whether or not he specifically talked about this radar site. I didn’t ask him about the time interval, but I’m quite certain he reviewed the relevant time period.

  129. TBill says:

    @All
    Thank you for the discussion above. I am thinking three countries probably saw MH370 heading towards Andaman Sea, not including Indonesia. Most of my contacts seem to feel Indonesia only had secondary radar coverage that night.

    DonT good idea on what Kate Tee might have seen, and I assume the implication is, perhaps not the same night. Bottom line, right now we do not know of any eyewitness account that seems to actually be MH370.

  130. Viking says:

    @Victor Iannello

    You say that the HPA may have 60dB gain in multiple stages. That is in principle possible, but as far as I remember such a gain was not available at the time INMARSAT designed and installed the MH370 system. In addition, it would probably not have been a good design. The reason is that going through all the losses and then amplifying from very low power would give poor signal/noise performance, since amplifiers were far from ideal in those days. Finally, there might have been power consumption, reliability and security issues.

    For instance, the most powerful amplifier I used in 1990 had moderate gain (10-20dB), but several tens of W output. It contained a TWT amplifier, which needed kV input, and the voltage supply had the nickname the electric chair. I think that would not be safe on an airplane. Besides TWT’s are quite fragile in case of turbulence.

  131. Viking says:

    @370Location

    I sent you a couple of emails. Did you get them?

  132. Victor Iannello says:

    @Viking said: You say that the HPA may have 60dB gain in multiple stages. That is in principle possible, but as far as I remember such a gain was not available at the time INMARSAT designed and installed the MH370 system.

    Your memory may be mistaken.

    Mike found a document for the Honeywell SD-700 SDU which is dated February 2001. That model replaced the model of the SDU installed in 9M-MRO. However, the document describes a 40-Watt (continuous) HPA with the following characteristics:

    INPUT: 1626.5 MHz to 1660.5 MHz
    Gain: 60 dB ± 1 dB with 0 dB back-off attenuation
    OUTPUT: 1626.5 MHz to 1660.5 MHz

    The RF signals in the HPA pass through five stages of class A amplification followed by two stages of class AB amplification. The signals then are routed through an output power detector after which they exit the HPA. The HPA output is connected to the diplexer and antenna subsystem.

    I think any theory that hypothesizes that the drift of the OCXO is related to the heating from pre-amplification within the SDU is unlikely. The amplification for the SATCOM installed in 9M-MRO most likely occurs in the HPA, as it does for the SDU-700.

  133. Peter Norton says:

    @Victor Iannello said: “their radar data suggested a turnback over the Malaysian peninsula”

    “Suggested”? In my opinion it always was a clear-cut case for the Malaysian military. Their radar tracked MH370 before and after the loss of the transponder, including the U-turn at IGARI. Therefore they cannot say, they were not sure. This cannot be true.

  134. Peter Norton says:

    DrB says: « Unfortunately, no distance-based and Doppler-based data can discriminate between two “mirror image” routes (N and S) with a line of symmetry through the satellite. The ranges, the range rates (i.e., the Doppler shifts), and the second derivatives of the range (i.e., the slopes of the Doppler shifts) are identical, so one cannot tell them apart. In effect, there are always two route solutions to match BTOs and BFOs, as I mentioned recently. When the satellite is over the equator, a North route and a South route are both possible. »

    Yes, that’s what I thought.
    But doesn’t Victor’s statement disagree ?
    « the slope of the sawtooth would be different for a northern and southern path »

  135. Don Thompson says:

    @viking

    You do understand that the Inmarsat AMS(R)S operates (and has always operated) in the L-band? We’re not discussing Ka/Ku band aeronautical comms.

    That solid state power amplifier design had evolved, in the late 1980s, to operate effectively in L-band spectrum was a key enabler for the Inmarsat aeronautical satellite system.

  136. Victor Iannello says:

    @Peter Norton: I agree that any path that satisfies the BTO values between 19:41 and 00:11 would show a nearly constant BFO slope of -2.6 Hz/min, whether the plane went north or south. The aircraft to satellite range in that time interval is closely approximated by a parabola, and the second derivate (the concavity) is constant. The uplink Doppler is zero at around 19:36 and decreases by 2.6 Hz/min after that time. At the time of the call at 23:14, the uplink doppler is (-2.6)(218) = -567 Hz.

  137. ventus45 says:

    @Victor

    Are you seriously saying that he only saw one radar – Satrad 231 Lhok Semauwe (TRS 2215 R), and none of the others ?
    The ‘shutdown to save fuel’ may be plausible for Satrad 231, but not for the most critical ‘northern outpost, ie Satrad 233 Sabang (TRS 2215 D), which was often touted by Indonesian Authorities as ‘strong’, and it is the most critical one to examine for the 18:20 to 18:40 time period.
    Even Satrad 234 Sibolga (TRS 2215 D) may have seen something at extreme range.

    Is there any chance you could find and talk to that guy again, and get any more answers to my original questions of March 12, 2024 at 7:13 pm above ?

  138. Mick Gilbert says:

    @ventus45

    Overnight/weekend shut downs to save fuel would be more likely for Satrad 233 Sabang; most supplies, including diesel, have to barged over to Sabang from Banda Aceh.

    You will find that when it comes to the Indonesian military there’s is a fair gap between political rhetoric and practical capabilities.

  139. David says:

    @Brian Anderson, George G. Rumour has it that. “…. there may have been a problem with one of the pilot’s seats, in that the electrical adjustment motor unexpectedly moved the seat forward so that the pilot’s body impacted the control column, disconnected the A/P and forced the nose down.”

    That would be novel.

  140. Mick Gilbert says:

    @David

    Moving flight deck seats and inflight upsets are not entirely novel. There was the incident with Royal Air Force Voyager ZZ333 back on 9 February 2014, where the Captain’s camera, which was on the arm rest of his seat, jammed against his side-stick controller creating some interesting negative G experiences for the pax and crew. The PIC was court martialed for it.

    Mentour Pilot gives a very good account of it – https://youtu.be/Dl-Fl66Jfao

  141. Andrew says:

    @Mick Gilbert
    @David

    RE: “Moving flight deck seats and inflight upsets are not entirely novel.”

    In the RAF incident, the camera had been placed in the space immediately behind the side stick and in front of the armrest, such that when the Captain moved his seat forward, the armrest forced the camera into the side stick, with somewhat predictable results.

    I’d be surprised if forward movement of the seat alone would have caused the pilot’s body to “impact” the control column in the LATAM incident, unless he’s a VERY large man. The seat is designed to move all the way forward without touching the control column, even when it’s occupied by a pilot. That was certainly the case with the B777 and I doubt the B787 seats are any different. If forward movement of the seat was responsible, I suspect there was some contributory factor that has not been revealed.

  142. Victor Iannello says:

    @ventus45: He was talking to the Indonesian military officers that were responsible for the radar. I can’t be sure which sites he visited, but he was quite confident that there was no data because the relevant sites were not turned on.

  143. Tim says:

    @all,

    Wow, Starship seems to have slashed down near the 7th arc.

    I wonder if we can learn anything from the future debris drift .

  144. DrB says:

    @All,

    1. What if the amplitude of the saw teeth observed in the phone call BFOs is not a 5.0 Hz resolution in the SDU transmitter frequency control but rather quantization of the predicted nominal range rate to 1 m/s?
    2. The Doppler equivalent of 1 m/s range rate is 5.49 Hz at the band center frequency of 1.646 GHz.
    3. 1 Hz Doppler steps are the equivalent of 0.182 m/s range rate.
    4. What if the transmitter frequency quantization is in range rate, not in Cosine(Doppler Angle) or in transmitter frequency?
    5. Further suppose the resolution of the SDU transmitter frequency control is 1 Hz, which it must be not greater than, in order to create the observed inter-step slopes (and which don’t equal the actual Doppler slopes).
    6. The 1 Hz steps seen in the first part of the 18:40 BFOs can’t be due to the actual Doppler, because that slope is less than 3 Hz/min (or only one 1 Hz step every 20 seconds). Therefore these 1 Hz steps in BFO seen every 3/4 second must be in the transmitted frequency.
    7. The 18:40 BFO plot shows 1 Hz steps about every 3/4 second (i.e., we see four steps in 3 seconds, which is the period of the saw teeth).
    8. Maybe the BFO steps are actually 5.49 Hz in amplitude and correspond to exactly 1 m/s in range rate.
    9. Step amplitudes from 5.0 Hz to 5.5 Hz are acceptable fits to the phone call BFOs.
    10. Next suppose the calculated transmitted frequency is an integer with 1 Hz resolution.
    11. Further suppose the actual transmitter frequency reliably follows the value of the integer frequency command currently present in a register in the SDU.
    12. Further assume the adjustment of transmitter frequency is done asynchronously with a given transmission. Instead, the frequency is being continually adjusted “in the background”, at least every 0.75 seconds and perhaps more often, and is not synchronized with any message transmission.
    13. When a transmission is desired, the SDU simply transmits using the commanded frequency available in the register. So, it has 1 Hz resolution (but it also has 5 Hz steps).
    14. Further suppose there is an error in the prediction of the pre-compensation nominal Doppler shift, such that the calculated nominal BFO slope is in error (being too large by 5X).
    15. This calculation error creates an incorrect observed slope between the 5 Hz steps, but that error goes to zero at the beginning of each 5 Hz step.
    16. In particular, the observed BFO slope between the 5 Hz steps is equal to the “correct” actual Doppler slope plus an induced slope error.
    17. A non-accelerating route should have a very small slope in the observed BFOs between steps, typically about -3 Hz/minute at 04:29 and 23:14.
    18. The observed inter-step BFO slopes are -13.6 Hz/minute at 04:29 and -15.0 Hz/minute at 23:14.
    19. Most of the observed slope is probably caused by the SDU calculation error.
    20. Correcting the observed inter-step slopes for the calculation error gives -2.6 Hz/minute at 04:20 and -4.0 Hz/minute at 23:14 for the actual Doppler slopes.
    21. These actual Doppler slopes are consistent with straight and level flight at those times with no accelerations due to maneuvers (such as turns or speed changes).
    22. The next question is, what error in the SDU calculation of the nominal Doppler shift could produce the BFO inter-step slope error and yet not accumulate an error larger than the 5 Hz step size?
    23. Suppose each complete calculation of the predicted nominal range rate (perhaps done at regular time intervals) was rounded or truncated to 1 m/s. The equivalent Doppler shift of that resolution is 5.5 Hz.
    24. Next suppose that, until such time as the predicted and rounded nominal range rate toggles from its last value by 1 step (of 1 m/s, or by 5.49 Hz), the SDU simply predicts the change in range rate based on the elapsed time between the times of the two most recent “toggles” of the rounded/truncated range rate.
    25. So the SDU might do this:
    (1) Current Range Rate = Range Rate 1 + (Range Rate 1 – Range Rate 2)*(Time – T1) / (T1 – T2)
    where the most recently toggled value is Range Rate 1 at time T1, and
    the toggle before that was Range Rate 2 at time T2.
    26. This equation linearly projects the most recent range rate slope data until another toggle (i.e., a change in the rounded range rate) occurs.
    27. Note that Range Rate 1 and Range Rate 2 are rounded to the nearest m/s.
    28. The second term in the equation above is not rounded.
    29. As soon as either, the (a) rounded range rate computed from the aircraft data, or (b) the extrapolated value of the range rate, changes from the previously stored value (by at least 1 m/s), the projection error becomes zero because the current value from (a) is inserted directly in the register controlling the transmitter frequency. Note that the extrapolated range rate can also trigger the change from the old to the new values from Step (a), although almost all the time the values will be unchanged. That is, the extrapolation can trigger resetting the rounded frequency, but most of the time it gets reset to the prior value.
    30. Thus, the projection error cannot accumulate beyond a magnitude of 5 Hz. Every “toggle” of the compensation value reduces the extrapolation error to nearly zero.
    31. This model produces the non-accumulating error feature we observe.
    32. Next, what about the inter-step slope error (which is the range rate slope error in the extrapolation equation?
    33. This model accounts for the 1 Hz steps seen between the 5 Hz steps, because the transmitter frequency control has 1 Hz resolution. Furthermore, I assume the calculation of the time-projection of the range rate is done to much greater precision than 1 m/s, using floating point arithmetic.
    34. The commanded transmitter frequency, updated at least every 0.75 seconds, has 1 Hz resolution:
    (2) Transmitter frequency = INTEGER[ (1.646E9/3E8)* Current Range Rate ]
    where the Current Range Rate is a floating point number.
    35. Suppose there was a 5X scale factor error in the second term of the range rate Equation (1). Such an error would mean the second term would have a large slope error, because the slope would be 5X greater than desired.
    36. For the two phone calls at 04:29 and 23:14, the nominal range rates are both decreasing with time. So, in those cases Range Rate 1 will be less than Range Rate 2.
    37. Thus, with a scale-factor error, but no sign error, we should see the Transmitter Frequency decreasing with time between the 5 Hz steps, and that is what we observe. So, the data for those two calls are consistent with a scalar error, and not a sign error.
    38. Next, what about the 18:40 phone call? The nominal range rate here is also decreasing, but at a much higher acceleration than for the other calls. Note the much larger inter-step BFO slope of -96 Hz/minute measured at 18:40. In level flight with no maneuvers, the 18:40 Doppler is slowly decreasing with time at about -3 Hz/minute (and is not very different from the other two calls). At 18:40 some maneuver is apparently occurring during the call, and the combination of the maneuver and the slope error produces an observed -96 Hz/minute BFO slope.
    39. Next consider the ratio of the observed slope to the predicted slope: At 18:40 we have -13.6 / -2.6 = 5.2X. At 23:14 we have -15.0 / -3.0 = 5.0 X. So, two of the phone calls, where we know or suspect there were no ongoing maneuvers, the impressed slope is 5X larger than the correct slope.
    40. At 18:40, taking the measured slope of -96 H/minute and dividing by the same factor of 5 scale error gives -19.2 Hz/min for what would have been measured if the slope scale factor error is also 5X at that time. Since the expected BFO slope at 18:40 with no accelerations is -3.0 Hz/minute, the additional slope of -19.2 – (-3) = -16.2 Hz/minute is probably real and due to a maneuver. I find that a modest slow-down from 480 KGS to 470 KGS over one minute at 18:40 is sufficient to match this slope.
    41. Perhaps the coding of Equation (1) somehow had an extra factor of 5 inserted (or more likely 5.49?).
    42. Suppose instead of the term in Equation (1) of (Range Rate 1 – Range Rate 2) with units of m/s the software coder used (Doppler 1 – Doppler 2) with units of Hz. That would make the slope 5.49X too large, and this 5.49X is also consistent with all three sets of BFO measurements.
    43. In summary, I have described a reasonable model for how the SDU might control the transmitter frequency which fully explains five observables: (a) the smallest observed frequency step is 1 Hz, (b) 5 Hz steps are impressed on the measured BFOs, (c) the 5 Hz steps appear much more frequently than expected, and (d) in between the 5 Hz steps the slope of the BFOs is 5X higher than expected, and (e) the errors don’t accumulate to more than 5 Hz.
    44. To summarize, rounding of the range rate to 1 m/s precision produces the 5.49 Hz steps in transmitter frequency and in BFOs.
    45. A coding error which uses the change in predicted Doppler shift rather than the predicted change in range rate causes the inter-step slopes of the pre-compensation Doppler to be 5.49X larger than the correct values. It is possible to correct this error post-mission.
    46. There is no evidence of any ongoing climb, turn, or speed change occurring at 23:14 during MH370 or at 04:29 during MH371.
    47. There is evidence for a slight slow-down of 10 knots / minute during the descent at 18:40.

  145. Victor Iannello says:

    @DrB said: 20. Correcting the observed inter-step slopes for the calculation error gives -2.6 Hz/minute at 04:20 and -4.0 Hz/minute at 23:14 for the actual Doppler slopes.

    The uplink Doppler shift rate, calculated directly from the satellite-aircraft range fit from the BTO data, predicts -2.6 Hz/min after 19:41. Do you have the values reversed?

  146. Peter Norton says:

    @DrB
    @Victor Iannello

    My apologies for being confused now. I’d be most obliged if you could help me understand:

    I always thought the BFO data conclusively tells us MH370 went south (on condition the BFO data was not spoofed – in which case a mirror northern route is possible).

    However @DrB’s comment seems to say the opposite, namely that the BTO and BFO data isn’t enough to distinguish between a northern and southern route:

    « Unfortunately, no distance-based and Doppler-based data can discriminate between two “mirror image” routes (N and S) with a line of symmetry through the satellite. The ranges, the range rates (i.e., the Doppler shifts), and the second derivatives of the range (i.e., the slopes of the Doppler shifts) are identical, so one cannot tell them apart. In effect, there are always two route solutions to match BTOs and BFOs, as I mentioned recently. When the satellite is over the equator, a North route and a South route are both possible. »

    These two assertions seemingly contradict each other, no ?
    What I am misunderstanding here ?

    And contrary to @DrB’s assertion above that “a North route and a South route are both possible”, he seems to have found a completely new way to distinguish between a northern and a southern path as @Victor wrote here:

    « @DrB: That is VERY clever! […] I really doubt anybody has considered this before. So with that in mind, it would become harder to spoof the BFO with fake satellite inclination parameters so that a northern path has the BFO signature of a southern path, as the slope of the sawtooth would be different for a northern and southern path, even though the BFOs might be very similar. »

    I took this as saying that you have found a completely new tell-tale sign that would give away a spoofing of the BFO data: The sawtooth would be different for a northern and southern path.

    If I understand this correctly, you can now say conclusively that MH370 must have gone south because
    (a) the BFO data matches a southern route much closer than a northern route (see chart above) and
    (b) the BFO data can’t have been spoofed, because the slope of the sawtooth would be different for a northern path.

    Is that correct ?

    As I said before, if this is true, it would be a major break-through to eliminate the entire Northern hemisphere without a shadow of a doubt. Eliminating a northern path would help focusing the search efforts in the South (whereas currently there still are weekly podcast episodes promoting a Northern path). I must admit that I always found and still find Jeff Wise’s theories intriguing, but if the slope of the sawtooth would be different for a northern path, that would sound the death knell for all northern path theories, no ?

  147. DrB says:

    @Victor,

    The numbers you quoted are the saw teeth slopes divided by 5.5. There is a second component on the slope due to the overall “tilt” of the sawtooth. To get the total BFO slope, you have to add tilt to the sawtooth slope / 5.5. I have done that as explained below.

    The slope of the range rate is calculated to be equivalent to -1.7 Hz/min at 04:29 (using the ACARS route data), and -2.7 Hz/min at 23:14 (using the UGIB route). Note these range rate slopes have nothing to do with BFOs.

    I also fitted the actual slopes of the BFOs, and correcting for the SDU calculation error and including the overall sawtooth tilt, the total range rate slope based on BFOs is estimated to be 0.0 Hz/min at 04:29 and -1.7 Hz/min at 23:14.

    The differences between the two methods indicate the typical error in retrieving range accelerations from BFO slopes. Therefore, the typical error in estimating the range rate slope from a few cycles of BFO saw teeth appears to be 1-2 Hz/min. This retrieved BFO slope uncertainty puts an upper limit on the detectable maneuvers (i.e., accelerations) that might be ongoing during a phone call.

  148. DrB says:

    @All,

    1. The Inmarsat GES in Perth measures the received frequencies (the BFs) from the SDU with 1 Hz resolution. That means there is never a measured BFO step of less than 1 Hz, even if the transmitter had its frequency controlled in steps smaller than 1 Hz. So, there is no benefit to make the SDU transmitter frequency resolution less than 1 Hz.
    2. When the aircraft is at the gate, its velocity is zero, and the pre-compensation Doppler shift is zero and won’t change. It should never toggle. There should be no 5 Hz BFO steps at the gate.
    3. Therefore, the BFO offset is accurately determined using the gate data. It is not corrupted by the SDU error, and there is no bias error to correct.
    4. Whenever the aircraft is moving, the pre-compensation frequency will vary, and the 5.5 Hz steps will occur. That means that there are times when the transmitted uplink frequency is in error by 5.5 Hz, and there are times when the error is zero.
    5. Therefore, so long as the slope of the nominal calculated range rate does not change sign, BFO errors between 0 and -5.5 Hz occur when the nominal range acceleration is negative. The RMS error is 5.5 Hz / SQRT(12) = 1.6 Hz. The mean error is -2.75 Hz.
    6. Similarly, BFO errors between 0 and +5.5 Hz will occur when the nominal range acceleration is positive.
    7. The BFO read noise is estimated by analyzing the residuals after fitting a saw tooth waveform to each BFO phone call data set. Their RMS values are 0.7 to 0.9 Hz. Thus, the typical BFO read noise is about 0.8 Hz RMS.
    8. It is clear that the BFO probability density function is dominated in flight by the SDU coding error because its RMS error (1.6 Hz) is twice the read noise (0.8 Hz).
    9. It is also important to understand that, when the aircraft is moving, the expected BFO value is biased by the SDU coding error. In fact, that bias is +/- 5.5 Hz / 2 = +/- 2.75 Hz, assuming random transmission times. When the nominal range acceleration (i.e., the nominal Doppler slope) is negative, the average of many BFO readings will be 2.75 Hz less than the “true” value.
    10. When the nominal range acceleration is positive, the BFO bias is +2.75 Hz, and the average of many BFO readings will be 2.75 Hz higher than the “true” value.
    11. These findings allow one to statistically compensate the measured BFOs (to remove the BFO bias caused by the SDU coding error) with a fairly high degree of reliability if the route is sufficiently well determined at a given time that there is no doubt about the sign of the nominal range acceleration.
    12. One can in principle remove this BFO bias error and then re-fit route parameters, for instance, from 19:41:03 until 00:11:00. For this portion of the MH370 route, the range acceleration is always negative for fixed lateral navigation modes, and the ‘corrections” to be applied to the existing BFO values are to simply add 2.75 Hz to the BFOs from 19:41 through 00:11.
    13. The sign of the nominal range acceleration after 00:11 is not highly certain because the aircraft may have slowed down upon first engine flame-out (circa 00:11), and course changes almost certainly occurred after 00:17:30.
    14. It is not possible to correct all the BFOs individually, because we don’t know exactly when the BFO measurement occurred during the sawtooth cycle. We can only apply a statistical correction for the bias in the expected value. We also can’t remove the 1.6 Hz RMS BFO noise introduced by the SDU error.
    15. My explanation of this major component of BFO noise finally makes understandable Inmarsat’s empirical criterion that the magnitude of the BFO error could be up to 7 Hz even when the route was well known. You can get up to +/- 5.5 Hz of BFO error from the SDU coding error, and then you have about a +/-1.6 Hz additional read noise (at 2 sigmas), making +/- 5.5 +/- 1.6 = +/- 7.1 Hz errors possible for a single isolated BFO even with accurate knowledge of all aircraft data.

  149. DrB says:

    @Peter Norton,

    With a stationary satellite above the equator, it is impossible to distinguish between “mirror-image” routes N and S of the equator based on BTO (range) and BFO (range rate) measurements.

    My new analysis technique for phone-call BFOs allows us to independently determine the second time derivative of range (i.e., the range acceleration, AKA range rate slope and AKA BFO slope) at several points along the route.

    I never said one could distinguish N and S MH370 routes from the Inmarsat data by any means, new or old, because I know you can’t with a stationary satellite. The two routes can have the same ranges at the same times (producing equal BTOs), the same range rates at the same times (producing equal BFOs), and the same range rate slopes (producing the same sawtooth BFO slopes). The latter won’t have different signs for the BFO slopes of N and S mirror routes.

    You can tell the aircraft went south by when and where crash debris were found in the Indian Ocean.

    A second indicator of a southbound route was the sighting by Kate Tee.

    A third indicator comes about because of the inclination of the satellite. It has a motion toward and away from the equator, so it has a N-S velocity component that induces a Doppler shift toward the aircraft which is asymmetric for N and S routes. The Z-dot speed of Inmarsat F-1 is -1.5 m/s at 19:40 and 81.9 m/s at 24:10. So these satellite speeds parallel to the Earth’s axis are sufficiently large to create a measurable difference in the BFOs for N and S mirror routes, especially late in the flight. More or less, the satellite is moving south at a good clip at 00:10 and reduces the net Doppler to a southbound aircraft in the southern hemisphere, but it increases the net Doppler to a northbound aircraft in the northern hemisphere. This difference in BFOs will be distinguishable in the fitted route parameters because it is on the order of a 100 Hz difference in the required aircraft-to-satellite Doppler to match the BFO values. What that implies is that you can’t fit the MH370 data set by simply changing all the S latitudes to N latitudes. The symmetry is broken, so the mirror image of the southbound route can’t fit the same BFOs. However, that does not prove there is not a reasonable fit for a northbound route which is different from the best-fit southbound route. I have not tried to fit any northbound routes, so I don’t know whether or not this is possible.

    What the BFOs told us early on was that the aircraft was initially flying toward the satellite, and then it flew away from it. That it headed S when flying away from the satellite was an early assumption, not a conclusion.

    If you want evidence, independent of debris reports and visual sightings, that the aircraft flew south rather than north, my third point above about the satellite velocity destroying the BFO symmetry is a solid argument, but modeling northbound routes to look for the absence of any reasonable route fit would need to be done to make that case solid. In other words, you still have to demonstrate that there is no flyable northbound route that reasonably fits the 19:41 to 00:11 data.

  150. DrB says:

    @All,

    There is a typo in my 1:06 message above: The F1 Z-dot speed at 24:10 should be -81.9 m/s, not (+)81.9. It is moving “southward” at a significant speed.

  151. Niels says:

    @DrB
    Regarding your 7:33 pm post: Interesting thoughts.
    Looking at eq. 5.9 in the DSTG book: f/c = 5.49 m-1
    Which is multiplied by the whole vector thing (the nominal range rate [m/s]) which you suggest might have some strange error pattern with an amplitude max. 1 m/s.
    I’m wondering how the denominator is calculated (below the vector inner product) in eq. 5.9. And how the numerator and denominator are represented as numbers. If that is indeed how it was done. Is there perhaps a binary long division involved with limited precision and some rest term which accounts for the inter-step slopes?
    But for any “model” to explain the saw teeth: how to prove it is correct with the little data we have?

  152. Don Thompson says:

    @DrB wrote ‘36. For the two phone calls at 04:29 and 23:14, the nominal range rates are both decreasing with time. So, in those cases Range Rate 1 will be less than Range Rate 2.

    04:29? The Stratos Log, showing the record of SATCOM traffic with 9M-MRO as it operated the MH371 and MH370 services does not show a SATVOICE call at 04:29. Did you mean to write 18:39?

    In very simple terms, you are hypothesising a 5Hz ‘box’ imposed by the SDU’s doppler pre-comp while the GES channel units discriminate in 1Hz steps?

  153. Viking says:

    @All

    I am sorry for being absent yesterday. I had some sheduled work to do. I will try to catch up today.

  154. Viking says:

    @Don Thompson

    You are completely correct about the development of semiconductor-based amplifiers in the late 1980-ies. That is also the reason that I used examples of what was available in 1990. After 1990, a couple of things happened, partly due to the fall of the Berlin wall. Initially we found out that Russia had developed competing (but cheaper) technology based on radio-tubes, produced in Ukraine. Around 1992 Ukraine started exporting it (against the laws of Russia as far as I know). However, further development of western semiconductor technology outcompeted the tubes relatively fast. The 2001 model is certainly based on this more recent development.

    @Victor Iannello

    For the reasons described above, I am quite sure the older model of HPA in MH370 had less impressive specifications, and possibly a couple of weaknesses. Therefore, the SDU may have needed a pre-amplifier anyway.

    More importantly, the temperature stabilization in the older model was almost certainly only using reading from one point, most likely at the last (most power consuming and hottest) stage. If both temperature and pressure fell, this causes temperature gradients, so things like gain-equalizers and the first amplifier stages got relatively cold, while the temperature of the last stage remained constant.

    I am not saying temperature gradients change the frequency (stochastic realization shifts will be near zero by symmetry, since the SDU frequency was near the middle of the amplification band), but the output power is likely to increase (as observed, – and as I will discuss later).

  155. Viking says:

    @Victor Iannello

    Concerning the frequency performance of the SDU during the 23:14 phone call, I am still convinced it was predominantly due to thermal effects. If they did not originate in the presence of a pre-amplifier, they may well have come from increased power consumption in the electronics during the phone call, e.g. from GPS-correction related calculations. I had problems with that kind of crosstalk during experiments in 1992.

  156. DrB says:

    @Don Thompson,

    During MH371 cruise, between 04:29:15.419 and 04:30:15.413 UTC, there were 132 BFO measurements. I assumed they were during a 60 second satellite phone call. These are plotted in Figure F-4 in UGIB (2020).

    You asked: “In very simple terms, you are hypothesising a 5Hz ‘box’ imposed by the SDU’s doppler pre-comp while the GES channel units discriminate in 1Hz steps?

    In simple terms, yes. The SDU is artificially “dithering” the transmitter frequency in a way which is not generally recoverable. In some cases, and with additional knowledge of the route, we can figure out whether the “box” is above or below the correct frequency.

  157. TBill says:

    @DrB
    I would put simulator flight south considerably over any unsubstantiated eyewitness sighting.

    Peter’s need for flight south verification I am afraid mirrors even the most bright NoK. They are hearing a barrage of conspiracy theories which are attractive vs. the apparent truth.

  158. DrB says:

    @Niels,

    You asked: “I’m wondering how the denominator is calculated (below the vector inner product) in eq. 5.9. . . . .”

    I don’t know how the calculation is done in the SDU. It may be done differently than what DSTG did. The equations do not matter. What matters is that the nominal uplink range rate is quantized (converted to an integer) with 1 m/s resolution. That’s what creates steps of 5.5 Hz in the transmitted frequency.

    You also asked: “But for any “model” to explain the saw teeth: how to prove it is correct with the little data we have?”

    My theory of what is occurring in the SDU explains all the strange observable behaviors, which I previously listed. It matches the MH371 and MH370 phone call BFOs within 0.8 Hz RMS.

    To judge for yourself, I have prepared figures showing the saw teeth fitted to BFOs in three phone calls. You can get it here.

  159. Viking says:

    @All

    If we assume the unusual statistical BFO distribution at 23:14 is due to thermal effects, we are now ready to handle the entire BFO data set. At some time after 18:40 but long time (at least two hours) before 23:14, somebody must have opened a door or big hatch causing pressure-loss and temperature drop. Why would somebody do so? If the purpose was suicide it would have been infinitely more easy and convenient to just let the air out of the plane through a valve while leaving the heating on, passing out and die peacefully from shortage of oxygen. Therefore, we can only come up with one reason to open a door or hatch – the person wanted to attempt parachuting out of the airplane.

    Where could that have happened? The only realistic place is over Bandar Aceh where there was plenty of streetlight and relatively flat ground to land on. This is exactly where Kate Tee observed a large airplane diving down to low height, and flying slowly. She even concluded that it looked like someone was going to jump out or emergency-land in Aceh. With the airport closed and the route passing perpendicular to the landing strip, this is ruling out the second option. Therefore, attempted parachute jump is the only option. This is consistent with the airplane flying low and slow with an open door over Bandar Aceh, and then returning to previous normal speed and height under pre-programmed autopilot control with the open door soon after passing a waypoint.

    We only need to know the flying height and the thermal time-constant of the airplane to make a good estimate of the temperature (and pressure) as a function of time if it had an open door and continued towards Christmas Island. That is what we did in version III of our paper, and obtained good agreement with all BFO values and more importantly with the received power at the satellite (which nobody else have explained properly). Remember here that most microwave amplifiers of the relevant generation have an output power dependence on temperature around -0.05dB/°C, so a 20°C drop in temperature increases the power roughly 1dB. This explains the majority of the odd increase in received power with increasing distance to the satellite.

    If you insert the pressure at 11 km height, it corresponds to a factor 4 on the time-constant, which is within the range 3-4 found from the BFO values at 23:14. Please remember the reference is a normally working pressure cabin at 18:40 and not conditions at sea level. Therefore, 11 km flying height at 23:14 is a good match.

    As a final remark on the BFO errors, it is now possible to use an uncertainty of 4 Hz (as most people prefer based on previous BFO statistics, see e.g. the Holland paper) and still have excellent agreement. However, this only goes for the solution near Christmas Island. For the ‘consensus’ solution in the south things do not fit any longer, even with 7 or 16 Hz error. Basically this means that the data from the attempted phone calls rule out the ‘consensus’ solution entirely, and explains why the wreckage has never been found.

  160. DrB says:

    @All,

    We don’t know if the SDU truncates or rounds the range rate to 1 m/s resolution. If it truncates the range rates, then one has to add 2.5 Hz to the BFOs from 19:41 to 00:11 because those data are biased low by ½ m/s.

    If the SDU rounds the range rate value, then there is no bias in the BFOs, just additional “noise”. In that case, no offset adjustments are needed to the MH370 BFOs for the previous southbound route fits.

  161. Niels says:

    @DrB
    I hope I understood your method correctly: I checked the second derivative of the range vs. t around 23:14 but to change the range rate by 1 m/s I would need about 188 s, which is about 10 times longer than we observe based on the step period. Now this is based on the real range function and the satellite is also accelerating -> I’ll try to construct the range function vs. stationary sat. position.

  162. DrB says:

    @Niels,

    The range rate slope at 23:14 using the UGIB (2020) route is -2.70 Hz/min for the nominal satellite location and -2.53 Hz/min for the actual satellite. So, for the SDU to calculate a change of 1 m/s (equivalent to 5.5 Hz) in the nominal range rate should require 122 seconds. The period of the sawtooth fitted to the BFOs is 22.15 seconds, which is about 5.5X more often than expected.

    The sawtooth inter-step BFO slope at 23:14 is one -5.5 Hz step amplitude per sawtooth period of 22.15 seconds, or -14.90 Hz/minute, if the overall tilt of the sawtooth is constrained to be zero. Because we have only about 3 cycles, the overall tilt is not well determined. Therefore, it is better to constrain it to be zero and allow the period to vary to find the best overall slope measurement. That measured slope is exaggerated by the SDU error by a factor of 5.5X, so we predict an actual change in the nominal BFO 5.5X smaller, or -2.71 Hz/min. This agrees closely with the -2.70 Hz/min of the UGIB route.

  163. airlandseaman says:

    Viking: I see Don and Victor have already answered the question about the HPA gain and drive requirement. The HPA gain is digitally controlled (power agile). The nominal RF output (1645 MHz) from the seven combined channels in the SDU is nominally +15 dBm (31.6 mW). Therefore, there is nothing inside the SDU that could cause a “Key Down” thermal effect on the OCXO.

  164. Don Thompson says:

    DrB wrote ‘During MH371 cruise, between 04:29:15.419 and 04:30:15.413 UTC, there were 132 BFO measurements. I assumed they were during a 60 second satellite phone call.

    In the air-to-ground direction, during the period stated above, the aircraft transmitted a sequence of T-channel bursts that carried the 30min periodic FMS progress reports comprising four ACARS blocks destined for MAS OCC.

    The T-ch speed and modulation was 1200bps, B-PSK. I believe you have double counted the number of independent BFO measurements concerned with those 8 separate T-ch bursts.

    During the MH371 service all half-hourly FMS progress reports were received as expected whereas only one during the MH370 service.

  165. DrB says:

    @Don Thompson,

    For that MH371 data, I observe that BTO and BFO values can change when two adjacent events have time differences of at least 0.16 seconds. These look to be independent. Some elapsed times are only 0.04 seconds, and in those cases the BTOs and BFOs don’t seem to change, so these pairs of events may have redundant BTOs and BFOs.

    Using all the data, including some redundant events, has no material effect on my analysis.

  166. Brian Anderson says:

    @DrB
    There are two points of interest that have always intrigued me as to the possibility of calibrating a particular hypothesis. One is the fact that the satellite is virtually stationary at about 19:41 [actually I think it is closer to 19:36], and the other is that it is very likely that the aircraft was flying tangentially to the satellite at about 19:52.
    In the first case the satellite contribution to the BFO [Doppler] ought to be zero, and in the second case the contribution of the aircraft to the BFO [Doppler] ought to be zero.
    Are these two points able to be used, even if a little interpolation of the BFO is necessary, since there is only one observation at 19.41, to help verify your hypothesis, or indeed to help establish the aircraft track at 19:41.

  167. Don Thompson says:

    @DrB

    For the T-channel traffic, in the period 04:29:15.419 and 04:30:15.413 UTC, there were 8 bursts. That means 8 independent BTO measurements. The deconvolution, FEC decoding, and descrambling involves sequential pairs of SUs, hence the a single BFO extracted for the pair of SUs and reported for the log entries of two SUs.

    During that same period there are 8 R-channel bursts, from which independent BTO and BFO measurements are derived.

    So, (8×8)+8 = 72 independent BFO measurements.

    While I do agree that this analysis isn’t materially affected, I suggest it’s best to properly describe the observed events.

  168. David says:

    @All. Former Qantas pilot Mike Glynn, with Andrew Banks’s assistance, has drawn a direct connection between the southern Indian Ocean points recorded on 2nd Feb 2014 on Captain Zaharie’s home simulator and a plan by him to divert the 4th Feb 2014 flight he piloted to Jeddah, Saudi Arabia to the southern Indian Ocean.

    That was about five weeks before MH370’s.

    He suggests a possible reason for Zaharie not utilising that Jeddah flight with this aim was that a third pilot would be needed for that, as has been raised here.

    That plan envisaged turning off the track to Jeddah at 10 deg N towards the US base at McMurdo Sound, Antarctica.

    After fuel exhaustion it foreshadowed a long glide then a final dive from 4000ft.

    For those that can access The Australian it is here:
    https://www.theaustralian.com.au/inquirer/secret-flight-path-of-mh370-captain-zaharie-shah/news-story/011d30d8539a87b7639e74f324a4a339

    Its title is, ‘Is this the smoking gun? Sinister details fuel MH370 captain focus’
    then; ‘A Qantas pilot’s take on the chilling scenario suggested by independent research into Zaharie Shah’s home simulator.’ By Mike Glynn

    It is an extract from a book by him, to be published shortly: ‘MH370: Answers From a Pilot.’

    While I have copied it I gather that copyright extends to newspaper articles in Australia so am unwilling to post that, though I will send @VictorI a copy in case he can get around that issue.

    Perhaps Mike Glynn or @Andrew might be able to help.

    In providing an explanation as to what the purpose was of this simulation clearly his article’s interpretation is telling.

    While the two points in the simulator suggest there was high speed between them, his planned flight to Jeddah did foresee a 90 miles glide after MEFE. Thus while the fuel for the MH370 flight was less, if a parallel that would have concluded with a long glide too.

    A steep descent after MEFE or a long glide? Just the steep descent would be consistent with the final log on request BFOs, though both with a final dive from 4000ft.

    Either way the simulation points to the likelihood that MH370 was piloted to the end and by whom.

  169. Niels says:

    @DrB
    After recalculating the second derivative in another way I get much closer to your 122 s for the step period at 23:14 so that looks fine.
    I would prefer if the factor 5.5 could be explained better though (than through a coding error, point 42 from your 7:33 pm March 14th posting)

  170. Niels says:

    @Brian Anderson
    When I derive the sat-ac distance r from BTO measurements and then interpolate with a third order polynomial I get the function r(t), which has a minimum (dr/dt = 0) around 19:55:30 in my calculations. Is that how you approx. came to the estimated 19:52?
    A follow up question there: It seems to me the latitude for flying tangential would depend on the track; did you derive the relation between the latitude and track in your analysis?
    I’m currently analyzing 20 million randomly generated paths, and I could check how the distribution for LEP changes if I add this possible relation between track and latitude at 19:55:30 (of course with some error margin).

  171. Mick Gilbert says:

    @David

    I’m more than happy for Mike to clarify on this point but it appears that the “range ring” from 10N is based on an estimate of remaining fuel plus glide if you apply a “typical” fuel load for MH150, rather than the actual fuel at 10N of 62,700 kg per the simulation data point.

    Probably also worth noting at least few other points. In the recovered sim session:

    1. from 10N, the simulation aircraft was almost certainly flown south-east, back towards Banda Aceh rather than south towards 45S1.

    2. from 10N, the fuel jettison function was almost certainly used, resulting in fuel exhaustion somewhere off the west coast of Sumatra.

    3. it was only after fuel exhaustion had occurred, and the simulation aircraft had been in a brief unpowered descent, that it was manually relocated down to 45S1.

  172. Victor Iannello says:

    Deep Sea Vision wants to search for MH370. 60 Minutes Australia interview with DSV’s Tony Romeo on Sunday.

    https://twitter.com/60Mins/status/1768774174984597598

    PS DSV is talking to some of us.

  173. Viking says:

    @Brian Anderson and @Niels

    It is an interesting subject you are bringing up. One that I had actually planned to postpone until later. Near 19:41 there is a significant degree of correlation between the flight route of MH370 and the ‘Eigen-movement’ (sorry for using a German-inspired word from quantum mechanics, but the meaning becomes clear below) of the satellite near its most northern extremum. The exact values on a minute timescale depend on which of two possible intrepretations you use:

    1) Simple version (anti-correlation): The route soon after 19:41 had a slight (and smooth) change of heading (a few degrees). The resulting scenario sends MH370 to the ‘consensus’ solution in the Southern Indian Ocean.

    2) Complicated version (correlation): The route soon after 19:41 contained almost a U-turn (180 degrees minus roughly the same few degrees). The resulting scenario sends MH370 towards Christmas Island.

    Because of the correlation/anticorrelation issue it is almost impossible to decide which of the two is correct (like in quantum mechanics). My figure 2 is probably the only way – at least the only one I could come up with, – and it points to the U-turn.

    If you look at the presumed Jeddah simulation on February 2, there is an anti-correlation with the Eigen-movement of the satellite (near its most southern extremum). In other words Shah chose the simple solution there. Perhaps he left that simulation to be found and mislead the investigators? That would also explain why he turned the SDU back on (a mystery for many investigators).

    This thought has kept giving me the creeps for 10 years for the following reason: Exactly two years before Shah’s Jeddah simulation I gave the following presentation at a conference in Sydney Australia:

    ’Generating and Sensing Signals for Quantum Cryptography using Phase Encoding in Compact Silica-on-Silicon Mach-Zehnder Circuits with Bragg Gratings’, Presented as oral at the APOS conference, Sydney, Australia, January 31 – February 3, 2012

    I had a printout of the presentation on my breakfast table for last minute rehersing on February 2. Guess who was also sitting in the breakfast room of the hotel (Mercure hotel near Central in Sydney)? Two tables from me was Captain Shah together with another pilot from Malaysia Airlines. As I picked up more food from the self-service table he could easily have walked past my table and seen a nice figure illustrating how to hide with quantum entanglement. In another figure was a discussion of possible thermal crosstalk and how to avoid it.

  174. Brian Anderson says:

    @Niels,

    Yes, interpolating the BTO with a 3rd order polynomial and extracting the point at which dr/dt=0 is exactly the way I did it . . .many moons ago. It was the fundamental observation which led to my “mid-flight speed” hypothesis late in 2014. Based on the accuracy with which we knew of the data and measurements at that time, I can accept a couple of minutes either way.
    I agree that the latitude at that time depends on the track, [or vice versa] and this is the interesting question. I was never able to derive it.
    Hence the question for DrB, and my interest in your result too.

  175. Brian Anderson says:

    @Niels,

    Just to clarify . . I reverse engineered a BTO for the time 19:01 too, on the basis that the track looked like it may have been pretty straight from that time, and that helped with the polynomial fit. I ignored BTOs before that time.
    Those adjustments could also affect the precise time for the derived tangent time.

  176. Niels says:

    @Brian Anderson
    Perhaps the relation between track and latitude is not too difficult: I would think that at t the velocity difference vector between sat and ac has to be tangent to the sphere around the satellite defined by r(t). This probably means that the in plane component of the velocity difference vector has to be tangent to the virtual ping ring which can be defined for given r(t) by intersecting the sphere with earth surface. As we have a polynomial r(t) we can define a virtual ping ring at any desired moment in time assuming there are no strange U-turns, for which the overall trend in BTO and BFO imo leaves little doubt.

  177. Mick Gilbert says:

    @Viking

    Re: “Two tables from me was Captain Shah together with another pilot from Malaysia Airlines.

    I am curious as to how you recognised the fellow some two years prior to his notoriety? And how you could tell that he was with another MAS pilot?

  178. airlandseaman says:

    Re: MH371 BFO patterns?

    In addition to the group of BFO values circa 0430 that Bobby analyzed, there were similar groups every 30 minutes (ACARS reports). I picked 3 more (during the stable cruise phase) to compare in this note: https://bit.ly/3TnPB1I

    I find it difficult to see a consistent pattern (saw tooth or otherwise) across these samples.

  179. DrB says:

    @Peter Norton,
    @All,

    1. I have done a comparison of the MH370 BTO and BFO errors for northbound and southbound routes.
    2. The results are available here.
    3. I built a new flight model which assumes a constant ground speed at a constant flight level.
    4. I ignored the local weather.
    5. I assumed there was sufficient fuel on board to fly until 00:11.
    6. I assumed an initial bearing using LNAV (i.e., following a geodesic route).
    7. I solved for the 19:41 latitude, longitude, and ground speed which minimized the sum of the normalized BTO and BFO errors in units of sigmas.
    8. For the BTORs I used one sigma of 29 microseconds.
    9. For the BFORs I used one sigma of 2.4 Hz.
    10. The normalized error is the RMS value of the residuals divided by the assumed standard deviation. So, a value of 1 is an excellent fit. A value of 2 is a low-probability, marginal fit. Values larger than 2 are considered to be unacceptable.
    11. All southbound routes from 172-195 degrees had normalized BTORs less than 2 sigmas.
    12. For the southbound routes, initial bearings from 175-187 degrees had normalized BFORs less than 2, and the 19:41 locations were reachable on time from the last radar contact position. The 00:11 latitudes of these acceptable southbound routes are from 30.4 to 37.1 degrees S.
    13. Southbound routes from 188-195 degrees are rejected because the 19:41 location is too far south from the last radar contact position to be reached on time.
    14. The primary discriminators for southbound routes are the BFO errors and the 19:41 location.
    15. Because of the southbound speed of the Inmarsat F-1 satellite at the times of interest, the BFORs are highly discriminating between southbound and northbound routes.
    16. No northbound route has acceptable BFO errors, with the best case being more than 20 sigmas. Therefore, no northbound routes can possibly match the MH370 BFOs.
    17. The BTO errors for northbound routes are all greater than 1.7 sigmas. Therefore, all northbound routes have, at best, marginally acceptable BTO errors, and some routes are much worse.
    18. Northbound routes from 300-330 degrees are too far north at 19:41 to be reached from the last radar contact position.
    19. Northbound routes from 6-70 degrees are too far south at 19:41 to be reached from the last radar contact position.
    20. Northbound routes from 331 to 6 degrees are reachable at 19:41, but their BFO errors are totally unacceptable, being more than 22 sigmas.
    21. As shown in the figure, the northbound cases are plotted as red dots. None are acceptable, and by huge factors. The red numbers next to the points are the initial bearings in degrees.
    22. As shown in the figure, the southbound cases are plotted as black dots, and the black numbers are the southbound bearings.
    23. Acceptable southbound routes have initial bearings from 175-187 degrees, and their 00:11 latitudes are 30.4 to 37.1 degrees S.
    24. In my opinion, this exercise demonstrates that no northbound LNAV route can possibly be consistent with the Inmarsat data.

  180. DrB says:

    The link to my N-S comparison plot seems to be broken. I’ll try it again. Look here.

  181. Andrew says:

    @David

    I’ll let Mike Glynn explain, if he’s willing. The theory is his work; I only reviewed the fuel calculations.

    If Mike’s theory is correct, it explains the significance of the recovered simulator data and adds weight to the theory the aircraft’s disappearance was pre-planned. However, it does not necessarily explain what happened the night MH370 disappeared.

  182. DrB says:

    Oops! Wrong plot. I hope the third time is the charm. Look here.

  183. Victor Iannello says:

    @DrB: Yes, we’ve known since Inmarsat published the comparison of calculated BFOs for northern and southern routes that the measured BFO values favored the southern routes. The satellite inclination breaks the symmetry.

    I think what @Peter Norton was referring to were these two papers I wrote in the spring of 2015 that discuss northern routes and how a SATCOM hack of a particular kind would give a northern path the BFO signature of a southern path. Note that those papers were written before any debris were recovered and before the captain’s simulator data were available.

    https://www.dropbox.com/s/693pvqgqpawglj6/2015-04-29%20Northern%20Routes%20for%20MH370.pdf?dl=0

    https://www.dropbox.com/s/0gav5kh74ll6xkd/2015-05-16%20Northern%20Routes%20and%20BFO%20for%20MH370.pdf?dl=0

    For northern and southern paths that satisfy the observed BTO data, the uplink Doppler should match for all paths, and cannot be used as a discriminator (assuming the uplink Doppler could be extracted from the BFO data, which now seems very difficult). On the other hand, the AES pre-compensation values would differ. In the proposed hack, the pre-compensation algorithm is manipulated (by changing the satellite inclination parameters from zero) in a way that the BFO values of a northern path would be similar to a southern path.

  184. DrB says:

    @Brian Anderson,
    @Niels,

    1. Here is everything you wanted to know, and probably more, about aircraft routes which are tangent to spheres centered on the satellite location and the nominal satellite location.
    2. The UTC when the satellite velocity (i.e., the range rate) w.r.t. the Earth is zero is 19:40:56. At this time the satellite is not moving in the Earth reference frame and the downlink Doppler from the satellite to the GES in Perth is zero.
    3. The time when the aircraft range rate to the nominal satellite location is zero depends on the aircraft route. For the 180 degree UGIB (2020) route, this occurs at 20:03:00. This can also occur at 19:41:03 if on a course of 174.8 degrees.
    4. The time when the aircraft range rate toward the actual satellite is zero depends on the aircraft route. For UGIB (2020) this occurs at 19:48:57. This can also occur at 19:41:03 when on a bearing of 178.1 degrees.
    5. The time when the satellite range rate toward the aircraft is zero depends on the aircraft location. For the UGIB (2020) route this occurs at 19:54:57.
    6. The time when the combined range rate between the satellite and the aircraft goes to zero depends on the aircraft route. For the UGIB (2020) route this occurs at 19:48:51. This can also occur at 19:41:03 when on a bearing of 178.2 degrees.
    7. The time when the predicted BFO is minimized depends on the aircraft route. A minimum of 104 Hz can occur at 19:41:03 when on a bearing of 179.3 degrees, or a minimum of 83 Hz could occur at 17:48:56 if on a bearing of 180 degrees.
    8. I don’t see from these results any new way to constrain the MH370 route besides what has already been done – by fitting the 19:41 location and bearing, as was done by UGIB (2020).

  185. sk999 says:

    Victor,

    I reread the second of your two papers, the one proposing the satellite inclination “spoof”. I have some minor comments:

    1. Your wrote that “As part of the log-on process, an AES updates its System Table …” That is not necessarily true. The system table is in non-volatile memory and survives a power reset. The system table maintains a revision number. Only if the revision number is out-of-date is the table updated. (At least, this is true for the MCS-7200.) So the inclination will not necessarily be reset at the 24:19 logon.

    2. I read Ruben Santamarta’s paper and watched his video on SATCOM vulnerabilities. For the Cobham Aviator 700 (which you pointed out provides Classic Aero service like the MCS-6000), he identified a possible security vulnerability in the Swift Broadband service. I don’t believe that an MCS-6000 supports Swift Broadband. Likewise, the backdoor in the MCDU interface involved a screen requiring the entry of a password. I couldn’t find a comparable screen for the MCS-7200, presumable the same is true for the MCS-6000. The only way I can see manipulating the system table is by uploading new software with custom modifications. But once you do that, you introduce the possibility of spoofing the BTOs, which are sacrosanct in the Jeff Wise universe.

    3. I think Gerry Soejatman’s idea of spoofing the IRS data is more feasible than you represented. I would guess that both ground speed and ground track are used by the Doppler compensation calculation but are not used by the beam steering unit (which instead uses heading, along with other parameters). Gerry makes it sound like it is easy to reach into the E-11 rack and “Take out the feed cable …” for the IRS ARINC-429, but it isn’t that easy. These lines (there are two) are in the middle of a large cable bundle feeding a massive connector. Rather, I would think it easier to access in the MEC, where there is an Inertial Reference Bus ARINC-429 output on each AIMS cabinet that looks to be much easier to access. Well, these buses also go to the GPS receivers, so who knows what spoofing the data would do.

  186. DrB says:

    @Victor Iannello,

    1. The pre-compensation of the expected uplink Doppler is computed in the AES based on the aircraft location and velocity vector and an ASSUMED nominal satellite location (with no satellite velocity information). That’s it.
    2. The calculation of this uplink frequency pre-compensation does not depend on any communicated “satellite inclination” or other parameters besides the assumed (from a data table) constant satellite altitude, latitude, and longitude for the particular satellite in use. The possibility that the satellite inclination parameters were communicated from the GES to the AES was an incorrect notion early on about how the SDU worked, and which we now know is incorrect.
    3. Therefore, you can’t “spoof” the SDU using satellite inclination transmitted to the AES because it does not get any of those parameters from an external source.
    4. Even if you changed the internal SDU value for the satellite inclination, you are not affecting the actual downlink Doppler. At most you are changing the location of the satellite used to compute the pre-compensation Doppler shift.
    5. To manipulate the BFOs using the SDU you would have to re-program the SDU, while in flight, so the nominal satellite had a velocity which was time-dependent in a way to make an actual northern route match the BFOs for a pre-planned southern route.
    6. In my opinion, it would be virtually impossible to write the SDU code in advance so as to make an actual northbound route match a pre-planned hypothetical southbound route within a few Hz in the BFOs.
    7. Another possibility that gets you part of the way there is to change the sign of the aircraft latitude and the sign of the N-S velocity component received by the SDU from the IRU. This also seems very difficult to do in flight without disrupting the FCS.
    8. The notion that the BFOs can be manipulated in flight to match the predicted BFOs of a southern route seems like a fantasy to me. That’s not to mention the fact that nobody at the airline or at Boeing, and almost all of the Inmarsat personnel, had a clue what a BFO was in 2014, much less that it was being recorded.

  187. Mick Gilbert says:

    @DrB
    @Victor Iannello
    et al

    Re: “8. The notion that the BFOs can be manipulated in flight to match the predicted BFOs of a southern route seems like a fantasy to me. That’s not to mention the fact that nobody at the airline or at Boeing, and almost all of the Inmarsat personnel, had a clue what a BFO was in 2014, much less that it was being recorded.

    That was a point made by Peter Foley during his lecture at the Royal Aeronautical Society in Canberra the other week.

  188. TBill says:

    @All
    I have an essay (back in 2021) on the sim cases. My interpretation is it represents a flight south to SIO, based off the Jeddah flight. I found that the sim fuel loaded at N10 was exact amount needed to reach the Magnetic South Pole using at 180 South Mag path, and my working hypothesis is that was the basic structure from which variations for different MAS flights may have been worked out. Active pilot to end. We now know from ATSB these were types of MSFS temp files(thanks to Mick Gilbert working with ATSB to get more info a few years ago). (The data is still partially secret – I say apparently redacted – but ATSB has it and has given guidance.)

    Pilot probably was not aware of the temp files, so the old idea of him intentionally leaving data to be found is less good…looks candid data. This is my opinion, but I believe Malaysia hid this data for the obvious reason it is highly sensitive, and I would speculate FBI advised Malaysia and presumably Saudi Arabia of the plan, which FBI would have to take seriously. As MikeG says 3 pilots to Jeddah, so if I am FBI, I am wondering how many involved? I further speculate if Malaysia had released the sim data, even as late as 2016, it would have been explosive news. Instead we had redacted unclear data, that Victor and Yves worked hard to interpret partial data.

    That work by Victor stands the test of time, but we do have more data now, so I no longer think NZPG was the target…I know it looks like it…just bad luck the data lined up to NZPG, and Malaysia’s fault for redacting and holding secret the sim data. But it looks like Malaysia tried to give what they could, but it was too late to really allow factoring into prior searches.

  189. Niels says:

    @DrB
    Many thanks for your March 16th 9:54 pm posting. To start with: I’m also not sure the tangent method could in the end help to select candidate paths or limit a distribution.
    Typically, there is not a single minimum dr/dt as there could be different valid polynomial fits to the BTO derived data points r_i (t_i).
    Hence, the question would be if one could define a range t_min – t_max for the time range in which the minimum typically should occur, and a connected set of polynomial functions. The method would then become something like: for a path to be potentially valid it should have a velocity difference vector tangent to a virtual ping ring at the aircraft position at t_0. The virtual ping ring connected to a polynomial minimum r(t_0) where t_0 is in the range t_min – t_max.
    A first question therefore on your points 6: Is the path that gives a combined zero range rate at 19:41:02 with track 178.2 degrees indeed a valid path / could you share some more details?

  190. Victor Iannello says:

    @DrB said: The pre-compensation of the expected uplink Doppler is computed in the AES based on the aircraft location and velocity vector and an ASSUMED nominal satellite location (with no satellite velocity information). That’s it…The calculation of this uplink frequency pre-compensation does not depend on any communicated “satellite inclination” or other parameters besides the assumed (from a data table) constant satellite altitude, latitude, and longitude for the particular satellite in use. The possibility that the satellite inclination parameters were communicated from the GES to the AES was an incorrect notion early on about how the SDU worked, and which we now know is incorrect.

    Sorry, but this is absolutely false. As explained in the paper, the satellite inclination and ascending node time are broadcast as parameters in the System Table. The SDU has the capability of using these parameters for its AES pre-compensation. As it happens, the inclination was broadcast as zero for IOR at the time of log-on for MH370, so the pre-compensation is calculated as if the satellite was above the equator.

    Even if you changed the internal SDU value for the satellite inclination, you are not affecting the actual downlink Doppler. At most you are changing the location of the satellite used to compute the pre-compensation Doppler shift.

    You are misunderstanding. There is no need to compensate or understand anything about the downlink Doppler, or any other component of the BFO chain other than components that are route specific.

    To manipulate the BFOs using the SDU you would have to re-program the SDU, while in flight, so the nominal satellite had a velocity which was time-dependent in a way to make an actual northern route match the BFOs for a pre-planned southern route…In my opinion, it would be virtually impossible to write the SDU code in advance so as to make an actual northbound route match a pre-planned hypothetical southbound route within a few Hz in the BFOs…Another possibility that gets you part of the way there is to change the sign of the aircraft latitude and the sign of the N-S velocity component received by the SDU from the IRU. This also seems very difficult to do in flight without disrupting the FCS.

    As explained in the paper, the BFO spoof only requires a change in two satellite parameters. Basically, the inclination parameter is set to twice the true satellite inclination. No other real-time or a priori calculations need to be made.

    I don’t think the BFO was spoofed, but not for the reasons you listed which are mostly incorrect.

  191. Victor Iannello says:

    sk999 said: Your wrote that “As part of the log-on process, an AES updates its System Table …” That is not necessarily true. The system table is in non-volatile memory and survives a power reset. The system table maintains a revision number. Only if the revision number is out-of-date is the table updated. (At least, this is true for the MCS-7200.) So the inclination will not necessarily be reset at the 24:19 logon.

    I understand this. The assumption is the spoof involved a change in the revision number of the table that is stored.

    One question I’ve had that has not been answered is what occurs if the revision number broadcast by the satellite changes after log-on. Does the SDU update the System Table?

    One penetration vector I considered long ago is whether an onboard GES emulator after log-on could override the actual P-channel signal and broadcast a System Table with fake inclination parameters with a new revision number. Then, the table could be broadcast with the same fake inclination parameters but with the correct revision number. With these parameters, stored, the fake inclination parameters would persist even when the true System Table is received because the revision numbers would match.

    In any event, I don’t think the BFO was spoofed.

  192. Victor Iannello says:

    @Niels said: Typically, there is not a single minimum dr/dt as there could be different valid polynomial fits to the BTO derived data points r_i (t_i)

    Looking at the polynomial fit of the aircraft to satellite range at 19:41, 20:41, 21:41, 22:41, and 24:11, the standard deviation of the BTO error from the fit is 74 µs (range error of 11 km) for a second-order fit, while that for a 3rd order fit is 10 µs (range error of 1.5 km). For the third order fit, the minimum range occurs at 19:55.

  193. Paul Smithson says:

    @DrB. You said: 13. Southbound routes from 188-195 degrees are rejected because the 19:41 location is too far south from the last radar contact position to be reached on time.

    This is incorrect. The best-BTO fit no-loiter from a turn initiated off N571 takes you to 39.3S. There is ample opportunity to reach the requisite 1941 latitudes for 7th arc termini 38.8-39.8S without requiring speeds >M0.84 at FL340.

  194. Paul Smithson says:

    Why would you expect anything other than an imperfect polynomial fit if we know there were significant headwinds for last hour of all candidate paths thereby “distorting” the arc 5-6 portion? What’s more interesting is that fixed speed great circle path produces perfect fit to arcs 2-5 (but predicted overshoot of arc 6 to the tune of error ~330), illustrating need for slow down.

  195. Viking says:

    @Mick Gilbert

    You asked how I could remember his face after two years? The reason was that he did something unusual and impolite. I had a foot injury at the time, so I was walking relatively slowly for 2 weeks. He took advantage of that and sqeezed into the line (jumping a long line) for the self-service table right in front of me. I almost dropped my coffee, and I got really angry, thinking what an arrogant bastard. Therefore I remembered his face.

    Concerning identification, both men had pilot uniforms. In addition, there were several women in stewardes uniforms in the breakfast room at the same time.

    Initially (in 2014) I was a bit uncertain if they were from Malaysia Airlines or some other Asian carrier. Therefore I picked the same hotel when I had business in Sydney again in 2016. It was very slear that Malaysia Airlines used this particular hotel as their hub in Sydney, and there were no staff members from other airlines there.

    I know it looks like a conspiracy theory, but I can prove everything. There were roughly 150 people who attended my talk later that day (and many noticed my foot problem), one of them gave me a lift back to the hotel twice (same reason). In addition, I have a copy of the receipt from the hotel, proving that I did indeed have breakfast that morning at a cost of 25 AUS$. Some mornings I had a burger across the street instead, since it was faster and cheaper.

  196. Viking says:

    @All

    Concerning a possible U-turn soon after 19:41.

    What if I can prove that an airplane did indeed make a U-turn exactly at the right spot at the right time using other independent information (not from Inmarsat)? I guess that would change the situation.

  197. Niels says:

    @Victor

    There was a (hopefully obvious) mistake in my post 🙁 “.. minimum dr/dt =o”

    I also found the minimum range for the 3rd order polynomial around 19:55. However the low sd in BTO error for the third order polynomial might suggests there is some room to slightly morph the function and hence move the minimum. The question what kind of function to expect would also be relevant. It’s interesting but I’m not sure if I follow much further down this avenue..

  198. DrB says:

    @Niels,

    You asked: “A first question therefore on your points 6: Is the path that gives a combined zero range rate at 19:41:02 with track 178.2 degrees indeed a valid path / could you share some more details?”

    Regarding point 6, the relative range rate between the satellite and 9M-MRO is zero at 19:41:03 on a bearing of 178.170 degrees at the UGIB route location of 2.9350N 93.7875E using 480 kts ground speed. That is not the best 19:41 location for an entire route that also minimizes the relative range rate at 19:41:03. Fitting a route so the 19:41:03 relative range rate is equivalent to less than 1 Hz, and minimizing the BTORs/BFORs, I get a 19:41:03 bearing of 178.28 degrees and a position of 2.91N 93.61E. The ground speed is 470 kts, the normalized BFORs are 1.00 and the BTORs are 1.61 (which is a bit large). This is a marginally valid route. I don’t see any reason for the relative range rate to be near zero at 19:41:03 except coincidence.

  199. DrB says:

    @Paul Smithson,

    You said: “This is incorrect. The best-BTO fit no-loiter from a turn initiated off N571 takes you to 39.3S. There is ample opportunity to reach the requisite 1941 latitudes for 7th arc termini 38.8-39.8S without requiring speeds >M0.84 at FL340.”

    As far as I know, no one has demonstrated a flyable route from the last radar contact at 18:22 that seamlessly connects to the 188-195 degree bearing routes while satisfying ALL the intervening 18:25-18:40 satellite data and which has sufficient fuel. Sure, if you ignore what happens between 18:22 and 19:41, you can connect those routes, but I don’t recall seeing a route example that fits all the BTOs and BFOs. If I am wrong about this, please provide a link to such a route. The fuel is also a huge issue, because you can’t achieve 00:17:30 MEFE if you cruise continuously after 18:22. You need a period of fuel savings, such as a HOLD or some legs low and slow.

  200. Peter Norton says:

    David says: « I will send @VictorI a copy in case he can get around that issue. Perhaps Mike Glynn or @Andrew might be able to help. »

    Maybe I can help with this link to an archived copy of your newspaper article about the flight sim:
    https://archive.is/h5XKs

  201. Peter Norton says:

    @DrB says: « I don’t know how the SDU computes the pre-compensation Doppler shift. »

    @Victor Iannello:
    Doesn’t Thales help with the search for MH370 by providing the required information about the SDU ?
    Can’t the IG obtain the required information from Thales rather than the hard way through number crunching ?
    You all put a lot of effort into something the manufacturer could provide, one would hope.

  202. Victor Iannello says:

    @Peter Norton: Thank you!

  203. Paul Smithson says:

    @DrB. I don’t take 1822 as a hard data point but prefer to start path models at the 18:28:15 arc in vicinity of N571. As long as you include turn dynamics (AOB 15) you will find that pretty much any prior with single turn will end up on a bearing between 189 and 191 dependent on where arc 1 is crossed. You asked for a full route. As previously proposed try MEKAR-IGEBO-RUNUT-end at FL360 M0.840. Alternatively, for FL340 models start at 18:35:00 with BTO=12160 anywhere between 7.2N and 6.2N; or for FL360 models start at 18:35:00 same latitudes, on BTO=12130. All offer excellent Bto fit with great circle, constant M. Fuel adequacy is another matter but this conundrum afflicts all solutions, including UGIB, unless unusual fuel saving actions are inserted.

  204. Peter Norton says:

    Viking says: « why he turned the SDU back on (a mystery for many investigators) »

    @Andrew:

    AFAIK there are 2 ways to turn off the SDU:
    • circuit breaker in the EE bay
    • isolating the left A/C bus in the cockpit (which seems to be the consensus here)

    There is no other way, correct ?

    I would assume flying sans left A/C bus to be quite stressful due to the barrage of triggered warnings and (I assume) lost A/P (which incidentally also explains why MH370 was piloted manually post IGARI) ?
    So wouldn’t it be very obvious for the pilot to reconnect the left A/C bus (and thereby the SDU) for a less nerve-wrecking hours-long flight into the SIO with A/P and without all those distracting warnings ? Or would the pilot have been able to disable all those warning ?

    This would easily explain why the SDU was turned back on (but not really why it was turned off in the first place).

  205. Peter Norton says:

    sk999 says on March 16, 2024 at 9:59 pm:
    > I would guess that both ground speed and ground track are used by the
    > Doppler compensation calculation but are not used by the beam steering unit
    > (which instead uses heading, along with other parameters).

    Could this divergence be used to determine whether the BFO data was spoofed ?

  206. Peter Norton says:

    > DrB says on March 16, 2024 at 7:14 pm:
    > 1. I have done a comparison of the MH370 BTO and BFO errors for northbound and southbound routes.

    Many thanks for your work and sharing your results.

    > 13. Southbound routes from 188-195 degrees are rejected because the 19:41
    > location is too far south from the last radar contact position to be
    > reached on time.

    I would caution against relying too heavily on the radar data.
    Can we know for sure that both the location and the timestamp are precise ?

    > 24. In my opinion, this exercise demonstrates that no northbound LNAV route can possibly be consistent with the Inmarsat data.

    While a straight path seems logical to me for an hours-long flight over the absolute nothingness of an ocean, I would not assume a straight northbound path over land since it needs to take into account, among other things, radar coverage and minimizing the possibility of detection (which can also be observed post IGARI).

  207. Peter Norton says:

    > TBill says:
    > March 15, 2024 at 10:20 am
    >
    > Peter’s need for flight south verification I am afraid mirrors even the most
    > bright NoK. They are hearing a barrage of conspiracy theories which are
    > attractive vs. the apparent truth.

    @TBill:
    First of all, thought-terminating clichés such as “conspiracy theory” should not have a place on a thoughtful scientific blog. Conspiracies occur all over the planet, every minute, every hour. Thus whether or or not a theory involves a conspiracy says nothing at all about its validity.

    Second of all, your statement doesn’t do me justice. What is bad about “verification”? Science is based upon verification, not guesswork. I never said I deem a northern path likely (though I freely admit being intrigued by Jeff Wise’s theory due to it’s sophistication). But the point is this:

    A northern path (with tampered BFO data) has not yet been ruled out mathematically.
    Only by circumstantial evidence.
    So however unlikely, apparently it’s possible that MH370 flew north.

    Wouldn’t it be great to eliminate the entire northern hemisphere definitely once and for all by demonstrating mathematically that a northern path is impossible ?

    As you say yourself, some NoK may still cling to that tormenting hope. And there is a Netflix documentary, a weekly podcast and articles swirling around, nurturing this possibility and creating doubt about finding the plane in the south. So if that’s where the plane truly is (in the SIO), then all this creates a lot of distraction for the search efforts. That’s why I said, a mathematical proof for the impossibility of BFO spoofing and thus for a northern route would help focusing the search in the south.

  208. Niels says:

    @Paul Smithson
    What is a typical 19:41 lat for the route ending S39.3?

  209. Peter Norton says:

    @DrB

    Please correct me if I am wrong. My understanding is:

    (1) A stationary satellite doesn’t tell us whether MH370 went north or south:
    « With a stationary satellite above the equator, it is impossible to distinguish between “mirror-image” routes N and S of the equator based on BTO (range) and BFO (range rate) measurements. »¹

    (2) But our moving satellite does tell us MH370 went south, because due to its N-S movement “the mirror image of the southbound route can’t fit the same BFOs”.¹

    (3) So the only way MH370 could have flown north (despite the incompatible BFO data for a northern path) is by spoofing the BFO data (i.e. Jeff Wise’s theory based on Victor Iannello’s “brilliant work showing how simply it could be done just by changing a single parameter in the SDU”²)

    I think the above points are nothing new but have been settled years ago.

    What’s seems to be new is @Victor Iannello’s recent statement above:

    « @DrB: That is VERY clever! […] I really doubt anybody has considered this before. So with that in mind, it would become harder to spoof the BFO with fake satellite inclination parameters so that a northern path has the BFO signature of a southern path, as the slope of the sawtooth would be different for a northern and southern path, even though the BFOs might be very similar. »³

    I took this as saying that based on your new analysis (specifically the different sawteeth for a northern and a southern route) “it would become harder to spoof the BFO” as @Victor said. Maybe not only harder but outright impossible? If so, could the slope of the sawteeth be a definite proof for either a northern or a southern flight and thereby settling this issue once and for all? This would be an enormous breakthrough! When I read @Victor’s posting, I thought you were onto something very exciting, that could toss the possibility of BFO spoofing out of the window.

    If not, then why did @Victor say, “it would become harder to spoof the BFO” ?
    What makes BFO-spoofing harder? And why?
    And in what way would it become harder than “just changing a single parameter in the SDU” ?
    What additional efforts would be required ?

    –––
    ¹ https://mh370.radiantphysics.com/2024/03/05/ocean-infinity-proposes-new-search-for-mh370/#comment-36239
    ² https://www.jeffwise.net/2017/01/05/zaharie-shahs-secret-psych-evaluation/comment-page-1/#comment-200608
    ³ https://mh370.radiantphysics.com/2024/03/05/ocean-infinity-proposes-new-search-for-mh370/#comment-36116

  210. Victor Iannello says:

    @Peter Norton: My statement was not correct. We originally thought the sawtooth was the results of AEC pre-compensation held constant and the BFO slope between jumps was essentially the changing uplink Doppler. If this were true, then the uplink Doppler would essentially be the same for all paths that satisfy the BTO criteria, which means my statement was wrong. But things are even more complicated because the BFO slope between jumps appears to not be the rate of change of the uplink Doppler, i.e., there might be other factors that contribute to the BFO slope, whether intended or not.

    So, perhaps Bobby can still extract useful information from the BFO clusters, but I think it will be more difficult than I originally envisioned.

  211. Paul Smithson says:

    @Niels.
    Start 183500 at 6.7N 95.0711E. Fl340, M0.836, initial azimuth 190.128. I get 1941 latitude -2.3688 and longitude 93.467. My Bto all calculated at geo height 35000ft. 7th arc 39.39S. Let me know if that works for you.

  212. airlandseaman says:

    @Peter:

    Re: “Can’t the IG obtain the required information from Thales rather than the hard way through number crunching ?”

    Believe me, I am trying. I contacted a Thales engineer I met in London in 2017, but he has not responded. I am continuing to seek the critical information we need through several other contacts. Hopefully, one will pan out soon.

    In the mean time, here is what we know so far:
    1. The Racal Prototype hardware flown on 3 planes in the 1989-90 time frame used a TX up-conversion chain that had “…100 MHz and 200 MHz local oscillators for up/down conversion, frequency selectable in 1 Hz steps to counteract the effects of Doppler…”.
    2. We know more details about the SD-700 SDU. It had an up-conversion scheme using a 209 MHz Channel Synth, 164 MHz Doppler synth, but with 10 Hz steps, and a final mix using a 1270.08 MHz LO to the 1645 MHz TX band. Details here: https://bit.ly/3v5QaFz
    3. The later SD-710/720 and the companion HS-720 had provisions for 1 Hz Doppler compensation steps.
    4. We also know the Doppler update rate was software selectable at installation to be either 30 or 60 Hz (default) on the HS-600 (High Speed version of the SDU).

    Obviously, both the Doppler synth resolution (1 Hz, 5 Hz, 10 Hz, ???) and the update rate is important to know when try to decipher what BFO patterns mean. From other documents, I think it is safe to assume the update rate is OTOO 50 Hz, but the SD-600 Synth resolution is still uncertain.

  213. Peter Norton says:

    @Victor Iannello:
    thank you for the clarification.

    If as a byproduct of your work, you and @DrB end up disproving a northern path with BFO spoofing, please let us know.

    I know most of you don’t see this as necessary, given the debris and the flight sim data, etc. but it would settle the north/south-question for good and put it to rest.

  214. Peter Norton says:

    @ALSM:
    > Believe me, I am trying. I contacted a Thales engineer I met in London in 2017,
    > but he has not responded. I am continuing to seek the critical information we
    > need through several other contacts. Hopefully, one will pan out soon.

    Thank you for the feedback. It’s good to know that you are on to this. Best of luck.

    It’s somewhat unexpected that it’s so difficult to get them to talk. One would assume that the manufacturer would readily help with the search efforts … but maybe even for them it’s not easy to come up with the information for an older product of theirs.

  215. Niels says:

    @Paul Smithson
    The 19:41 position you mention should be feasible. However I also tend to think the fuel needed will be a problem, especially if you apply FL340 and M084 all the way.
    I’ve worked on a method to estimate an upper limit for available fuel at 19:41 by connecting N571 18:30 position to different Lat, Lon combinations at 19:41 (I calculated a complete 2D grid) by a TT straight segment in holding mode at the FL that best matches the distance to travel in 71 minutes.
    Even with this “soft” fuel limit applied it seems hard to get beyond S38.0. There are some paths left but the cumulative probability gets really low south of S38. I’m working on a short summary which I can hopefully share by Tuesday or Wednesday. Without any fuel limit applied paths ending close to S40 would imo not be impossible with an early turn, no loitering and staying at high altitude cruise.

  216. Niels says:

    @Paul Smithson The 19:41 position you mention should be feasible. However I also tend to think the fuel needed will be a problem, especially if you apply FL340 and M084 all the way. I’ve worked on a method to estimate an upper limit for available fuel at 19:41 by connecting N571 18:30 position to different Lat, Lon combinations at 19:41 (I calculated a complete 2D grid) by a TT straight segment in holding mode at the FL that best matches the distance to travel in 71 minutes. Even with this “soft” fuel limit applied it seems hard to get beyond S38.0. There are some paths left but the cumulative probability gets really low south of S38. I’m working on a short summary which I can hopefully share by Tuesday or Wednesday. Without any fuel limit applied paths ending close to S40 would imo not be impossible with an early turn, no loitering and staying at high altitude cruise.

  217. Peter Norton says:

    from my earlier comment: « a mathematical proof for the impossibility of BFO spoofing and thus for a northern route would help focusing the search in the south. »

    Just to illustrate my point:
    Ocean Infinity wants to scan the seabed again. Should it?

  218. sk999 says:

    Peter Norton asked:

    “Could this divergence be used to determine whether the BFO data was spoofed?”

    Not that I can think of.

  219. Peter Norton says:

    posted 1 hr ago:
    > I think even Victor says that the data gaps are not sufficient to hide the whole
    > plane, but he thinks pieces of it might be there. Where that would leave the main
    > wreckage I don’t know.

    @Victor Iannello:
    Does this accurately portray your position (I assume not) ?
    If not, maybe you want to set the record straight ?

  220. Andrew says:

    @Peter Norton

    RE: “There is no other way, correct ?”

    Correct, unless you pull the cables out of the box itself. There is no ON/OFF switch.

    “I would assume flying sans left A/C bus to be quite stressful due to the barrage of triggered warnings and (I assume) lost A/P…”

    There would be some initial EICAS alerts plus a Master Caution, all of which can be cancelled. Some systems would be lost, but the major systems have a high degree of redundancy, powered by other sources. The autopilot would not be lost.

  221. Peter Norton says:

    @Andrew:
    Thank you. What practical problems for a pilot would result from disabling the left A/C bus ?

    > “The autopilot would not be lost.”

    Sorry for my error. Why is the A/P not lost?

    From AF447 I remember that the A/P disengaged because of the degradation from normal law to ALT2.

    Wouldn’t disconnecting the entire left A/C bus in a B777 also result in degradation of the flight control law to secondary mode, which according to Skybrary results in loss of A/P ?
    « 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. »

  222. Victor Iannello says:

    @Peter Norton: Do you think my making a comment here will “set the record straight”? If only it was that easy.

  223. Andrew says:

    @Peter Norton

    Yes, the B777 autopilot would be lost if the primary flight control system (PFCS) degraded from normal to secondary. However, de-powering the L AC bus does not cause the PFCS to degrade to secondary mode because of the redundancy designed into the system. Without going into massive detail, essential elements of the system have several identical components powered by different sources. If one falls over, another continues to provide the data the PFCS needs to continue operating in normal mode.

    In the AF447 accident, the flight control system degraded to alternate because it lost airspeed data when all the pitot probes were momentarily blocked by icing. That’s a very different scenario to the loss of AC power on one side.

  224. David says:

    @Peter Norton. Re the Mike Glynn article and your, ‘Maybe I can help with this link to an archived copy of your newspaper article about the flight sim: https://archive.is/h5XKs.
    Thanks though that doesn’t open, at least for me.

    ‘The Weekend Australian’ has told me that they would ‘entertain’ releasing the article from copyright next Monday (here): ie the two days’ elapsed period so far is too short.
    Supposing they do and no alternative comes up in the meantime, I will post it then.

    @Mick Gilbert. Yes a response from Mike Glynn to what you raise re the simulation would be helpful.
    About Peter Foley’s presentation, that is not yet up loaded to the Royal Aeronautical Society’s Australian site and I know not when it will be. Did he have anything more to say that is relevant to a future search, or accident cause, that you can impart?

    @Victor. The interview of Tony Romeo, CEO of ‘Deep Sea Vision’ and ex USN on ‘60 Minutes’ Australia.

    To access that, some might we willing to brave ‘9now’, which offers free access on disclosure of e-mail address. Enter without a log-in, select ‘News and Current Affairs’, ’60 minutes’, the ‘Latest’, then click on the last segment at 42:06. Then fidget through about 10 unexciting ads.
    Finally for those that have had the tenacity, success enters.
    Alternatvely, here is the final URL in case that should help, though I believe that will require you to open an account, albeit free, and with challenges as above yet to come:
    https://www.9now.com.au/60-minutes/season-2024/episode-7

    However, to save that struggle, I present you with my summary, at no cost.
    The program indicates:
    – that he has a Hugin 6000, shown utilising a standard stern ramp. However the ‘hangar’ of the vessel shown has room for just the one and the vessel is small, trawler size, without boomed cranes. Possibly he has more AUVs and bigger vessels: he says he can cover 4 X the area searched so far.
    – he located what may be Amelia Earhart’s Lockheed, though that is still to be confirmed. Once done he says he would “look around and engineer a solution to bring it up.”
    – He makes no mention of an ROV and since the (maybe) Lockheed image appears to be from sonar from above, it may be he didn’t have one or the cranage, at least there and then.
    -as to MH370, “finding the black box will unravel everything”.
    -he has modified the Hugin he says, which has 36 hrs endurance and searches 50m above the seafloor.
    – judging by what is on the map shown, by my eye his search would focus on about 32½˚ to 35˚S, 93½˚E. Map annotated SIO then, NOAA, USN, NGA and GEBCO.
    Speaking of GEGCO he like others may need prior bathymetry to conduct a search in a new area, though AUVs in place of towed might lessen that.
    – he adds that planning is underway and his company, “has been asked to submit a search proposal to the Malaysian government.
    – as to whether he would go ahead without Malaysian approval he said he. “would like the Malaysian government to participate a little bit. It is a very expensive search.” So whether he would charge for his search, as distinct from expect a reward, is unclear.
    – it may be that he could conduct a supplementary search of selected areas ie outside the main search.
    -also, while beyond ’60 Minutes’ scope, there is the issue of quality management and or sonar calibration, though OI has not disclosed either (so far as I am aware).
    – were I the Malaysians I would favour disclosure of those and any bathymetry, whoever did a search, and also the outcome if not found, ie including the find-probability-if-there realised, area by area, particularly where steeply sloped and disclosing spots missed. Whether these should be left to searchers is a good question but they are important background for further searches.
    -naturally also not covered by ’60 Minutes’ is the scale of any recovery operation, and about which the NOK might be of divided opinion. The scale is evident from ATSB planning for that (eg floating accommodation at the site for many investigators, observers, coroners,the law etc).

  225. Mick Gilbert says:

    @David

    G’day David,

    Peter’s presentation was very straight up and down, very facts-based. He is a very good presenter.

    Peter kicked off with an acknowledgement of the contributions from all the relevant parties (IG got a mention). The presentation itself was structured in basically a chronological fashion; stepping through the basic details of the flight, the initial search efforts either side of the Malaysian Peninsula, the shift to the SIO and the Australian involvement, the surface search, the preparation of the underwater search area, the DSTG work, the selection of Furgo, the first hit out, the drift work subsequent to wreckage finds, analysis of the flap, First Principles Review, the OI work, and the conclusion addressed the newly proposed OI search area.

    Unsurprisingly, there was nothing “new” presented.

    It is a pity that it hasn’t been uploaded yet, not so much for this group but for the many people who seem to be only now taking an interest in it. It would be a go-to piece for anyone who wanted a roughly 50 minute precis; a terrific foil to the Netflix show and other associated ramblings.

    Separately, I got the opportunity to meet and chat with Mike Glynn, and a few of the ATSB people. I had a good yarn with two of the ATSB fellows who had basically been with it from when the balloon went up. I was struck by the magnitude of the task they were dealing with in the early days when the surface search shifted to SIO, and how quickly newly emerging information superseded what was previously the “best” information; a real moving feast.

    It was pretty clear that both Peter individually, and the ATSB collectively view it as unfinished business.

  226. TBill says:

    @Peter Norton
    Apologies. I was reacting to a panel discussion with Blaine, Grace and Naren.

    What I was trying to say:
    An enormous human and scientific effort has yielded hard evidence that MH370 crashed in the Southern Indian Ocean (radar, Satellite, debris finds).

    Failure to find MH370 in a specific SIO search area does not weaken the hard evidence. Rather the hard evidence is insufficient to make any guarantee whatsoever for finding the aircraft.

  227. Peter Norton says:

    David says:
    > @Peter Norton. Re the Mike Glynn article and your, ‘Maybe I can help
    > with this link to an archived copy of your newspaper article about the
    > flight sim
    > Thanks though that doesn’t open, at least for me.

    Sorry, I don’t know why the link doesn’t open for you.
    I just verified again, it does work for me.
    Here are some alternatives, which all work:

    https://archive.fo/h5XKs
    https://archive.ph/h5XKs
    https://archive.today/h5XKs
    https://archive.is/20240315174529/https://www.theaustralian.com.au/inquirer/secret-flight-path-of-mh370-captain-zaharie-shah/news-story/011d30d8539a87b7639e74f324a4a339

    Do any of these work for you ?
    If not, let me know and I’ll try to find another solution.

  228. Peter Norton says:

    @Andrew:
    Thank you for your insights and correction of my misconception.
    I had always thought that flying without the left A/C bus would cause all sorts of problems and would be very impractical. But if A/P is not lost and all warnings can be cancelled, it may be less outlandish than I thought.
    What would be the biggest practical problems (if any) for a pilot when flying without the left A/C bus ?

    @TBill:
    Thank you. No problem. And I agree with your latest comment. But:
    > “hard evidence that MH370 crashed in the SIO (radar, …)”
    We have radar evidence for a crash in the SIO ?

    > Victor Iannello says:
    > Do you think my making a comment here will “set the record straight”?
    > If only it was that easy.

    @Victor:
    I was just trying to help.
    Maybe a direct reply over there ?
    I actually do think he’ll take that into account.

  229. TBill says:

    @Peter
    The Mike Glynn article version you posted yesterday worked for me. Thank you.

  230. Peter Norton says:

    @Amelia Earhart’s plane:
    The sonar image seems to show the plane in one piece under water.
    Isn’t that almost impossible after ditching ?

    @Victor Iannello:
    @Mick Gilbert:
    What do you think about Mike Glynn’s flight sim article ?
    To me it seems the article mixes facts and speculation which are presented as facts.
    Example:
    « He created a circle called a range ring centred on 10N. »
    I have never heard of that before. Is this a proven fact ?

  231. Victor Iannello says:

    @Peter Norton: No, not proven, but certainly possible.

  232. flatpack says:

    @Viking

    Just an aside re the two simultaneous phone call attempts:- at the time that info became available I saw it as a deliberate attempt to call both the cockpit phone and the cabin phone so that if one picked up, the other would keep ringing.

    I speculated that the ops personnel making the call had a suspicion that the plane had been deliberately diverted and wanted feedback from both pilots and cabin staff and that they were following some SOP to do thst.

  233. David says:

    @Peter Norton. Response to one of those 5 URLs by my contraption is, “This site can’t be reached” and “archive.ph unexpectedly closed the connection”. Others the same, including that earlier, except the “ph” changes.

    Whatever, I see that @TBill now has access. Assuming that applies widely I will leave aside my impending post.

    Thanks.

  234. Ajay Sapra says:

    Is it possible that the debris of mh17 flight are implanted to prove mh370 distruction while it still stand somewhere in miliyry airbase

  235. TBill says:

    @flatpack
    I like your thinking, but how could ops suspect diversion? If they had their thinking caps on, the fact the 1840 calls went thru would be first hint plane still flying.

    I did not realize there was two calls until Viking mentioned it.

  236. Viking says:

    @flatpack and @TBill

    Sounds like an interesting possibility. I need to think a bit more about it.

  237. Viking says:

    @All

    Concerning a U-turn soon after 19:41, let us start with ‘the smoking gun’. Then we can go for the ‘bullet hole’ and the final proof afterwards:

    A geostationary Japanese weather satellite far out over the Pacific Ocean took a picture containing short contrail stripes of both a northbound path (of MH370?) near the southern tip of the longest island in the Andaman Sea and a corresponding southbound leg of a route (turned slightly less than 180 degrees) near the next island @20:30. Between these two, there is a third contrail-segment from another airplane.

    A low-altitude Chinese infrared satellite caught the heading segment of contrail from the same (other) airplane further south around 19:50 proving that it was southbound, most likely heading for Singapore based on further contrail pieces seen by the Japanese satellite. More importantly, the Chinese satellite also caught a U-turn (possibly the final major turn for MH370?) along the edge of a cloud far up in the Andaman Sea. The position agrees within 5 km with our theoretical prediction of a U-turn. It is a nice camera shot since the airplane is around 75% through the U-turn. This is a smoking gun for our solution, since U-turns are extremely rare under normal flying conditions over the open sea, – in particular crossing an airway with risk of a collision.

    This is the same as finding a smoking gun at a crime scene. Now we just need a bullet hole and a fingerprint to have a final proof it was MH370 making a U-turn.

  238. Ajay Sapra says:

    The phone call family members of passengers recieved after the incident supports my point of view.

  239. Mick Gilbert says:

    @flatpack

    Would you care to elaborate on the process undertaken by a ground station “to call both the cockpit phone and the cabin phone“.

  240. Ajay Sapra says:

    According to my understanding, what happened that night

    Someone hijacked the cockpit, while other one went down to switch off the communications and after plane went off the radar , they took the plane to some desired place.

  241. Andrew says:

    @Peter Norton

    RE: “What would be the biggest practical problems (if any) for a pilot when flying without the left A/C bus ?”

    A bunch of things would be lost if the left AC bus were unpowered, but most of them shouldn’t cause too much concern. The main problems would be the loss of TCAS and the Satcom SDU.

  242. Mick Gilbert says:

    @Peter Norton

    G’day Peter, regarding Mike’s article mixing facts and speculation which are presented as facts, the range ring is speculative, for sure.

    Suffice to say that the data recovered from the Captain’s home flight simulator is easily one of the most misunderstood, and consequently misrepresented, items relating to the disappearance.

  243. flatpack says:

    @Mick Gilbert

    There is no real ‘process’ as such, merely placing two calls in quick succession. If one call is picked up in the cockpit, the other should keep ringing in the cabin, if the cabin terminal is still powered.

  244. Mick Gilbert says:

    @flatpack

    What makes you think that you can direct a satellite call to the pax cabin? Do you think it’s set up like an extension?

  245. TBill says:

    @Ajay
    Realistically, it is the reinforced cockpit doors that tell us the the Captain probably did it. The Capt had means, motive, opportunity, and we have to add to that since 9/11, Fort Knox cockpit barrier to better enable a rogue pilot.

    I personally wish we could be blame it on unknown perpetrator, because I have no interest in blaming pilot…my only gripe is that someone in the cockpit can do this so freely. Most deniers want to rule out 3rd party hijack, and go with fire or mechanical, because if it was nefarious, the who-done-it answer is almost undoubtedly ZS. Cockpit door is virtual AI computer, answers that question automatically.

    In any case I can accept your scenario, and this person was active whole flight and probably flew at least 150 nmiles from Arc7 to hide the plane. Well planned, and somewhat similar to sim cases. Wink, Wink- but not our pilot.

  246. Viking says:

    @All

    What do the ‘bullet hole’ and the ‘fingerprint’ consist of?

    A satellite picture IR@22:00 from the French weather satellite Meteosat 7 over the Indian Ocean delivers both. The previous pictures (between 19:00 and 21:30) are unfortunately absent because the satellites solar panels passed through the earth shadow, so correction for an hour wind drift is necessary. Slightly north of the position from where Kate Tee observed an airplane diving towards her there is a so-called fall-streak hole in the thin, hazy cloud-cover, proving that an airplane did actually dive at that position (the ‘bullet hole’). In addition, the contrail passing through the hole ‘inverts’ in infrared. Before the hole, it is thin and white in IR (normal for a plane flying above the clouds at night) while after the hole it became thick black (clearly visible) indicating that the airplane was now below the clouds where the contrail absorbs heat from the ocean and cools the cloud above making the IR image turn black with time. When the contrail reached land in Aceh, there was no longer any cloud cover, and it turned white again. This is practically a fingerprint. The only problem is that Kate got the time one gybe wrong as we already suggested in our paper. If her gybe-number were correct, there would most likely not have been any trace of contrail or drop-hole left at 22:00. Instead, there might have been something in the Japanese satellite picture at 20:30, but there is nothing at that position at that time. The southbound contrail stops near the second Andaman Island as one would expect.

    Until recently there was also a Japanese satellite picture available from 21:00 (unfortunately now deleted) showing a much smaller fall-streak hole and white contrail until a few km into Bandar Aceh confirming the exact time the airplane passed. This means that it could only be MH370, thereby confirming the fingerprint. There is no longer any doubt Kate Tee saw MH370 flying low and slow over Bandar Aceh.

    With correct gybe assignment by Kate Tee, the independent group would probably have solved the mystery several years ago. This is the reason we always urge students to write their observations in the logbook before they forget important details. As a last detail, we would like to point out that with the contrail below the thin, hazy cloud the optical contrast becomes very different, so Kate Tee thought it was smoke instead of just a normal contrail.

    For those who might like to regenerate Japanese satellite pictures (Himawari 7) from the Internet Archive try this link: https://sc-nc-web.nict.go.jp/wsdb_osndisk/shareDirDownload/03ZzRnKS#

    However, I warn you that they are in a horrible format and all text is in Japanese. I got copies from another source (collaborating university in USA). Unfortunately deleted several years ago (sorry, I forgot to copy the link and the 21:00 picture, so it is lost forever).

    Some METEOSAT 7 pictures are still available from Weather Graphics, the rest from other places.

  247. Niels says:

    @Viking
    Can you please share all the relevant images you refer to and that still exist, and indicate all “drop holes”, “contrails” etc you mention clearly in the images?

  248. Peter Norton says:

    @Andrew says:
    > A bunch of things would be lost if the left AC bus were unpowered,
    > but most of them shouldn’t cause too much concern.
    > The main problems would be the loss of TCAS and the Satcom SDU.

    IMO both are not problems but advantages for someone who wants to disappear
    (which seems to be the case here).

    Ok, so if there are no major inconveniences for piloting the aircraft and as an additional bonus the hijacker gets rid of TCAS and the SDU, I see for the first time how a case could be made for intentionally disconnecting the left A/C bus (if it’s possible the hijacker could have had or obtained any knowledge of what systems would be lost).

    @Mick Gilbert says:
    > the data recovered from the Captain’s home flight simulator is easily
    > one of the most misunderstood, and consequently misrepresented, items
    > relating to the disappearance.

    Good day to you too, Mick.
    What’s your current assessment and did Mike Glynn’s article change it in any way ?

  249. Mick Gilbert says:

    G’day Peter,

    Regarding, “What’s your current assessment …”

    The most simplistic and widely put about interpretation of the Captain’s home flight simulator data is a continuous and contiguous “suicide route” constructed by joining the locations recorded for six flight files that had been recovered; what I’ve always referred to as the “string around the map pins” approach. Simplistic, somewhat damning, and, to my mind, wrong.

    When you understand how the recovered flight files were created, and you incorporate ALL of the data, it becomes evident that there are three distinct elements or phases to the session.

    In the first phase of the session, the Captain was almost certainly simulating the take-off and departure of his then upcoming flight to Jeddah on MH150; both the take-off time and the fuel load are there or thereabouts for MH150. This was a route that he hadn’t flown for some three months. The data shows that after what appears to have been a fairly standard departure from KL, the Captain simulated what might have been some sort of in-flight upset (we see meaningful changes to the Maximum and Minimum G-force recorded) that was then followed by his turning the aircraft around. This all occurs as the aircraft was crossing over from airway B466 to N571, but before it had reached VAMPI.

    This is fairly important, I think. At this point in the session, with the aircraft still in the Strait of Malacca, not having yet reached N571, he was turning the aircraft away from a flight path further up the Strait and likely either heading back to his departure airport, KL, or possibly heading to the then nearest suitable airport, Medan, Indonesia. Simply joining this point to the next point over in the Andaman Sea doesn’t make a lot of sense in terms of it being either continuous and contiguous.

    That first phase of the sim session ended there with the simulation aircraft just shy of VAMPI at FL400, turning left through 255/256° in a 20° AOB turn.

    After that, the aircraft was relocated manually using the Map function to the eastern edge of the Bay of Bengal, roughly equidistant from Port Blair and Car Nicobar. While the Captain had flown through that region on the MH17 return flight from Amsterdam to KL just two weeks prior, it is probably worth noting here that the aircraft may not have been repositioned with any degree of specificity – it is not on an airway but it is close to the E90-N10 grid intersection that’s shown on the simulator map.

    From the Bay of Bengal location the aircraft was then flown back towards Indonesia/Malaysia such that the NAV1 and NAV2 navigation aids autotune to the Banda Aceh VOR. This is important – the aircraft did not fly south towards the next sim point in the SIO, rather it flew south-east possibly still tracking back towards its destination (KL or Medan) from the previous phase in the Strait of Malacca.

    Notably, during this phase the simulator aircraft was almost certainly jettisoning fuel such that it reached fuel exhaustion somewhere near Banda Aceh, Indonesia. It began a brief unpowered descent after fuel exhaustion had occurred. The second part of the sim session ended at this point, with the aircraft having reached fuel exhaustion somewhere near north-western Sumatra.

    Again, it is probably worth stressing here that the simulation aircraft reached fuel exhaustion somewhere in the northern hemisphere, probably just off the north-west coast of Sumatra. This is contrary to the commonly put about notion that the aircraft was flown to fuel exhaustion deep in the Southern Indian Ocean.

    Something else worth noting here, this phase ran for about 42 minutes elapsed sim time. Elapsed sim time is not necessarily the same as “real world” elapsed time, as sim time can be compressed by accelerating the sim, and stretched by pausing. But it should be noted that on the day that the flight simulation was undertaken, Captain Zaharie took a 45 minute phone call from his first cousin and aircraft engineer, Zulhaimi Bin Wahidin, commencing at 9.49am. Given the similar duration for the fuel exhaustion flight leg I have wondered whether the two might have been coincidental – for example, he started the fuel jettison and was then distracted by the phone call and only got back to the simulation when the tanks were dry. There’s no evidence that the two are linked but it would be remiss not to mention the possibility.

    After that second phase, the simulation aircraft was then relocated to the Southern Indian Ocean about 940 nm south-west of Perth, Australia. Here again, it is probably worth noting here that the aircraft has been relocated close to a grid intersection that’s shown on the simulator map, this time E104-S45. Shortly after that relocation, after another brief period of unpowered descent, the aircraft’s altitude was manually adjusted down from its then current 37,650 feet to 4,000 feet.

    Taken in its entirety, is the sim session suspicious? Probably, yes. Could it be construed as practising a diversion south into the SIO to fuel exhaustion? I don’t think so, not in any practical sense.

    Regarding “… and did Mike Glynn’s article change it in any way ?

    Mike certainly makes an interesting observation, one that hasn’t been touched on before. I don’t think that it rises to the standard of “smoking gun”.

  250. Viking says:

    @Niels

    Please send me an email, so I can send pictures to you.

  251. Niels says:

    @Viking
    I expect I’m not the only one interested to see evidence/data supporting your claims.
    You explained you release your findings step by step to have discussion on each section. We can only have a proper discussion here if you share the supporting data/evidence/methods that go with the claims. Can’t you share relevant images and/or parts of images through a cloud link? Or write a summary on this part including images and share that to start with?

  252. ventus45 says:

    @Mick Gilbert
    That first phase of the sim session ended there with the simulation aircraft just shy of VAMPI at FL400, turning left through 255/256° in a 20° AOB turn.

    How far short of VAMPI ? ( lat / lon )

  253. George Tilton says:

    @Victor Iannello

    After spilling iced-tea into my laptop several weeks ago which trashed my harddrive, I find that several files I was working on were not on my last harddrive image back-up.

    There was a paper published by a working group (Inmarsat?) showing communications traffic from a 777 parked on the tarmac from 16/09/2014 14:46 to 17/09/2014 09:13.

    There were two figures showing the BTO error, Figure-1, and Figure-2 and an analysis that justified the 59 microsecond error that subsequent investigators have used in their models.

    I need Title, Authors and download link so that I can cite the paper in the study I am working on.

    Any help would be appreciated…
    Regards,
    George

  254. Victor Iannello says:

    @George Tilton: You may be referring to a paper entitled “Burst Timing Offset (BTO) Characteristics” published on Dec 23, 2014, by the ATSB, which described work performed by the MH370 SATCOM Working Group.

  255. George Tilton says:

    @Victor,

    Thanks!

    I will google that now that I have a title.

  256. TBill says:

    @Peter Norton
    In case you are interested, I have very short YouTube showing how easy it would be to isolate LEFT BUS to depower SATCOM. I made the video a few months ago for Jeff Wise, in his podcast he told listeners this was a very difficult task. You be the judge.

    https://www.youtube.com/watch?v=SmP1t2cOTJk

  257. DrB says:

    @All,

    Measuring the slope of the pre-compensation Doppler shift imposed on the AES uplink transmitter frequency is possible during several periods when a sufficient number of independent BFO measurements were made in rapid succession during Flight MH370.

    These periods occurred circa 18:40 and 23:15 UTC.

    The observed BFO slopes are unexpectedly large, causing saw teeth to appear in the observed strings of BFOs in three MH370 and MH371 cases I have studied. Three effects are observed in each BFO sequence. First, there are discontinuous steps in frequency of about 5.5 Hz. These appear to be due to the SDU using a nominal range rate variable which is quantized in units of 1 m/s. Second, these steps occur about 5.5 times more frequently than one expects (due I think to a coding error in the SDU). This conclusion is based on the predicted pre-compensation Doppler slope during the MH371 example when we have simultaneous recorded data for track, speed, altitude, ROC, etc. Third, the exaggerated slope in the BFO data does not accumulate a large BFO error, because the 5.5 Hz steps occur whenever the accumulated error reaches 5.5 Hz, triggering a reset to a small error and creating the “steps”.

    The steps seen in the BFOs can occur in less than 0.2 seconds, demonstrating they are not due to actual aircraft acceleration or to thermal effects in the OCXO used to establish the base transmitter frequency.

    All the examples I have studied appear consistent with this model of frequency control in the SDU.

    While I believe the SDU code contains an error, the fact that it exaggerates the BFO slopes is a blessing in disguise. That allows me to measure very small Doppler frequency slopes, and this fact allows me to place rather tight constraints on the aircraft accelerations during the two MH370 phone calls. These constraints then make it possible to discriminate certain routes at those times.

    My theory of how the SDU actually works is unproven. It is a logical explanation for the observed behaviors. I note that we don’t need to recover any part of 9M-MRO to test this theory. All that is needed is to inspect the code listing for the SDU software version used by 9M-MRO, which should still be available today from the manufacturer. I leave this exercise to others.

    To figure the constraints on the aircraft accelerations during the two MH370 phone calls, I first need to estimate the error in the observed BFO slopes. At 18:40 the observed “baseline” BFO is 88.9 Hz and the slope is -103 Hz/min. At 23:15 the observed baseline BFO is 219.5 Hz and the slope is -14.9 Hz/min. Correcting for the slope error factor of 5.5 X, the observed BFO slopes were actually -18.7 Hz/min at 18:40 and -2.7 Hz/min at 23:15. Based on the sensitivities observed when fitting a sawtooth waveform to the measured BFOs, I estimate the fitted period of the sawtooth waveform cannot be in error by more than +/- 10%. That, in turn, constrains the slope error to also be +/- 10% of the measured slope. Therefore, at 18:40 the actual BFO slope error is +/- 10% of -18.7 Hz/min or +/- 1.9 Hz/min. At 23:15 the slope error is +/- 10% of -2.7 Hz/min or +/- 0.3 Hz/min.

    In order for a MH370 route to be consistent with these constraints, at 18:40 the predicted BFO must match 88.9 Hz within about 3 Hz (at one sigma) and the BFO slope must be consistent with -18.7 Hz/min +/- 1.9 Hz/min. Thus, the BFO slope should probably lie between -16.8 H/min and -20.6 Hz/min.

    At 23:15 the BFO must match 219.5 +/- 3 Hz (one sigma) and the BFO slope is expected to lie between -2.4 Hz/min and -3.0 Hz/min.

    I will address the 23:15 case first, because it is simpler to analyze, with no expected or proposed major turns or climbs. The first question is, what limits can be placed on LNAV routes in terms of ground speed changes or track changes?

    For the UGIB (2020) route at 23:15, which is on a track of exactly 180 degrees at LRC at FL390, I predict a BFO of 218.4 Hz and a nominal uplink Doppler rate of -2.7 Hz/min. Thus, both 23:15 route conditions are easily satisfied by the UGIB (2020) route. Next, I evaluated the sensitivity of that route in terms of track change (true bearing rate) and speed change. The sensitivity is ¼ kt/min of speed change per -0.3 Hz/min in nominal uplink Doppler. Therefore, the acceleration in ground speed is very tightly constrained to be a fraction of a kt/min. Certainly, no manually-induced or even FCS-induced speed setting changes were underway at 23:15. The ground speed was remarkably constant during the phone call then. The sensitivity to track changes at 23:15 is +0.025 deg/min per 0.3 Hz/min. Therefore, the track bearing was also remarkably stable at 23:15, changing by less than 0.025 degrees during the phone call.

    The next question is do other proposed routes also satisfy the 23:15 BFOs and slope?

    I analyzed two cases. First, I looked at the “39S Route” flying a geodesic with an initial bearing of 191 degrees at 19:41:03 from 3.50S 93.28E at a ground speed of 482 kts at FL360. The predicted location at 00:11 is near 38.88S. At 23:15 this route had a predicted BFO of 226.9 Hz, which is 7.4 Hz, or more than two sigmas, above the predicted value. This is a very unlikely match. The predicted nominal Doppler slope with no accelerations is -3.0 Hz/min, which is a reasonably acceptable match to the observed value of -2.7 Hz/min +/- 0.3 Hz/min (at one sigma). Next, I analyzed the Doppler rate due to the changing track of the geodesic route (which is about 0.018 deg/min). This bearing rate induces a nominal Doppler rate of about -0.3 Hz/min, so it is not possible to exclude this route based solely on the Doppler slope. Its two main deficiencies are the poor BFO match and a lack of fuel.

    Second, I looked at a 186 degree route, ending near 36.61S at 00:11, starting at 0.77S 93.63N at 19:41:03, and flying at FL390 with a constant ground speed of 480 kts. The predicted 23:14:30 BFO for this route is 223.4 Hz at 29.14S 90.37E at a bearing of 186.867 degrees. The predicted BFO is 3.5 Hz high, which is acceptable. During one minute of flight the geodesic’s bearing increases from 186.867 to 186.876 degrees. The predicted nominal uplink Doppler slope is -2.7 Hz/min, which is quite acceptable. The sensitivity to speed changes is the same as the 180 degree route, being about ¼ kt for a -0.3 Hz/min slope. The sensitivity to bearing changes for the 186 degree route is also nearly identical to the 180 degree route, being about +0.025 deg/min per 0.3 Hz/min. The changing geodesic route bearing is only about +0.009 deg/min at 23:15, so one can’t distinguish between a 186 degree True Track path or a geodesic by using the Doppler slope method.

    To summarize, assuming my theory of the SDU coding errors is correct, the 23:15 BFOs imply a bearing rate limit of 0.05 deg/min and a ground speed acceleration limit of 0.5 kts/min, both at two sigmas. The 180 and 186 degree routes fit the BTOs, BFOs, and the 23:15 BFO slope very well. The 191 degree route has a large, and therefore low probability, BFO error at 23:15, but it fits the BTOs and the BFO slope acceptably well.

    It is clear, because of the very low speed change and bearing change limits, the aircraft was being autopiloted and probably was following a true track or LNAV geodesic route with normal automatic cruise speed control. No turns or climbs/descents were underway then. I also doubt the aircraft was in a constant heading mode for lateral navigation. Certainly, this would not be sufficiently stable in bearing to demonstrate such tiny BFO slope errors.

    There is the question of whether a magnetic track route can be excluded. A magnetic track route is highly unlikely for two reasons: (a) the BTO/BFO residuals don’t match the data nearly as well as the “straight” routes, and (b) the true bearing in the SIO would change rapidly with location. For example, the UGIB (2020) route has a magnetic declination which changes by 8 degrees between the 23:15 and the 00:11 locations. That is an average rate of 0.143 deg/min, which is equivalent to a BFO slope of +1.7 Hz/min. This high positive slope is well outside the measured slope of -2.7 +/- 0.3 Hz/min. Therefore, I can say with confidence that the MH370 BFOs at 23:15 are incompatible with constant heading (either true or magnetic) or magnetic track navigation.

    The MH370 route possibilities at 18:40 are more complex because of potential descents and/or turns. I’ll post my analysis of that data when it is complete.

  258. Viking says:

    @Niels and @Victor Iannello

    I have spent most of the day preparing 4 files with illustrations that I can upload for further discussion. Please tell me where you would like them.

    1) Overview picture showing where the different evidence is collected (PDF around 150kB)
    2) Interactive Powerpoint presentation illustrating results from the low flying Chinese IR satellite (2.5MB)
    3) Picture from Himawari-7 (relatively poor quality) showing the 3 contrail segments. The U-turn is also left as a faint ecco near the NW corner in agreement with the Chinese data (PDF around 150kB)
    4) Interactive Powerpoint presentation illustrating results from Meteosat-7 near Bandar Aceh @22:00. Here you can see a faint white IR contrail from the north leading into the the fall streak hole in the middle, followed by the black contrail leading to Bandar Aceh. I use the near-IR picture as a reference. Due to lots of water vapor in the muggy night near the equator, the near IR only shows contrail evidence when the airplane is flying high (beginning and end). Actually it is possible to see the airplane starting its dive and retuning to normal height after Aceh (new to me). This file is around 2MB.

    Both interactive files are userfriendly, since you only need to push ‘arrow down’ to toggle with the speed you prefer.

  259. Andrew says:

    @TBill

    For what it’s worth, your video appears to show a fault in the software modelling. The EICAS messages that appear in the video when the left AC bus is isolated include HYD PRESS DEM L. That is not correct; it should read HYD PRESS DEM R. The left hydraulic system demand pump is powered by the right AC bus, while the right system demand pump is powered by the left AC bus.

  260. TBill says:

    @Andrew
    OK thank you. That would be PMDG777 issue. But they were close, it sounds like. I am using the so-called STEAM version I do not know if they keep it current.
    What is the implication of losing that hydraulic system?

  261. Mick Gilbert says:

    @ventus45

    I estimate that the turn away from VAMPI commences around 10nm before the waypoint, at about 6°3’37″N, 97°42’01″E.

  262. TBill says:

    @DrB
    OK I am listening…

  263. Ventus45 says:

    @Mick Gilbert

    Thank you for that position.

  264. Andrew says:

    @TBill

    RE: “What is the implication of losing that hydraulic system?”

    The hydraulic system is not lost in this scenario. The L & R hydraulic systems each have two pumps: an engine driven pump that operates whenever the respective engine is rotating, and an electric pump that operates when system pressure is low or when the control logic anticipates high system demand (take-off and landing, for auto speedbrake operation and braking). In this scenario, the R demand pump is inoperative but the associated engine driven pump is operative.

    The L & R system demand pumps don’t normally operate during the cruise, so the loss of the R system demand pump has no consequences for the cruise phase unless the associated engine driven pump or engine were to fail. In that event, the R system would be lost, but the other hydraulic systems would provide enough redundancy to keep all the flight controls powered, except for two spoilers (#3 and #12 on the L and R wings respectively).

    On reflection, there are two problems with the sim software. It not only shows the wrong hydraulic pump as inoperative, it also displays an EICAS alert when there shouldn’t be one. The HYD PRESS DEM L/R EICAS alert should only be annunciated when the pump output pressure is low and the pump is commanded on. The pump shouldn’t be commanded on in this scenario, so there shouldn’t be any associated EICAS alert. There would (I think) be a status message on the lower EICAS.

    You might notice another EICAS alert: HYD PRESS PRI C1, which indicates the Primary C1 pump in the centre hydraulic system is inoperative. Again, that has no consequence during the cruise. The centre system has four pumps, two electric primary pumps that operate continuously and two air-driven demand pumps that operate during periods of high demand. If one of the electric pumps fails (in this case the C1 pump), the remaining pump continues to pressurise the system, with assistance from the demand pumps as required.

  265. TBill says:

    @Andrew
    Thank you very much for that explanation. Interesting to hear low consequence during flight. LEFT BUS isolation is almost essentially how to turn off SATCOM and not have any other issues. At IGARI, I personally suspect more power was cut off, but certainly LEFT BUS off is apparent minimum requirement.

  266. DrB says:

    @All,

    1. In order for a MH370 route to be consistent with the satellite data constraints, at 18:40 the predicted BFO must match 88.9 Hz +/- 3 Hz (at one sigma) and the predicted nominal Doppler slope must be consistent with -18.7 Hz/min +/- 1.9 Hz/min (at one sigma). Thus, the nominal Doppler slope should lie between -16.8 Hz/min and -20.6 Hz/min (at one sigma, or with a 68% probability).

    2. The UGIB (2020) MH370 Route at 18:40:00 has the aircraft near 7.52N 94.57 E on a 270 degree course while descending at 1,800 fpm and at 250 KIAS at a Flight Level of 203. The predicted BFO then is 86.7 Hz, which is an acceptable match. Thus, both the BTOs and the BFOs circa 1840 are good matches to the Inmarsat data [as previously demonstrated in UGIB (2020)]. What about the Doppler slope at 18:40? Does it match the apparent -18.7 Hz/min?

    3. The answer is “yes” because the predicted nominal Doppler slope for this route is -17.1 Hz/min. That is close to the “observed” value (after correction for the scale factor error in the SDU) of -18.7 Hz/min. Therefore, the predicted Doppler slope for the UGIB Route lies within the one-sigma error bars, indicating good agreement.

    4. So, there is no discrepancy in the UGIB (2020) route at 18:40 in terms of matching all three observables (BTO, BFO, and nominal Doppler slope). An exact match to the observed Doppler slope occurs when the ROD is 1,980 fpm, but this produces a mismatch in BFOs. The optimum combination of Flight Level and ROD occurs at FL = 271.8 and ROD = 1,711 (when the course is 270 degrees).

    5. The UGIB (2020) route circa 18:40 is in a FLCH descent at 250 KIAS while tracking at 270 degrees. Note that, as the aircraft descends, the true air speed decreases with time because of the increasing air density. The TAS change over one minute depends on the Flight Level. The Flight Level is also decreasing with time because of the descent. So, here we have a situation wherein the descent rate is primarily constrained to make the BFOs match, because the BFO is highly dependent on the ROD, whereas the nominal Doppler slope does not depend at all on the ROD, since the SDU ignores vertical speed. So, circa 18:40 we have a fairly accurate estimated position, and we know the airspeed is close to 250 KIAS. The ROD may then be determined to make the BFOs match, given a course, and the Flight Level will determine the rate of change in true air speed during the 1-minute phone call. So, we see that the observed BFO slope provides some additional information about the Flight Level. There is an assumption here that we know the course (bearing). If I use 270 degrees, per UGIB, then I find the following at 18:40:00:

    Latitude 7.52 N
    Longitude 94.57 E
    Track 270 degrees
    Calibrated Air Speed 250 KIAS
    Delta SAT 10 C
    True Air Speed 345 Kts
    ROD 1800 fpm
    Flight Level 203 hft
    Predicted Nominal Uplink Doppler 558.2 Hz
    Predicted BFO 86.7 Hz

    6. At 18:41 I predict the following:

    Latitude 7.52 N
    Longitude 94.47 E
    Track 270 degrees
    Calibrated Air Speed 250 KIAS
    Delta SAT 10 C
    True Air Speed 335 Kts
    ROD 1800 fpm
    Flight Level 185 hft
    Predicted Nominal Uplink Doppler 541.1 Hz
    Predicted BFO 86.9 Hz

    7. Both BFOs are within 2.2 Hz of the measured “baseline” BFO value of 88.9 +/- 3 Hz. Therefore, the BFOs are an acceptable match.

    8. The predicted nominal Doppler slope is (541.1– 558.2) = -17.1 Hz/min, which is a good match to the “measured” value of -18.7 Hz/min +/- 1.9 Hz/min.

    9. So, we see that no adjustment in the proposed UGIB route is needed to match the BTOs, the BFOs, and the nominal Doppler slope.

    10. I can get acceptable matches to all observables for courses from 240 degrees to 300 degrees, but some bearings in this range have abnormal descent rates. For example, the ROD at 240 degrees bearing is only 930 fpm, which is abnormally low. At 300 degrees bearing the ROD is 2,400 fpm, which is abnormally high. At 2,000 fpm the best-fit course is 282 degrees with FL = 241. At 1,800 fpm, the best-fit course is 273.6 degrees with FL = 259. At 1,600 fpm, the best-fit course is 266 degrees with FL = 301. At 270.0 degrees course the best-fit ROD is 1,711 fpm with FL = 272. Therefore, the course can’t be far from due West in order for the ROD to be in the “normal” range circa 1,700-2,000 fpm.

    11. The nominal uplink Doppler slope observed at 18:40 of -18.7 Hz/min cannot be matched by level flight or any climb or descent in level flight. There must be an acceleration occurring to cause the nominal uplink Doppler slope to become significantly more negative over time.

    12. For example, level cruise at a bearing of 205 degrees provides an excellent match to the BFOs, but the nominal Doppler is only -3 Hz/min. Therefore, the benefit of knowing that the Doppler slope is much larger than 3 Hz/min then is that ALL routes with constant track and constant speed may be excluded at 18:40.

    13. One way to match the Doppler slope is through an ongoing deceleration. One possibility is to undergo a slow-down of -16.6 kts/min on a track at 202.6 degrees, with no turn and no descent. But why would the aircraft be slowing down in level light? This does not make sense. There are more probable solutions which do not require “non-standard” flight.

    14. It is a necessity for the aircraft to slow down during a significant descent from cruising altitude. The UGIB Route demonstrates how a significant Doppler slope is created during a descent because the aircraft is slowing down (not because it is descending). We already know that if we only need to match the BFO value, then one cannot distinguish bearing and ROD. One bearing with no ongoing descent can match the BFO. A different bearing with an ongoing descent can also match the BFO just as well. However, those two cases will have very different Doppler slopes. Only the descent case will have a large-magnitude Doppler slope, because of the deceleration in horizontal speed which occurs at constant KIAS.

    15. There is only one other option left to explore. Consider an ongoing turn at 18:40. What turn rate would produce a matching Doppler slope, and is this a reasonable value? One can get a good match to all observables with a bearing which is 205.2 degrees at 18:40 and 203.8 degrees at 18:41. That is a (left) turn rate averaging only 1.4 deg/min over one minute. This turn rate is much too slow to be a standard turn, and it is much too high to be induced by a constant-heading or a magnetic track mode. Therefore, I conclude that a normal ongoing turn or choice of lateral navigation mode cannot match both the Doppler slope and the BFOs circa 18:40. Only an ongoing (standard) descent can do that,

    16. If one assumes the aircraft is being flown in a standard manner, regarding autopiloted turns and descents, the only match to all the data circa 18:40 is an ongoing descent with a slow-down in true air speed while on a westerly course, as proposed by UGIB.

    17. Southwesterly routes using standard lateral navigation and with no descent cannot match the 18:40 Doppler slope and are therefore excluded.

  267. Victor Iannello says:

    @DrB: One possibility is the descent at 18:40 was not in FLCH mode but in VS mode, which means there was thrust added to match the MCP speed and the descent rate was controlled with the elevator. This could explain the low variation in BFO values compared to what was seen during the descent of MH371, as the vertical speed is directly controlled, and the vertical speed has a large influence on the BFO.

    Why would the pilot choose a VS descent rather than FLCH? Well, if the cabin was depressurized, a rapid descent would rapidly increase the pressure, and this would hurt the pilot’s ears because of the differential pressure across their ear drums. By lowering the descent rate, it gives more time for the differential pressure to equilibrate, and there is less pain.

    Private pilots in unpressurized cockpits understand that high descent rates lead to ear pain. With passengers onboard, descent rates are typically limited to around 500 fpm, which also means the descent angle can be quite shallow for faster planes. An experienced pilot can tolerate higher descent rates, but the VS mode would still reduce the pain.

  268. Viking says:

    @Victor Iannello

    Since you did not come up with any suggestions to where I could upload the four files, I decided to do something different today. Inspired by observation of black contrails through thin clouds, I tried looking for shadows of the contrails I found near Christmas Island. The visible contrails are difficult to see, so few people believed me. However, what about the shadows?

    I used the IR camera in Meteosat-7 as a thermal camera. It is somewhat cumbersome, but it produced beautiful black contrail shadows on top of the cloud cover. In some places, the original white contrail is also visible.

    This opens a completely new possibility. By simple measurement of the distance to the shadow combined with knowledge of the solar height it is possible to calculate flying height, above the (relatively low) cloud cover. Hereby, I have now shown that the flight height decreased from 8.5 km near Christmas Island to 0 km when the second engine flamed out. Simultaneously the speed fell to below 400 km/hour. I guess the clouds were at around 2 km, so the total height is close to my original estimate (11 km).

    I cannot imagine any pilot would allow such a scenario without immediately turning around and try to land at Christmas Island. Since no other airplanes were lost that night, there is only one possible explanation. The contrails were from MH370.

    Now I guess you would like to have the original Meteosat-7 IR data. Send me an email and you will get the two relevant files (500KB each).

  269. DrB says:

    @Victor Iannello,

    It is possible to match the average of the 18:40 BFOs with a 500 fpm ROD, a course of 215 degrees, and a Flight Level circa 250. However, the nominal Doppler slope is only -5 Hz/min, which is far short of the -18 Hz/min needed to match the observed saw teeth in the BFOs.

    As I said before, the only “standard” flight maneuver which provides the correct Doppler slope is a slow deceleration, but at 500 fpm that deceleration is still far too low. I don’t know any other method of matching the Doppler slope than the deceleration occurring during a circa 1,800 fpm ROD at constant KIAS. I’m happy to evaluate all suggestions, but 500 fpm does not match. One needs about -10 kts/min in ground speed to produce the apparent Doppler slope.

  270. Mick Gilbert says:

    @DrB

    Bobby, regarding “46. There is no evidence of any ongoing climb, turn, or speed change occurring at 23:14 during MH370 or at 04:29 during MH371.” above, how can you be sure about that for MH371?

    There are a series of six position reports in the 04:29:19 – 04:30:13 transmission, covering 04:04 – 04:29 in five minute intervals. The aircraft most definitely makes a heading change in the course of that 25 minute period preceding the transmission. There’s also evidence of minor ground speed fluctuations up to about 3 percent during that period.

    https://www.dropbox.com/scl/fi/vt6khdr2rsyj2ykcx0p4q/MH371-04.04-04.29-position-reports.-jpg?rlkey=eodovmo4gao3be4yqkatktkb3&dl=0

    At the time the transmission is being sent the aircraft is some 90-odd nm south-south-west of Hong Kong. I don’t think that you can eliminate the possibility that the aircraft was at that time turning right towards one of the waypoints on the HK/Sanya FIR boundary. (Andrew might have a view on this.)

    Separately, there appears to be a lot predicated on there being an SDU coding error. If there was not the sort coding error you envisage, what are you left with?

  271. DrB says:

    @Mick Gilbert,

    A plot of the MH371 ACARS latitudes and longitudes from 04:24:01 to 04:39:01 fall on a “perfect” straight line with a fitted R^2 = 0.9999. Therefore, there is no evidence for any course change in that time period. The reported altitude is unchanging at 40,000. The CAS during this period varied from 250.4 to 253.8 kts. Therefore, there were no turns, no climbs, and only small air speed changes, and these were even smaller in the one-minute period from 04:29 to 04:30.

    The SDU coding error produces a very unusual signature. It is highly distinctive in both amplitude and period. I doubt there is a different type of error which would have the same “signatures” in the three cases I studied but which would be somehow incorrectly corrected in any of them by the method I used.

    If someone could get the code listing from the vendor, we would soon know whether or not my explanation for the unexpected BFO behavior is correct.

  272. Viking says:

    @Mick Gilbert

    It is no surprice there are a couple of heading changes for MH371 near Sanya. The reason is they not allowed to fly near the large Chinese Navy base in Sanya.

  273. Victor Iannello says:

    @DrB: I am not suggesting that the descent was at 500 fpm. I understand that does not match the BFO. I am trying to give a rationale for a VS descent rather than an FLCH descent to produce a fairly steady vertical speed to match the fairly steady BFOs.

  274. Victor Iannello says:

    Viking said: Since you did not come up with any suggestions to where I could upload the four files, I decided to do something different today.

    I did not think you were serious when you asked me this. A simple Google search shows that there are so many possibilities: Dropbox, Google Drive, One Drive, Box, and others.

  275. Andrew says:

    @Viking

    The area in question is inside the Hong Kong FIR. It is nowhere near the PLA-N base located near the city of Sanya at the southern end of Hainan Island.

  276. Andrew says:

    @Mick Gilbert

    Aircraft normally enter the Hong Kong FIR from the Guangzhou FIR at a designated waypoint. Once picked up by Hong Kong ATC, overflying aircraft are often cleared direct to a waypoint on the ‘exit’ side of the Hong Kong FIR, subject to traffic.

    I don’t know what route MH371 was flying, but from the chart you posted it looks as though the aircraft was tracking direct to IKELA. There are no routes any further West of IKELA, so a right turn doesn’t look very likely.

  277. Mick Gilbert says:

    @DrB

    Thanks Bobby, yes, I can see that now.

    Are you seeing similar saw-toothing in the BFOs for the 04:49-05:00 transmission when MH371 is established on L642?

  278. Mick Gilbert says:

    @Andrew

    Thanks for that Andrew. Somewhat dimly, I had not accounted for the position reporting subsequent to the 04:29-04:30 transmission. From those it appears that the aircraft eventually joined L642 and crossed the FIR boundary at EPKAL.

  279. Andrew says:

    @Mick Gilbert

    EPKAL/L642 makes sense. Aircraft headed to Singapore/Kuala Lumpur/Ho Chi Minh from the Hong Kong area normally go that way.

  280. TBill says:

    @Victor
    Is there a way to mitigate the ear pain on descent such as ear plugs? Do military pilots have that issue?

    Anyways, interesting idea. But I apply it differently. Right now my flight path is level at 1840 (turn southerly). I have long considered 400-ft/min descent after twilight and before 2314 call. Previously I had no particular reason for slower than FLTCH other than it fit the data depending on scenario.

  281. DrB says:

    @Mick Gilbert,

    There is only one BFO in the MH371 period from 04:49 to 05:00, so you can’t possibly discern a sawtooth then.

    However, from 05:29:16 to 05:30:17, 132 BFOs were recorded, maybe half of which are independent (per Don Thompson). A plot of the next dense grouping of MH371 BFOs circa 05:29 is available here.

    This plot again shows the saw teeth. The first two cycles are quite plainly seen. The third cycle is muddled, perhaps by changes in the actual uplink Doppler. A vertical speed of only 1 m/s will induce a BFO shift of a better part of 5.5 Hz. So, there might have been some turbulence circa 05:30:00 that distorted the third cycle of the sawtooth waveform in the BFOs.

    @Victor Iannello,
    @Andrew,

    How is the desired vertical speed entered for VS descent mode?

    What is the minimum resolution, or step size, in entering the vertical speed?

  282. Victor Iannello says:

    @DrB: You dial in the vertical speed on the MCP in increments of 100 fpm, in parallel with an airspeed setpoint.

    Using FLCH, the thrust is full for a climb and idle for a descent, and the elevator controls the airspeed. In VS mode, the thrust is adjusted to control airspeed and the elevator controls vertical speed. This means that if a sufficiently high VS is selected for a climb, the speed will decrease towards stall. Similarly, if a sufficiently high VS is selected for a descent, the speed will increase towards overspeed. I think for large altitude changes, it would be rare to use VS for the climb or descent. But considering the stability of the BFO values, and the potential to slow the descent to mitigate ear pain, I thought the VS mode might have been selected at 18:40.

  283. airlandseaman says:

    Re ear pain…The relatively rapid depressurization circa 17:21 was probably an ear issue too. I believe the plane was probably repressurized circa 18:23, when the Left Main AC bus was repowered, and the altitude was probably still closer to 40K ft. Of course, these are still “working assumptions” until Thales or Honeywell, or Inmarsat confirm the SD-600 Update rate and Step Size. In addition, we need to understand the algorithm (firmware filter) that takes as input the raw nav data updates and drives the Doppler Synth.

  284. Andrew says:

    @DrB
    @Victor

    Adding to Victor’s comments re FLCH SPD mode, the autothrottle advances or retards the thrust levers to provide 500 FPM vertical speed for each 1000 feet altitude change, and the AFDS attempts to reach the MCP selected altitude within two minutes if able. Otherwise, the autothrottle uses idle or climb thrust to reach the MCP selected altitude.

    I agree that it’s rare to use VS mode for large altitude changes, but it’s certainly possible, particularly if the pilot wants to limit the rate of descent, for example. It’s also rare to use VS mode for a climb, because of the risk of speed decay if the pilot sets a rate of climb that is too high for the available thrust.

  285. Andrew says:

    @TBill

    The most effective way to mitigate against ear pain on descent is to use the valsalva manoeuvre, which is usually done by closing one’s mouth and pinching one’s nose shut while expelling air, as if blowing up a balloon. The increased pressure inside the airway then forces air into the Eustachian tube, equalising the pressure on either side of the eardrum. Yawning can also help equalise the pressure by opening the Eustachian tube. That’s why it’s very important not to fly with a head cold, because the Eustachian tube can become blocked by mucus, which prevents the pressure equalising and can lead to eardrum rupture.

    Military pilots suffer the same problem, but they are trained how to use the valsalva technique to keep up with the pressure changes.

  286. DrB says:

    @Victor Iannello,
    @Andrew:

    Thank you for addressing my question.

    If my BFO analysis is correct, at 18:40 the ROD must have been close to 1800 fpm. If so, then why would a pilot who desired such a (high) descent rate ever use VS rather than FLCH? There would seem to be no significant advantage in this case.

    The relatively benign change in the 18:40 BFO baseline, after removing the saw teeth, has always been a concern for FLCH mode. However, personal experience in commercial airliners demonstrates a wide variety of bumps and lurches during descents. Occasionally the descent is very smooth, with no discernible turbulence. Maybe a similarly stable atmosphere explains the steady BFO baseline seen at 18:40, even if using FLCH.

    I am also thinking that the pilot might have been anxious to restore atmospheric pressure after laborious breathing using the supplemental oxygen mask for more than an hour. That might have motivated a high descent rate, despite ear pain, after diversion and depressurization circa 17:21.

    Another motivating factor might be the pilot’s desire not to overshoot IGOGU for the south turn, while still passing under the minimum flight level for N571. You could not do both using a 500 fpm ROD after the right lateral offset was completed.

  287. Victor Iannello says:

    @DrB: If the descent was started at cruise altitude, a more typical FLCH vertical speed at the top of descent might be around 2,400 fpm, so setting the vertical speed to 1,800 fpm might have been less painful at the start of the descent.

    Certainly, the turbulence caused by convection is much less at night than during the day, so perhaps that partially explains the steady BFO.

    I never proposed a long 500 fpm descent. It doesn’t match the BFO and it would be way too shallow for an airliner. I only referenced it because a pilot in an unpressurized plane might limit a descent rate to 500 fpm as a courtesy for passengers. I know for me flying alone, my descent rate is limited more by concerns I have about shock cooling the engine.

  288. David says:

    All. Malaysia now expects OI search proposal early May. Search area apparently undecided as yet:
    https://www.thestar.com.my/news/nation/2024/03/23/ocean-infinity-wants-another-crack-at-finding-flight-mh370

  289. Joseph Coleman says:

    @ David
    If Malaysia are to accept a Search, it might possibly involve finishing off anything left over or overlooked due to difficult Terrain in the original search area, however minute that may be, so they can be sure it’s not there, as a lot of work went into it previous. Then look at scanning elsewhere. Would be nice to see both @DeepSeaVision and @Ocean_Infinity and anyone else willing to Search, work together not competitively. It would be important to find Answers by working together.

  290. TBill says:

    @Re: Victor
    Those with long memories may recall Victor has one very early flight path memo 180S w/ 100-ft/min descent for the whole flight. Good memo actually, as most all are.

  291. Victor Iannello says:

    @TBill: Thank you for reminding me of that paper from 2016, which can be downloaded here:

    https://www.dropbox.com/s/zynbvxyv22r49ny/2016-06-25%20Possible%20MH370%20End%20Point%20North%20of%20Search%20Zone.pdf?dl=0

    Using a magnetic heading of 180S, a descent of 100 fpm (the minimum possible via autopilot), and a speed of M0.84/310 KIAS, it’s estimated that the plane would cross the 7th arc at 31.5S latitude. The descent is required so that below the altitude cross-over of 31,560 ft, the TAS (and GS) continuously decrease as the flight path curves to the east due to winds and magnetic declination.

  292. Joseph Coleman says:

    @Anyone

    Do you ever think all the dark Blue areas outside the Box from the Bayesian will ever be searched. Imagine searching elsewhere and then in many years time finding the Wreckage there. I suppose the more that take part in searching the quicker of eliminating certain areas.

  293. flatpack says:

    @Mick Gilbert

    You asked “What makes you think that you can direct a satellite call to the pax cabin? Do you think it’s set up like an extension?”

    I think that both the cockpit and cabin telephony units can make calls and receive calls made to the aircraft. If seat-side handsets were fitted and enabled (which they were not) then first class pax could also have made calls using their credit cards. I seem to remember that the SDU itself could handle up to five simultaneous calls.

    To answer your question, I do not think that you can direct a satellite call specifically and solely to the pax cabin, which is why I speculated that MAS ops staff had made two calls simultaneously.

    But I could be wrong.

  294. Niels says:

    @all
    A major issue in defining the search area for MH370 is properly estimating the available fuel amount at 19:41 UTC, which is important for selecting feasible flight paths from 19:41 – 00:19 UTC. Attached a summary of the approach I have been developing focusing on the interval 18:30 – 19:41. This will be part of the bigger paper I’m working on, based on analyzing 20 million (TT + GC) random generated possible flight paths. Comments and suggestions are welcomed.

    https://www.dropbox.com/scl/fi/k303ha1uh9llai7tdu7ka/MonteCarlo_v10.pdf?rlkey=b1hlxbtf27ecd9voumb1ail4o&dl=0

  295. TBill says:

    @Niels
    Thank you for the paper. This is also a focus of mine. I currently make the assumption that fuel efficiency was a high priority. I want to go back to 1720-1825 period to see what the minimum fuel (worse case) use might have been. I tend to assume MRC/high altitude for the portion you are looking at. I believe it is possible Rt GEN was disengaged at IGARI (DFDR off and save fuel). I consider the goal may have been fuel remaining Arc7 (after SATCOM Off), if we had a case of intentional hiding of aircraft.

  296. Niels says:

    @TBill
    You said: “I tend to assume MRC/high altitude for the portion you are looking at.” Do you typically combine that with a rather southerly 19:41 location then?

  297. Don Thompson says:

    @flatpack, @mick Gilbert

    Ground to air SATVOICE calls may be addressed and routed within the SDU by ‘called terminal ID or by ‘Q No‘. The latter is a priority mechanism.

    In the case of all three ‘Call Announcement signalling units transmitted from the GES to 9M-MRO, two at 18:39 and one at 23:13, the called terminal ID was defined as ’00’ and the Q No/priority (10/0xAh) is translated as ‘Other “safety” C channel request/assignment signalling.

    The implication of both these parameters, called terminal ID and Q No. is that the call would be routed to the Audio Management Unit, with a call alert within the flight compartment only.

  298. flatpack says:

    @Don Thompson

    Thanks for that.

    Do you have a view as to why there were two calls made simultaneously?

  299. TBill says:

    @Niels
    I favor the nominal 180S path at the start which vary from approx. 0 to 3N at 1941. I favor approx. 1.5N at the moment. In any case, the 180S path requires some “loiter” or delay, which I believe may have been going around Indonesia FIR but at some point approaching ISBIX for the FMT turn south. I am similar to UGIB except the report opts for descent/slowdown, but I believe the UGIB report notes that there is choice for high altitude fly around with similar fuel consumed. I also question the right offset from N571, I think it could have left offset to ANOKO. I can go either way on it, but why is MH370 wasting fuel/time to jog North? I am saying the deliberate hide case is save fuel. Also I question LRC speed to Arc7. Hitting Arc2 at 0-1N allows MRC cases. Note that the deliberate case allows maneuvers before Arc6.

  300. TBill says:

    @All
    I recently put together a 60-sec video on YouTube to show the MH370 IGARI FlyBy as discussed recently by Mentour Pilot…previously @sk999 has a 2020 report and 2023 YouTube video, I believe Victor covered in 2019. Apparently at the instant IGARI was reached, and BITOD was the next waypoint, is when the Xponder was turned off, incompletely for a moment. This video is just supplemental and it attempts to show exactly how the pilot would experience waypoint changing at IGARI.

    https://youtu.be/GeO6eEMdAdk

    (caution always rely on real MH370 data for exactness, the PMDG777 simulator is just a reasonable facsimile but does not cut corners exactly the same etc.)

  301. George G says:

    @Niels,

    Your Comment#36390 of March 26, 2024 at 3:02 am

    In the attachment you wrote:

    “Fuel amounts saved at descent and
    consumed extra to ascend back are assumed to more or less cancel each other.”

    This seems a bit like getting something for nothing.

    The assumption would result in a slightly relaxed constraint on fuel available for the remaining flight.

  302. ventus45 says:

    @Niels

    I think you will find that there is a significant net loss in both time and fuel for a given distance in a descent / climb scenario for MH370.

    The only way I can conceive to make it ‘equalish’ would be to have an aircraft that had a low idle descent rate and a very low idle descent fuel flow rate as well, coupled with a very rapid climb rate at a moderate climb fuel flow rate (both relative to maintaining level cruise flight values).

    This requirement is more consistent with a powered glider than an airliner.
    The U-2 might just manage it, but I doubt any airliner would even come close.

    (@TBill)
    Perhaps you could simulate a descent from say FL350 to FL200 and then an immediate climb back up to FL350 (recording the details of ROD, time, distance and fuel for descent, and ROC, time, distance and fuel for ascent), then compare the results to maintaining FL350 cruise for the same distance ?

    The figures would be very interesting. I have a BOE gut feeling the fuel loss could be more than 50 percent, and the time/distance made good loss could be more than 10 percent.

  303. Niels says:

    @GeorgeG, Ventus45
    It is a good point to consider more in detail. My approach was to find an upper limit to available fuel and rather be a bit generous (not to cut out paths that could potentially be relevant) given also possible error margins in the overall fuel consumption modelling. It is interesting to compare my table 2 with table D.1 of UGIB to have some reference.
    The biggest issue(s) are actually for those lat/lon points where I have extreme low FLs (like 100). For most of those there is a considerable “overshoot” as the 18:30 and 19:41 positions are too close -> the straight line connection is really very hypothetical there. Also, for holding configuration, the fuel consumption per unit time is lower at FL200, so I’m considering to apply that as a FL lower limit for all 19:41 positions (as I was trying to estimate the most fuel efficient way to connect 18:30 to 19:41).
    Note that the descent/climb considerations are less of an issue towards the southerly 19:41 positions, which are most relevant for the southerly cut-off of 7th arc positions.

  304. Niels says:

    @TBill
    MRC paths at around 180 deg TT occur in my calculations, however not in high numbers / probability, please see link. I mainly see LRC and ECON modes, some M082 and M084, and MRC at low intensity.

    https://www.dropbox.com/scl/fi/1tvkfpubmnrr3jjw5ausi/Thrust_Modes.pdf?rlkey=l4q1fou6rg9yut4iqc0xetrcm&dl=0

  305. TBill says:

    @Niels
    Are you assuming no pilot maneuvers to Arc7?

    @Ventus
    UGIB report compares fuel for different Arc1 to Arc2 scenarios, with the rule-of-thumb that flying more distance at high altitude comes out about the same as descent/ascent, assuming the same Arc2 end-point (approx 3N for UGIB). However, what I would say is that it is possible to get further south with the same fuel, say down to 1N. UGIB is taking a bit extra loiter as needed to allow hitting Arc7 at LRC speed. My pilot is looking to end of flight, and wants to get as far South on Arc2 as possible, consistent however with apparently not wanting to violate Indonesian airspace (until Indo cannot see MH370 anymore).

    All the creativity UGIB puts into Arc1 to Arc2 (one engine etc), I see as not coming unto play until after Arc5. I see Arc5 to Arc6 the way everyone else sees Arc1 to Arc2 (many options).

  306. Andrew says:

    @ventus45

    RE: ”The figures would be very interesting. I have a BOE gut feeling the fuel loss could be more than 50 percent, and the time/distance made good loss could be more than 10 percent.”

    The -200ER performance manual shows the following for a descent from FL350 to FL200 followed by immediate climb back to FL350 vs continuous cruise at FL350:

    Descent (210 T, M0.84/310 KIAS):
    Dist. = 49 NM
    Time = 7 min
    Fuel = 110 kg

    Climb (210 T, 310 KIAS/M0.84, ISA+10°C)
    Dist. = 65 NM
    Time = 9 min
    Fuel = 1750 kg

    Cruise (210 T, M0.84, ISA+10°C)
    Speed = 494 KTAS
    Dist = 114 NM
    Time = 14 min
    Fuel flow = 6750 kg/hr
    Fuel = 1575 kg

    The difference between the descent/climb figures and continuous cruise is 285 kg (18%) and 2 min (14%).

  307. Victor Iannello says:

    @Andrew: Using your numbers, the descent/climb case only uses about 3% more fuel over the 16 minutes required compared to the cruise case for the same duration. So if there was a deviation from straight flight over those 16 minutes, i.e., the cruise case took a longer path to traverse the same distance as the descent/climb case, the fuel consumed between the two cases could be fairly close.

  308. ventus45 says:

    @Andrew

    Thank you for that – very precise.
    I must get a new envelope !

  309. Victor Iannello says:

    AIN has an interesting article on GNSS (GPS) jamming and spoofing, which appears to be increasing in frequency.

    https://www.ainonline.com/aviation-news/air-transport/2024-03-04/gnss-jamming-and-spoofing-events-present-growing-danger

  310. Niels says:

    @All
    I have been busy checking my flight path generation procedures more extensively. Previously I had for example compared my results for LRC, CTT180 deg with the UGIB main candidate path and found a good match. In the past I had compared some different track angles with results generated by Richard Godfrey while still using excel based calculations, also with good match. Using those old excel sheets as a reference, all together I had good trust in my LRC, CTT results. I now tried to verify LRC+LNAV and ECON mode flight paths as well as, which is not that easy as there are no flight path details shared by others to compare with. The best I could think of for the moment was trying to match some entries of table 8 in the paper “Blowin’ in the Wind” (Richard, Bobby, Victor 2019). For all but one of cases considered, I could reproduce the regions of interest. I found that there was a strange deviation in my ECON Mach numbers, which in the end I could trace back and fix. Mach numbers would typically be too high, resulting in a southerly shift of some 7th arc latitudes. The consequence: I had to recalculate about 3 million flight paths, which I completed in the past week. Through the link I share some of the new results. Note that flight levels are between 310 (index 0) to 410 (index 10).
    The good news is that results (focusing on fig. 5) imo seem to match a bit better with latitude distributions found by others before. Details of procedures etc. and discussion of results will be part of the paper I started writing. The bad news is that when comparing with S33-S36 as focus area, my results now indicate that this area might be a bit narrow both at the southern and northern ends, at least when considering SatCom data + “soft” fuel limit only.
    As a final step in the calculations, and based on previous work by @sk999, I have generated 50 different sets of BTO and BFO data by adding random errors to the measured data (uniformly distributed within 1 sigma for all BTO and BFO data points). And will now repeat the complete statistical analysis for these 50 different data sets. This will typically take two/three days in calculation time.
    The 7th arc latitude distribution is expected to widen when considering different data sets for BTO and BFO generated through depositing random errors on the measured values.

    https://www.dropbox.com/scl/fi/pa1f6bb968atjtrzfni2r/update.pdf?rlkey=e6kkat2hi8g32nx7l07xet4ah&dl=0

    @TBill
    Indeed, this is all based assuming no pilot inputs after at least arc3. I omitted the 19:41 BFO value from my analysis as there has been quite some discussion in the past if a climb was still ongoing. I omitted the 00:19 BTO and BFO values from my analysis because of assumed prior engine flame-out. To estimate 7th arc positions, in the numerical integration for after arc 6 I extended the preceding autopilot settings.

  311. TBill says:

    @Niels
    I assume Arc3 to Arc5 can be modeled maneuver-free, but Arc2 to Arc5 looks mostly constant allowing for BFO allowance for a maneuver resolving at Arc2. I was responding to your earlier comment about MRC, I believe MRC probably works well until Arc5, but then Arc6 is reached too soon unless there were slow down/maneuvers, which is my belief.

  312. Niels says:

    @TBill
    I’m performing some runs where I remove the arc 6 BTO and BFO and the 23:11 phone call BFO from the statistics. Indeed MRC looks more prominent. I’m plotting arc5 latitude probability distribution, and path probability weighted thrust mode occurrence vs. arc5 latitude. To compare I also plot arc 5 latitude probability distribution and the thrust mode occurrence vs. arc 5 latitude for the original statistics. Plots follow tomorrow; it’s getting late here.

  313. Niels says:

    @TBill
    The path probability weighted flight level occurrence suggests especially higher flight levels, so in the 380 – 400 range, when I filter on MRC mode only. Is that what you expected? Lat index 0 -> S15, Lat index 30 -> S30, FL index 0 -> 310, FL index 10 -> 410.

    https://www.dropbox.com/scl/fi/nuprieleuyyzr6kjoznq8/fl_arc5_arc5stat_10_-8_newprob_MRC_68221.tif?rlkey=zk7s6gzlh3ck5gyeogdeo244m&dl=0

    I have to double check before sharing more results. Did you ever look at M084 towards arc5?

  314. TBill says:

    @Niels
    …been eclipse chasing…get back to you in a few. We had clear skies in Arkansas…TX and NY had some cloud issues.

  315. Victor Iannello says:

    @TBill: In Roanoke, Virginia, the eclipse was 88%. Near the peak, I was able to capture a short video during a hole in the clouds.

    https://twitter.com/RadiantPhysics/status/1777420870203408814

  316. Niels says:

    @TBill, VictorI
    Nice! I remember seeing the 1999 eclipse from somewhere high up in the French Alps. Interesting experience.

  317. @all

    Digital Malaysian Military radar data retrieved.

    For your info, it took us some time to verify the data and here we are with a completed detailed analysis of the unpublished radar data coming from the Malaysian Military tracker. Malaysian acting Minister of Transport committed to publish this data in one of the press conference in March 2014. Here it is via an indirect channel.

    This original data recently discovered by us is the only one known so far in numerical format with geodetic coordinates of the points on the track from Kuala Lumpur until 18h22 UTC. Altitude information is provided until reaching IGARI only. No time stamps are provided, thus estimation of instantaneous velocities would be pure speculation 🙂

    The important conclusions confirm our analysis on the reconstructed trajectory (reported at http://www.mh370-caption.net). They are:

    1- the aircraft was manually piloted from IGARI until Pulau Perak Island (at least). Noticeably, the manual U-Turn infered and simulated by us in 2022 at a banking up tu 38° is perfectly matching the numerical data.
    2- an approximate vertical profile could be determined thanks to the cross-analysis of Malaysian radars coverage leading to a better knowledge of this segment of the flight. In particular, an emergency descent would have been simulated confirming the depressurisation of the airplane as hypothesised in our previous report.

    All this consolidates our own conclusions made in our previous report.

    Some of you in the past had concurring conclusions (Mike Exner on manual piloting for example, ATSB in one their early report for the FL etc.)

    The report, data and an accompanying video are available at https://www.mh370-caption.net

    Have a good reading 🙂

    JLuc Marchand

  318. Joseph Coleman says:

    @JLuc Marchand

    https://www.mh370-caption.net/wp-content/uploads/Digital-radar-data-KLumpur-LSTRP-analysis.pdf Page 91
    “At 18:15:48, when the last ADS-B message was received from Emirates EK343, the situation is illustrated in Figure 103”

    EK343’s last known reported Position on flight aware going up the malacca Straits was at 02:07 anything after that seems estimated. Fig 103 Doesn’t illustrate what the sentence says about last know position. Do you have other Position info specifically for this, we are not Privy to.

  319. airlandseaman says:

    @JLuc Marchand:

    Please provide the link to the Geoscience Australia website where you obtained the radar data.

    I’ll review your full report when I return from our eclipse adventure. It was mostly cloudy in Leakey, TX, but we did get a few good looks during totality. I did look at the altitude time series. Your new altitude profile is definitely wrong. We know from the KB civil PSR data that the altitude at KB was ~40,000 feet.

  320. Tim says:

    @JLuc Marchand,

    Thanks for your detailed analysis. You’ve shown, what to me seems a classic hypoxic flight profile. Perhaps a phugoid motion just after the IGARI turn and then a meandering autopilot ‘off’ flight path. All seems to point to a hypoxic ghost flight with no one at the controls.

    There is absolutely no reason a nefarious pilot would consider the need to take the autopilot off.

    The fact that the autopilot is off screams out loud that mh370 was a mechanical failure issue.

  321. Victor Iannello says:

    @Tim: Despite claims to the contrary from Malaysian investigators and others, there is no definitive evidence that the autopilot was disengaged at the turnback just after IGARI. In fact, the “entry” and “exit” waypoints match a plane banked at 25 deg at FL350 and M0.81. All that is required is to start the turn before reaching the entry waypoint. You can clearly see this in this figure:
    https://www.dropbox.com/s/6py60qljvxg05a6/2019-12-18%20Simulated%20Turn%20at%20IGARI.png?dl=0

    There is also no evidence for hypoxia. The deviation from “straight” flight is due to radar noise, which is evident from the short time constant associated with the many of the jumps.

  322. Victor Iannello says:

    @JLuc Marchand: Thank you for the JSON file that was used in creating the figure shown on the Geoscience Australia website. This is helpful in creating a more accurate representation of the flight path from the military data that was previously only graphically represented. However, as you know, there are some important limitations of the data:

    1. No timestamp data is available
    2. The azimuth and range data for each target is not available
    3. There is no altitude information

    Therefore, any conclusions about altitude and speed are difficult if not impossible to determine from that data set in isolation.

    On the other hand, we can get information about speed and altitude from the civilian radar data near Kota Bharu radar site. Looking at the range, azimuth, and timestamp data across the Cone of Silence in combination with the meteorological data, it is possible to determine the relationship between hypothetical altitude and speed. That relationship says that at a pressure altitude of 39,300 ft (geometric altitude around 41,500 ft), the groundspeed would be 525 knots, the true airspeed would be 500 knots, and the Mach number would be 0.87, which is Mmo. Those values are all within the capabilities of the aircraft.

    By contrast, at your proposed pressure altitude of around 30,000 ft (geometric altitude of around 31,800 ft), the groundspeed would be 565 knots, the true airspeed would be 560 knots, and the Mach number would be 0.92. That speed is unrealistically too high. I really don’t believe that altitude is correct.

  323. Paul Smithson says:

    @JLuc Marchand, thank you very much for sharing this data. Preliminary observations:-

    1.I share Victor’s view that the “air turn back” can be very well-approximated by a 180 degree turn at normal AOB if we anticipate some coasting/overshoot on the radar depiction of this turn as well as allowing for rather poor angular discrimination at this range. I’ll post separately the .kmz of my reconstruction of that turn and the speeds/AOB involved.
    2. The excel file that you have linked does appear to include the “military” data and not only the primary radar from Kota Bharu and Butterworth. This is because a) we can see that the gap between those two radar records now has datapoints b) the periodicity of the datapoints beyond Penang is consistent with the rotation speed of the military radar ~10s rather than the civil primary radars ~4s.
    3. There is very close agreement in track between this “military radar” and the primary radar trace that ALSM had previously shared.
    4. It is pretty obvious where a datapoint is missing from the military trace. Counting the last 20 points and allowing for one obviously missing, I compute a groundspeed of 493kt. From the Butterworth radar I’d estimated about 507-509kt, declining slowly – so it is quite a bit lower. It would be useful to obtain the precise cycle period of Western Hill radar – is it exactly 10.00s?
    5. The LKP position in this file corresponds very well with figure 4.1 of Bayesian Methods since the end of that track coincides conveniently with a distinguishable feature on the google earth seafloor depiction. There’s no doubt in my mind that this is the same dataset.
    6. This is obviously a different dataset from that used for the “LIDO” slide insofar as that included intermittent radar returns all the way out to the LKP with exception of the lancuna around VAMPI.

  324. Victor Iannello says:

    @JLuc Marchand: Numerous times in the report there are claims similar to this one: “The aircraft was manually piloted as the lateral navigation characteristics of its trajectory do not match the LNAV capability of the auto-pilot.”

    For some reason, you consistently ignore the more likely case that the autopilot was engaged in heading (or track) select mode, with waypoints displayed on the MAP used as a reference for navigation. After the turn around Penang Island, LNAV was engaged either by joining a leg between waypoints, e.g., FF04-VAMPI, or by joining a radial inbound to VAMPI. (Yes, I know that FF04 is associated with an instrument approach.)

    This was described in detail in a report from 5 years ago:

    https://mh370.radiantphysics.com/2019/01/12/mh370-flight-around-penang/

    I see nothing in the data from which you can decisively conclude there was any hand flying. The track segments are basically straight, i.e., consistent with occasional small changes in heading, and the jumps in radar target position occur over time intervals that are too small to be physically realistic, i.e., the jumps are consistent with radar noise.

  325. Don Thompson says:

    Victor Iannello wrote ‘However, as you know, there are some important limitations of the data:

    1. No timestamp data is available
    2. The azimuth and range data for each target is not available
    3. There is no altitude information

    Therefore, any conclusions about altitude and speed are difficult if not impossible to determine from that data set in isolation.

    Precisely what I came here to comment after considering J-LM’s comment earlier, above.

    What is being claimed by J-LM as ‘Digital Malaysian Military radar data retrieved‘ looks to be merely a JSON representation of the KML data that described the track depicted in Google Earth in Fig 2.1 of DSTG’s Bayesian Methods in the Search for MH370. The JSON data scraped from Geoscience Australia provides nothing new or credible whatsoever.

  326. TBill says:

    @Jean-Luc Marchand @Victor
    What caught my eye is the 31 deg bank circle in Fig 51.
    Recently someplace I read that 30 deg bank was pre-programmed in a B777 for some holding patterns. I do not know if the the U-Turn could be explained by entering/exiting a tight holding pattern.

    Maybe Andrew can comment, but it seems like holding pattern banks are pre-programmed and not impacted by the Bank Angle setting (max 25 deg).

  327. Andrew says:

    @TBill

    Yes, the MCP-selected bank limit is ignored whenever LNAV is engaged. The bank limit in that case is determined by the FMC.

    The commanded bank angle in a holding pattern is variable, depending on aircraft speed and wind. The FMC computes a bank angle to keep the aircraft within ‘protected’ airspace, and the AFDS then tracks the holding pattern using a maximum bank angle of 30°. The maximum bank angle is typically commanded at higher altitudes.

  328. 370Location says:

    The “new” radar data is simply extracted from the ArcGIS map provided years ago by Geoscience Australia.
    It’s an impressive collection of work.

    To get the radar JSON data, start at the MH370 Data Release – Basemap page and look for Radar Polylines.
    Following the links gets to an SQL Query page.
    For Object Ids enter: 2,3
    (2 is Air Defense Radar Path, 3 is Flight Path)
    Also click on ReturnZ=True and change the format to JSON.
    Click GET et voila

  329. Andrew says:

    For anyone scratching their heads (like me!):

    The Radar Polylines page mentioned in @370Location’s comment above is reached by selecting the “Flight Path” link in the “Layers” section of the MH370 Data Release – Basemap page.

    The SQL Query page is then reached by opening the URL on the right hand side of the Radar Polylines page (https://services1.arcgis.com/wfNKYeHsOyaFyPw3/arcgis/rest/services/RADAR_Polylines/FeatureServer/1) and selecting “Query” under “Supported Operations” at the bottom of the page.

  330. @All
    So far I see, comments are mainly on the executive summary and not on the detailed analysis. So the substantive content seems missed and distracted by these light-hearted comments.
    As a preamble, remember that this data does NOT come from radar sensors but is the result of radar tracker processing. Thus the track is made up of calculated points and not echoes.
    If you read the report, you will see that the data includes points produced out of military data and probably also of some civilian approach radars, as the Minister said in March 2014.

    A few words nevertheless to help you arrive at the heart of the analysis which includes 3 objectives (without immediately going to “calculation” as some would be tempted to do):
    1- To check data quality -> done successfully, this is the best digital data on the military track and it can be used numerically with confidence
    2- Determine how the aircraft was controlled -> done, it was under A/P LNAV function up to IGARI, manually afterwards to Pulau Perak at least
    3- Extract altitude information if possible -> done, altitude information can be extracted at certain locations thanks to a cross-checking with extra data on radar horizons

    Considering the comments so far, do I feel the syndrome “not invented here, thus not worth considering…” ?

    Any brick of data is worth considering… but I can’t force anybody 🙂

    @Victor
    – “…no timstamps, azimuth, range and no altitude…”
    Yes of course and that’s what we explain all along the analysis. But for lateral navigation quality evaluation, the ground projection is fully sufficient. Talking about azimuth and range is not relevant (see preamble above)

    – “…conclusion about speed not possible…” : excatly, that is why we placed several caveats in the doc about the temptation to compute instantaneous velocities. But you probably did not reach them yet at that time.

    – “…conclusion about altitude not possible from this set in isolation…” : Exactly. But this is the object of the 3rd objective by using additional information computed separately. The different radar coverage horizons have been used to cross-correlate the data especially in key points luckily provided by the gaps in the track. Entry and exit of the gaps allow to infer the altitude approximately.
    Again, it appears that you made this comment without having reached this section of the report.

    – “…the ground speed would be 565kt ..” : where did you find this value in the report? maybe from your previous computation based on uncertain ASTERIX time stamps? We clearly show that instantaneous speeds cannot be inferred from any radar data as they all went through a processor which “timely restamped” the data (this is also true for the ASTERIX data by the way). Here we estimate that the aircraft could have possibly reached 530kt max using long time intervals… please refer to Tables 8, 9 and 10.

    -“…says that a pressure altitude of 39,300ft …” : If the aircraft were at FL390, meaning a climb, there would have been no gap in the military track after the U-turn whatsoever as both Western Hill and Bukit Ibam would have got the aircraft in their line of sight. In that location, the flight was globally crossing the radar horizons towards their decreasing altitudes, thus a gap means a descent and it cannot be otherwise. In addition, in the south of Penang, the copilot’s phone was detected… thus FL300 or FL320 max.
    Here again, it appears that you did not reached this section in report, yet.

    – “…you ignore the case was the autopilot was engaged … VAMPI” : In the report we evaluate a lot of times the possibility of piloting via Select Heading on the MCP (and even waypoints in FMC). We show that it does not fit at all or it would mean changing the heading every minute and half or so … which is a sort of manual piloting :-). Would you seriously see an experienced pilot doing so ? The oscillations of the track are much better explained by manual piloting. From Pulau Perak to VAMPI? maybe, but the track inferred from the LIDO image points shows a different picture : a non-linear oscillating trajectory globally south of N571… the LNAV function of the autopilot would do much better than this i.e. flying exactly on the route in straight line.

    – “…track segment are basically straigth…” : “basically” ? are you serious ? It is time to use number crunching and distance measurement, and simply compare the perfect linearity of the path before IGARI achieved under LNAV of the A/P and compare it with any segment after IGARI as we did … These segments are obviously not “straight”. Please Victor, would you be so kind to explain why the track is as it is ? especially if under A/P LNAV.

    @Paul smithson/@TBill/@Andrew
    -“…180 turn at normal AOB…” & “..31° bank angle…”: Figures 51 and 52 show that it is impossible. The illustrative circles are at fixed banking. But an aircraft does not jump to 25° or 31° at once. The examples are there to show the boundaries. In contrary, the yellow curve is a turn up to 38° that we simulated, it started from 0° and had to increase to 38° to match the track. The circles don’t match even the one at constant 31°. To achieve this turn in matching the digital data you must bank up to 38° which is only possible manually. The automation would never accept such a banking.
    -” …precise cycle of Western Hill…” : see preamble, points are NOT radar echoes, so not relevant. In the report the points are timely separated in a repetitive pattern of approx 9/9/12 sec. Remember, the data unveiled here are NOT from the radar heads.

    @Don Thompson
    – “…JSON data … provide nothing more new …” : First, my pleasure to have provided you with this data :-), did you have before such precision in a numerical form?. For the format, the database allows you to select the one that fits you best. Second, nothing new ? this is the only numerical data on the military track. Contrary to what you think this data was at the source of the creation of the DSTG image (and not the contrary). Several reasons for this. 1) the presence of coasting at several locations indicates an outpout of a radar tracker. A simple digitisation of the DSTG image would not reveal this coasting. 2) the DSTG mentions interval of about 10sec, we found that the pattern is 9/9/12sec actually which is in fact more realistic and probably explains why the DSTG had to reinforce their Kalman Filter as they did not notice it. 3) This is the closest data one could get on the Military data and several indication being them in the data or one other document give hints on their genuine origin.

    @370 Location
    – “click GET et voilà” : Bingo ! well done 🙂

    And let’s give credits to trise5631 who pointed me to this database !

    Remark: this is the only post I will produce on the analysis as the provided report is fully self-understandable and the reasoning could be redone by anybody who reads it completely 🙂

  331. Victor Iannello says:

    @JLuc Marchand: We have so many disagreements that I won’t try to reach consensus. And it’s not because I have not read the report, nor is it because the data “was not invented here”, as you boldly and incorrectly claim. I’ll provide a short list:

    1. You try to determine altitude by estimating the radar range of Western Hill and Bukit Ibam. However, we don’t know the radar timing gate for Western Hill (which would limit the range), we don’t know if Bukit Ibam was operating, we don’t know the refraction index, and we don’t know what altitude was assumed when the range/azimuth data was converted to latitude/longitude. Yet, we have the timestamp, range, and azimuth for the civilian radar data from Kota Bharu. (Don has extracted the times as stamped by the radar head, which should be accurate.) Looking at the KB radar data near the cone of silence, we can calculate the groundspeed as a function of assumed geometric altitude, and using the detailed radiosonde data, we can infer the true airspeed, Mach number, and indicated airspeed. At FL393, the Mach number would be 0.87. At FL300, the Mach number would be 0.92. Unless the civilian data is wrong, the plane did not fly at FL300 near Kota Bharu, which means your assumptions about radar range and operational sites are wrong. Also, for all we know, some of the jumps in position seen in the military data could be due to jumps in the assumed altitude, as we KNOW that military altitude was recorded, and we KNOW that altitude data is erratic.

    2. You conclude that the plane MUST have been hand flown after IGARI. I view that as only a possibility. I’ve shown (and provided the relevant links) that prove the turn after IGARI and the turn around Penang could have been flown with the autopilot engaged. And yes, small changes in heading are consistent with the autopilot in heading select mode, where the pilot is making small adjustments to fly near whatever waypoints he is using for navigation on the MAP display. Heading select provides much more flexibility than LNAV, as changes in heading can be made quickly without fiddling with the FMS.

    3. The LIDO radar image is consistent with military radar data that is noisy and unreliable. I’ll add that I talked with the NTSB representative that inspected Malaysia’s military radar and concluded that the equipment was not properly maintained and even had birds nesting in the antenna.

    4. You asked, “Would you see an experienced pilot doing so?” There are as many opinions about the way a pilot would have flown MH370 as there are pilots. Flying with the autopilot engaged in high workload situations (such as during and after the turnback) is easily justified. The same for navigating in heading select mode (although I do believe the civilian radar data after Penang shows a “classic” intercept of an LNAV leg as you would see in automated flight).

  332. TBill says:

    @Jean-Luc Marchand
    I have no philosophical problem with A/P off, I actually favor that. I am just trying to understand what are the new facts vs. interpretations. The SIR report of course already says probable manual sharp U-turn at IGARI, based on simulator studies. Some here disagree with the SIR on this interpretation.

  333. Gilles Diharce says:

    I read the paper of JL Marchand and I agree with a lot of his method.
    As I read your comments, it seems you didn’t read fully his report. It seems you have a preconceived vision of what can be done with it but you didn’t pay attention to the caveats clearly written.
    I found JL very cautious with what can be assessed from these data.
    His study give a new vision of the aircraft flight path over Malaysia.

    Let me notice that some papers of some studies you have produced for years are not perfect and especially from aeronautical point of view.
    If the JL study is not perfect, yours were not too.

    All elements pointed by JL are well sourced and carefully analyzed.
    You don’t agree with some points of view of JL and especially when you consider that this plane could have been manually piloted.
    But you refused to admit that radar track is not sufficiently reprensentative of a LNAV track.

    IG doesn’t have the monopoly of the technical study in this affair.

  334. Victor Iannello says:

    @TBill: Nobody disagrees that a manual turn would be required if the start and end of the turn occurred as simulated in the SIR. However, using only those two positions, and incorporating the uncertainty of those positions, an automated turn with bank set to 25 deg is certainly possible, despite the certainty that some ascribe to hand flying at the turn.

    https://www.dropbox.com/s/6py60qljvxg05a6/2019-12-18%20Simulated%20Turn%20at%20IGARI.png?dl=0

  335. Victor Iannello says:

    @Gilles Diharce: Did you read my comments?

    I can’t PROVE the plane was not manually piloted. I just believe there is not conclusive evidence it was.

    And I explained why the assumptions required to extract altitude may not be correct, especially since the result is in contrast with the civilian data near Kota Bharu, where we have the range, azimuth, and timestamps (all of which are missing in the new data set). Do you believe the civilian radar data is incorrect?

    And I agree that the plane was not flown in LNAV mode, except after Penang. Where have I said otherwise? Why do you and others equate autopilot with LNAV?

    I get the same accusations about piloted flight after fuel exhaustion, even though I have said MANY times that I don’t dismiss that possibility. In fact, I have been recommending search areas that INCLUDE that possibility for years now. What I HAVE said is it is prudent to start the next search by completing what was not already properly searched close to the arc before going wider.

  336. Gilles Diharce says:

    ok Victor.
    Of course, extracting altitude is difficult but the method of JL can be interesting and viable in some points.

    This aircraft was piloted after IGARI and after the U-turn, the track is not consistent with a LNAV, TRK or HDG mode. I am aware of the difference between autopilot and LNAV. We can have a different assertion of this portion of flight. Data are not sufficient but we can try in depth study as JL did.

    After PENANG, the aircraft is still piloted and a VOR radial outbound is similar with what we observe. Of course we can’t be 100% sure. But I agree that the track is more linear in the straight of Malacca.

    For the end of the flight, I agree we must include what was not properly searched but you should avoid searching inside the arc. It is less likely. Why not expanding the search area outside the 7th arc?

  337. Victor Iannello says:

    @Gilles Diharce: To accept that the aircraft flew at FL300 over Kota Bharu requires the civilian radar data to be wrong. I don’t think this is likely. There is a much higher probability that one or more of the assumptions in JL’s analysis are incorrect. I’ve already presented some possibilities.

    After Penang, I don’t think an outbound VOR radial was flown, as there is not a match to a VPG radial or any other VOR radial. Rather, it looks like an LNAV leg was intercepted and joined. 5 years ago, I proposed the leg was FF04-VAMPI (FF04 is the final approach fix to ILS 04), but an inbound course to VAMPI could have been programmed in the FMC, and that course could have been intercepted and joined (similar to intercepting and joining an inbound course to a VOR) using the autopilot, as I described in this post: https://mh370.radiantphysics.com/2019/01/12/mh370-flight-around-penang/

    You disagree that the portion of the flight path after the turnback and Penang could have been flown using the autopilot in heading select mode. I will attempt to resurrect the work I did years ago which shows this could have occurred, i.e., the path matches well to a series of segments of nearly constant track. If navigating in heading select mode using waypoints shown on the MAP, you would expect occasional small turns, as over time, the changes in atmospheric conditions would cause the aircraft’s projected track to slowly drift away from the target waypoint. Even if using track select mode, the track can only be selected in increments of 1 degree, so you would expect small corrections.

    As for the proposed search area, I’m not against biasing the search area towards the outside of the 7th arc, as I agree that that side of the 7th arc is more likely.

  338. Victor – Thank you for all your research. Can I suggest you provide an update on your conclusions as it is difficult to gain from a simple reading of the posts and the various comments. Could I also suggest you analyse the Sergio Cavaiuolo interpretation of the Inmarsat data (2014-2022) which indicates a path west towards the Maldives? His substantial reports are linked from my blog. Also, check out my video summary of what I believe happened to MH370 here: https://youtu.be/a3x4Ka_ra7w?si=DyYuXhg8SNOPa78z. Thank you. Michael, Australia.

  339. airlandseaman says:

    Jean-Luc Marchand – CAPTION:

    1. You state that the KB and BW civil radar data we made available was “processed data”, not raw data from the radar sensors. That was true for the original files we made public. But a year later we were able to obtain the raw radar sensor data (raw range and azimuth direct from the radar heads).

    2. The raw KB and BW radar head data (shared here) allowed us to compute the altitude at Kota Bharu quite accurately. It was ~40,000 feet as reported here (and by several others): https://bit.ly/3HhSzzj. It was certainly no where near 30,000k feet. This method was far more accurate than inferring an altitude from low elevation radar coverage maps. As Victor noted, that method ignores atmospheric refraction and other weather related affects on radar signals.

    3. The assertion that the altitude at Penang must have been no more that 30-32,000 feet because the co pilot’s cell phone could not have been received from an altitude of 40,000 feet is not true. As I demonstrated in this paper (https://bit.ly/2DRZjo9), an altitude of 35,000 (or 40,000) feet at Penang was consistent with the required link margins.

    4. You also assert that we have not had the military data in digital form before your paper. Again, that is not true. In 2016, Steve Kent (sk999) digitized the same plot you scraped the JSON file from. His data is available here: https://bit.ly/3JfHYpw

  340. sk999 says:

    ALSM,

    The file you linked to is not a digitized version of the ATSB track (that’s in a different file) but rather my digitization and numerical integration of Fig. 4.2 from the DSTG book giving the Kalman-filtered ground track and speed, starting from the last ACARS point. Thus, it is a completely independent of the ATSB track other than that both are derived from the original military radar data. Aside from the hairpin turn and the slow turn around Penang, the two routes match pretty darn well (as I showed in a report from Nov 20, 2016, which can be found here:

    https://docs.google.com/document/d/1o_Rtk4QHrnCyJ-aKZ48XO4mxcW42QGY5m2fOVokVSTY/edit?usp=sharing
    )

    Jean-Luc,

    Nice work pulling out that JSON file. The raw data are a bit of a mess, and I concur with the choices you made for pasting them together. Regarding reconstruction of timestamps, I note that in the Royal Malaysia Police Report, Folder 4 – SKMM Analaysis, page 21, Diagram 3, as part of the analysis of the cell phone signal from Fariq Hamid, there is a map showing the path of MH370 passing south of Penang Island, and there are 4 points with timestamps labeled. I had digitized those positions some time ago, and they match points in your table but with 3 timestamps that are 1 sec later than yours and one that is 1 sec earlier.

    It is clear that, contrary to many people’s expectations, primary radar is hardly a precision tracking mechanism.

  341. airlandseaman says:

    sk999:

    Thanks for the clarification, Steve. The important point I was trying to make is that, as you state, “…both are derived from the original military radar data.”

  342. paul smithson says:

    @JLuc Marchand. Thanks for your reply.
    You said: “…precise cycle of Western Hill…” : see preamble, points are NOT radar echoes, so not relevant. In the report the points are timely separated in a repetitive pattern of approx 9/9/12 sec.

    Can you tell me how you derived/estimated periodicity of 9.75s?
    If these points aren’t radar echoes (or, more precisely, a graphical representation of processed discrete radar returns) what are they?

    Out of interest, having applied 9.75s periodicity instead of 10s, I get a groundspeed across the peninsular from just after KB to just before crossing the coast of 528kt, which corresponds very closely to our earlier estimate of speed at the end of the KB primary radar record.

  343. ventus45 says:

    The repetitive pattern of 9/9/12 seconds every 30 seconds, indicates to me, that the antenna rotation speed was most probably 20 rpm.
    Thus there would have been ‘a sweep past the “target”‘ every three seconds.
    This would mean that for the ‘9’ second data, ‘only one in three hits’ was ‘logged’, and for the ’12’ second data, ‘only one in four hits’ was ‘logged’.
    Does anyone have an explanation for this apparent pattern ?

  344. DrB says:

    @ventus45,

    Suppose the radar antenna rotation speed was 20 RPM, so new data are available every 3 seconds. Next suppose the data logger, which is not synchronized with the antenna rotation, sampled every 10 seconds. Then you would generally save the radar data with spacings of 9, 9, and 12 seconds every 30 seconds.

  345. TBill says:

    @Victor
    A somewhat less obvious part of the debate relates to power settings at IGARI. Assuming deliberate diversion, the pilot had a minimum choice of LEFT BUS isolation to depower SATCOM, which seems (see further above) to have relatively little impact on aircraft. Alternately I believe Blelly/Marchand propose a much more extreme approach of all power turned off (LEFT BUS, LEFT XFER BUS, RT BUS, RT XFER BUS). In the latter case, RAT deploys, A/P is not available, and also believe DFDR/CVR are depowered.

    Mentour Pilot has recently seemingly embraced the more drastic power-off scenario, which some (eg; JJWise) critique as hard to believe. To some extent we are hearing defense of the complete power-off scenario.

    My opinion, we do not know exact power strategy the pilot may have chosen. I tend to favor an approach between the two extremes, if feasible, leaving LEFT XFer BUS powered will allow AutoPilot operation and RAT would not deploy. CVR would operate but could be erased later. Believe if it was me, I’d go ahead and disengage RT GEN totally if I could, as well as RT XFER bus to depower DFDR and allow improved fuel efficiency. Presumably bleed air is off at this point, further increasing engine thrust.

    Under the more unorthodox power scenarios, the normal operating envelop is presumably expanded due to increased thrust. Estimating fuel consumption debit vs. normal CI=52 (~MRC) is difficult.

  346. Victor Iannello says:

    @Michael Organ asked: Could I also suggest you analyse the Sergio Cavaiuolo interpretation of the Inmarsat data (2014-2022) which indicates a path west towards the Maldives?

    Sergio uses network timestamps recorded in the database to calculate the round-trip time (and distance) from the GES to the satellite to the aircraft and then back. However, those timestamps have neither the accuracy nor the resolution to precisely compute the round-trip distance. On the other hand, the BTO methodology has been shown (using known positions) to have a round-trip accuracy (1-sigma) of 29 µs.

    If Sergio wants to prove his method works for MH370, he can apply his methodology to MH371, for which the position and timestamps are known. He’s never supplied this analysis despite the request. On the other hand, the range calculations using BTO have been demonstrated on MH371 and many other flights.

  347. Victor Iannello says:

    @TBill: We can be quite sure that the left main bus was depowered. To extend that to depowering the right main bus and the left and right transfer busses is a guess supported by no evidence but justified by what some claim “a pilot would do”. Good luck trying to reach consensus. It certainly makes zero sense to me that a pilot flying an FBW aircraft wishing to complete a mission would deliberately disable all forms of electrical power generation except for a small propeller spinning in the slipstream. If the claim is it would increase the thrust, what would that gain you? The speed would still be limited by aerodynamic considerations (a small amount greater than Vmo or Mmo, whichever limits the speed). A climb could be completed faster at higher thrust and perhaps could fly a bit higher, but the claim is the aircraft descended from FL350 to FL300, and the speed is not limited by thrust at lower altitudes.

  348. Mick Gilbert says:

    @airlandseaman

    Mike, regarding your point 3 above about the FO’s cell phone registration, something that was pointed out to me by a telecommunications engineer who had worked for Celcom Malaysia, was that the BBFARLIM2 antenna is tilted upwards by a few degrees in elevation to provide coverage of the rising terrain to the south of station. This is unusual for an urban area where down-tilt is routinely used to control the coverage footprint.

    Most attempts at determining the likelihood of connection/registration do not account for the tilt-up.

  349. Brian Anderson says:

    A friend has just referred me to this interview. Oh dear . . a collection of thoroughly debunked “evidence” woven into his own conspiracy theory.
    US based observers here may already be aware. Victor and Mike will certainly be aware, having been quoted.
    More misinformation, more conspiracies, No understanding of stuff that is real.
    https://rumble.com/v4paq53-the-truth-about-flight-mh370-decoding-a-decade-of-deception-redacted-with-c.html?utm_source=newsletter&utm_medium=email&utm_campaign=Redacted%20News

  350. Victor Iannello says:

    @Brian Anderson: I stopped paying attention long ago.

  351. ventus45 says:

    @DrB

    Thankyou, that makes sense.

    So does that imply that the only way to get an overall ‘smoothed’ trajectory would be a four step process:
    (a) start with one point, then create 30 second segments, and average them.
    (b) then increment by one data point, and then create new 30 second segments, and average them.
    (c) then increment by one more data point, and then create new 30 second segments, and average them.
    (d) then finally, take the newly created interlaced segments, and average them ?

  352. Andrew says:

    @ventus45
    @DrB

    RE: “The repetitive pattern of 9/9/12 seconds every 30 seconds, indicates to me, that the antenna rotation speed was most probably 20 rpm.”

    Isn’t 20 rpm a bit fast for a long-range surveillance radar?

  353. ventus45 says:

    @Andrew

    It is high, and that is the core of the problem that needs to be resolved. It directly implies that the ‘data set’ is a compilation of hits from multiple radar heads (long thought to be the case anyway) that were simultaneously tracking the target some of the time, and perhaps only one radar head at different times. For the Penang turn and beyond, there are definitely two candidates, Butterworth and Western Hill, but we ‘supposedly’ only have Butterworth data, and it is definitely NOT a 20 rpm system.

  354. DrB says:

    @ventus 45,

    You said: “So does that imply that the only way to get an overall ‘smoothed’ trajectory would be a four step process . . . .”

    The 10 second updates of the logged radar data are usually adequate for identification, tracking, and intercept planning purposes. I am not sure what purpose you have in mind for a “smoothed” trajectory. If it is to estimate ground speed, then you won’t be able to do that precisely unless you have the data collection time stamps for each logged location estimate. If you only have the 10-second resolution time stamp of the data logger, then you will be limited to +/- 5% peak error in speed precision using locations which are 100 seconds apart. To get to +/- 1% in average speed peak error, you need logged locations which are logged 500 seconds apart. If the logged data included data collection time accurate to 1 second, then you could reduce the time intervals required to estimate ground speed by 10X.

  355. ventus45 says:

    @DrB

    What I am trying to do, is ‘nail’ the GS between each of the data points for the segment post the Penang Turn, after it straightens up heading for Vampi, and in particular, from there to the last Butterworth hit near Pulau Perak.

  356. TBill says:

    @Victor
    @JLuc
    Re: Holding Pattern to achieve IGARI Turn
    I have done some FSX PMDG777 cases for UTurn, and it seems to verify a tight Left turn via HOLD at 30deg bank is quite easy to initiate with the AutoPilot. I assume the pilot has a number of AutoPilot choices: accept VNAV at CI52 which slows down to about 240KIAS (which will give some radius reduction). Or possibly stop the VNAV and steeply ascend. Optional manual flight period at end of turn, to exit the Hold.

    Background- a few weeks ago, I started looking into HOLD patterns to describe end-of-flight. Believe there is an argument that MH370 could have entered the water in a descending circle banking right-wing-down. From that study, I learned that B777 HOLD pattern allows 30 deg Bank, I realized this might help explain IGARI turn as well.

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