Commentary on Neil Gordon Interview

seabed-search-w-confidence

Today I’d like to discuss some of the implications of what DSTG scientist Neil Gordon said in the course of the interview I published yesterday.

In particular, I’d like to look at what he told me about the ATSB’s interpretation of the 0:19:37 BFO value. Essentially, Gordon assures us that the experts have looked at what the manufacturers know about how these boxes work, and the only interpretation they can come up with is that the BFO value was the result of a very steep rate of descent–specifically, 5,000 fpm at 00:19:29 and then 12,000 to 20,000 fpm at 00:19:37. This is got a gentle deterioration; it’s accelerating at about 1/2 g, so that in another 8 seconds, at that rate, the descent will be at 19,000 to 35,000 fpm, that is to say going straight down at 187 to 345 knots. Remember that the plane had already been losing speed and altitude for five to fifteen minutes before the second engine even flamed out, and losing more altitude in the subsequent two minutes before the 00:19:29 ping was logged. Thus, both velocity and acceleration point to a situation in which the plane will be hitting the surface in short order. Bearing in mind that the plane would be in a spiral dive if unpiloted, I can’t see how it could have traveled more than 5 nm from the last ping, let alone 15nm, let alone 40 nm. It would have hit soon, and it would have hit hard.

One possible explanation would be the idea that the plane was in a phugoid: plunging quickly, then rising again, then plunging again. But as I wrote in a previous post, simulator runs by Mike Exner suggest that these extreme rates of descent are characteristic of the later stages of an unpiloted post-flameout plunge, when phugoid effects are overwhelmed. Thus, if the ATSB is correct in interpreting the final BFO value as a very steep plunge–as Gordon assures us they must–then the plane should be well within 15 nautical miles of the seventh arc.

The chart above (based on the invaluable work of Richard Cole) shows a band of seabed, marked in red, defined by an outer border that is 15 nm beyond the 7th arc and an inner border that is 15 within the 7th arc. As you can see, this band has almost entirely been searched out to the 99% confidence level as defined in Figure 2 of my previous post (located at the intersection of the 7th arc and 94.85 degrees east). All that remains is a rectangle approximately 17 km wide and 150 km long, for a total area of 2,550 sq km.

According to Figure 3 in that same post, the DST calculates that the probability that the plane crossed the seventh arc northeastward of 96.75 degrees east longitude is effectively zero. To search to this longitude would require covering another 3,700 or so sq km. Thus, to cover all the seabed that MH370 could plausibly have reached, if the ATSB’s BTO and BFO analysis is correct, would require another 6,250 sq km of seabed scanning, which is more or less what the ATSB has been planning to search anyway. Unfortunately, the search at present is not taking place in either of these remaining areas.

As I see it, there are four possibilities at this juncture:

  1. Both the BFO and the BTO analysis are correct, and the plane is lying somewhere in the remaining 6,250 sq km described above.
  2. The BTO analysis is correct, but the BFO analysis is wrong. In this case, the plane was not necessarily descending with great rapidity, and instead might have been held in a glide, and is most likely in “Area 1” shown above.
  3. The BTO analysis is incorrect, and the BFO analysis is correct. The plane was indeed descending very rapidly during the last ping, but the plane was further to the northeast somewhere in “Area 2.”
  4. Both BTO and BFO analysis are incorrect. The plane could be just about anywhere.

I happen to believe that the DSTG knows what it is doing, and that 2 through 4 are not the case. On the other hand, the unsearched areas remaining are at the far fringes of likelihood, and so don’t feel that #1 is a high-probability option, either. No doubt some will argue that the plane might have been overlooked within the area already searched, despite assurances from officials that if it was there they would have seen it.

Frankly, we’re running out of compelling options.

177 thoughts on “Commentary on Neil Gordon Interview”

  1. @JW

    So, why do you suppose Gordon put the probability of finding the plane at two thirds if everything was just right? I would love to understand his thinking on that statement.

    Am I reading/interpreting this comment correctly?

  2. @DennisW, Great question. I find it hard to square this statement with the probability distribution function maps that Gordon has published in his “Bayesian Methods” paper and book, which, as I pointed out in the last post, make it look like the 120,000 sq km search area more or less matches up with the 90 percent confidence isobar. The ATSB itself cited a 90 percent figure. What’s more, most of the pdf that extends beyond the search area does so laterally, that is to say, outward from the seventh arc. Since that 90 percent assessment was made, the ATSB has shifted its assessment of the 00:19 BFO so that the endpoint of MH370’s flight should lie closer to the 7th arc.

  3. @DennisW

    My idea. The green area above (120000sq.km. approx) covers 70% of the probability distribution of the Bayesian in the DSTG report, or possibly some newer distribution we haven’t seen (he mentions changes since Dec 2015). They had a budget of 120000sq.km. and that is where they deployed it for maximum effect (00:28:55 in the transcript).

    Therefore, the probability of finding the plane was 70% (on the basis of the model).

  4. @Richard

    Thx. I understand what you are saying, but the statement I am referring to is:

    “Well, I’ve just told you, we’ve only searched just over 75 percent of the probability. When we started I’d have said there was a one in three chance you wouldn’t find it, even if everything was as you’d expect.”

    My interpretation is that Gordon had a 1/3 expectation of not finding the plane given than the DSTG search area was completed. Is this not how you understand his remark above? It seems like you think his 1/3 comment refers to the area searched so far. I suppose it could be interpreted that way.

  5. @Jeff, @Dennis: furthermore, we have yet to actually press Dr. Gordon on the disconnect between the DSTG oval’s width and the clear indications of Mike’s flight sim results (to which the 00:19 BFO interpretations, if correct, merely add an exclamation point). Both the DSTG (per Richard C) and Mike seem to deem their disparate results ATSB-endorsed. Furthermore, to the extent 1st engine flameout time is pushed earlier (per ATSB, Dec/15), the plane’s potential energy by Arc 7 is further diminished – and its range further compressed – relative to Mike’s results. What gives?

    Fugro may have already falsified ~99.9% of a PROPERLY constructed density function. I fear the width of the DSTG’s oval was driven more by the width of the area already scanned by Dec/’15 than by actual flight dynamics. Confirmation bias, anyone…?

    More generally: why are highly-placed people now seeming keen to OVERstate the degree to which $200M of taxpayer money failed to falsify a single SIO theory? I did not see any such pessimism expressed back in 2014, when it could have actually helped inform search strategy.

    Normally, one would expect things like radar-tracked path segments, fuel limits, BFO error components, scanner efficiency, debris buoyancy results, and end-of-flight to IMPROVE over time. Yet all have deteriorated since 2014…? I smell a rat.

    It is hard to ignore the fact that, IF we are witnessing a cover-up, such a tactic would fit any such theory like a glove: far better to push the narrative that search leadership was beset by bad luck – and a whole host of fiendishly-hard-to-pin-down inputs – than to sit back and risk having to field hard questions.

  6. There is still no confirmation from Boeing the outboard flap(piece) was stowed in the wing when the plane hit the water.
    When it was it could not have survived an impact the way it did like suggested now by Gordon and the ATSB (high speed impact).
    And when stowed in the wing it could not have seperated by flutter either IMO.

    The drifter-based drift analysis conducted with the debris finds in mind and where nothing was found (Oz shores etc.) all point to a crash area at least north of 36S. Mostly outside the current priority search area.

    When the plane entered a phugoid after second engine flame out, graphic shows it could have flown for another 8 minutes past ~0:17. Maybe the plane hit the water-surface just starting another phugoid climb?

    Anyway regarding the outboard flap, retracted or not, there must be something wrong with the interpretation of that 0:19:37 BFO data IMO.

    Hope confirmation on that outboard flap is soon to come.
    Maybe @Jeff Wise could ask Gordon about this too?

  7. @DennisW

    I think we agree, but perhaps not.

    The search is complete to a few percent, so my remarks refer to its completion point. 120000sq.km. does not cover the entire Bayesian area, obviously. Gordon is saying it covers something less than 72% of the probability distribution. Hence, even if the reality corresponded to the model, there is a 28% (rounded by him to one third) chance that the location of the aircraft would not have been searched.

    The area searched is significantly less than the area marked in the DSTG maps (and not symmetric with respect to the 7th arc line of symmetry), and the area marked in the maps is itself significantly less than the 90% contour. So I think Jeff’s statement that they have covered 90% is an overestimate. I think 90% was their round figure statistical target (but not achieved), simplified to a searchable rectangle.

  8. Ge Rijn – On what do you base your opinion that flutter could not have separated the flap from the wing? There have been photo’s posted showing plane pieces missing after a high-speed event.

  9. @Richard C, re: your question from prior thread: given your preamble, it is hard to expect anything but derision in response to any list I post – and you’re on record as deeming unimportant many aspects of the physical record I deem important – so I’m not sure what value there is in the two of us regaling the gathered throng with yet another page out of Python’s Argument Sketch.

    But in a nutshell: by the end of 2014, we had the concerns I listed in my first audit (linked below). In addition, we had several observations my audit did not cover:

    1) empty Oz shorelines, which I think you concede is at least somewhat pertinent

    2) zero radar detections post-18:22 reported to search leadership, let alone to the general public

    3) 2 separate acoustic event detections, each at flight path-compatible times, each indicating a possible equatorial-area impact; yet nothing on 7th Arc

    4) an array of eyewitness accounts whose credibility seems inversely correlated to their compatibility with an SIO impact, &

    5) 1st-hand (to me) evidence that efforts of truly independent MH370 auditors were being carefully & systematically deflected.

    It is easy to rationalize away one or two of these in isolation. It is hard to rationalize away the whole lot in aggregate.

    My general (unsolicited) advice to you:

    – (a quibble) suggest downplaying role of tactility in determining whether or not evidence is “physical”; by your definition, the ISAT data is not “physical” evidence

    – (critical, IMO) also suggest we revisit distinction between evidence and “absence of evidence”. If I throw a ball up in the air – and it doesn’t come down – its failure to appear back at ground level is pretty compelling evidence that something happened to it whilst airborne. If the ISAT data predicts flight path detection by radar, detection of impacts by listening devices, and detection of surface debris SOMEwhere, SOMEhow (sat/air/ship/shore) by Dec/14 – and NONE of these appeared – this is important information.

    2014 audit:
    https://drive.google.com/file/d/0B-r3yuaF2p72ZkNWN1U5bklEbTA/view?usp=sharing

  10. @Richard

    Thx. I was interpreting Gordon’s statement differently, but I now think your interpretation is correct.

  11. @Richard Cole:

    My take on this is that Neil’s comment referred to the total probability from his initial analysis and it was just the most likely ~70% of this area they selected to search.

    Has anyone heard about the 1 in 3 statement before this interview from an official source or by anyone involved in analysing the data? This came as a big surprise to me.

  12. @Brock

    Apologies for the flippant tone of last message.

    I understand the position.

    On a point of definition, and perhaps a lawyer is needed, the signals evidence, of all sorts, doesn’t seem to me to count as physical evidence. I doubt that lack of an item could count as physical evidence as well, but perhaps there are situations where it can.

  13. There is also possibility #5: The BFO value at 18:40 was misinterpreted as indicating a southerly direction wheras it could as well indicate a descent at that time. Gordon clearly says in the full transcript it is entirely possible that MH370 was descending at that time and therefore eventually winding up further northeast of the search area. I think it would make some sense for MH370 to continue to display avoidance behaviour with regard to Indonesian airspace as it did in the route obversed by Malaysian radar. The assumption that MH370 turned south at some point before 19:41, but not necessarily by 18:40 informed the first ATSB report in June/August 2014 and is consistent with the drift studies so far published (in journals, websites and government reports).

  14. @Nederland

    Yes, the are many inconsistencies emerging. If one looks at the excellent graphic linked by Dr. Cole, it is apparent that the area close to the 7th arc has all been scanned. I post the link again below to save readers the time of looking for it.

    https://www.dropbox.com/s/ncnxr792kjhi0wo/Search-area-current.pdf?dl=0

    If the rapid descent and the DSTG analytics are both correct, it is game over. We are about 100% done relative to checking those boxes. The plane has not been found. So piggy-backing on Jeff’s list of possibilities we have:

    1> The DSTG analytics or the data are wrong.

    2> The rapid descent analytics or the data are wrong.

    3> The wreckage was missed.

    Personally, I am leaning to door #1. The debris finds also paint a picture which strongly supports a more Northern terminus than 33S. A late FMT with a dalliance NW of Penang gets my vote at the moment.

    Finishing the current search area to include distances beyond what has already been searched seems contra-indicated by the confidence placed in the rapid descent profile.

  15. Neil’s comments on the radar data between #00:11:53 and #00:25:48 are interesting.

    What happened to the so called ten second data ?

    Neil said:
    #00:15:28-7# We just got a picture of a radar screen with a position on it.
    (and)
    #00:15:42-3# I guess it was but they’ve just got snapshots off the radar screen.
    #00:16:09-8# Well, I’m speculating here but I would imagine they’ve recorded a video of the screen, but they don’t necessarily have a digital backup of the measurements.

  17. @DennisW

    Maybe the first shot was the right shot?

    http://www.atsb.gov.au/media/5243942/ae-2014-054_mh370_-_definition_of_underwater_search_areas_18aug2014.pdf

    Here on p. 16 the ATSB explains the FMT could have happened any time before 19:41 and that means the wreckage most likely is in the Broken Ridge area.

    I just can’t believe they were unable to see at that time that the 18:40 BFO value means a change of direction either southerly or a vertical descent (as they elaborated in their October 2014 report). If they didn’t take it as indicating the FMT by 18:40, surely there were good reasons for that.

  18. @Nederland

    True there, but I am referring to the search strategy itself now. It does not seem consistent to harbor a conviction relative to a rapid descent, and also to finish searching the priority area when the unscanned areas are located far from the arc.

  21. Byron Bailey has recently written a piece in the Australian calling for an inquiry into the MH370 search. He had a point here;

    The Australian: Inquiry needed into MH370 effort. http://google.com/newsstand/s/CBIw6Nv5yS0

    (I suspect behind a paywall)

    However he champions the conscious pilot controlled ditch hypothesis. I find it difficult to believe Captain Z could sit in the cockpit for 6 hours with 238 recently deceased PAX/crew behind him.

    The program SIO coordinates, depressurise, ghost flight is very believable. However this has receded as a workable hypotheses with the presumed failure of the 120,000 sq.km search zone

  24. Another from the Australian.

    The Australian12:00AM September 9, 2016

    AMANDA HODGE
    South East Asia correspondentJakarta
    @hodgeamanda

    “A Malaysian court has ordered the government and Malaysia Airlines hand over all relevant documents relating to the ­disappearance of Flight MH370, in a critical ruling that families of missing passengers hope will ­provide long-awaited answers to a 2 ½-year-old mystery.

    A Kuala Lumpur high court judge yesterday granted general discovery to relatives of 32 ­missing passengers who were on board the flight from Kuala ­Lumpur to Beijing which went missing in the early hours of March 8, 2014.

    Some 76 plaintiffs, comprising 66 Chinese nationals, eight Indians and two US citizens, allege the airline failed to give a proper ­account of events that occurred during the flight, which relatives were later informed by text message had gone down in the southern Indian Ocean.

    In a March 3 statement of claim the families also allege negligence, breach of contract, breach of statutory duty and breach of the Montreal Convention by Malaysia Airlines Systems.

    Malaysia Airlines Bhd (MAB), Malaysia’s Department of Civil Aviation director general, the Royal Malaysian Air Force and the government of Malaysia are also named as defendants.

    Since the plane’s disappearance families of the missing passengers and crew have consistently accused the Malaysian government of hiding information and failing to keep them informed of major developments and decisions.

    Tommy Thomas, lead counsel representing the plaintiffs and one of Malaysia’s most senior lawyers, told The Australian the court’s decision to grant general discovery was more a “matter of course” than a major legal victory.

    “You can’t do a trial without documents. It’s as simple as that,” he said.

    Mr Thomas said of particular relevance to his clients were “all conversations relating to the plane turning back”.

    “Those conversations would be critical because that was the time to save the plane,” he said.

    “Nobody was asking them to shoot down the plane. Nobody shoots down their own country’s plane but how about following it to find out where it goes?”

    The aircraft made its last contact with air traffic control at 1.19am (Malaysian time) before disappearing from radar screens.

    According to information pieced together by investigators, over the course of the next six hours it is believed to have made several turns, deviating westward from its planned flight path to cross the Malay Peninsula, passing just south of Penang before flying across the Strait of ­Malacca, and heading south over the Indian Ocean.

    Both the government and MAS have until October 20 to comply with the discovery order or appeal the plaintiffs ­application for access to 37 documents, including notes, memos, cargo manifest and all relevant investigative reports into the disappearance of MH370.

    Lawyers for the Malaysian government have previously ­objected to the discovery application as a “fishing” expedition.

    MAS lawyer Saranjit Singh said he understood the plaintiffs were entitled to general discovery against MAS to assist their case against the government of ­Malaysia, online Malaysian news site Malaysiakini reported.

    But, he added, his client needed to read and understand the grounds of judgment to determine whether it should appeal the order.”

  25. Malayasinki quoted above, 8th Sept:

    “The High Court in Kuala Lumpur today ordered the government and Malaysia Airlines System Bhd (MAS) to provide a general discovery document to 76 relatives of 32 passengers who were in the doomed MH370 flight that disappeared in March 2014.
    This is on the grounds that the plaintiffs are entitled to the information, as they have brought suits against the government and the airline.”

    The rest behind a paywall.

  26. @LaurenH

    I know the pictures of the ChinaAir Boeing 747 h.stabilizers with severe flutter damage that landed after a high speed dive event. In this event no wing flaps seperated by flutter. Only the ailerons suffered some minor damage.

    http://www.rvs.uni-bielefeld.de/publications/Incidents/DOCS/ComAndRep/ChinaAir/AAR8603.html

    It’s just my opinion that outboard flap could not have seperated by flutter. When it was retracted the leading edge had to suffer clearly visible more severe damage too IMO. And the inboard side (it’s widest part) is completely intact including the trailing edge. IMO this part of the flap would be the first part to get damaged and break in case of flutter. It did not.

    Ofcourse I cann’t be completely sure. I’m not a Boeing-investigator.
    I hope Boeing will soon deliver their report on this and the ATSB will publish it.

  27. Hi David
    Thanks for the info re A. Hodge at the Australian.
    Just had a look and would you believe it, its been chopped up
    and missing a fair bit what is in your copy. Same dateline etc.
    Could be censored? Don’t know
    Cheers Tom L

    A Malaysian court has ordered the government and Malaysia Airlines to hand over investi­gative reports, memos and notes on the disappearance of Flight MH370 to 76 plaintiffs suing for negligence and breach of duty.

    A Kuala Lumpur high court judge granted general discovery yesterday to relatives of 32 missing passengers who were on board the March 8, 2014, Kuala Lumpur to Beijing flight.

    The families, comprising 66 Chinese nationals, eight Indians and two US citizens, allege the airline failed to give a proper ­account of events that occurred during the flight, which relatives were later informed by text message had gone down in the Southern Indian Ocean.

    In their March 3 statement of claim, they also allege negligence, breach of contract, breach of statutory duty and breach of the Montreal Convention by Malaysia Airlines Systems.

    Michael Yap, representing the plaintiffs, said outside court the government had until Oct­ober 20 to comply with the order.

    The plaintiffs have sought ­access to 37 documents, including notes, memos and all relevant investigative reports into the disappearance of MH370.

    The government has objected to the application, branding it a “fishing” expedition.

    MAS lawyer Saranjit Singh said he understood the plaintiffs were entitled to general discovery against the agency to assist their case against the ­government of Malaysia, website Malaysiakini reported.

    But, he added, his client needed to read and understand the grounds of judgment to determine whether it should appeal the order.

  28. @Tom
    Just checked this story in The Australian again and its as quoted by David above. Strange.
    http://www.theaustralian.com.au/news/world/court-orders-release-of-mh370-probe-documents-to-families/news-story/f8bc39c99876e597279952c1b08a95c5
    I suspect though that the documents they are asking for are just to support their legal case and may not be very helpful in finding the plane; it would be very surprising if they were granted access to the full radar data etc..

  29. Thank you Tom. The longer version I posted is that printed and seems the later (more to the top) in the list of stories. Hence I suppose the one you have put up to be an earlier version. I think the main differences are the longer version lists cargo manifest specifically as a requirement and lists the DCA and RMAF as defendants.

    My conjecture would be that the short version was based on the Malaysiansinki article, later expanded by further enquiries.

    In either case the import is there.

  30. @AM2. Thanks. Did not see yours.

    It might be a beginnings….The reported allegation is very broad, “allege the airline failed to give a proper ­account of events that occurred during the flight,..”

    Still that only makes an allegation against the airline. What of DCA/RMAF and Government? Sought from the Government and MAS are, “…..37 documents, including notes, memos and all relevant investigative reports into the disappearance of MH370.” The 37 does not seem much but “all investigative reports” does. Just Government and MAS? Why would DCA and RMAF be listed?

    Wait and see, once more.

  31. @Richard: you have nothing for which to apologize; I’m sure I’ve flirted with the line of decorum more than have you.

    Suspect we can simply snip the word “physical” out of my first post, and we’d both be happier.

    And I understand your position.

    Richard, I commended your analytical consistency in an earlier post – I should commend your tone as well. With my audits (slash pestering…) of search leadership, you have always been very tough – which I really, really wanted – but also very fair – which I really, really need.

    It has been a privilege disagreeing with you – if that still makes sense any more to anyone on this crazy, partisan planet.

  32. “Nobody was asking them to shoot down the plane. Nobody shoots down their own country’s plane but how about following it to find out where it goes?”

    If they did not do that then it is a crime. I suspect that they did, but MH370 was not there. Should be interesting when they bring this to the court.

  35. huh, that North Korea is crazy if they thinks that world will be talking with them and accepting them as they are trying to mount warheads on the ends of rockets… sure, we can accept and admit great technical progress in rocket and nuclear science, but … rather at least try to develop some cancer cure or so… thats far better approach

    or if it is theirs part of game theory, to almost suicidally put together rest of the world against them, then… OK; but its really ugly ransom, you know, Un

  36. @Nederland
    “I just can’t believe they were unable to see at that time that the 18:40 BFO value means a change of direction either southerly or a vertical descent (as they elaborated in their October 2014 report). If they didn’t take it as indicating the FMT by 18:40, surely there were good reasons for that.”

    There is no reason to wonder.
    The 1840 FMT to the south was an untouchable assessment for long time on all blogs and from all experts. It had to hold for the assumption that the radar data have to be wrong and was the starting point of most all southern tracks computations. Possible climbs and descents were not welcome, as “air transport planes are not flown that way”

    I’m glad there is a rethinking going on now. Better now than never.

  37. @Suzy Crowe,
    The link you posted to freemalaysiatoday.com has credible descriptions from family and friends of where Zaharie was at in his life and interests. It is consistent with what a Malaysian in his position might be involved in, not the nefarious intent that is being pinned on him.
    In particular: “He wanted the daughter to work in Australia and they (Faizah and Zaharie) would go there,” Asuad was quoted as saying.
    Zaharie, who was 53, was said to have planned to retire at 60 and move with his wife to the city in Victoria, so that they could spend more time with their daughter who works there as an architect.”

  39. @Jeff Wise:

    From Bayesian Methods, Chapter 4, Aircraft Prior Based on Primary Radar Data:

    “For the accident flight, primary radar data provided by Malaysia is available from after the loss of communications up until 18:22:12. The radar data contains regular estimates of latitude, longitude and altitude at 10 second intervals from 16:42:27 to 18:01:49. A single additional latitude and longitude position was reported at 18:22:12.”

    You extensively discussed the the last primary radar position at 18:22:12. For me that never was an interesting issue. Why didn’t you ask questions about the radar data between 17:25 and 18:01:49?

    What did the unfiltered, un-smoothed data look like?
    What were the altitudes?

  40. @ Jeff Wise

    “…the plane might have been overlooked…”

    Whether we want to believe in unpiloted phugoids with a harrowing finish or you want to believe that a pilot flying a “suicide route” timed out his fuel exhaustion with a high-speed impact above a 19,000′ trench, I’d love to see some attention paid to the probability that there is no “plane” to find.

    The BFO data says high speed impact. The size of the Mozambique fragments say it. The phugoid-finish theory supports it. The suicidal VNE+ hand-flown dive theory definitely supports it.

    The confusing thing which caused everyone to wonder about controlled ditching was the minimally damaged flaperon. (Unless you were in the “detached due to mach flutter” camp). If they are from 9M-MRO, I hope the shrapnel-level Mozambique pieces put to bed the notion of controlled ditching.

    We’re looking for a pair of toasters in two or three miles of seawater.

    It’s the pink elephant, no?

  41. @Ge Rijn. “..I know the pictures of the ChinaAir Boeing 747 h.stabilizers with severe flutter damage that landed after a high speed dive event.”

    The damage was not from flutter. It was overload. It pulled 5.1g. See the report 1.12 and just above.

  42. Re : 1/2 g acceleration.

    I was looking at @Gysbreght’s graph from two posts ago. And in this simulation the plane drops from 5000fpm to 12000fpm in about 20sec (eyeballing it on the screen). That’s quite far from the 8sec it took…

    One explanation could be that someone was actively pushing the plane into a dive.
    But let’s just assume for a minute that the plane was not under active control.

    A few months ago, @VictorI produced a nice graph representing the associated descent speed to last BFO anywhere on the 7th arc. One conclusion of this graph was that at a point somewhere in China a stationary airplane could have generated the last BFO.

    So at that spot on the 7th arc, it’s quite easy for a plane to generate an acceleration from close to stationary to fully stationary in 8 sec.

    The further south you go along the 7th arc, the more “difficult” it is to obtain such an acceleration in those 8sec.

    My question is the following :
    Shouldn’t the given allow us to define a limit on the arc where an aircraft left at it’s own device couldn’t reach that acceleration?

  43. sinux posted September 9, 2016 at 5:45 AM:

    Re : 1/2 g acceleration.
    I was looking at @Gysbreght’s graph from two posts ago. And in this simulation the plane drops from 5000fpm to 12000fpm in about 20sec (eyeballing it on the screen). That’s quite far from the 8sec it took…

    It is actually 34 seconds from 5000 fpm to 12000 fpm in that simulation. It is due to the bank angle increasing from 47° to 69° in combination with the phugoid motion that started at 2nd flame-out.

  44. @Matt Moriarty

    If allowed I like to say something on this to consider.
    IMO the possibility (at least to me) of a controlled ditch attempt was not only starting with the find of the flaperon.

    To me (and others I guess) it started with the (IMO most) logical assumption the flight was controlled by an active pilot from beginning till the end. At least it was till 18:25 everyone seems to agree on.
    IMO there is no reason, clear indication, let alone evidence this suddenly changed somewhere later in flight.
    The assumption the flight turned into a ghost flight probably was invented because it was the only workable assumption?

    Considering the found debris the great majority is related to the wings and control-surface parts. A few cabin pieces were found. Those pieces are not chattered beyond recoqnision and IMO could also have seperated in a low-speed impact event (see the Asiana crash landing interior photos).
    Not one part of the fuselage is found yet.

    The vertical stabilizer piece IMO is the most telling piece till now, pointing to a high speed impact.
    But the outboard flap section contradicts this still IMO.

    Boeing should be able to confirm the ATSB findings the flap section was probably retracted when it hit the water.
    Then they also would confirm it did not seperated due to flutter.

    I think their conclusions on the outboard flap-section will be decisive and can be able to put a succesfull ‘ditching-scenario’ to bed once and for all, or not.

    With the latter leaving other options open that could have left big pieces of the plane sinking: a AF447 kind of crash or a failed ‘ditching’ like the Ethiopian Comoros-crash.

    I’ll await the Boeing analizes of the outboard flap-section to make up my mind about it further.

  45. @David

    Thank you for that. I overlooked it.
    So no flutter-damage in this high speed dive event you think?

  46. @sinux

    Alternatively, you might approach the problem from a different angle, and assume that the 2nd BFO is probably an artifact.

    There are two persuasive reasons why the 00:19:37 ROD is probably spurious:

    1) The 00:19:29 and 00:19:37 BFOs comprise a very brief snapshot of the aircraft’s descent rate, approx 2 minutes after 2nd engine flameout(if we go along with the generally accepted APU startup, SDU logon time sequence). A snapshot, whose timing is arbitrarily determined by the APU startup/SDU reboot sequence. And yet we are being asked to accept that this 8 second arbitrarily timed snapshot purely by chance,caught the aircraft in the process of it’s 0.6g death dive, accelerating from 5,000fpm to 15,000fpm? That is asking an awful lot, in my humble, considered opinion!
    How many more seconds before the aircraft either broke up in the air or hit the water at high speed? Think of it, if the Startup/Logon sequence had taken a few seconds longer than it actually did, we would have missed all the action.

    2) No mangled wreckage was found near the 7th arc. A few items have been washed up, mainly restricted to the RH wing trailing edge.

    The logical conclusion from this line of reasoning is that the 5,000fps at 00:19:29 is quite possibly real, but the 15,000fps, 8secs later, is most probably not.

  47. @Ge Rijn. Flutter if it exceeded its flutter boundary of course but even in that case you have the problem that if flutter caused trailing edge separation most likely it would be an even higher speed for the remaining surface to go the same way.Two separate events.

    I would like to see the pitch coefficient at high speed to see if the aircraft would exceed flutter speed without a pilot push forward, that is unless it was in a tight spiral when I think Gysbreght’s model indicated the induced drag would hold it back from high speed.

    Which is not to say that the surfaces or parts thereof could not have separated due to overload at under Vmo as per the 747.

  48. A quick question/s to the knowledgeable:

    Could Z have known or guessed about the possibility to track the plane through the Inmarsat data? Could he, through how the blackout was timed, predict/affect the points in time (40 min past), when ground station tried to make handshake? Could he, thus, through irregular flying at those points in time (or other means available to him), affect the values and data we have in such a way as to misrepresent the actual end location of the plane? Could the last arcs be somewhere else, realistically? Would that be likely given the form of the values as they exist (shaped by some normality as they seem to be).

  50. @Johan, You wrote: “Could Z have known or guessed about the possibility to track the plane through the Inmarsat data?” The answer is an unequivocal “no.” And thus for your subsequent questions, too.

    @David, You wrote: “The damage was not from flutter. It was overload. It pulled 5.1g. See the report 1.12 and just above.” Apologies, to which report are you referring? This is a very interesting idea, which I don’t recall having heard before.

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