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andihce
June 13, 2025, 16:45:00 GMT permalink Post: 11900682 |
SLF here, retired physicist, but with much engineering (esp. systems engineering) background and considerable interest/experience in fault-finding in complex (not aircraft) systems.
I think it is helpful here to work through some possible failure scenarios in some detail. You could usefully partition these into two separate groups: “RAT was deployed” and “RAT was not deployed.” I’ll mostly follow the former here. \xb7 By following this path, I think we can exclude incorrect flaps setting or premature flap retraction as the primary cause of the crash. It’s difficult to see how improper use of the flaps would be correlated with RAT deployment. Everything in this case points to a loss of engine thrust. \xb7 The first question is, why did the RAT deploy? As I understand it, manual deployment by a pilot is possible, or automatic deployment caused by detection of major electrical or engine failures. I haven’t found an authoritative, detailed discussion of this, or about the time to deployment, which is relevant here as there is so little time involved. \xb7 According to tdracer , if the primary issue was a major electrical failure, that should not have caused any engine rollback. Thus, absent pull back of the throttles (which surely would have been corrected by the pilots), there should not have been a loss of thrust. \xb7 Thus we are left with engine rollback as the likely underlying problem. Absent other issues, a single engine rollback should not have been a major problem, so dual rollback, unlikely as it might be, seems a reasonable conclusion. \xb7 This is consistent with the reported mayday call, although that report needs confirmation. \xb7 It is difficult to understand a dual engine rollback. Various causes have been suggested but ruled “unlikely” here. However, it is not possible to rule out a unicorn event, like the dual engine rollback experienced by BA 38. Leaving aside the cause, it is useful to look at the consequences. \xb7 There would have been a major loss of electrical power (apart from battery backup), assuming the APU was not running. I don’t know if is possible the APU might be used at takeoff (e,g., to unload the main engines), or if any evidence from the tail photo at the crash site provides a meaningful indication (e.g., intake door status). \xb7 Are there other indications of loss of electrical power? The reported statements of the surviving passenger may have some relevance, but I would want to see the results of an interview by crash investigators. \xb7 What about the loss of Flight Aware ADS-B data shortly after takeoff? There have been a few mentions of this, but not much discussion. Could this indicate loss of electrical power? I hope this is of some use. I’m happy to defer to professionals or others here for better information/analysis. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): ADSB APU Dual Engine Failure Electrical Failure Engine Failure (All) MAYDAY RAT (All) RAT (Deployment) |
andihce
June 13, 2025, 21:51:00 GMT permalink Post: 11900947 |
The probability of something (or maybe several somethings) being a primary cause of this crash is near unity. The question, what possible causes are likely? To take a specific item of speculation that might case dual engine rollback, fuel contamination was suggested. I don't remember all the points made in this context, but some were: no other aircraft presumably using the same fuel supply had issues; why would both engines apparently fail near simultaneously?; why would they fail just after rotation?; and so on. The consensus seemed to be, not impossible, but unlikely (presumably in the sense I just described). Accidental (or even deliberate) fuel shutoff was also suggested. Again, the consensus seemed to be, possible, but unlikely for this type, since previous ergonomic causes of such accidental shutoff had long since been addressed. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) |
andihce
June 14, 2025, 13:40:00 GMT permalink Post: 11901493 |
​​​​​​​Note "feel", rather than "hear". Ordinarily you would first be aware of the sound of the engines spooling up, before you felt acceleration. Possibly he was subject to a somatogravic illusion as the plane accelerated downwards. But if indeed the engines were spooling up, the question is, from what thrust level? They could have rolled back, and somehow were recovering. of their own accord or from pilot action. All this is hanging on a pretty fine thread, Subjects (links are to this post in the relevant subject page so that this post can be seen in context): New York Times |
andihce
June 14, 2025, 16:37:00 GMT permalink Post: 11901634 |
I did read and search this thread, but I found nothing about ADS-B loss just before the end of the runway and at 71 ft high, according to FR24. ADS-B coverage is poor on the ground on the north-east part of the airfield (hence the fake news about taking off from the intersection) but I don't think it would be lost once airborne, except if it has been shut off... electrical failure ?
more precisely, loss of the two Main AC buses (ADS-B not powered by Standby AC) I guess you have to make a post on just this one item to get it noticed! But I agree that this piece of data deserves close attention, and is potentially confirmatory of certain scenarios which lead to electrical power loss. I'm no expert on Flight Aware's ADS-B data, but other posts here show other flights taking off on this runway happily reporting data further down the runway and (well) after takeoff. How else do you explain the cessation of ADS-B data from this flight from shortly after takeoff until the crash? Subjects (links are to this post in the relevant subject page so that this post can be seen in context): ADSB Electrical Failure FlightRadar24 |
andihce
June 15, 2025, 18:32:00 GMT permalink Post: 11902696 |
Flightradar24 (I know, I know) has a short blog on the (very minimal) ADS-B data available. There's only around 4s of useful data available from 21ft o 71ft altitude (last packet received 0.8s later), But: it's odd seeing the speed DROPPING shortly after takeoff. Even if you calculate total energy (kinetic + potential) it's falling, i.e. the engines aren't producing thrust. (In fairness reported speed doesn't match my calculated speeds, but even with mine I don't see power). Also: if you assumed no thrust from 71ft AGL @ 172kt you'd reach 250ft at 160kt. Isn't that roughly where they ended up? Noisy data, but this suggests the engines stopped producing power almost as soon as the wheels left the ground. (If someone could download a CSV of another similar flight and send to me I can do a compare and contrast of Total Energy)
For instance, what about induced drag (admittedly much complicated, I imagine, by varying ground effect) once rotation begins? A comparison with another 787-8 flight from the same runway and under similar conditions (meteorological, load, etc.) might be ideal. Are there not tools accessible to ordinary users for making detailed such simulations, rather than a back of the envelope calculation? I daresay Boeing has made such simulations already, and have a pretty good idea of whether and when thrust loss might have occurred. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): ADSB FlightRadar24 |
andihce
July 13, 2025, 18:03:00 GMT permalink Post: 11921493 |
Electrical effects of engine rollback
As I understand it from previous discussions, without the APU, all electrical power except for that DC power provided by battery to essential systems would have been lost. With the copilot as PF, would he have lost his instrument displays? If so, possibly additional startle effect and workload for him. Why did the ADS-B information keep going on for so long? My understanding from previous threads was that loss of ADS-B was considered an indication of loss of electrical power. What else would be expected with loss of power? Some general speculation: I find it hard to understand the long delay from what must have been the onset of obvious issues to the time the first engine is set to "RUN". I wonder if much more cockpit dialog intervened, e.g. PF requesting PM to turn the fuel switches back on (since he had his hands full), and eventually operating the switches himself, with the delay and time gap between the two switches being turned to "RUN" being attributable to being preoccupied with flying the aircraft under trying conditions. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): ADSB APU Fuel (All) Fuel Cutoff Switches Preliminary Report RAT (All) RAT (Deployment) RUN/CUTOFF Startle Effect |
andihce
July 13, 2025, 20:45:00 GMT permalink Post: 11921635 |
Sorry to reply twice, but's worth noting that Samaritans responders (Befrienders in the US?) are trained to ask if the caller has considered a means of killing themselves. If they have, they move right up to a red alert. Sometimes the question is the first time the person recognises that they do in fact have a plan ready to go.
I know such cases have happened (or may have happened, as in MH370), and perhaps cannot be excluded here with what we know at present, but I for one would be far more inclined to suspect something along the lines of the various "brain fart" possibilities that have been mentioned, absent further data. Subjects: None |
andihce
July 15, 2025, 16:47:00 GMT permalink Post: 11923081 |
I'm not saying pilot suicide is common, its exceedingly rare. But the likelihood of this cooked up scenario that you would have to come up with is infinitesimally small (i would say impossible but nothing is impossible). It literally has never in modern day aviation happened, and we would probably have to fly for hundreds more years to even possibly approach a likelihood of a single event happening. Suicides while rare have happened and not just 1.
Again I'm not even saying its suicide, you prob may only know if you heard the CVR and even then their could be a question. What I'm saying is anyone downplaying that as an option because it's "rare" but then goes down the path of concocting some crazy failure scenario has now come up with a situation that is orders of magnitude more improbable, just because its uncomfortable for them to think of the suicide as being a possibility. We are looking at a selected, specific event , not "all flights". From what we know about this event, there appear to be only two likely explanations: pilot error (brain fart or whatever), and deliberate, malicious pilot action. Some may still argue that we should prefer the "brain fart" explanation as "pilot suicide is so rare". I hope that is the case, but extensive discussion here seems to consider that the "brain fart" explanation, given the specific circumstances and information we know as perhaps comparably unlikely. One of these two "unlikely" explanations is likely true. Last edited by andihce; 15th July 2025 at 17:38 . Reason: Removed reference to Germanwings Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CVR |
andihce
July 15, 2025, 17:15:00 GMT permalink Post: 11923095 |
And again, Germanwings is a terrible example. Different phase of flight, very typical behavior for suicide, being initiated alone in a relatively tranquil moment without external stresses and, most importantly, unobserved. While most suicides are not concealed they are almost always carried out in private with even the more public kinds usually having an element of isolation (person standing on bridge or other elevated platform). Unlike what many seem to believe here suicidal people do not lose their ability for rational reasoning. They are not acting irrational in their own mind. They have just arrived at the conclusion that they do not wish to continue living and are then acting out that decision in a sometimes terrifyingly rational manner. It is seen as irrational from the outside because we as observers obviously do not want anyone to die.
And even ignoring that, with the Germanwings incident it was known relatively quickly that the Copilot of the flight had mental health issues and was considering suicide. It. Does. Not. Fit. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Mental Health |
andihce
July 15, 2025, 17:59:00 GMT permalink Post: 11923134 |
[QUOTE=JustusW;11923090]How kind of you to so thoroughly engage with my overview of the facts. Feel free to point out any "abuse of statistics" I made in my post. It's not exactly rocket science to divide the number of known and suspected suicides by the number of departures...
To address this directly, the critical flaw is what a statistician would call " a posteriori analysis ". A typical statistical approach would be to take the data you have (number of suicide-caused crashes and number of flights, both over some given time period), make some assumptions such as that this is a stationary process (not changing in time, e.g., because of improvements in aviation), a random process (non-deterministic), etc. and then generate the statistic (average number of suicides per flight). That statistic might have some usefulness if for example you devised a priori an experiment, in which you would follow the next ten years of flights, hypothesizing that the number of suicide-crashes would correspond to your previously determined average rate, and then tested the actual result vs. the prediction (with such a low rate of suicide flights, there would of course be the possibility of large statistical uncertainty in the previously determined average, and in the subsequent measurement). But when you select a specific flight, and not merely a flight, but one that ended in a crash, and not merely a crash but one where suicide is suspected, and expect that average to have some relevance, you have stepped deep into the quagmire of a posteriori analysis. The statistic you have simply can't be properly applied to the situation you are attempting to apply it to. The current case is not even remotely representative of (a random selection from) the population (all flights) for which the statistic was derived. Last edited by andihce; 15th July 2025 at 18:44 . Reason: clarification Subjects: None |
andihce
July 15, 2025, 19:58:00 GMT permalink Post: 11923219 |
A major part of statistical analysis is a posteriori. It is not invalid or critically flawed methodology. And of course it can be applied here in the manner I have chosen. I have not used it to argue anything, but merely as foundation for an examination of the actual cases and to refute the false numbers thrown around here previously. Namely the claim that more people have supposedly died recently to pilot suicide than to any other cause. Which is simply false.
I have specifically examined the actual incidents of suspected and confirmed pilot suicide and contrasted their significant differences with the Air India accident. I have concluded based on those differences and the known data about behavior of people committing suicide that the Air India accident does not show even marginal overlap with any confirmed or suspected cases of pilot suicide and is inconsistent with our general understanding of the mental conditions leading to suicidal behavior. I have not, and will not make a statistical argument against this case being pilot suicide. I will however refute attempts at misrepresenting the statistical facts about pilot suicide. I will say that in reading your earlier post, I came away thinking you were arguing for the unlikelihood of suicide in this case, at least in part because it is unlikely in the world of commercial aviation as a historical fact. If that's not the case, I apologize. But I will add I think other commentary here has fallen into this trap, as discussed in my referenced post. Last edited by andihce; 15th July 2025 at 19:59 . Reason: formatting Subjects: None |
andihce
July 16, 2025, 13:21:00 GMT permalink Post: 11923732 |
I may be having a "brain fart" myself here, but do they definitely not?
The timestamps most certainly are not synced so the blue boxes on my image almost certainly need to move a little left or right, but actually when I looked at them before I think it's pretty close. What is it that makes you think they are out (genuine question!). As an aside, I have no knowledge of the software used by Flight Aware reporters, but I would be surprised if, at the very least, the computer involved was not set up with NTP (Internet Network Time Protocol) to synchronize its clock. This would set the computer's clock to within a small fraction of a second of correct time. For even greater accuracy, an inexpensive GPS device could be interfaced with the computer. Last edited by andihce; 16th July 2025 at 13:42 . Reason: typo Subjects (links are to this post in the relevant subject page so that this post can be seen in context): ADSB Fuel (All) Fuel Cutoff Switches |
andihce
July 17, 2025, 15:37:00 GMT permalink Post: 11924473 |
If it is suicide, which certainly seems to be most people's opinion, I still can't wrap my head around the fact that there are a lot more "certain" ways to do it, this crash was potentially survivable, he would have known the aircraft would come down at a relatively low speed and rate of descent. Plus other factors like the FO potentially intervening or relighting the engines in time. If you've made the decision to commit suicide, don't you choose a way that has less doubt? It just seems like a really odd way to bring down an aircraft.
* that the captain knew the terrain in front of the runway offered no "safe" spot to set the aircraft down * that he knew there was a high fuel load * that all he had to do was guard the FCS's (already set to CUTOFF) with his hand, which would make it very difficult for the FO to intervene while desperately trying to fly the aircraft as best he could under the circumstances * that without autopilot in this phase of flight the FO had to continue to fly the aircraft * that at this very low altitude, there would be no option like a turn back to the reciprocal runway * that engine cutoff at this time would be almost certainly be unrecoverable with even a short delay before the FCS's were set back to RUN (add your thought here) and this choice, perverse (insane) as it is, makes more sense. I want to add one separate thought: the authors of the Preliminary Report had to know that people reading it, reading what it actually said, and inevitably reading between the lines, would likely focus on deliberate action by the captain as a highly probable cause. Don't you think, that if there was any mitigating factual information available to them, that they would have included it? Secondly, regarding recently "leaked" information, if it indeed comes from the investigating team, is certainly a breach of protocol, but since the Preliminary Report would seem to clearly exonerate Boeing and GE, and point to pilot error at the very least, what would be the motivation for a leak at this point? I would guess it might come from frustration that the Preliminary Report has failed to state facts that make almost inevitable a conclusion as to probable cause (for instance, who in the cockpit said what and when, and what else was said that we weren't told about). Possibly it also reflects concern that the investigation has not focused more on factors relevant to that conclusion. Last edited by andihce; 17th July 2025 at 16:11 . Reason: Additional thoughts Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) Fuel Cutoff Switches Preliminary Report RUN/CUTOFF Switch Guards |
andihce
July 17, 2025, 16:32:00 GMT permalink Post: 11924513 |
I did look at a satellite view of the area earlier. To my non-expert eye, the less built-up area to the right of the flight path does not look very promising, and given where the aircraft came down, there did not seem any hope of reaching the river. If the captain was responsible, with his experience, I assume he had a pretty good idea of the likely outcome. Of course, we're assuming a rational decision was involved.
Subjects: None |
andihce
July 17, 2025, 19:07:00 GMT permalink Post: 11924581 |
Subjects: None |
andihce
July 17, 2025, 21:46:00 GMT permalink Post: 11924691 |
I had no problem getting access via that link from here (in the US).
Despite promising 'new details' the article tells us what we already knew: That the FO was flying, the captain monitoring; thus almost certainly the one who operated the switches. It says nothing else of any value, except that it misquotes the report, so can't exactly be trusted to accurately quote other sources too. It tells us about the two pilots, but reveals no useful background, it also tells us that Air India's chief executive has said not to jump to conclusions and that the investigation is far from over. It's a masterpiece of space-filling journalism mentioning sources and 'US officials' not disclosed as connected to the accident or investigation and therefore likely to actually know anything, just voicing opinions. That article tells us the following new (relative to the Preliminary Report) information: "The first officer who was flying the Boeing 787 Dreamliner asked the more-experienced captain why he moved the switches to the \x93cutoff\x94 position after it climbed off the runway, these people said. The first officer expressed surprise and then panicked, these people said, while the captain seemed to remain calm." I would say that information (if true) is significant, especially about the pilots' demeanor. It implies that further words were spoken in the cockpit, beyond what was mentioned in the Preliminary Report. What these unknown words were may be of great significance. Now you may argue this is "fake news", but I find it hard to believe that the WSJ would publish such information without some reliable source. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Preliminary Report Wall Street Journal |
andihce
July 17, 2025, 22:22:00 GMT permalink Post: 11924716 |
We are all of course (perhaps rather morbidly) fascinated and curious about this incident, and trying to reason out what happened with insufficient data - well, at least I am. And to be honest, I am not nearly as concerned about "throwing someone [dead] to the wolves" (to put it rather harshly) than if the pilots had survived and their reputations and livelihoods would be threatened - I have read about plenty of cases where surviving pilots were innocent, even heroic and masterful in their efforts to save life, yet at least in the beginning, were falsely pilloried for what happened. The difficulty with waiting for the Final AAIB Report comes with the possibility of malicious action. I don't know anything about Indian law, but I would imagine that if this incident had happened in the US, it would already be part of a criminal inquiry (not to mention lawsuits), and not simply under the jurisdiction of the NTSB. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All) NTSB |
andihce
July 18, 2025, 01:11:00 GMT permalink Post: 11924787 |
And that's the way it will be. I'm not in any way fully versed in the laws of the nations involved, but my understanding is that the presumption of innocence stands until a guilty verdict is returned in a trial. And bringing a deceased individual to trial just isn't done. The inability to face one's accuser being a primary reason. Innocence will stand.
We are not conducting either a criminal trial, or a civil trial here. I would rather call it (perhaps optimistically) a "scientific enquiry". I think the standard to be applied is whatever we (individually or collectively) think is reasonable, is order to fairly reach a meaningful conclusion. The standard for a criminal trial need not apply. For instance, a determination of "probable cause" for an aircraft accident is hardly something that would pass muster in a criminal trial, yet it is commonly the output of an air accident investigation. Last edited by andihce; 18th July 2025 at 01:32 . Reason: Formatting Subjects: None |
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