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sabenaboy
June 19, 2025, 14:51:00 GMT permalink Post: 11906087 |
OK, I promised some
informed speculation
when I got back, so here goes:
Disclaimer: never worked the 787, so my detailed knowledge is a bit lacking. First off, this is perplexing - especially if the RAT was deployed. There is no 'simple' explanation that I can come up with. GEnx-1B engines have been exceptionally reliable, and the GE carbon composite fan blades are very robust and resistant to bird strike damage (about 15 years after the GE90 entry into service, I remember a GE boast that no GE90 (carbon composite) fan blades had needed to be scrapped due to damage (birdstrike, FOD, etc. - now that was roughly another 15 years ago, so is probably no longer true, but it shows just how robust the carbon composite blades are - far better than the more conventional titanium fan blades). Not saying it wasn't somehow birdstrike related, just that is very unlikely (then again, all the other explanations I can come up with are also very unlikely ![]() Using improper temp when calculating TO performance - after some near misses, Boeing added logic that cross-compares multiple total temp probes - aircraft TAT (I think the 787 uses a single, dual element probe for aircraft TAT, but stand to be corrected) and the temp measured by the engine inlet probes - and puts up a message if they disagree by more than a few degree tolerance - so very, very unlikely. N1 power setting is somewhat less prone to measurement and power setting errors than EPR (N1 is a much simpler measurement than Rolls EPR) - although even with EPR, problems on both engines at the same time is almost unheard of. The Auto Thrust (autothrottle) function 'falls asleep' at 60 knots - and doesn't unlock until one of several things happens - 250 knots, a set altitude AGL is exceeded (I'm thinking 3,000 ft. but the memory is fuzzy), thrust levers are moved more than a couple of degrees, or the mode select is changed (memory says that last one is inhibited below 400 ft. AGL). So an Auto Thrust malfunction is also extremely unlikely. Further, a premature thrust lever retard would not explain a RAT deployment. TO does seem to be very late in the takeoff role - even with a big derate, you still must accelerate fast enough to reach V1 with enough runway to stop - so there is still considerable margin if both engines are operating normally. That makes me wonder if they had the correct TO power setting - but I'm at a loss to explain how they could have fouled that up with all the protections that the 787 puts on that. If one engine did fail after V1, it's conceivable that they shut down the wrong engine - but since this happened literally seconds after takeoff, it begs the question why they would be in a big hurry to shut down the engine. Short of an engine fire, there is nothing about an engine failure that requires quick action to shut it down - no evidence of an engine fire, and even with an engine fire, you normally have minutes to take action - not seconds. The one thing I keep thinking about is someone placing both fuel switches to cutoff immediately after TO. Yes, it's happened before (twice - 767s in the early 1980s), but the root causes of that mistake are understood and have been corrected. Hard to explain how it could happen ( unless, God forbid, it was intentional ). Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Engine Failure (All) Fuel (All) Fuel Cutoff Switches Preliminary Report RAT (All) RAT (Deployment) V1 |
sabenaboy
June 20, 2025, 07:45:00 GMT permalink Post: 11906669 |
"Both engines failed or shut off close to rotation" explains all of the evidence : it explains an unremarkable take-off roll, loss of lift, absence of pronounced yaw, loss of electrical power, loss of the ADS-B transponder, RAT deployment, the noise of the RAT banging into place and revving up, emergency signs lighting up, a possible mayday call reporting loss of thrust/power/lift, and a physically plausible glide from a little over 200 ft AAL to a crash site 50 feet (?) below aerodrome elevation. It explains what we saw on the videos, what the witness reported, where the aircraft ended up, and the ensuing sudden catastrophe. I don't believe we have evidence for anything else right now—I'd be happily corrected on that. The EAFR will tell the story, but the reason for the crash will always remain a "mystery" because the B787 was not equipped with EPTPR's! ( E nhanced P ilot's T hought P rocess R ecorders) I think AI171 will go down in history with MSR990 an MH370. ![]() Subjects (links are to this post in the relevant subject page so that this post can be seen in context): ADSB AI171 EAFR Engine Failure (All) Engine Shutdown MAYDAY RAT (All) RAT (Deployment) Takeoff Roll |
sabenaboy
June 21, 2025, 14:46:00 GMT permalink Post: 11907810 |
I was wondering what the cockpit jumpseat policy in Air India is? Is it known if someone was flying along in the cockpit?
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Jump Seat |
sabenaboy
June 29, 2025, 07:12:00 GMT permalink Post: 11912832 |
How about giving the hamster in the wheel some rest again?
Subjects: None |
sabenaboy
June 29, 2025, 10:57:00 GMT permalink Post: 11912954 |
Subjects: None |
sabenaboy
July 10, 2025, 05:30:00 GMT permalink Post: 11918768 |
*(just one of them) Subjects: None |
sabenaboy
July 13, 2025, 19:08:00 GMT permalink Post: 11921544 |
Please stop with this utter nonsense.
The throttle quadrant was replaced in 2023 for unrelated reasons. The report states so. Crews don\x92t habitually places any items near those switches and ffs how would sand even get in there. These switches were manipulated by hand and (again) even Indian media is reporting there may have been an issue with the crew. https://www.ndtv.com/india-news/air-...-probe-8864239 Subjects: None |
sabenaboy
July 13, 2025, 21:11:00 GMT permalink Post: 11921663 |
That totally clears up any doubt then, because a media interview where claims are made without any substantive evidence at all are clearly to be taken as gospel.
What I found interesting when viewing the Captain's background, was that he was a long-time carer for his aging father, and had called home before the flight to confirm that he would be in contact again once arrived in London. Also that he was highly respected with no history of difficult personal interactions, and had passed all medical clearances. I'm sure we're all open to actual evidence though.
Without any substantive evidence at all...
![]() The two fuel cutoff switches were put in the OFF position. If you have ever used those switches yourself, you will know that it can not be accidental. A deliberate action from one of the pilots is BY FAR the most plausible (or only) explanation. I feel very sorry for the innocent pilot in the cockpit and the hundreds of other victims. Having passed many medical examinations, I can assure you that psychological testing is not part of the periodic medicals.
I'm sure we're all open to actual evidence though.
Please enlighten me about how much time you have spent in an airline cockpit... Judging by what you contribute I suspect it will not be much. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) Fuel Cutoff Fuel Cutoff Switches |
sabenaboy
July 14, 2025, 06:38:00 GMT permalink Post: 11921895 |
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CVR Fuel (All) Fuel Cutoff Fuel Cutoff Switches RUN/CUTOFF |
sabenaboy
July 14, 2025, 07:02:00 GMT permalink Post: 11921905 |
Look at 5.06 in the video, he simulates the CVR comments immediately after the cutoff and times the gap until they are switched back on. He may be right, but that timeline has no more validity than the CVR comments being 1 second before the switches are turned back on again, which could paint a very different picture (inadvertent or mechanical).
The point he's trying to make is that this 10 sec delay is consistent with his assumption that it was all premeditated by the captain. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CVR Fuel (All) Fuel Cutoff Switches |
sabenaboy
July 15, 2025, 13:25:00 GMT permalink Post: 11922940 |
Hopefully
this video
will help to avoid hamsterwheel questions about how those FCS's work.
Subjects: None |
sabenaboy
July 15, 2025, 14:32:00 GMT permalink Post: 11922988 |
The authors of the preliminary report would surely have known that the report as drafted would raise strong suspicions of an intentional act by one of the pilots to shut off the fuel switches. If the investigators had evidence that would indicate that it was not (or may not have been) a deliberate act (from for example the rest of the verbal exchanges between the pilots) then surely they would have included such information in the report in order to avoid such a conclusion from being drawn by the reading public. This suggests that there is no such evidence.
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 |
sabenaboy
July 15, 2025, 14:50:00 GMT permalink Post: 11923003 |
Of course, we now have to wait and see what the investigation ultimately reveals: technical error or human intervention.
I think that in this phase of flight and situation, it's truly a masterpiece to first recognize the problem and then, with the presence of mind, reset the fuel control switches to "Run." We don't yet know which of the two pilots did this, the PF or the PM. Nevertheless, it apparently happened in a fraction of a second. The switches were put to OFF in short succession of each other right after takeoff and only 10 seconds later they were switched back to run with about four seconds delay in between the two switches. 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 |
sabenaboy
July 15, 2025, 14:55:00 GMT permalink Post: 11923005 |
![]() Subjects: None |
sabenaboy
July 16, 2025, 07:16:00 GMT permalink Post: 11923480 |
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): APU CVR Dual Engine Failure Engine Failure (All) Fuel (All) Fuel Cutoff Switches RAT (All) RAT (Deployment) |
sabenaboy
July 16, 2025, 08:56:00 GMT permalink Post: 11923539 |
What action should be taken after this crash?
After 9/11, many countries and airlines changed their jumpseat policies, restricting access to the flight deck to active crew members only. That was a knee-jerk reaction. Imagine there had been jumpseaters on the doomed 9/11 flights — wouldn’t they have tried to stop the cockpit intruders? With jumpseaters present, the pilots would at least have stood a better chance of defending themselves and avoiding being overpowered so quickly.
After 9/11, reinforced cockpit door locks were also introduced. But did that really make aviation safer? Consider Germanwings 9525, or MH370. On narrowbody aircraft, these locks don’t even prevent a group of terrorists seated in one of the front rows from storming the cockpit when the door is opened for a meal or a bathroom break. And yet, after GW9525, no one suggested removing the locks — despite the fact that they contributed to that tragedy. Instead, many airlines — including mine — introduced a policy requiring that no pilot ever be left alone in the cockpit. But to what end? Would a flight attendant really be able to stop a determined pilot from committing suicide? It takes only seconds to shut off fuel control switches, pull engine master switches, and activate fire handles. A flight attendant could just as easily do those things, or take the cockpit fire axe and attack the remaining pilot, then lock the door. How rigorous are the background checks for flight attendants compared to pilots? And now, in the US, some pilots are even allowed to carry guns in the cockpit. How long before that leads to catastrophe? I fear it’s only a matter of time. I suspect there will again be knee-jerk reactions to AI171. Perhaps making it harder to operate critical switches? Would that really improve safety? Or installing CCTV in the cockpit? Would that prevent pilot suicide, or simply make it harder to hide? And would the cost and complexity really be worth it? In my view, the biggest opportunity for improvement lies not in aircraft design, but in human resources. How can we better support pilots who are feeling down, stressed, or depressed? I don’t believe every crash necessarily calls for a technical or procedural fix. In this case, I see no compelling reason to change the aircraft itself. Of course, the one sure way to eliminate pilot suicide would be to remove pilots altogether and fully automate flight. But I believe it will take a long time before such a system is truly safer than what we have today. The best course of action for now is the same as in many situations in the cockpit: sit on your hands, resist the urge to act impulsively, and thoroughly investigate what would truly be the most effective response. In my country, the ministry of transport has adopted the goal of “zero” road traffic fatalities. That’s unrealistic — even absurd — unless you ban all forms of transport altogether. Perhaps we should acknowledge that not every incident or accident needs to be followed by a remedial action. In the case of AI171, any action we take should focus squarely on human factors. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AI171 CCTV Fuel (All) Fuel Cutoff Switches Human Factors Jump Seat |
sabenaboy
July 16, 2025, 09:15:00 GMT permalink Post: 11923558 |
Not being a jet pilot. If you have the throttles at full power and the engines are set to cutoff, and they spool down, when you reset to run, will they start and go to full power, or do you have to set the throttles to idle first, then when started go back to full power..? and why don't you have to retard the throttle(s) to idle first, before you can shut the engine down..?
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 |
sabenaboy
July 16, 2025, 10:30:00 GMT permalink Post: 11923618 |
It is both fascinating and unsettling to observe how the media in India consistently refuse to acknowledge that suicide may be the most likely scenario. Key voices\x97such as former pilots and the airline pilots' union\x97continue to dismiss the possibility that a pilot could have deliberately moved the fuel control switches to the cutoff position. They rely on factually incorrect arguments and emotional reasoning. For instance, some suggest a potential defect in the Boeing 787\x92s fuel cutoff switches. However, the FAA's Special Airworthiness Information Bulletin (SAIB) they reference was specifically issued for the Boeing 737, not the 787.
An overview of public statements made by pilots in the media can be found here. https://feitoffake.wordpress.com/202...room-in-india/ Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) Fuel Cutoff Fuel Cutoff Switches Special Airworthiness Information Bulletin |
sabenaboy
July 17, 2025, 08:16:00 GMT permalink Post: 11924208 |
It really baffles me how the French prosecutor was able to come out
just
two days
after the Germanwings 9525 crash
and lay out the likely cause in remarkable detail \x97 even identifying it as an apparent suicide by the co‑pilot. Yet here we are with the Air India 171 crash: it took the AAIB an entire month to release a so‑called \x93preliminary\x94 report, and even then it\x92s vague, incomplete and raises more questions than it answers.
To me, this is unacceptable. If the French could piece things together and be honest about it in 48 hours, the AAIB should have been able to do better than this. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All) |
sabenaboy
July 17, 2025, 08:34:00 GMT permalink Post: 11924220 |
Last edited by sabenaboy; 17th July 2025 at 08:39 . Reason: Edit added and then removed again Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Thread Moderation |