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BrogulT
June 20, 2025, 14:02:00 GMT permalink Post: 11906995 |
I think that even if the DEL-AMD leg were flown totally empty for repositioning that it still would have been over MLW if it carried enough fuel for AMD-LGW. And we know from witnesses that the DEL-AMD leg was not empty. AMD is a regular stop for AI and has fuel, why would they tanker it in?
Subjects: None |
BrogulT
June 21, 2025, 19:48:00 GMT permalink Post: 11908009 |
30+ years of my experience as an aircraft engineer that forms a plausible (IMO) explanation of what may have happened.
That wing tank fuel could have picked up a fair amount of water. It is conceivable to me that the suction tube pickup could have been immersed in water, settled out from the fuel in the wing tanks. A supply likely heavily water contaminated. It would take a few seconds for that contaminated fuel to actually reach the engines, but when that contaminated fuel hit, Thrust would have been significantly reduced. The EEC's would have been doing their best to maintain the thrust, firewalling the throttles would probably have little effect at that exact moment. The engines would have likely worked through that bad fuel in a shortish period of time, but a period of time that our crew did not have. First, water in fuel is not a novel concept and I would presume that the designers of the 787 knew about it. You've simply stated that water might collect and settle out, but how much water might you expect under those conditions (57% humidity doesn't seem terribly high to me) and what features and procedures are already there to mitigage water contamination issues? Your theory would imply that there basically aren't any. IDK how the tank venting system works, but the idea that some huge amount of water could have condensed in the tank from the outside seems preposterous. Second, how much water do you think it would take to cause a sustained flameout in one of those engines? Remember that they have automatic continous relight, so you're going to have to sustain your flame suppression long enough for them to wind down completely. I think those engines were probably using something like 2 gallons per second of fuel along with 250lbs of air heated to over 1100F. Any fuel in the mix would burn and the water would be converted to steam so you'd need mostly water for a long time. So if you think a hundred gallons of water could have gotten into each tank then perhaps I'd buy your theory--which, btw, does fit the known facts pretty well. But I think that short of some woeful neglect, Boeing and AI already know about and have methods of dealing with water contamination. At least I hope so. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Relight |
BrogulT
June 21, 2025, 20:48:00 GMT permalink Post: 11908045 |
Subjects: None |
BrogulT
June 22, 2025, 00:03:00 GMT permalink Post: 11908164 |
Subjects: None |
BrogulT
July 10, 2025, 15:01:00 GMT permalink Post: 11919078 |
Propellerhead
You are correct, a low level altitude capture would back off the throttles as the FMA goes into ALT.
Subjects: None |
BrogulT
July 11, 2025, 21:48:00 GMT permalink Post: 11919853 |
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Authority Gradient Fuel (All) Fuel Cutoff Switches Preliminary Report |
BrogulT
July 12, 2025, 00:16:00 GMT permalink Post: 11920034 |
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): APU Relight |
BrogulT
July 13, 2025, 14:05:00 GMT permalink Post: 11921344 |
He was a former Navy pilot employed as a FedEx flight engineer. Obviously he wasn't part of the assigned crew on that flight, but he was a qualified crewmember not just some random FedEx forklift driver.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Jump Seat |
BrogulT
July 13, 2025, 14:32:00 GMT permalink Post: 11921359 |
If it was an action by the captain, then claims that the plan was unlikely to succeed are disproven by the fact that it did succeed and probably with at least a few seconds to spare. He would have known that it would take a short bit of time for the FO to fully figure out that both engines had stopped and why. He would have known that shutting down for more than 10 seconds would spool down the engines far enough to make a relight either slow or unlikely and if need be, he could take further action. He also would have known that a crash into urban Ahmedabad would be catastrophic. I'm not saying his plan was perfect, but it is "reasonable" considering the stated goals and options available. Last edited by Senior Pilot; 13th July 2025 at 17:54 . Reason: Unacceptable accusation at this time Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Relight |
BrogulT
July 13, 2025, 16:09:00 GMT permalink Post: 11921411 |
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Muscle Memory |
BrogulT
July 13, 2025, 16:27:00 GMT permalink Post: 11921424 |
Subjects: None |
BrogulT
July 13, 2025, 20:29:00 GMT permalink Post: 11921621 |
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): APU |
BrogulT
July 13, 2025, 21:18:00 GMT permalink Post: 11921673 |
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All) AAIB (India) Preliminary Report |
BrogulT
July 13, 2025, 21:54:00 GMT permalink Post: 11921706 |
Meaning no disrespect to pilots (indeed, quite the opposite), and admittedly I'm no psychologist, but it strikes me that to postulate that a pilot might cause the crash of a large aircraft because of suicidal thoughts is to
seriously understate the action taken
, because such action also means the likely death of all passengers and aircrew, presumably all or most of whom are perceived as innocent bystanders by the actor. Whatever term you want to apply to that action, it is far more and far worse than individual suicide, and I would think it needs a pretty substantial and convincing body of evidence, including psychological evidence, to explain..
Unless we face up to, study and discuss these issues they'll keep happening occasionally, perhaps even more frequently. If we keep going with preventing pilots from getting assistance by giving them a choice to 1) pretend everything is OK or 2) immediately hand in their medical, we'll stay right where we are. Subjects: None |
BrogulT
July 13, 2025, 22:14:00 GMT permalink Post: 11921727 |
I
assume
something of the same happens in India. However, I can not find any evidence online that a criminal investigation has been launched there and it seems AAIB (India) continues to lead the investigation.
This suggests that, with all the evidence gathered by the investigators so far (which is substantial), there are no grounds to conclude that a criminal act had been committed. In other words, this is an accident and not deliberate. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All) AAIB (India) |
BrogulT
July 14, 2025, 04:36:00 GMT permalink Post: 11921851 |
The extract below shows that from Idle to 83% N1 took 5 seconds after the initiation of a TOGA, so I think your estimate of 30 seconds is probably too high. However, after reading that report, I am of the opinion that AI 171 had no chance of recovering. If the FCS switches had been set to Run within 5 seconds of being set to Cut Off, there might just have been a chance, but it is not at all certain.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): APU FADEC Fuel (All) Fuel Cutoff Switches Relight TOGA |
BrogulT
July 15, 2025, 13:03:00 GMT permalink Post: 11922916 |
There is a 10 second gap between cutting fuel and re-enabling it and a 4 second gap between switches during re-enabling. Is there a mechanical reason why these switches would be slower to operate in either direction? There are obviously reasons such as startle factor and stress that might negatively affect the speedy operation of switches by anyone, but I am nonetheless curious if this might not be a pointer to some sort of mechanical issue after all, such as asymmetric wear or FOD.
The fuel switches were switched off with a gap of 1 second (allowing for 1Hz sampling, between 0 and 2 seconds).
They were switched back on, about 10 seconds later, with a gap of 4 seconds (between 3 and 5 seconds). What might account for the much slower switch on, especially given the serious nature of the situation? 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 |
BrogulT
July 15, 2025, 14:03:00 GMT permalink Post: 11922970 |
"Quite possibly"? A qualified, informed person has taken the time the share exactly how the 4 sets of contacts work on this switch and how they are connected to the plane's electrical system. Go back and find that and read it. It's not an open question. Broken or shorted wires would show up as specific faults, not as just a misreported switch position.
As for the locking mechanism, I don't have this switch but I do have various electronic devices with multiple examples of locking toggle switches with similar functions. They all share a common attribute in that while you can sort of balance the toggle in the middle, the internal toggle mechanism will not snap and change state until you go past that point. So if the switch is in the OFF position, it will not turn on until you go over the hump--and vice versa. So to get the switch in that condition you'd have to first switch it on and then back it off to the middle position. IDK for sure how the specific switches in question behave, but snap-action toggle mechanisms are pretty universal so I'd assume they are similar unless someone with access to one says otherwise. Last edited by BrogulT; 15th July 2025 at 14:59 . Subjects: None |
BrogulT
July 16, 2025, 18:08:00 GMT permalink Post: 11923894 |
That's a not a very meaningful common characteristic to use for comparing these events. Anyone who studies human behavior should include the
ability to adapt
to their analyses. Bacteria adapt to antibiotics by evolving, armies adapt to new weapons by adopting new defensive techniques and suicidal people who want to jump off a bridge can adapt to a chain-link fence by bringing a wire cutters. The obvious hole in your anti-theory here is that part of the theory of most known or suspected pilot suicides involve getting the other crewmembers out of the cockpit. Now that many airlines have adopted policies to prevent anyone from being alone in the cockpit, anyone contemplating suicide by crash will have to come up with a new plan. Now add in the addtional requirement that they hope to "die heroically" as a someone has previously said and now you have an even narrower set of possibilities.
Last edited by BrogulT; 16th July 2025 at 22:05 . Reason: clarity Subjects: None |
BrogulT
July 16, 2025, 22:20:00 GMT permalink Post: 11924037 |
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FDR Fuel (All) Fuel Cutoff Switches Honeywell |