Posts by user "katekebo" [Posts: 7 Total up-votes: 0 Pages: 1]

Question to 787 pilots or engineers familiar with this particular aircraft. Can excessive AOA cause a flame out, especially at certain throttle settings?

Not a pilot, but an engineer with some experience in accident / incident investigation.
One thing that strikes me in this and the previous closed threads is the lengthy back-and-forth discussion about potential technical faults that could lead to this accident.

However, there has been relatively little discussion about the #1 cause of all airplane accident - pilots' mistakes.

Except for the initial conversation about mistakenly retracting flaps instead of landing gear, which eventually was dismissed in favor of engine failure as there has been an almost unanimous agreement that even if such mistake was made, it was recoverable.

But what if the pilots made more than one consecutive mistakes?

Mis-diagnosing the first abnormal behavior and making things worse by performing another action that instead of correcting the first mistake, turned the situation unrecoverable. The history of aircraft accidents is full of examples when a first, relatively benign issue was made much worse and eventually tragic by pilots' subsequent actions.

Frankly, I think it is much more likely that the pilots made several consecutive mistakes than eventually led to the crash than a 1-in-a-billion unrecoverable mechanic failure. I'm looking forward to the CVR and FDR transcripts and I suspect that we will learn that after whatever happened first (pilot's mistake or minor technical failure), it was subsequent pilot's action that turned a manageable situation into a tragic accident.

This is pure speculation but I can envision the following sequence of events that would match the timeline and the little we know from the CVR and sequence of events.
- While PF is concentrated on flying the airplane, PNF moves the switches from RUN to CUTOFF in quick succession (for whatever reason).
- PF doesn't notice that the switches have been moved (again, he is concentrated on flying) but soon perceives the loss of thrust and sees a message on EICAS.
- PF looks down to check throttle position. It takes him a couple seconds to realize that the switches are in CUTOFF position.
- PF asks PNF (and his superior) "Why did you cut off the engines?" (or something similar). PNF anwers that he didn't (a lie, but we don't know if deliberate or just confusion / mental breakdown)
- PF realizes that PNF is in a wrong mental state, and attempts to restart the engines. It takes him a couple of seconds to move both switches because his other hand is on the yoke trying to stabilize the airplane.
- By then the airplane has lost too much energy for a successful recovery. One of the pilots calls MAYDAY because he knows that they are about to crash.
This sequence would match the timeline between the initial fuel cutoff, and when the switches were moved back to run position, and would actually indicate great presence of mind and quick decision from the PF.
Again, this is pure speculation but it would match well with the little information we have.

To those who still try to put the blame on the switches...
- If the switches were defective (wrong type without the detent was installed), this airplane has been in operation for 10+ years - somebody would have noticed.
- If the switches were defective due to wear, it's impossible that both would fail simultaneously at exactly the same time. Have you ever seen all FOUR wheel bearings in a car fail within one second of each other?
- If this was an electric issue (spilled coffee theory), there is no way that ALL electrical contact simultaneously shorted into the exact condition to cut off the fuel. We would see one or two contacts fail first and some kind of "command disagreement", but not a nearly instantaneous total failure. Maybe only if somebody spilled a glass of mercury over the switches ...
The only plausible explanation is that somebody moved them (for a reason unknown).

If there was some kind of Stabiliser error message during the timeline of this accident it would certainly be mentioned in the preliminary report. I am sure that the investigators would have noted it and arrived to similar conclusion you did. A Stabiliser error message would be too relevant piece of information to ignore it in the preliminary report.

Very similar to what I described in my post
Preliminary Air India crash report published

I just read this on avherald.com, and I haven't seen this being discussed here (I may have missed it, in which case please delete my post)

On Jul 12th 2025 (UTC) India's media report that the investigation is NOT focussing on a human action causing the fuel switches to appear in the CUTOFF position, but on a system failure. Service Bulletins by Boeing issued in year 2018 recommending to upgrade the fuel switches to locked versions to prevent inadvertent flip of the switches, as well as the FAA/GE issued Service Bulletin FAA-2021-0273-0013 Attachment 2 relating to loss of control issue (also see above) were NOT implemented by Air India. The stated MN4 computer with faulty soldering, that might weaken and lose contact due to the thermal stress after a number of cycles, interprets data and commands fuel metering valves - with the lost contact attaching the MN4 processor to the EEC intermittent electrical contact, loss of signal processing and engine control faults can occur. The SB writes under conditions for the SB: "An LOTC (Loss Of Thrust Control) event has occurred due to an EEC MN4 microprocessor solder ball failure." According to discussions in the industry it may be possible with the number of cycles VT-ANB had already completed, the solder balls were weakened sufficiently to detach the MN4 from the EEC momentarily due to loads during the takeoff rotation leading to the loss of control of thrust and shut down of the engines.

I had a quick look at the SB and it refers to a computer mounted directly on the engine. I find it extremely unlikely that BOTH computers on two different engines might fail simultaneously. So I take this latest information with a grain of salt ("India's media report").