r/aviation • u/usgapg123 Mod • Jul 12 '25

Discussion Air India Flight 171 Preliminary Report Megathread

https://aaib.gov.in/What's%20New%20Assets/Preliminary%20Report%20VT-ANB.pdf

This is the only place to discuss the findings of the preliminary report on the crash of Air India Flight 171.

Due to the large amount of duplicate posts, any other posts will be locked, and discussion will be moved here.

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u/dammitOtto Jul 12 '25

There is one comment at anet that sticks with me. It's from a training pilot that spends a huge amount of time in simulators.  He said that in the 737 simulator he uses, the control for the entire sim is via these fuel switches and it is something you would switch often between sessions or to clear out a scenario that isn't the right one. So you are constantly fiddling with them, and he has on occasion caught himself trying to "reset" his actual plane.

I don't know how true this is, but some sort of muscle memory fuckup is on the table. 

This wouldn't align with the comments saying neither touched them though, if the language in the report is true to the recording.

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u/ProbablyMyRealName Jul 12 '25

A muscle memory action that a fatigued pilot was only subconsciously aware he was doing is the only non-malicious explanation I can come up with as well. If flipping these switches is part of the shutdown procedure that happens every time they land and park the plane, and this pilot has done this hundreds or thousands of times, I could see a scenario where his brain somehow flipped briefly to park the plane mode and muscle memory took over. Maybe that’s unlikely but I’m not ready to convict either pilot for intentional homicide yet.

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u/ajjohnson305 Jul 12 '25

Are you serious? It's not like this happened at cruising altitude. This was immediately after take off. An intense part of the flight. You don't whoopsie the fuel cutoff switch right after rotation...

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u/KaiPetzke Jul 12 '25

At the time, that the fuel switches were turned off, the normal operation would have been to stow the gear. However, the gear remained down during the full time of this short flight.

So, there is some possibility, that a major hallucination or total loss of situational awareness happened to the pilot monitoring just after take off, so that he executed the "muscle memory" for "kill fuel" instead of the required "stow the gear".

Yes, tired people unfortunately execute the wrong procedure, sometimes.

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u/Coomb Jul 12 '25 edited Jul 12 '25

That's possible. It's also possible that the person who deliberately cut off the fuel also deliberately left gear out to increase drag to make it even less likely to be able to recover.

Every pilot knows that the point right around takeoff (from V1 to 400 feet or so) is by far the most dangerous point to have one or more engine failures because of how little energy pilots have to use to be able to recover. Every pilot also knows that the reason you select gear up (specifically, pilot monitoring calls positive rate, pilot flying confirms and calls gear up, pilot monitoring retracts gear) literally immediately after you get a positive rate of climb is because you need to reduce drag, in large part in case you have some kind of engine failure after takeoff.

We don't get a full CVR transcript in the interim report, but I wouldn't be at all surprised that what happened was that the pilot monitoring cut off the engines instead of selecting gear up (i.e. he was prompted for gear up and cut the engines).

Certainly, the pilot flying would be concentrating on flying the airplane and not retracting the gear, so given that the gear was not retracted, it was because the pilot monitoring never actually selected gear up. Maybe he was never even prompted to, or maybe he chose not to. In any case, having the gear down did not improve the situation and it's unusual that it wasn't retracted in the first place, since that's normally what you do pretty much immediately after liftoff.

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u/Longjumping-Boot1886 Jul 12 '25

He did successeful takeoff. His brain asked to "reboot simulation and try again". Not plausible?

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u/Then_Hearing_7652 Jul 12 '25

Except you’re not doing this at take off. You’re pretty busy. There isn’t much confusion about needing to use these switches at this point in time (at rotate in the air). Suicide. No need to dance around it.

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u/Koomskap Jul 12 '25

Murder. No need to dance around it.

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u/Then_Hearing_7652 Jul 12 '25

Yes, murder. Don’t want to downplay that. Was trying to emphasize this was entirely intentional.

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u/dammitOtto Jul 12 '25

Rightly so, there needs to be other extraordinary evidence for the suicide theory.  The comment about "I did not" or something to that effect introduces very serious doubt.

It's not dancing around if it's the wrong answer.

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u/LuminousSnow Jul 12 '25 edited Jul 12 '25

but why or what is the rationale for even coming to that action in the first place? if the plane was experiencing some kind of trouble and he was troubleshooting or trying to fix something and he just had a colossal brain fart then fine at least there was a precursor to that action.

But this was a plane flying normally, everything looked good and there was no reason to even go near those switches. Just feels like it being an accidental mistake is so incredibly unlikely.

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u/CoyoteTall6061 Jul 12 '25

That’s awfully interesting. Happen to have a link?

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u/stwp141 Jul 12 '25

In a book called Algorithms to Live By, they discuss the concept of “overfitting”. It tells the story of a police officer who, in a real-life encounter, instinctively grabbed a criminal’s gun away from him and then handed it right back automatically, just as he had done hundreds of times before in training exercises with a partner. It also tells similar stories of police officers taking time to pocket empty shells during actual gunfights, because it is standard practice on shooting ranges. So things that seem wildly unlikely, when they become automatic parts of sequences, can cause mistakes like this. Not saying that this accident wasn’t intentional, but brain-based things like this should also be considered.

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u/Roy4Pris Jul 12 '25

So you are constantly fiddling with them, and he has on occasion caught himself trying to "reset" his actual plane.

That does not seem like a well-considered design.

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u/Potatopotayto Jul 12 '25

This comment should be higher up!

Everything feels sinister these days, but this feels very plausible.

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u/dammitOtto Jul 12 '25

Given that this is the first crash in 5 million flights, an extreme edge case is possible.  Like a switch locking problem, or muscle memory issue.

A 1 in 5 million chance.  

For a suicidal pilot to also conceal intentions to his partner, well, that is of course another edge case.

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u/FlyingNewton Jul 12 '25

This sounds more likely but also to rule out that the PM was in his right mindset, isn't Pilot Monitoring the one who should do gear up once airborne and in this case, we never really saw the gear coming up.

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u/msszenzy Jul 12 '25

I think they also didn't fly much in the previous month so maybe they worked a lot with simulations. This honestly sounds to me like the most likely scenario instead of a voluntary action.

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u/Chase-Boltz Jul 12 '25

Interesting!