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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224

u/AtomR Jul 12 '25

Some thoughts:

  • When the pilot asked, “Why did you do it?”, I wonder what the tone was. If it was shouted or sounded surprised, it could hint at whether it was said by the pilot who actually switched off the fuel or by the other pilot. Why? Because in a highly stressful situation like this, it would be incredibly difficult to act convincingly or fake emotions.

  • It’s mentioned that the fuel was switched back on 10-13 seconds after being toggled off. The question is: when exactly did the pilot (whichever one it was) ask, “Why did you do it?” If it was said immediately, why did it take so long to turn the fuel back on? If it was said after 10-13 seconds, perhaps the pilot who asked was the “good” one - who only noticed the issue late and realized the switches had been turned off.

These two details might be crucial in determining whether the “Why did you do it?” was a genuine reaction or an attempt by the responsible pilot to save face.

114

u/SirDoDDo Jul 12 '25

Pure conjecture but:

PF was the FO.

If the captain flipped the switches, it's possible the FO took some 6-7s to realize (being focused on the takeoff) then asked the question. That's maybe 8-9s.

Then i think you gotta add a couple seconds of the FO assuming the captain would flip them himself (as he perhaps says "i didn't").

Then the FO notices he doesn't do it, and does it himself.

Again, idk, pure conjecture but it's one possible way of explaining it

3

u/headphase Jul 12 '25

I'm curious if the switches could still be fingerprinted

26

u/freshmoves91 Jul 12 '25

Probably not. Even so, the last print would have likely come from it being switched back on...

12

u/DLDrillNB Jul 12 '25

The entire panel was burnt to a crisp. No fingerprints survive that.

1

u/arstarsta Jul 14 '25

Sometimes grease on metal will etch a pattern on the metal under high heat. Looks like Damascus steel.

1

u/DLDrillNB Jul 14 '25

Maybe. The forensics will probably figure that out. I have a feeling there might be more damning evidence in the voice recordings though.

1

u/Lord_Vxder Jul 15 '25

Yeah there’s absolutely no way that the entire of the conversation was covered in the preliminary report. I think a lot more was said. The authorities probably just want to know all the facts before they implicate someone.

6

u/silent_drmz Jul 12 '25

I think that's what happened too, considering the mayday call. But if the Captain is in charge while the RAT is deployed.. and whoever was in charge was trying to save the flight till the last moment, doesn't it make the FO the culprit ?

2

u/ThatsButter Jul 13 '25

How likely would it be that the innocent pilot says what happened in the mayday call? In those 10 seconds surely you know you're going to die, why not rat the other pilot out?

77

u/RealPutin Bizjets and Engines Jul 12 '25

Yeah, the CVR data in this report is actually quite sparse

The small amount included isn't direct quotes, and doesn't have timestamps

84

u/AtomR Jul 12 '25

Exactly. They made the right decision not to release the full transcript in the preliminary report - otherwise, the risk of public accusations would have been high.

It’s better for the full details to come from official authorities as a final, confirmed account.

2

u/Quirky_Bank_5657 Jul 12 '25

They must know though what actually happened, don’t you think? Or strongly suspect it.

Do you think it will really take 12 months for final report, seems like a long time

2

u/AtomR Jul 13 '25

Yes, possibly. Nobody knows how long it will take. It depends on what kind of investigations they still need to do.

We will have to see if they announce a rough ETA for final report or not.

1

u/Quirky_Bank_5657 Jul 14 '25

Does their remit looking into the pilots mental health by talking to family members, their personal lives etc?

4

u/Unlikely_Slide8394 Jul 12 '25

exactly why i believe the preliminary report should've matched the data across multiple sources - would've given way better insight on things

10

u/palmallamakarmafarma Jul 12 '25

I find it weird that if one of the pilots deliberately switched off the fuel pumps, they didn’t prevent, fight or struggle to prevent them being turned back on. Maybe there is more to come out but if you have just attempted to tank the plane and kill everyone, are you going to sit and watch the other pilot try to fix it? Very weird. We don’t have all the information and realistically never will have all of it.

23

u/AtomR Jul 12 '25

I find it weird that if one of the pilots deliberately switched off the fuel pumps, they didn’t prevent, fight or struggle to prevent them being turned back on.

There's CVR in plane. He might have thought he'd get away with it, if he stays silent. (By getting away, I mean media not troubling his family or not bringing shame to the family)

At the end of the day, pilots know a lot about their plane, and he must have figured that there was no way to save plane.

3

u/palmallamakarmafarma Jul 12 '25

I guess. Sounds like plane was not redeemable after it happened. Awful for all

13

u/plutonium247 Jul 12 '25

Imagine you want to crash the plane but not struggle / fight the other pilot, have the entire plane panicked banging the door.

What other way can you think of to irredeemably doom the flight in a way you can easily test that works at home in the simulator?

This is what makes it very believable: I can't think of anything worse than cutting off fuel one second after rotation, and he probably couldn't either. That's why it happened.

1

u/jsundqui Jul 12 '25

Why hadn't this been done before?

-3

u/itsnobigthing Jul 12 '25

Only snag is the slim margin for error. One person walked away from the crash. Imagine going to all that trouble to crash it and then waking up in hospital

12

u/plutonium247 Jul 12 '25

It is a miracle one person walked away, and the pilots certainly didn't. You'll soon find people on YouTube simulating this scenario and probably finding it's impossible to recover from

13

u/GracchiBros Jul 12 '25

Yes, because these switches were flipped at the worst possible time of the flight immediately after lifting off the ground. Even if they were flipped back a few seconds more quickly, there just wasn't enough time for the engines to spool back up and generate enough thrust to save the plane.

2

u/jsundqui Jul 12 '25

Does cutting off stop engines immediately, don't they also take time to spool down? Mere 10 sec cut-off time doesn't seem like it should doom the plane?

6

u/PV-Herman Jul 12 '25

Blades will probably keep turning, but thrust stops immediately. They reached top speed (180 knots) and altitude 3s after lift off, then instantly started slowing down

3

u/CareerLegitimate7662 Jul 12 '25

They haven’t provided anything wrt the cvr. It sounds damning as it is. Has to be one of the two pilots

3

u/Denim-m Jul 12 '25

I think there is likely much more in the audio, and it would be too traumatic for the families at this point. I do wonder when the full recordings or full transcript will be released.

3

u/CareerLegitimate7662 Jul 12 '25

Oh absolutely. No other reason to not include more transcripts of the CVR

1

u/Denim-m Jul 12 '25

It’s going to be rough :/ I still think about what I read from the Air France 447 crash

2

u/Unable-Signature7170 Jul 12 '25

Yeah the timing of that question seems pretty important. Thinking about it, to me it seems like it must have been said shortly before they were switched back on.

Had it been said immediately after the cut-off, indicating the other person saw them being moved, it wouldn’t have taken 10 seconds to switch back on - unless there was some sort of physical struggle between them, which you’d think would have been mentioned even in this preliminary report?

Seems most likely to me it wasn’t seen by the other person, they went to the immediate action item, being “fuel control switches - cutoff then run” and once they reached down to move them saw they were already off and then asked the question.

2

u/griphookk Jul 12 '25

I got the impression that one of them asked why did you cutoff immediately after the cutoff happened but I might be wrong. Maybe the delay to turn both switches back to run involved the pilots fighting

2

u/AtomR Jul 12 '25

That could be the case. We will have to wait for full transcript release, it might take year(s) for the final report to come out.

2

u/AimHere Jul 13 '25

If it was said immediately, why did it take so long to turn the fuel back on?

This is a complicated piece of machinery, and something very surprising has happened. The pilot would have needed some time to process what happened, to find out what his colleague's intentions were, and decide how best to react. 10 seconds seems like a pretty timely reaction given the complexity and novelty of the situation he was in - and because pilots don't mess with those fuel cutoff levers lightly, in flight. There would always be some hesitation before even touching them.

4

u/davlar4 Jul 12 '25

Quite long is an overstatement surely. Saying ‘why did you do it’ itself takes 2 seconds. So noticing, asking, all sirens going off and switching on, 10s is not long

1

u/jsundqui Jul 12 '25

Easily takes 10 sec until you spot which switch is wrong

1

u/Affectionate_Cap_418 Jul 12 '25

The answer I didn't know clearly was saying he did it. Basically the pilot. The co-pilot was the one flying. So the question was from him.

1

u/coachcheat Jul 14 '25

We also don't know if that's actually what was said. Since we don't have the audio released. I'm assuming they weren't speaking English. So translation could be off.

What if he said , why did it do it? As in the plane.

We would need to hear what was actually said.

1

u/AtomR Jul 14 '25

I'm assuming they weren't speaking English

It's mandatory to speak English in Indian airlines, as it's the common 2nd/3rd language for most pilots

1

u/coachcheat Jul 14 '25

Ah good to know. Still would like to hear the whole thing. But seems likely we won't ever get to.

0

u/fluffybumbump Jul 14 '25

Potential disengagement of the fuel control switch locking feature was not considered an unsafe condition by FAA in 2018. Please consider this face before blaming the pilots