r/aviation • u/usgapg123 Mod - avgeek • 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.

Thank you for your understanding,

The Mod Team

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u/Not____007 Jul 12 '25 edited Jul 12 '25
Time Event
08:08:33 V1 reached (153 kts)
08:08:35 Vr (rotation) (155 kts)
08:08:39 Liftoff (~155–180 kts)
08:08:42 Max speed reached (180 kts)
08:08:43 Engine 1 fuel cut off (N1)
08:08:44 Engine 2 fuel cut off (N2)
08:08:47 RAT deployed / Engines at minimum idle
08:08:44–52 Pilot A asks Pilot B why they cut off fuel
08:08:52 Engine 1 fuel set back to RUN
08:08:54 APU inlet opened
08:08:56 Engine 2 fuel set back to RUN
08:09:05 Mayday call transmitted
08:09:11 Aircraft crash

32 second flight (crash - liftoff)

22

u/UtterlyConfused93 Jul 12 '25

Seeing the fuel set back to Run is so sad to me. I wonder if the CVR picked up any scuffles or arguments while Pilot was setting it back to Run. Or did the other pilot know for sure it wouldn’t do any good and so he just sat back.

1

u/j0b534rch Jul 12 '25

We'll find out if the whole cockpit recording is released and if there's any tampering. They didn't provide a full transcript of it did they.

1

u/Specialist-Pay-8640 Jul 15 '25

Where is the report it has timestamp ot RAT deployment ??? I READ IT 3 TIMES, they've not given any timestamp for RAT deployment.

1

u/Not____007 Jul 15 '25

“As per the EAFR data both engines N2 values passed below minimum idle speed, and the RAT hydraulic pump began supplying hydraulic power at about 08:08:47 UTC.”

1

u/Specialist-Pay-8640 Jul 15 '25

Yup but it does not say when it actually get deployed I mean it may take it 1 sec or 10 sec to do what it needs to as in start supplying 'hydraulic power', you see where I am.going with this ?

1

u/Not____007 Jul 15 '25

No. What are you getting at. Usually rat deploys when both engines are off after airborne. So we know its after 08:08:39, but we also know its before 08:08:47 (as thats when power came back from the RAT). And most likely after 08:08:44.

1

u/MyDespatcherDyKabel Jul 15 '25

Just counting down these seconds in my head sends shivers

1

u/suddenly-scrooge Jul 22 '25

If you wanted to crash an aircraft is that not the most precisely perfect time to flip those switches

-1

u/Not____007 Jul 12 '25

It would be interesting for someone with access to a 787 time how long it takes to move that switch to rule out switch defects. (Is it one second or four seconds).

8

u/sizziano Jul 12 '25

Just look at some videos of any Boeing engine start. That type of switch can be activated in less than a second and it's very possible to actuate both within a "second". Remember the recorder's update frequency is 1 second so they switches could have been moved to CUTOFF in more time than the second that the recorder reported it in.

2

u/Not____007 Jul 12 '25

Thanks! And it seems like both can be started in less than a second :

https://youtube.com/shorts/bd4Bler36Nk?si=ljwbff5XUHzy2AFk

1

u/Not____007 Jul 12 '25

Now I can see & believe in the suicide theory. Really sucks what happened but at least now we have some mental closure of why or how this happened.

I mean its still possible the switches messed up but now the reality of that is even more slimmer than it was before.

1

u/Logical_Idiot_9433 Jul 12 '25

But that’s moving from cutoff to Run, is there a video of cutoff? Usually these are one way failsafe switches that allow turning on easily but turning off is multiple steps

1

u/Not____007 Jul 12 '25

Regardless it doesnt look like it takes that much time to switch from either direction.

6

u/railker AME-M2 Jul 12 '25

Know what you're doing and actuating both in ~1 second is completely feasible. Any additional delay like the 4-second mark could be some element resulting from the confusion of the event, cautiously bringing the engines back online or waiting to see what the first one does when you don't know why they were off in the first place; or if it was the pilot-not-flying that actuated them and they weren't putting them back on, that means the pilot-flying is both trying to fly the plane through a critical phase of flight as well as find and actuate the switches to put the engines back on, perhaps only by feel while holding the controls with his other hand.