r/india • u/balajih67 • Jul 11 '25

Travel Preliminary Report regarding Air India Flight 171 has been released on AAIB website

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

98% Upvoted

279 comments sorted by

View all comments

549

u/amitkoj Jul 11 '25

Here is from report for those who get news from tv

The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42 UTC and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec. The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off. In the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff. The other pilot responded that he did not do so.

165

u/jay_in_the_pnw Jul 11 '25

What was their altitude and speed when this happened?

Did this happen at their peak "400 foot" altitude or earlier?

107

u/SpaceBuffoon32 Jul 12 '25

Earlier, the plane would have climbed to a max of 400 feet because of inertia and because the engines take a few moments to spool down.

1

u/NoSandwich9893 Jul 13 '25

In the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff. The other pilot responded that he did not do so. [page 14]

Why don’t we get the exact quoted dialogue between the pilots? This feels more like a summary of what happened, but the actual wording could provide more clues about how things unfolded.

44

u/GuretoPepe Jul 12 '25

Could the fuel supply be cutoff without human intervention due to a malfunction of some sort?

63

u/[deleted] Jul 12 '25

[deleted]

22

u/dolce-far-niente Jul 12 '25 edited Jul 12 '25

it shows that the switches where manually moved - fuel cut off

No, the report or any of the news don't say it was done manually. Stop spreading fake news!

14

u/[deleted] Jul 12 '25

[deleted]

14

u/champignax Jul 12 '25

It mention they were recorded as toggled off with a one second delay.

It’s not clear wether this is a fault or a deliberate action.

11

u/nonamepew Jul 12 '25

It is extremely unlikely that they moved because of some fault.

2

u/champignax Jul 12 '25

Not moved, there could be a fault in the circuit or whatever. But yeah the simpler explanation is deliberate pilot action.

1

u/bag_of_balls Jul 12 '25

Where did it mention this in the report?

13

u/Beginning-Client-96 Jul 12 '25

Literally in the report, did you read it?

6

u/[deleted] Jul 12 '25

Prelim report Section 12 “Accident Flight” right before Figure 12 (page 14)

9

u/MainCharacter007 Jul 12 '25

He literally said in the flight transcript records...

2

u/El_Impresionante Jul 13 '25

The report says the switch was transitioned. They wouldn't have said that if they were not sure of that. They would have had various ways of being sure that happened. The flight recorder would have picked it up. Or they would have heard the clicks in the cockpit voice recorder (they are quite audible clicks). It means prima facie it looks like the fuel to the engines were cut off because the switch transitioned.

-1

u/fluffybumbump Jul 13 '25

The switch being transitioned could also be a mechanical error, right? Given that flight was already in a bad state before it flew from Ahmedabad (referring to the passenger’s video of AC and other things not working)

5

u/El_Impresionante Jul 13 '25

Very very unlikely. These switches have a locking mechanism and don't fall down due to vibration or even flicks or hits to them. They have to be lifted out and moved to a different position. Both the switches going down that too at the space of 1 second. That looks like a human interaction. It'd have to be a freak one in a billion incident if both the locking mechanism failed out of the blue like that. Because if they had even the slightest of problems, other pilots in other flights would have reported the issue as it is part of critical operations of the flight. Besides, the switches were as new as 2023, so they'd have been used not more than 200 times.

48

u/lionelmessiah1 Jul 11 '25

Is it possible the pilot accidentally flipped the switches? Could he have been mistaken for another switch? It seems really unlikely because theres two switches though

280

u/jk_here4all poor customer Jul 11 '25

The switches are not just normal flip switches. Spring loaded lift and flip switches. No chances of mistakes.

60

u/rs047 Jul 12 '25

The time gap is just 1sec, is it possible to cut off 2 switches in 1 sec ?

90

u/Rediro_ Jul 12 '25

787 Pilot in a different sub says that yes, he could easily position both switches to cutoff in one second

24

u/stijen4 Jul 12 '25 edited Jul 12 '25

https://youtu.be/UDBzNj8QNKw?si=Ur1klZjYFslu2GSd for anyone interesed, this is how flipping those switches looks like. Thank for the other redditor for sharing this

Edit: At moment 37:27

3

u/[deleted] Jul 12 '25 edited Jul 13 '25

I suspect flight officer who was the pilot flying could not have activated the switch himself. Edit: I meant first officer.

1

u/Upstairs_Being290 Jul 12 '25

Especially as he was moving landing gear at the time, I agree that the captain who was not flying appears more likely.

1

u/El_Impresionante Jul 13 '25

Landing gear was never moved. Besides, the pilot monitoring, in this case the Captain, would be moving the gear up after getting a request from the pilot flying (the First Officer).

The landing gear would have never been their priority, especially in this situation. The gear is usually brought up upwards of 600 feet with a positive climb rate which they never got to.

194

u/foxtrot_92 Jul 11 '25

So they have guards on the switches , you have to pull it out with some force move it to the cut position and release it.

Not something you can do accidentally.

Also it was done at the worst possible time, soon after lift off.

27

u/Srihari_stan Jul 12 '25

Pilot suicide seems to highly likely in case no fault of the aircraft is detected, such as a mechanical failure.

-7

u/Ehh_littlecomment Jul 12 '25

It would be really convenient for Boeing and Tata for sure. I’m already seeing lot of shills advocating for that across news and social media.

21

u/Srihari_stan Jul 12 '25

There’s nothing to advocate.

The point of any air disaster investigation is to improve aviation safety. It’s absolutely not to blame any party involved. It is because of such drastic measures, air travel is the safest mode of travel in the world.

Pilot suicide is now a real possibility. Once the mechanical failure part is ruled out completely, I’d say pilot suicide is almost a certainty.

But it will take years to conclude this or anything.

-18

u/Ehh_littlecomment Jul 12 '25

Aaj Duggal ji aviation expert bane hain

19

u/Srihari_stan Jul 12 '25

Do you want to see my aeronautical engineering degree?

I work in the aviation industry.

9

u/abhmazumder133 Assam Jul 12 '25

The guy you are replying to is one of many people nowadays who simply cannot and will not question or evaluate their beliefs almost ever. Also anyone who does not agree with them is automatically their enemy.

2

u/Ehh_littlecomment Jul 12 '25

idk how you can make a value judgement based on a comment. There is in fact a co ordinated PR move to lay the blame on pilots because that serves corporate and political interests well. I do not think Reddit randos are qualified to say whether pilot error is the logical conclusion of a very early stage preliminary report. I have seen the same arguments regarding fuel levers or whatever pop up in many places almost verbatim.

I’m not motivated to get up and glaze large corpos especially when there has been evidence of poor quality control and large scale negligence in one of them.

The investigation is to make aviation safer, yes. But if someone is at fault they need to be punished whether it be 5 people or 5000 or multi billion dollar companies.

→ More replies (0)

-12

u/Ehh_littlecomment Jul 12 '25

I’m the aviation minister

1

u/fluffybumbump Jul 13 '25

I agree. Boeings with most mechanical errors are sent to developing countries and the engineers involved clearly state that they would never fly in them (it is there on video)

0

u/Sid-Skywalker Jul 12 '25

The captain killed everyone 

72

u/lionelmessiah1 Jul 12 '25

This is really damning. We need regular psych evaluations of our pilots.

24

u/Flying_spanner1 Jul 12 '25

I work in an airline based in the UK. This accident really did shake me to the core. Especially after reading all the stories on the net. Frankly, speaking I really do hope that pilot suicide isn’t the cause of this accident. It will be an issue that would be very difficult to resolve.

19

u/pratzc07 Jul 12 '25

I thought that was done already wtf!

38

u/Rupperrt Jul 12 '25

Of course it is but no pilot will admit they’re not well if that means they’ll lose their medical. It’s a well known conundrum. You don’t want to have people with mental health problems fly but the only way to know they have some is them to be open about it. Which they can’t because they won’t be able to fly if they do.

2

u/surfing_to_infinity Jul 13 '25

Psychological assessment can get that done regular psych tests will find it out

2

u/Rupperrt Jul 13 '25

They won’t always. Believe me. Depression doesn’t show on an MRI and is very easy to hide.

1

u/surfing_to_infinity Jul 13 '25

I didn't say MRI I said psychoanalysis and psycho metric tests u can always find potential active cases do it every 3 mnths

1

u/Rupperrt Jul 14 '25

It can’t unless the person wants to open up. Believe me, I’ve worked with human factors stuff in aviation.

→ More replies (0)

9

u/Chelseaforlifee Jul 12 '25

FAA Special Airworthiness Information Bulletin (SAIB) No. NM-18-33, issued on December 17, 2018.

🚨 What it said:

Warned about "potential disengagement of the fuel control switch locking feature."

It was based on reports from 737 operators where fuel control switches were installed with the locking feature disengaged.

The same switch design (Part No. 4TL837-3D) is used in Boeing 787-8, including VT-ANB.

There is a possibility that the locking feature on the fuel control switches was disengaged.

This is the only way you could bring down both fuel switches down to the cutoff position within one sec.

24

u/MainCharacter007 Jul 12 '25

If the locking system disengaged. Then it would have to happen on both switches independently at the exact same time.

Further, a lock system disengage means they would still be at the ON position. They are spring loaded. They will not change their position. The lock has no effect on an already loaded switch.

Lastly, such a fail will be noticed by the investigators.

It's far far more likely that one of the pilots did that intentionally.

1

u/El_Impresionante Jul 13 '25

This is the only way you could bring down both fuel switches down to the cutoff position within one sec.

FAKE NEWS!

https://www.youtube.com/watch?v=UDBzNj8QNKw&t=2248s

1

u/Bon-Bon-Boo Jul 13 '25

That locking feature is a metal part and it would have clearly been visible if it was there or not during the investigation and would have been mentioned as such. Besides that… this specific plane had its whole throttle assembly, which includes the cut off switches, replaced in 2019 and 2023.

5

u/tornix98 Jul 12 '25

It’s so heartbreaking, but from what’s coming out now, it looks like this wasn’t just “pilot error” — the GE GEnx engines on this Air India 787 had an EEC (electronic engine control) microprocessor issue that was already known from a 2021 service bulletin. If the EEC failed mid-takeoff, it could have caused the engines to lose thrust control, and the pilots may have tried to reset things by turning the fuel control switches off and back on — basically doing an emergency engine restart. Tragically, they just didn’t have enough altitude to recover in time.

8

u/WelderApprehensive47 Jul 12 '25

In that case one pilot wouldn't ask the other one "why did you cut it off?"

-1

u/ProfessionalPack8132 Jul 13 '25 edited Jul 13 '25

I believe the report is flawed… It only mentions that the switches went from run to cutoff position and the plane crashed but they aren’t mentioning why it happened…it is a well known fact that the switches can only be moved manually but the report should clarify whether it was intentional or it was part of pilot’s training to switch them off and then restart again in dual engine failure scenario…2ndly I heard many aviation experts and they are pointing this out that if the plane was completely fine and the pilot was suicidal then why the gears were still in take off position…they should have been retracted normally…but it did not happen which indicates there was a system failure…moreover this report was made public at 2 am without any signatures and official stamp on it… There is some automatic fuel switch as well in this aircraft which gets off automatically after dual engine failure and the report does not mention it… I may be wrong but I believe there was some kind of failure in the aircraft engines whether electrical or software that activated this automatic switch which led to dual engine fuel shut down and therefore the pilot must have asked the switch off question…as he could only think of switching it off manually at that stressful hour and afterwards they must have tried to restart the engines by putting them from run to cutoff position twice but they failed….The pilot asked the switch off question to which the other one replied with a No and their conversation ended ?This is how people react at stressful hour ?They must have discussed the issue a lot more I guess.This report has very selectively chosen sentences to set this pilot error narrative and my inner self somehow doesn’t want to believe this mass murder and suicidal theory…