←back to thread

Preliminary report into Air India crash released

(www.bbc.co.uk)
334 points cjr | 2 comments | 11 Jul 25 20:23 UTC | HN request time: 0.411s | source
Show context
decimalenough ◴[11 Jul 25 21:24 UTC] No.44536914[source]▶
> 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.

So the fuel supply was cut off intentionally. The switches in question are also built so they cannot be triggered accidentally, they need to be unlocked first by pulling them out.

> 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.

And both pilots deny doing it.

It's difficult to conclude anything other than murder-suicide.

replies(25): >>44536947 #>>44536950 #>>44536951 #>>44536962 #>>44536979 #>>44537027 #>>44537520 #>>44537554 #>>44538264 #>>44538281 #>>44538337 #>>44538692 #>>44538779 #>>44538814 #>>44538840 #>>44539178 #>>44539475 #>>44539507 #>>44539508 #>>44539530 #>>44539532 #>>44539749 #>>44539950 #>>44540178 #>>44541039 #
alephnerd ◴[11 Jul 25 21:30 UTC] No.44536951[source]▶
> It's difficult to conclude anything other than murder-suicide.

Is it possible it could have been an accident or a mistake by one of the pilots? How intention-proofed are engine cutoffs?

replies(2): >>44537006 #>>44537365 #
ummonk ◴[11 Jul 25 21:38 UTC] No.44537006[source]▶
You have to pull the switches out (against a spring) to be able to move them over a notch and flip them. Not really something you can just mistake for another switch or bump into by accident.

I'd liken it to turning off the ignition by turning the key while driving your car. Possibly something that could happen if you're really fatigued, but requires quite a mental lapse.

replies(3): >>44537116 #>>44538841 #>>44539256 #
joezydeco ◴[11 Jul 25 21:51 UTC] No.44537116[source]▶
Report says the switches went to cutoff one second apart from each other. Can a human do the physical operation on two switches that quickly?
replies(2): >>44537174 #>>44537341 #
heisenbit ◴[11 Jul 25 22:19 UTC] No.44537341[source]▶
The timing is really curious.

08:08:35 Vr

08:08:39 Liftoff

08:08:42 Engine 1 cut-off

08:08:42 Engine 2 cut-off

08:08:47 minimum idel speed reached

?? One pilot to other: why cut-off. Other: Did not do it

08:08:52 Engine 1 run

08:08:52 Engine 2 run

1 second to switch them both off and then 4 seconds to switch them both on. No one admitted to switch them off. They are probably going with fine comb over the audio and also the remains of the chared switches.

Looks like the engines react very quickly to cut-off so it is not clear whether the question about the cut-off is prompted by a glance to the switches or the feel of the airplane.

The big question is whether the switches were moved or something made it seem as if the switches were moved.

replies(2): >>44537660 #>>44539629 #
ExoticPearTree ◴[12 Jul 25 05:45 UTC] No.44539629[source]▶
> Looks like the engines react very quickly to cut-off so it is not clear whether the question about the cut-off is prompted by a glance to the switches or the feel of the airplane.

The workload is pretty high during the takeoff phase. The engines react right away when fuel flow is stopped. The engine displays can have some lag before data is updated.

Relighting an engine at low speed is not feasible - most need 230-250kts IAS before attempting the operation. Maybe you could do it if the APU was still running and could provide compressed air, but it takes about 20-30 seconds to start up amd then probably 5-10 more to spool up to full thrust. I am speculating here a bit, but the pilot did not have enough time to save the plane even if he did everyting right and as fast as humanly possible.

All this aside is overshadowed by the limited amount of time the pilot flying (I would assume the captain in this case since there was only one ATPL pilot in the cockpit) had to troubleshoot the issue of a dual engine failure - as this is what would have felt to him - during takeoff.

replies(1): >>44541375 #
1. leetrout ◴[12 Jul 25 11:47 UTC] No.44541375[source]▶
> I would assume the captain

The report states the FO was pilot flying.

replies(1): >>44542221 #
2. ExoticPearTree ◴[12 Jul 25 14:13 UTC] No.44542221[source]▶
My bad. I assumed it was the captain since the report says the FO only has a CPL license. And I was a bit surprised he could fly on a comercial airplane with only that kind of license and not an ATPL one.