Re: OT: air india crash

Is it possible for an electrical fault that is remote from the switches to cut the fuel off (and generate associated warnings) even though the switches remain in the Run position? I presume the "black box" records the state of the resulting control wire at some monitoring point between switch and fuel cut-off valve, rather than recording the actual physical position of the switch.

Maybe the voice which asked "why did you cut off" was asking because of the warnings rather than because he actually saw the other person's hand move the switches.

Hopefully all will become a bit clearer in time.

In general, do air-crash reports generally consist of an interim report within the statutory 30 days and then nothing until the final report, or are subsequent interim reports produced as further information becomes available?

The publication of preliminary report probably has more to do with the need to ground other aircraft of the same or similar type if a design fault or maintenance problem is found.

In this case I think they have come to the broad conclusion that the aircraft fell out of the sky because someone turned off the fuel. It wasn't necessary a design or maintenance problem.

I assume the why, who, how questions will now be investigated.

The chances that the final report will not have so much coverage in the media so you may not be aware of the publication date.

One pilot on the PPRUNE web site claimed that his (unspecified) type of aircraft, which has the same fuel switches as the Air India one, and who was flying for an (unspecified) airline, has had multiple occurrences of inadvertent fuel shut-offs, but he didn’t elaborate further.

Someone else on the group mentioned an inadvertent FCO due to a bag of sandwiches moving the switches.

And it was reported that the aircraft thought it had left the ground, because the ‘on ground’ sensor was fitted to the nose wheel, and the aircraft had rotated but still had the main gear on the runway.

One of probably many Youtube analysis and explanation videos of the report with pictures and operation of the switches etc.

If a crash landing is inevitable, the pilot would wish to shut off fuel to the engines (at the last moment) to reduce the risk of fire[1]. An argument against the interlock you suggested.

Fuel spraying out under pressure is a big risk - especially around hot engine parts. I'm pretty sure that cutting the supply before a crash landing is a normal procedure.

Maybe - however articles have stated that the aircraft used the same type of switches as the 737 and that there had been a number of those installed with the safety mechanism disengaged, resulting in accidental actuations.

Hmm, on the checklist of things to do before you crash I bet that’s *way* down the list.

But two of them, one second apart? That’s a weird “accident”.

Tim

Am I the only one to think that it was remiss (to put it mildly) that when the switches with no safety interlock were discovered, an "all affected planes must be fixed before being allowed to fly" level of directive was not issued. I would say that inoperative safety interlocks is safety-critical. But I'm only a layman ;-)

A mandatory SAIB was issued for 737s but only deemed advisory for 787s.

If you read the AAIB report, it gives the timings of when the switches were moved to cut off, and when the RAM deployed.

As I understand it some safety interlocks were fitted incorrectly but discovered immediately the first time in use, possibly on trail flights.

This issue has been dismissed by a few pilots on Youtube as this would be easily immediately identified by any pilot trained on that aircraft.

Weird, isn't it. On PPRUNE, they are saying that Air India didn't implement the advisory SAIB. That's not to say the interlocks were faulty, though.

No. You are perfectly correct.

I fthe behaviour described had been observed the aircraft would have been grounded immediately.

Ergo the original assertion is bullshit. The fact that no one in the actual industry comes close to a better explanation than 'the captain did it deliberately' is enough for me....

AIUI as soon as *both* engines are shut down the RAT (not RAM) deploys

The aircaft does not wait for them to spool down

If there was the slightest suspicion on the switches, they could have changed it to mandatory for 787s and maybe grounded them until it was done, but they haven't ... which I think tells you a lot.

Matches what I've heard, in combination with the not-on-the-ground switch from the undercarriage, otherwise the RAT would deploy everytime they reached the terminal and switched off.

The report means that other aircraft of the same type don't have to be grounded or inspected.

And if the other pilot was still trying to fly the aircraft and making sense of what was happening? It has been suggested that pilot flying first indication of something wrong was hearing the engines spooling down rather than an in cockpit message or in cockpit observation.

The Indian aviation authorities are obliged to produce an interim report within 30 days, in case that needs to warn of type-safety issues.

Yes I realise that. I mean that I'm surprised that the brief extract of the pilots' words was included in that mandatory preliminary report, given that it *appears* to damn one or other of the pilots, even if not identifying which of the two. It means that there will be suspicion of both of them and both families will take the flak.