The black boxes from Air india disaster.

[Bonefish Blues]

I've read today that both fuel switches were back on, and 1 engine had spooled back up but had not developed enough thrust to keep them airborne.

I'm erring towards some sort of failure, rather than deliberate act.

The fuel was cut off because each fuel switch was turned off in quick sequence. This was realised in the cockpit, as the voice recording told us. The switches were turned back on again, also sequentially, but as you say, there was insufficient thrust to rescue the situation.

It is vanishingly unlikely that it was anything other than a human hand that did that. We have no idea as to why as yet.

 

[presta]

I used to work developing software for control systems and normally an indicator would reflect the state of the system rather than the position of a switch. But I have no idea about aircraft.

This specifically says that flight data recorders monitor control inputs, but there's no mention of outputs.

 

[wiggydiggy]

The fuel was cut off because each fuel switch was turned off in quick sequence. This was realised in the cockpit, as the voice recording told us. The switches were turned back on again, also sequentially, but as you say, there was insufficient thrust to rescue the situation.

It is vanishingly unlikely that it was anything other than a human hand that did that. We have no idea as to why as yet.

I'm keeping an open mind for now that the switches could have turned themselves.

 

[Bonefish Blues]

I'm keeping an open mind for now that the switches could have turned themselves.

Are you saying that the switches, which have to be lifted against spring pressure before they can be repositioned over a metal detent as a safety measure against accidental operation, turned themselves off in sequence?

 

[markemark]

Or the other pilot did it and said what he said to lay the blame on the other pilot.

There’s a very obvious conclusion. But I’ll wait until the final report. And I suspect most aviation experts will also wait despite their initial suspicions.

 

[Bonefish Blues]

Or the other pilot did it and said what he said to lay the blame on the other pilot.

There’s a very obvious conclusion. But I’ll wait until the final report. And I suspect most aviation experts will also wait despite their initial suspicions.

Juan Brown's video is interesting in the sequence of actions on a 787 flight deck at takeoff, and which pilot does what. The no 1 officer was flying this takeoff.

 

[glasgowcyclist]

There wasn't much left of the plane, and the fact it's crashed into an urban area, makes collecting the bits even more difficult.

I think you may be surprised. Pan Am 103’s wreckage was spread across 845 square miles, and most of it was recovered.

This flight only broke up on impact so the debris will be very much more contained.

 

[markemark]

Juan Brown's video is interesting in the sequence of actions on a 787 flight deck at takeoff, and which pilot does what. The no 1 officer was flying this takeoff.

Does only one pilot have the ability to flip the switches? If it’s both it could be either of them. The voice recording could be a person genuinely asking or lying.

 

[Bonefish Blues]

Does only one pilot have the ability to flip the switches? If it’s both it could be either of them. The voice recording could be a person genuinely asking or lying.

I said, and I repeat, we know a human hand operated the switches but we don't know why (and as you add, who)

It is the case that the pilot flying the take off is the busier of the two pilots during that phase of the flight.

 

[markemark]

In short, one pilot switched the fuel off for both engines in quick succession, then denied he'd done it.

So this was possibly (50/50?) incorrect. Where it was stated that the denier did it. it may have been him. It may have been the other.
This is why the report does not lay blame. And that the obvious conclusions may not be true. And that it’s worth waiting for the final report. Which may also not be conclusive.

 

[DaveReading]

The cause is the engine fuel supply was turned off. There was insufficient time for the engines to spool up once fuel supply was re-established. The interim report says that.

The main reason that a final investigation report often takes a year or more is that the probable cause is almost always a combination of contributing factors.

Yes the fuel supply to the engines was interrupted, but if that had happened at 10,000 feet instead of 100 feet it would have been a very different story. Or if the area around the airport had been flat, open country. Or, etc, etc.

Even the first event in the chain, turning off the fuel supply, could have had a number of causes: an intentional act, an accidental actuation, faulty switches, an electrical fault not directly associated with the switches ...

 

[Bonefish Blues]

[

The main reason that a final investigation report often takes a year or more is that the probable cause is almost always a combination of contributing factors.

Yes the fuel supply to the engines was interrupted, but if that had happened at 10,000 feet instead of 100 feet it would have been a very different story. Or if the area around the airport had been flat, open country. Or, etc, etc.

Even the first event in the chain, turning off the fuel supply, could have had a number of causes: an intentional act, an accidental actuation, faulty switches, an electrical fault not directly associated with the switches ...

Agree with your first two paragraphs.

Regarding the latter, the FDR records the physical position of the fuel cut-off switches so there's no doubt that Boeing and GE have established from the data that they were physically moved, consistent with the supply being cut and then re-established. If such a major system might be susceptible to electrical malfunction then there would have been groundings and/or ungent safety bulletins.

That's why I believe it is safe to say that one (or to our colleague's point perhaps even more than one in the most bizarre possible scenario) of the pilots physically moved the switches, causing the plane to come down.

As to the rest, yes of course there will be months of much more detailed crash investigation, including into its human element.

 

[DaveReading]

That's why I believe it is safe to say that one (or to our colleague's point perhaps even more than one in the most bizarre possible scenario) of the pilots physically moved the switches, causing the plane to come down.

The fuel cutoff switches are common to a number of Boeing types. There have been instances in the past where faulty switches have been fitted that did not require to lifted up in order to move them between Run and Cutoff, so I wouldn't be so quick to rule out inadvertent/accidental operation of the switches, which would be consistent with the reported confusion of the pilots as to why they had been operated.

 

[Bonefish Blues]

The fuel cutoff switches are common to a number of Boeing types. There have been instances in the past where faulty switches have been fitted that did not require to lifted up in order to move them between Run and Cutoff, so I wouldn't be so quick to rule out inadvertent/accidental operation of the switches, which would be consistent with the reported confusion of the pilots as to why they had been operated.

I mentioned that in an earlier post. They were installed on some on Type 737s and a bulletin issued in 2018.

Since then the console in this 787 had been replaced in 2019 and 2023 with no missing locks/detents reported.

Seems vanishingly unlikely to me.

Regarding confusion, who knows, I'm frankly reluctant to say much about that now. All we know is a voice asked why and a voice said they didn't*. There are all sort of scenarios that we can both rehearse that are very much more likely than a switch fault remaining unnoticed for several years and two console replacements which would cause the exchange that is reported (indeed, just for clarity lest I be picked up on it, it may not even have been an exchange...)

*Doubtless these will voices will be, or may already have been attributed and will be published in the final report. I have also read that is thought that the fuel switch operations may also be discernible.

 

[DaveReading]

I mentioned that in an earlier post. They were installed on some on Type 737s and a bulletin issued in 2018.

Since then the console in this 787 had been replaced in 2019 and 2023 with no missing locks/detents reported.

Seems vanishingly unlikely to me.

Regarding confusion, who knows, I'm frankly reluctant to say much about that now. All we know is a voice asked why and a voice said they didn't*. There are all sort of scenarios that we can both rehearse that are very much more likely than a switch fault remaining unnoticed for several years and two console replacements which would cause the exchange that is reported (indeed, just for clarity lest I be picked up on it, it may not even have been an exchange...)

*Doubtless these will voices will be, or may already have been attributed and will be published in the final report. I have also read that is thought that the fuel switch operations may also be discernible.

Yes, I think we can agree that we don't know yet which of the many possible scenarios is what happened.

If we did. we'd be in the wrong job.