Posts about: "Fuel (All)" [Posts: 1005 Pages: 51]

While I agree with your point entirely, I don't find it unusual or unexpected that there is resistance among many to accept or even acknowledge the possibility of suicide, but at the same time, it's no more fixated than the alternative camp which argues that suicide is the only possibility - and often promotes it via as erroneous 'evidence' as that suggesting the cutoff switches are faulty and the SAIB 'proves' it.

There's a genuine problem with understanding what 'evidence' means, and both sides seem to be suffering it.

So how many fuel control switches on the Boeing 787 were since the release of this SAIB found with a faulty switch locking?

As I've previously posted, there is the fact that the ADS-B data (in your diagram) continues long after electrical power from the engines would have been lost. Someone recently posted that the engines don't even need to run down for this to happen, saying that operation of the FCS to cutoff would shut down the engine VFSG's.

As an aside, I have no knowledge of the software used by Flight Aware reporters, but I would be surprised if, at the very least, the computer involved was not set up with NTP (Internet Network Time Protocol) to synchronize its clock. This would set the computer's clock to within a small fraction of a second of correct time. For even greater accuracy, an inexpensive GPS device could be interfaced with the computer.

Yes, but that doesn't mean the entire aircraft has no power.

https://fliphtml5.com/quwam/qhdw/Boo...cs_Electrical/ (page 96)

I don't know if the transponder is on the captain's instrument bus, but if so, it would have power from the main battery while the RAT is being deployed.

We are definitely seeing the loss of thrust in the ADS-B data.

So I've looked again and I think that basically the ADS-B data is 5 seconds out.

So in the diagram (can't modify right now but I will), the blue bar starts at 5 and ends at 13, max altitude marker at 8.

That would tie in with loss of power.

It would put, interestingly, engine cutoffs right at the earliest opportunity within the window available with sampling etc.

(Incidentally an apology to Musician who I incorrectly told earlier that such a movement would be inconsistent with max altitude record, I can see clearly now this isn't the case!).

SLF here with engineering background.

Regardless of what happened and why regarding the switches going to off, there is now a documented failure mode of the system that needs mitigation (?):
Fuel switches off at less than XXX ft lead to unrecoverable AC.

If fuel cut off during take off leads to unrecoverable at less than XXX ft or risk of error i.e. switching one vs the other, then inhibit them. I'm putting it too simplistically, but if after V1 the AC is GO and there is a range of altitude/speed that engines loss leads to unrecoverable some mitigation is needed.

In the meantime maybe ban jump seating during such phases of flight regardless of it is relevant to this accident. If there is intention for something like that, less people with access reduces the possibility of happening.

Too much discussion I think for the 10s to bring the switches back to on.... Pilots are not super humans. By that time the situation the AC was at must have been very clear, some hands shaking is expected...

I wonder if based on the data from the flight, sim-runs have been made to see if the situation would be more survivable had the AC 'slammed' itself back to the runway.

--> Any estimation of how many seconds in 'off' would not change the end result? If it is 2-3 seconds, its better to stop discussing if 10s response by pilots was ok or not. The 'why' and 'preventive' of going to 'off' is a lot more important.

Edit: Have been reading tdracer posts for many many years now. Thank you!

And just to be clear the switch fitted to the 787 is NOT that same part as used on the 737. It is a newer design that is visually similar, but CANNOT be installed 'incorrectly'.

- GY

The problem here with inhibiting the fuel cutoff is that what happens if you have an engine fire less than your XXX ft? You still need to turn off that engine, right? Now you could say turning off BOTH should be inhibited... what if they are both on fire and there's a nice flat space in front of you?

- GY

Everything in the preliminary report suggest one of the pilots moved both switches seconds after the liftoff to the CUTOFF position.
If there was a 0,0001 percent chance the switches were faulty and could have moved because of gravity of an object hitting is, there would be a safety bulletin released to all B787 operators

There has not been such a bulletin.

The reason why the report does not mention which of the pilots ask " why did you cutoff ? " is unknown. We also do not know why it was written the switches ' transitioned' instead of ' moved' .
My guess it was either for political reasons or because of a possible criminal investigation.

For a pilot there is no reason to set both switches to cutoff without any reason. There was no engine fire. There was no discussion in the cockpit about using the switches.
Nothing. A mistake is extremely unlikely. There is no reason why the hands of a pilot needs to be near the switches. I do not believe in a brain fart.

I have seen no documentation of such a failure mode. There are many flight crew actions that can cause loss of the aircraft but these are not failure modes. In any event the need for mitigation of a catastrophic failure mode depends on the probability of its occurrence.

Pull the fire handle(s)? Or do those that want the fuel switches to be inhibited also want the fire handles to be inhibited?

That almost started so well!

But the report doesn't suggest one of the pilots moved the switches - it avoids that question entirely. Instead, as you correctly state, it says the switches 'transitioned', which is the strangest way to describe a pilot physically switching them off. I could see that as merely cautious phrasing, but it then describes them as 'transitioning' on again.

Admittedly, I'm a bit rusty with this kind of work these days, but I believe (and so does a former colleague) that the reason these actions are described in this way is that there is no evidence discernible (in time for the report) to identify how those switches were moved. Or even - just to be pedantic since they began in RUN and were discovered in RUN amongst the wreckage - that they moved at all.

I'm not drawing any conclusions, just saying that in the absence of any evidence they could report, they didn't report on any evidence, and 'transition' is the choice how to do that.

I seriously doubt the report fails to identify which pilot asks 'why' and which says 'I didn't' for political reasons. There is too wide a constituency of members of the team and no purpose to be gained, but there would be a possibility it isn't mentioned due to potential legal/criminal investigation if it weren't for the fact that it clearly doesn't actually have that effect at all, and isn't in the AAIB-India remit anyway. If they have no evidence of mental health conditions for either pilot, it's a moot question at this stage in any event.

The only way you can read the report as an investigator is that they itemise all the material facts they know, and omit what isn't yet pertinent or known.

For what its worth - you can actually shut both 787 fuel control switches off simultaneously, with one hand. Did so myself a few days ago. Closest FCS in your purlicue & other gripped between thumb tip & index finger. Lift both and move aft. BTW, not suggesting anything other than it can be done.

I see a lot of posts about how rare it is for a pilot to deliberately crash the plane. But a rare event did take place. A plane full of people crashing right after take off is rare. So given that event has already occurred, whatever caused it howsoever unlikely it may be, is very likely the cause of this crash. Now what information do we have. Let's start with preliminary report, all can agree that everything was just fine until the switches "transitioned" to cut-off after rotation and max speed of 180knots. The way report is written is clearly a compromise. They have timestamps of all the events and including pilot conversation. They chose to release time-stamps for some events but didn't for a lot (including the pilot question about the switch and subsequent response). They released enough information to convey that there is no systematic issues/risks to the planes (which is what NTBS, Boeing would push for) but at the same time they worded the report in a way to not directly call out pilot error (deliberate or not). Now coming to that we know about the pilots:
Captain was single and unmarried; his mom died recently; he moved from Delhi to Mumbai to take care of his dad. Captain also reported to have taken a medical leave in not so distant past. So as you can imagine; he went through a lot recently and it's not out of realm of possibility that his mental state would take him to do something like what happened. He had enough experience; he knew the recovery will be very unlikely once the fuel is cut off right after rotation. He was also PM so would have his hands free to move switches.Moreover, the PF was a trainee and probably wouldn't question his captain right away It would also still preserve captain's legacy; (at least what he might think, keep in mind his nephews are also pilots) if it's not clearly a case of deliberately crashing in the mountains or rapid descent (like previous deliberate pilot crashes) and there is enough ambiguity to ascertain beyond reasonable doubt what happened

Finally, after 60 pages, I learnt something new - "purlicue". Thank you.

Not 'my' XXX ft (my bold in quote)
I read elsewhere in this thread that 'below 400ft (or whereabouts) no actions from the crew' as an SOP. What I read as SLF engineer --> between V1 and 400ft certification flies the AC unless there is failure outside certification bounds in which case we need the professional to attempt to save the day. So... what was the emergency IF hands were at switches area during that phase of the flight?

Read the part that both switches were set to 'off' in the report. Even if they were not and this is aliens, it is documented now.
I wrote that I'm SLF. For me the pilots or whoever is upfront is also a potential failure mode on the system.
I also wrote 'ban jump seating', you missed that.

How do you tell there is an engine fire from the cockpit? Same thing that tells you on the AC side can un-inhibit them. Or add a switch
If there is engine fire alarm at Vr what do SOP say?

FBW control law of AC has several modes that doesn't let pilots do stuff. How do you switch from the one to the other as a pilot? Same can go with engines control.

To avoid misunderstandings: I'm the type that wants human pilots at the front.

Lets focus on the omit of the report the name of the pilot who said " why did you cutoff" and the name of the other pilot.
Fact is there is a recording on the conversation recorded and available to the AAIB. There are multiple microphones in the cockpit. One for the cockpit, and one for each of the mic of the headset.
Even when the mics of the headsets were not working as a result of power failure, pure on the difference in voices the AAIB knows who said what.

So it was a choice not to write in the report what was known.

That is not correct. Normal procedure, as mentioned in various posts in this thread, is to only include facts without analysis. Determining which person said something on a compressed recording, likely containing various types of noise, will definitely require some analysis. Your statement is pure speculation and likely wrong. The CAM is per definition recording a lot of things and does not come with a neat automatically generated script with attributions.
A preliminary report can only contain what is certain. The attribution you want is unlikely to be available yet.

So now you're claiming the two fuel control switches were replaced the morning of the flight? The hamsters are getting dizzy....

That's not an overly detailed description. In fact, and this is the only fact, it doesn't say one word about the locking mechanism of the switches.
I don't know why most of the forum contributors cannot see this.

Winemaker, of course. Or maybe they were already a few days there. Maybe the locking mechanism was loose and started turning, so it wouldn't lock anymore. What the heck. I don't know. Does it really need that much of fantasy to imagine? We all have seen things getting loose with time. It is physically plausible. At least as much as laps or a depressed pilot.