Posts by user "Musician" [Posts: 83 Total up-votes: 0 Pages: 5]

Done: Camera in the cockpit, yes or no?

Land, Sea, Air, Space: 3 out of 4, I'd say.

You posed the question of motive ("why") and intent. That is a question an air safety board is ill equipped to answer; it is a question that every criminal investigation must answer, to condemn or acquit.

Thank you! Eyeballing the map overview at FR24 and the ADS-B data, that puts it at 8:08:49. That's 6 seconds after the loss of both engines, so the clock could still be 4 seconds fast—and would have to be fast if that was the first frame of the video where the RAT was fully deployed.

The problem with the switches with hinged covers is that they have a single, "safe" position when they're covered. But the fuel switch is safe at CUTOFF when parked, and safe at RUN when the aircraft is operating, so that won't work.

Hi appruser ! I have quoted Pip_Pip 's post above because the position provides a better means to link ADS-B data to the sequence of events, since it's coming directly from the aircraft. The time stamp comes from the volunteer-run receiver, which might experience clock drift. Based on the public CCTV video, we also have a rough triangulation for the rotation, which occurs next to the high-speed turnoff for the third taxiway.

Note that the good folks at FR24 did not apply temperature correction to the barometric altitude (they corrected for air pressure and runway elevation); pilots on pprune have done the corrections themselves and arrived at slightly different values, so take those altitude numbers with a grain of salt. Note also that the 787 sends altitude in 25 ft. increments, and I don't know how these are rounded (up, down, nearest).

We do not know how long the RAT has been deployed in this photo, we only know it can't have been deployed later. I have learned on this thread that the CUTOFF switch will also cause the VFSGs to disconnect, i.e. the B787 systems will electrically isolate the engine from the power buses before it has spooled down. With a dual failure, this would leave the main buses unpowered in short order, so if all of this is correct, the RAT would have clonked into place very soon after the second engine was cut off. This would not depend on the turbine speed.

I personally do not know what items are logged on the flight recorder, but I imagine RAT deployment was not among them. If so, the conditions for its deployment would be logged, but it requires an analytical step to conclude it did, and a preliminary report typically has no analysis at all. Hydraulic pressure to the flight controls is likely logged, so the RAT delivering hydraulic power would be a matter of record.

Where is the RadAlt antenna on a 787? Is it in the nose, or further back between the main gears?

Thirsty , any notion of an electrical fault must contend with fact that it affected several poles on two switches at nearly the same time in such a way that the signal remained valid; i.e. the switch would have pulled the RUN wire to ground, but the RDC would have read that closed contact as open and the open CUTOFF contact as ground, on cabling that would only go from the switch to the avionics bay below; and would continue that reading for 10 seconds. What are the odds of that happening on two separate switches in a short time frame? with no other electronics reported affected? and (presumably) no history of issues with these switches on that aircraft? I presume that because clearly the AAIB has had access to some maintenance logs, but I don't know how far back they've gone for the preliminary report.

Personally, I'm convinced that there was no electrical fault that caused both switch signals to be read as changed while the switches did not move; and will remain convinced unless the final report reveals evidence to the contrary. I hope that on second thought, you will be, too.

Thank you, ignorantAndroid . I think I wasn't fully awake when I asked, because we don't have RadAlt data at this point: I must've vaguely remembered some older investigation where it mattered how much it rotated up.
The idea is that in appruser 's image, the altitude depends on where the altimeter is, plus how much it rotates up: the barometric altimeter would be in or near the nose?

But obviously, the altimeter should read 0 on the ground when at QFE, so it's adjusted for its height above the ground when the wheels are all down on the ground.

As shown in your diagram, the GPS antenna is a few feet aft of the cockpit. I don't know whether that position is adjusted before it gets sent out.

Apologies if this post seems a little pointless, but when we're looking at altitudes accurate to within a few feet, we ought to be aware where that is when the aircraft is pitched up.

So what are the odds for "crash by brain fart"? for example, when a cargo pilot inadvertantly hits TOGA on descent and then plows the aircraft into the marsh compensating?

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.

I just checked the last one that was linked here: https://www.wsj.com/business/airline...crash-148b7e02 / https://archive.is/pembL That's two errors, or at least very misleading statements.

I think everyone agrees that the preliminary report contains sufficient evidence to start a criminal investigation. What this thread is in two minds about is whether the outcome of a criminal investigation is a foregone conclusion.

That's better than being at the mercy of speculation from the AAIB.

It's easy to go, "it must be suicide, there's nothing else in the preliminary report that explains it". Well, the things that might turn out to be a factor are not in the preliminary report because they're still being investigated. Fuel samples. The switches themselves, which suffered fire damage. A thorough understanding what can cause the transitions logged on the EAFR, and what did cause them.

YOU are one of the sources of "speculation of unknown origin".

It doesn't baffle me at all: they had the data to show that there was only one pilot in the cockpit, and that he frustrated the other pilot's attempts to get back in.

You can't expect an accident investigation to follow a set script. Accident investigations follow the evidence.

Edit: What we have here is a detailed reconstruction of the accident sequence. But we do not have that type of clear evidence of intent.

There is definitely information omitted. The report includes those facts the investigators judge to be relevant, based on the current state of the investigation.

When you look at a NTSB investigation with a public docket, there's always more information than what makes it even into the final report. That's a good thing.

Your argument goes like this:
1) There was a switch failure on a 737 that disabled the gate mechanism.
2) The switch on the 787 is of similar construction (edit: that's why it was included in the SAIB) .
3) Therefore, it is impossible that the accident 787 had a switch issue.

Do you understand that this is not logical?

And then you go on to cajole people who look forward to the AAIB thoroughly examining the switches they have in front of them, to generate actual evidence on whether these specific switches have an issue or not.
I agree that it is unlikely that the switches have an issue, but I still want the AAIB to look, so they can state it as a fact, instead of relying on guesswork.

Assumed: a pilot moved both fuel switches to CUTOFF, and that caused the accident.

Argument against intent:
1. The CVR, taken at face value, reveals that neither pilot was aware he had moved the switch himself
2. On a G650 simulator, CUTOFF after 10 seconds (then RUN after 10 more seconds) was barely recoverable. ( See upthread. ) This suggests the "unrecoverability" window on the 787 was quite short, making a suicide plan risky.
3. Similar accidents were survivable (someone said upthread).
4. Typically, pilot suicides start with the pilot alone in the cockpit at cruise altitude.
5. "Shut down both engines" is an action that often occurs after a flight, and could thus be learned as "muscle memory", and be subject to an action slip.
6. The airline stated that the captain's medical records were found "unremarkable".

Argument for intent:
1. It's the simplest explanation.
2. "I can't believe any pilot would do this unintentionally, and neither should you."
3. Pilot took 10 seconds to correct his "mistake"
4. Uncorroborated reporting has it that the captain did not sound panicked on the CVR.

Did I miss any points?

To be clear, given the facts in the preliminary report, I could not decide this question today.
Whatever happened in Ahmedabad is not affected by the outcome of our discussion.
I hope that the AAIB and the public prosecutor will gather as much evidence as possible, and then the question can hopefully be resolved from facts.

Yes. It would require evidence that we don't have to dispute that.
I expect the AAIB of India would not want it to be said that they did not look for that evidence as thoroughly as they could.
I also do not expect them to find that evidence.
But I want them to have looked, and then say with certainty that it does not exist.

It serves an example for "at first, everyone thought a pilot did it, but then it turned out they didn't".
It's not offered as an explanation.

The first impact was ENE of the grey marker. It looks like if they had passed slightly further north (but maybe south of the water tank), they could have reached one of the open areas with vegetation NE of Ghoda Camp Road. I'm not going to speculate on the outcome.

Ah, but that's analysis, and would usually appear in the final report, not the preliminary.