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

Air India finds \x91no issues\x92 with fuel switches on other Boeings after crash (The Guardian)

"WHAT A SURPRISE!!",

said no one, ever.*

*​​​​​ ​​(Except a few PPRune experts.)

Why "There has been no defect reported pertaining to the fuel control switch since 2023 on VT-ANB." instead of: The mishap switches have been checked and have no defects. Their locking feature is operational.

They have the switches.

It appears they can't please anyone. To include a piece of pertinent data is to throw a red herring, and to not include it is to combust pprune in cover-up conspiracies.

They are telling you that the crash aircraft had no reported issues with the fuel control switches (since 2023, which was I think when the unit was replaced), and subsequently also confirmed that there were no defects to report.

I would say it suggests they have concerns relating to the accident which are not yet fully investigated, so don't want to include a factual statement which may not be fact. It is a preliminary report after all. It's job is lay out the sequence of material facts.

FAA confirms that they didn't certificate the 787 with potentially dangerous fuel control switches ...

I fear we could discuss comorbidities until we're blue in the face. But no, I wouldn't dismiss the possibility of it being suicide, no. I just consider it to require any kind of actual prove instead of prove by the inability to come up with better explanations. As for the topic of concealment: It's obviously a grey area but the previously quoted 10-30% prevalence is based on studies trying to figure out exactly that. I certainly wouldn't feel comfortable opining on that number.

Suicidal ideation does frequently present with both imagined as well as examined scenarios. Especially in more severe cases many victims have a history of attempts. The impulsive variants are typically in lesser severities of depression and are actually more common in people with lower levels of suicidal ideation. It would certainly be the most likely scenario for a suicide that I could come up with. It's especially prone to happen in cases with sudden traumatic events on top of an existing baseline condition but can occur in any other condition as far as I know. It would also fit somewhat with an unremarkable history as a person suffering from mild to moderate depression might consider being able to cope on his or her own. And then obviously be less prepared for a spontaneous urge. The troubling part here is that it would be indistinguishable from an action slip without additional evidence as to the pilots state of mind. The observable scenario would be something like this: Immediately upon reaching v2 the Captain moves both fuel cutoff switches to their off state in quick succession. When queried by the FO he denies having done so and remains passive until impact.

This is a plausible scenario, but also one that would be impossible to determine causally. Try for yourself, but you can use either rationalization for the behavior and even use the same rationalization for the opposite behavior. There is no way to predict how anyone would react in that situation and no way to determine either way what that behavior indicates. Not even moving those switches back into the on position by himself would give a reliable clue as to his state of mind. The report would probably default to Human Error in this case, as the intent could not be determined.
The resulting suggestions, ironically, would be basically the same as well. Ease access to mental healthcare, improve training for avoidance, and most importantly: Improve resilience of systems against this type of action.

Based on the numbers available to us right now I can almost guarantee that if you have taken more than 10 flights in your life one or both of your pilots or colleagues on the other seat suffered from symptoms of moderate to severe depression. And you will with almost absolute certainty never actually know. The true question people need to ask themselves is "Do I want my depressed pilot to have access to psychotherapy or not?"

Totally wrong.

The TCMA shuts down one or more engines - but it doesn't move the switches to cut-off in any magical way. TCMA directly operates the fuel valves - but the switches stay on.
Of course there is no entry for the switches being operated on the EAFR when TCMA shuts down an engine!

Not a strong argument against; the majority of completed suicides examined by the US military didn't have indicators of serious MH issues (or suicidal ideation) in either the medical record, nor was family aware.

The study of suicidality is interesting, when it comes up against the examination of an event like this (whether murder/suicide is a possible explanation, why it might or might not be). Non-medical people will often focus on something that's a red herring because it seems strange in the context of a potential suicide, but in terms of the "natural history" of suicide, it might be a pretty common thing. I've been inv with suicide investigation as part of my work, and in some ways it's as frustrating to try to inform laypeople about what norms exist in that field as I imagine it must be for the professional pilots to have dilettantes like me opine on throttles and CRM.

This is just *one * example of dozens of factual incorrect statements made by Mary Schiavo about aircraft accidents. I am surprised that any journalist still takes her seriously.

Pilots are blameless??? What are we even doing here. The evidence shows that outside a 10^(crazy number) event happening, the pilots are 100% to blame. How could you read the report and conclude any differently. As far as we can tell they flew a perfectly working airplane into a building.

The displayed EICAS messages are very different when an engine is shut down via the fuel cutoff switch vice other reasons. The EAFR records those messages. I am quite sure they have eliminated the TCMA as a problem in this accident.

First, apologies for snipping almost all your post - it's not that I disagree with a word, but that we seem decreasingly able to read and properly digest what gets posted here, so I'd rather people read your actual post than my quote of it.

Secondly, even outside the question of legal definitions and legal liability, I've become increasingly concerned with the use of some terminology which doesn't just ascribe motives, but goes far enough to personally accuse a dead professional of many years standing, on the basis of no factual evidence so much as a wish to point the finger.

It's also rather ironic to participate in a Professional Pilot forum where non-pilots are criticised for their lack of knowledge and experience, then witness (presumed and apparent) professional pilots discussing human psychology and behavioural science as if they've been studying it all their lives.

I hope the mods can work out a framework by which this can be discussed without infringing on human decency and professionalism, but I can't see much sign without it that pprune would be a suitable place to further discuss the issues involved. The ad hoc editing done so far really isn't enough, despite the tough job they're doing.

Indeed, there are dedicated parameters for TCMA:

Eng1_TCMA_Shutdown_Local_EEC_A
Eng1_TCMA_Shutdown_Local_EEC_B
Eng2_TCMA_Shutdown_Local_EEC_A
Eng2_TCMA_Shutdown_Local_EEC_B

Originally Posted by za9ra22:
As has been previously pointed out, there's a lot of confusion in these threads about what evidence is and is not. Staying away from legal dictionaries, because we aren't engaged in a lawsuit or criminal trial here, I like this, from Oxford:

The fact that "they are switches designed to be switched from one state to another by a human hand" is not evidence indicating how the switches "transitioned" in this incident. It tells us how they are intended to be operated and it tells us a way that they could have been "transitioned" and that's all it tells us. By itself, the fact of the intent of the designers tells us nothing valuable about what happened on this tragic Air India flight. It doesn't help us to decide, based on evidence, whether human hands actually did move those switches or, if they did, how or why those hands moved those switches. It just isn't evidence for answering those questions, one way or another.

These threads are dominated by posters who are either certain they know how the fuel control switches were "transitioned" by human hands (and increasingly why) and by others who continue to explore and posit possible mechanical or system failures (although those posts seem to be fewer than they were). And then there are a few of us who continue to point out that we simply don't have sufficient evidence to know or decide what actually happened. I think there would be more of us with that view if more of us were more careful in considering what actually is evidence in this case and, if something is evidence, what it may be evidence of.

First off, as has already been pointed out, the French prosecutor was not working to ICAO standards for an accident.
Ok, so they put in the preliminary report that the captain intentionally turned both fuel switches to CUTOFF, causing the crash. The Captain and his family is vilified, criminal investigations are launched. Vengeful relatives of those killed in the crash attack - perhaps even kill - members of the captain's family.
Then it turns out that it's NOT what happened... The captain's reputation and his family have already been destroyed - irreparable damage has been done, and no amount of retractions and apologies for the mistake are going to correct that.

Is it really too much to ask that we allow the investigation team to verify and validate their information before we throw someone to the wolves?

Because the preliminary report can only contain verified factual information.
"There has been no defect reported pertaining to the fuel control switch since 2023 on VT-ANB." - This will have been verified by the investigation team fairly rapidly. Verified reportable fact, included in the preliminary report.

This could not have been done by the team in the time available. Bear in mind that the EAFR was not read until almost 2 weeks after the crash. Before that point there would have been little focus on the fuel switches, which were recovered in the run position (verifiable and reported). Once attention was directed to the switches, a small team will form just to forensically examine those switches. They will likely take WEEKS to even begin the detailed examination of the switches. Those switches have been through a crash and a fire. They dare not move them until every possible non-destructive examination technique has been used. What do you test first? just pulling the sleeve will move something. Moving the lever will move the contacts. Did fingerprints survive the fire?. You would want to x-ray them, measure wear on the locking, look at contact position. Electrically test the terminals. Does it need to be opened? They would get examples from the manufacturer and destructively test them.

Yes in the final report they would be in a position to make a statement like that. But in the preliminary - No.

A visual inspection would verify if the body had a dog and the barrel lined up with it and was behind the dog. Report had nice big pics of exemplar switches and low resolution small pics of mishap switches.

Apologies for the delay in responding to your posts. I see that you and others have stepped in, thanks.

I think for various reasons the ADSB data's absolute values are offset by some amount, for possibly all of the parameters. But there should be consistency in the deltas for the timestamp (by receiving station), the raw baro altitude, the Flightradar24 AGL values, and the airspeed. Flightradar24 themselves note that for altitude " ... the data is not above ground level, but it is consistent to itself."

08:08:46.55 ... 575ft ... 21ft ... 184kt
08:08:48.14 ... 600ft ... 46ft ... 179kt
08:08:48.61 ... 600ft ... 46ft ... 177kt
08:08:49.01 ... 600ft ... 46ft ... 177kt
08:08:49.46 ... 625ft ... 71ft ... 177kt
08:08:49.92 ... 625ft ... 71ft ... 174kt
08:08:50.39 ... 625ft ... 71ft ... 174kt
08:08:50.87 ... 625ft ... 71ft ... 172kt

From the Preliminary Report's airport cctv picture, the RAT was seen deployed at, by my estimate here , 150ft baro altitude, between 4-7 seconds after rotation. So the ADSB readings have to be prior to that.

What's interesting is that the ADSB data covers:
- 4-5 seconds of time (let's approximate 4 seconds from 46.55 to 50.55, ignoring the 0.32s for the moment)
- 50ft of altitude gain
- Declining airspeed from the 1st reading to the last in this final segment from the runway.

Big questions in my mind:
1. If the loss of ADSB corresponds to the E1/E2Fuel Cutoff switches being moved from RUN -> CUTOFF, why is the airspeed declining for the prior 4 seconds?
2. In 4 seconds, why is there only 50ft of altitude gain? that seems odd.
3. To account for only 50ft of alt gain, if we assume the 1st reading is on the runway just before rotation, the intermediate +25ft alt gain is at rotation (Nose up but MLG still on the runway), and the last 4 readings are in the air (nose up an additional 25ft), that means that 1 second or less after lift-off, ADSB was lost - this is before E1/E2 FCO RUN-> CUTOFF.

It's just weird .

I am not sure why 50 feet in 4 seconds seems odd right after liftoff in a heavy aircraft. That corresponds to 750 FPM. Seems entirely normal to me. The rate would have been increasing as the timeline advanced. I would also point out that RAT deployment verses the rat coming online fully are two different times. When that RAT is singled to deploy it bangs out nearly instantly. It begins producing its rated electrical and hydraulic power sometime after deployment.
The widely watched video shows a very normal initial rotation and climb.

Yes, even the switch thing can go nowhere without "interim reports".


It's a good point. If we're talking including the first 25ft or so after rotation the MLG is still on the ground; but when the lift-off occurs wouldn't it be nearer 1000fpm and accelerating upwards; after lift-off it would cover that height in 2 seconds or less.

Since the preliminary report states E2 cutoff after 3-4 seconds after lift-off, if that cutoff corresponds to ADSB interruption and which itself was only transmitting for 4 seconds, then 50ft after liftoff is a bit anemic?

But if we include the first 25ft after rotation but before lift-off, then, because the ADSB duration is only 4 seconds, it means that ADSB was interrupted before the E2 FCO operation. I don't know if there is a sliding window - part after rotation, part after lift-off that might meet all of these constraints.

That still leaves unexplained the declining airspeed seen in the ADSB data... did prior discussions on the ADSB data cover this? is there a good explanation?