Posts by user "OldnGrounded" [Posts: 77 Total up-votes: 0 Pages: 4]

OldnGrounded
June 21, 2025, 12:49:00 GMT
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Post: 11907719
Originally Posted by The Baron
There was no sign of asymmetric thrust failure, but rather, nearly total loss of thrust just after rotation. Something has caused a catastrophic electric failure that has impacted the air /ground logic functions. There are signs that this event is unique, although there have been cases in the past where the logic has failed and the aircraft no longer knows if it's airborne or not. The crew were probably faced with something they weren't trained for and overwhelmed them. There would have been not enough time to troubleshoot this.
TCMA continues to be one of the few (very unlikely) causes of/contributors to simultaneous shutdown of both engines. So far, though, I don't think we've seen a credible scenario explaining the possibility that TCMA was triggered in this accident. I'm not sure I understand your speculation.

In the scenario you are considering, it's clear that the air/ground state would be wrongly "understood" by the TCMA function. But we don't have, AFAIK , a credible theory for how that might happen. Surely it would have to result from either incorrect signals from the relevant sensors or a failure of the related logic in the FADEC TCMA function, or a combination of those. Indeed, I don't think we yet know exactly which sensor readings that logic depends on or how those readings are fed to the FADEC. Does your speculation include any thoughts about this?

Also, the FADEC TCMA function has to "believe" that the engine is operating at high power and not responding to thrust lever operation. In your proposed scenario, is this also a logic failure \x97 in both FADECs? Or false inputs from both TLs? Or are both engines actually operating at higher than commanded power levels?

Or do I misunderstand your post?

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FADEC

OldnGrounded
June 21, 2025, 17:05:00 GMT
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Post: 11907908
Originally Posted by syseng68k
Aerospace101:

I think tdracer said upthread, that there are two rad alt sensors, and one wow, giving three. Need to verify, `but if two out of three are in agreement, that might be enough redundancy.
tdracer was detailing the inputs to TCMA on a 74 and has said repeatedly that he doesn't know the details of that function on 787s. I'm sure of that because I misread his original post and based a post of mine on the misreading. The inputs he described were multiple WoW switches and multiple RAs, with inputs from each group required to determine that the aircraft is on the ground to enable TCMA-initiated shutdown. It seems likely that the 787 is similar, but that hasn't been established here. I've been looking but haven't found the details yet.

Last edited by OldnGrounded; 21st June 2025 at 17:06 . Reason: Clarification

Subjects: None

OldnGrounded
June 22, 2025, 01:35:00 GMT
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Post: 11908213
Originally Posted by Lead Balloon
Perhaps my earlier post was incredible and that's what prompted the SLF's question.

Let us assume a simple, hypothetical WoW sensor arrangement: One sensor per main landing gear.

One of those sensors is indicating weight OFF wheels and the other is indicating weight ON wheels. What does the TCMA in each engine interpret that ostensibly contradictory sensor information to mean? (Note: For the time being, ignore the question whether the information is erroneous. It may be true.)

Are both engine TCMA's in the 'in the air' state, are both 'on the ground', or is one 'on the ground' and the other 'in the air'?

Given the purpose of the TCMA, I would have thought that any 'doubt' in this case would be resolved in favour of the 'on ground' state for both TCMAs.

But maybe it's the other way around. Maybe any 'doubt' would be resolved in favour of both TCMA's being in the 'in the air' state.

I have difficulty in envisaging any advantage in the TCMA system being designed such that one engine's TCMA is in the 'in the air' state and the engine's 'on the ground'.

Whichever the design and outcome, there will be benefits and there will be risks.
Yes, all true. And I didn't think your earlier post was incredible, just that it was an exercise not intended to explain everything about air/ground logic. I think that, in the real world, it's most likely that the air/ground decision will take inputs from other sensors, not just WoW. Radio altimeters seem the most likely choice and we've been told they've been used on earlier Boeings (which I think I already knew or assumed). I'd certainly feel safer with that arrangement.

Subjects: None

OldnGrounded
June 22, 2025, 14:04:00 GMT
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Post: 11908564
Originally Posted by TryingToLearn
Since this damaged front recorder is the one thing which could solve the miracle of this crash, I would think twice before I would like to give it to a new lab as the first thing to play with.
The lab is new, not necessarily the scientists and technicians who work there. Indeed, that seems unlikely. And I rather suspect that those experts would be offended by a reference to their work in this horrific crash as "play." I know I would be.

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OldnGrounded
June 22, 2025, 14:51:00 GMT
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Post: 11908593
Originally Posted by TryingToLearn
I do SMD rework and failure analysis on automotive control devices and if there would be so much at stake, even if I would be a known expert, I would ask for something to 'play with' or in less offending words: test the equipment, process and success rate on something from the 'scrapyard'. Experience would prevent me from starting with the FDR from the flight.
Maybe they officially need a week to decide where to put it while exactly this is happening, they are doing a dry-run.
Sure. I often referred to the zillion-dollar systems I worked with as toys to play with, but only in some contexts and with some listeners. And I would likely be offended by my work in the context of a catastrophic event being referred to as playing. I think most of us might be.

Also, please note that I have no comment on whatever decisions may have been made or be pending, in this accident, about where to download and analyze the data. Well, no comment except that I see no reason to question the Indian authorities' ability to make those decisions appropriately and with adequate knowledge and expertise.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FDR

OldnGrounded
July 11, 2025, 23:01:00 GMT
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Post: 11919961
I don't see people arguing that a pilot didn't move the switches. I see people offering various alternative possibilities. I do see posters, and mods, insisting that we not suggest deliberate operation of the switches with evil intent without evidence and I think that's an excellent idea.

Also: The preliminary report does not include any specific language for the question and answer about moving the engine control switches . Please, let's stop the imaginary quoting and responses to it.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Preliminary Report  Thread Moderation

OldnGrounded
July 11, 2025, 23:34:00 GMT
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Post: 11920000
Originally Posted by violator
Even the 20,000 hour Sully needed 7 seconds to select the ignition switches to start, 12 seconds to take control and a whopping 17 seconds to call for the QRH checklist.
Yup, because even 20K-hour Sully is human, just like all the rest of us. A damned impressive human, of course. I'm just an easily-confused engineer, but even the most awesome sky gods here (and I am in awe of more than a few of them) cannot know what another pilot, or even they themselves, would do or how long it might take in a situation like the one in this accident.

Subjects: None

OldnGrounded
July 13, 2025, 14:48:00 GMT
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Post: 11921368
Originally Posted by Mrshed
IHowever, from a potentially naive position, my gut tells me this is actually an incredibly effective method of achieving that goal, moreso than the more obvious rapid descent from altitude, mainly because you have effectively removed any window of recovery.
(Engineer, not pilot.) Yes. The engines might relight \x97and I'm really impressed that they did \x97 but at that altitude and airspeed, spooling up and recovering thrust in time to avoid crashing seems extremely unlikely.

At this point, I agree that intentional operation of the FCS switches is the most likely cause of the shutdown. But that doesn't mean that we know or can know what the intent of the intentional action was. And I don't think we have any compelling evidence that the intent was to crash the aircraft and kill everyone aboard.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Relight

OldnGrounded
July 13, 2025, 16:23:00 GMT
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Post: 11921420
Originally Posted by BrogulT
I would suggest everyone that wants to analyze the likelihood of particular actions on the part of the crew, whether referring to "muscle memory" or "brain farts" or whatever, simply add the phrase " during the initial climb " to their thoughts and see how that sounds. Without callouts for raising the gear and other than sleepwalking, what explanation is there for flipping the fuel cutoffs down in sequence? And further, doing so precisely in the time window where it was most likely to make the situation unrecoverable?
The absence of evidence is not evidence. And, in any case, adding "during the initial climb" to a brain fart/muscle memory/seizure of some kind/psychotic break or whatever doesn't make make one of those possibilities any less likely.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Muscle Memory

OldnGrounded
July 13, 2025, 19:06:00 GMT
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Post: 11921543
Originally Posted by Contact Approach
Yes can we just accept this as a fact . . .
"This" apparently meaning that the Captain deliberately and with evil intent moved the FCS switches to CUTOFF and then accused the FO of doing it.

Of course we can't accept it as fact. There's no credible evidence indicating that it happened, much less dispositive evidence.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): RUN/CUTOFF

OldnGrounded
July 13, 2025, 19:45:00 GMT
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Post: 11921577
Originally Posted by Contact Approach
. . . we are after all the most qualified to know the most likely set of events.
No doubt you are most qualified to opine on the likelihood of the events you refer to. But no one is qualified to make confident pronouncements about what actually happened in the absence of evidence, and that's what some of us are objecting to.

Subjects: None

OldnGrounded
July 13, 2025, 19:50:00 GMT
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Post: 11921583
Originally Posted by Contact Approach
But there is evidence, pretty clear evidence!
Is there? Is there evidence for the scenario that you have endorsed, that the Captain deliberately, intending to crash the airplane, moved the fuel control switches to CUTOFF and then accused the FO of doing that? What is that evidence?

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All)  Fuel Cutoff Switches  RUN/CUTOFF

OldnGrounded
July 13, 2025, 20:21:00 GMT
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Post: 11921608
Originally Posted by Contact Approach
Some human in that flight deck moved both fuel switches to cutoff, physically moved them, one after the other. Another human, possibly either human in that flight deck then questioned verbally why they did that. This is factual and proven evidence as per the official report. Why are we not focusing on the who and why!?

Not sure how much more evidence you need to start a discussion.

We as operators are trying to put ourselves in that situation and describe likely outcomes based on present experiences. The most likely event is the PM orchestrating this, the Captain in this case. This however is up for debate\x85 the debate we should be having\x85 not APU doors.
I don't remember joining a debate about the APU door. In fact, I haven't seen such a debate, although I have seen some questions and speculation. I didn't read those posts carefully, but I got the sense that they were in the context of speculation about the possibilities for engine restart and thrust recovery, not about possible causal factors. Maybe I got that wrong.

I certainly don't need more evidence than we have for discussion. I just think a lot more evidence is necessary to conclude that either crew member on that flight deliberately killed the engines intending to crash the jet and, for some reason, accused the other of doing so. Indeed, I don't think we have any actual evidence for that. We simply have a set of circumstances that make that one of only a few possibilities we can reasonably imagine. Discussing it as a possibility is reasonable (although I don't think we can get anywhere on that path without evidence), but claiming that possibility as the one, the truth, what really happened, is not reasonable, not justified by the available evidence. And making unjustified claims that amount to accusing a pilot of mass murder, in a forum that citizens and journalists from around the world always turn to for information in the wake of a major airliner crash, seems like a very bad idea to me.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): APU  Fuel (All)  Fuel Cutoff Switches  Relight

OldnGrounded
July 14, 2025, 00:08:00 GMT
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Post: 11921795
Originally Posted by sabenaboy

The two fuel cutoff switches were put in the OFF position. If you have ever used those switches yourself, you will know that it can not be accidental. A deliberate action from one of the pilots is BY FAR the most plausible (or only) explanation. I feel very sorry for the innocent pilot in the cockpit and the hundreds of other victims. Having passed many medical examinations, I can assure you that psychological testing is not part of the periodic medicals.
It does appear to me that you're NOT open to evidence if you continue to deny that a deliberate pilot action is not plausible.

Please enlighten me about how much time you have spent in an airline cockpit... Judging by what you contribute I suspect it will not be much.
Unless I've missed it, za9ra22 has not been denying that a deliberate pilot action is not plausible. What za9ra22 and others \x97 I among them \x97 are arguing is that there is no credible evidence that either of the pilots deliberately moved the fuel control switches to CUTOFF intending to crash the airplane and kill all aboard . That is certainly one of the plausible possibilities, but only one of them. We don't know, cannot know, what actually happened, because we have available only fragments of evidence, fragments that don't come close to being sufficient to reach a conclusion. And accusing a pilot of deliberately killing hundreds of people, without conclusive evidence that he actually did so, is, IMHO, a grave injustice.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All)  Fuel Cutoff  Fuel Cutoff Switches  RUN/CUTOFF

OldnGrounded
July 14, 2025, 11:38:00 GMT
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Post: 11922109
Originally Posted by etrang
This is the summary
. . . His records have been handed to investigators, whose initial report said their focus was on the actions of the pilots rather than a technical fault with the plane. The Airline Pilots’ Association of India said it rejected the “tone and direction” of the inquiry.
My emphasis.

The preliminary report doesn't say that.

Last edited by T28B; 14th July 2025 at 12:07 . Reason: fixed brackets

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Preliminary Report

OldnGrounded
July 14, 2025, 11:48:00 GMT
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Post: 11922119
Originally Posted by slats11
. . . CCTV may well have prevented MH370 as well as this case. With both, a premeditated plan had the effect of creating confusion and at least some doubt .
Emphasis added.

We don't have evidence sufficient to reach that conclusion in either case. Maybe such evidence will emerge in the Air India crash investigation. Conceivably, investigators already have it (although, if they do, it should have been cited in the preliminary report), but we don't have it. If that's what happened in MH370, it seems pretty unlikely, at this point, that it's going to emerge.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CCTV  Preliminary Report

OldnGrounded
July 14, 2025, 16:41:00 GMT
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Post: 11922355
Originally Posted by STBYRUD
The fact that nobody apparently announced 'engine failure' as per training, but instead asked why the switches were in cut-off, speaks volumes. No need to labor the incredibly improbable double switch failure any further in my humble opinion.
Why do you think it is a "fact that nobody apparently announced 'engine failure'?" That was not included in the preliminary report or, as far as I know, in any other credible reporting here or elsewhere.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Engine Failure (All)  Fuel (All)  Fuel Cutoff Switches  Preliminary Report

OldnGrounded
July 15, 2025, 18:37:00 GMT
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Post: 11923165
Originally Posted by West Coast
More likely as with investigation reporting, ( the authors of the preliminary report are) simply calling balls and strikes and really aren\x92t concerned about the conclusions readers make.
Absolutely. The attempted reading of tea leaves to interpret what the authors may have meant beyond what they said, or what they intended to convey by not saying something else, may be fun for some, but it really contributes nothing to understanding this crash.

We know with reasonable (although not perfect) certainty that the fuel control switches were placed in CUTOFF almost immediately after rotation and were later moved back to RUN. We do not know who did that or why it was done and we don't have nearly enough information to answer those questions with any confidence.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All)  Fuel Cutoff Switches  Preliminary Report  RUN/CUTOFF

OldnGrounded
July 15, 2025, 18:43:00 GMT
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Post: 11923170
Originally Posted by sabenaboy
Oh, come on, get real. Do you really think that all investigators are immune to safeguarding the interest of the people/government that pay their salaries?
Not all, of course, but I absolutely do think that most investigators in roles such as the ones we are discussing are professionals who would and do resist improper influence. Immune? No, none of us are. Guarded against? Yes, that's what professionals with integrity do every hour of every working day.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Switch Guards

OldnGrounded
July 15, 2025, 18:47:00 GMT
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Post: 11923174
Originally Posted by nrunning24
Again I'm not even saying its suicide, you prob may only know if you heard the CVR and even then their could be a question. What I'm saying is anyone downplaying that as an option because it's "rare" but then goes down the path of concocting some crazy failure scenario . . .
Could you point us to posts by someone in this thread who had down both of those things?

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CVR