I think you may be inferring something that isn't actually true. It certainly isn't true in my case. Wanting to explore the details of a function known to be designed to shut down engines, in a case where unexplained shutdown of engines appears to be a likely cause or contributing factor, doesn't suggest that we are assuming TCMA is involved. It's just exploring the details of a a function that is designed to do that and doesn't put on a light, smoke and sound show, or produce obvious debris and residue, when it does.

I think those of us who are persistently trying to learn the details of the sensor inputs to and logic of TCMA (I prefer that characterization to "obsessed with") understand quite well the points you make here — at least those of us whose interest survives in this new thread. However, I at least, and I believe others as well, have also come to the tentative conclusions that (a) the accident aircraft had engines providing little to no useful thrust from nearly the first moments after rotation, and (b) the only possible reasons for that which have been considered here so far involve the sudden and approximately simultaneous shutdown of those engines, most likely by interruption of fuel flow (because that's one of the very few things we know that can do that without producing big bangs, flames and smoke, etc.).

I don't agree that it's more logical to posit that something we don't know about has shut down the engines rather than something that we do know about that is intended to shut down engines. Do you know of other routines/subroutines in the FADEC that shut down fuel supply?

I certainly don't assume that and I haven't seen posts from others (that I consider serious and reasonably well-informed) that "seem to assume" that.

Yes, we know that.

Right, and you won't see a serious attempt to do that until we know, at least, what specific sensor inputs the TCMA function uses to determine the air/ground state of the aircraft and the logic that uses those to make the determination.

Yes, but . . .

In the world we live in, much information, especially early in an investigation like this one, comes from insiders/officials speaking on background or anonymously (for various reasons) to their media contacts. Even the most conservative and responsible publications have little choice but to base reporting, at least partly, on such sources. Whether or not to trust such reporting, and how much to trust it, is left to us to decide. Personally, I'm convinced that the Times trusts the sources of its reporting and typically applies good judgment and good journalistic practices in making such determinations.

Good catch. When I quickly scanned the drawing, I stopped when I realized that it wouldn't tell me how the function actually works in the real world \x97 pretty normal for patent applications. Unless I misunderstand (it happens), I think you're right. That link doesn't make sense.

And they do have a new lab, as of this past April:

AAIB sets up flight recorders laboratory

More at linked site. The lab opening is also featured in the slide show on the top page of the AAIB website, following a series of slides for International Yoga Day.

I don't find your experience with the Times overly surprising. Sloppy research and reporting makes its way into the best news publications, which is why I was careful to use the modifier "generally" in the post you quoted. Copying and pasting from Wiki without attribution is certainly egregious. Still, I feel comfortable with the assumption that the Times/Sunday Times does indeed generally follow good journalistic practices. I accept that the reporter(s) did speak with "Indian authorities" and that those authorities did tell the reporter(s) that a bird strike had been ruled out.

As I said, I'm also pretty confident that the Indian authorities are competent to determine whether there was a bird strike. It would be fair to ask whether I'd be confident in that if they told the reporters that there was a bird strike or that they hadn't ruled it out. I'd have to admit that I'd probably have some difficulty with that, given that I think it would be obvious to us , even with as little evidence we have so far, if birds had taken out those engines. But I hope I wouldn't be too sure that I'm right and they were wrong.

And yes, thanks for correcting those fuel levels. I'd want them to be right if I consulted that Wiki entry. I often use Wikipedia as a starting place, but I remember that it's an encyclopedia and if I have more than a passing interest in the material of an entry, I follow and assess the cited sources there before reaching any conclusions.

Yes, and Boeing specifies at least some of the functionality required in the FADECs.

Yes, but Lead Balloon's posts on this were in response to your post suggesting that "you can't blame Boeing" because the engines and FADECs were built by GE. The real-world question might be who can't blame Boeing? I think the answer is probably that everyone who thinks blaming Boeing is advantageous would at least try to do so. And specification and collaboration would likely be and adequate basis for trying.

Again, I'm not suggesting that TCMA is causal or contributing in this accident, and I understand that there are multiple reasons why that is unlikely even if the air/ground determination was erroneous. I just still want to know what the air/ground inputs and logic are, because there just aren't many things we know about so far that could cause what most believe was at least an important contributing factor.

Edit: As Lead Balloon points out, it was the FAA that required TCMA. The fact remains that Boeing patented at least one version of the function and specifies/collaborates in implementation with the engine manufacturers — more than enough participation for anyone seeking to blame Boeing for (purported) failures.

Yes, but it's clear from context that the WSJ story is referring to the RAT and whatever they may understand from their sources is connected to it.

The story is paywalled, so the link that pops up for me may not work for you, but in case it does:

https://www.wsj.com/business/airline...QPg1BBGQ%3D%3D

Emphatically yes. This is both correct and important to understand. The first rudder hardover crash, UA 585, was in 1991. The second, USAir 427, was in 1994. The first NTSB report concluding that the probable cause was the PCU servo was not issued until 1999, in the USAir investigation. As FMJ says, that only happened because the Eastwind 517 PCU servo issue resolved (what? spontaneously? independently?) and the crew was able to recover control and land safely. The whole story is fascinating, enlightening and sobering.

Sometimes it's really, really difficult to determine the cause(s) of a catastrophic failure of a complex system and it may take a long time.

Sadly, we don't really do that. No one could. The tests can be only for those failure modes already known and those that are anticipated or imagined at any given time. In systems as complex as modern airliners, there will almost certainly always be others no one imagined before they appear on in-service equipment.

They're guarded by the switch design/operation itself. To move one of them, the toggle handle has to first be pulled outward.

I don't know. We can look.

OK. I don't doubt that you can find such articles, probably all the time. But that's not actually relevant as a response to the part of my post that you quoted. Nor are any of those newspapers the one we were talking about earlier. Personally, I can't imagine seriously trusting the Daily Fail. And there's a reason the Guardian is affectionately known as the Grauniad \x97 and it's not merely because of typos.

I think the cellphone interference concern is indeed partly focused on radio altimeters, and also on some voice comms. 5G shouldn't be problematic for the altimeters though. Modern ones operate at around 4.2-4.4 GHz, IIRC, and that's pretty far from any of the three bands 5G uses. I seem to remember reading that EASA tested for 5G interference and that it permits 5G use in the cabin. Whether that's true or not I don't know. And it wouldn't be easy, or even realistic, to police it in an airliner cabin.

Mods, feel free to remove this if you think it's not contributing.

Folks, the exchange here about the cutoff switches ("fuel control switches") is exactly the kind of discussion that contributes meaningfully to our collective understanding of one possible causal or contributing factor in the accident. Smart, well-informed people politely considering and evaluating the suggestions of others. No snark or sniping. Love it.

I hope/wish. I accept that it's not at all likely that TCMA is the/a culprit in this crash, but it is, like the cutoff switches, one of the few things designed and intended to shut down an engine in a very big hurry. It would be good to know as much as possible about how it determines the aircraft's ground/air state.

And add the radio altimeter(s). I think, but don't know, that they provide inputs to the FADEC TCMA function also.

I'm pretty sure that's not true. Everything I've found or read, and authoritative posts by tdracer, indicates that the required condition is thrust, as measured at N2 IIRC, higher than thrust lever position commands. The lever(doesn't) hsve to be at idle.

I haven't seen any videos, or heard of any, that might tell us when the RAT deployed. It was definitely below 400' AGL, because the airplane never got that high.

OK, enough quick, consecutive, posts from me for now. Off to do required chores.

Emphasis added.

Do we know this? If we do, I've missed it. And whether the FADECs receive signals independently from the sensors used to determine the air/ground state of the aircraft \x97 radio altimeters, WoW switches, something else I don't know about \x97 or receive a predetermined state or forwarded signals from another source is crucial to understanding possible failure conditions and the likelihood of simultaneous shutdown by TCMA in both engines. I think.

Well, in the context of the systems we're talking about here, why would it? The requirement is to "know" the actual air/ground state of the aircraft. The position of the gear lever doesn't help with that and might, if part of the voting, contribute to misidentification of that state.