Posts about: "EDML" [Posts: 31 Pages: 2]

I think it\x92s the lift vortex being dumped from the wingtip as he rotates, and throwing the dust into the air. Normally you don\x92t see it on a clean/ dry runway but it happens on every flight.

Exactly like the action of lifting the flap lever out of detent before moving it. What is significantly different is that you would have to do it twice. It is that which makes it improbable unless intentional.

I fully understand how that is coded, thanks to Tdracer for going in detail of DAL -A certified. However IMHO considering the unusual event, a bug on that piece of code should not be discounted.

What happens if the inputs are erroneous because of a mechanical or maintenance failure?

The funny/worrisome part about that is @Seven-Five said he is an experienced 777 driver! Seriously.

Looks like it is tilted during rotation as far as I can see.

Are you talking about the perfect world? We all make mistakes....

EDML: "No. The throttle position sensors (dual per engine) are part of the FADEC. The throttle position data is not transmitted through the ARINC busses of the aircraft".

To clarify, you are saying that the throttle position sensors are wired directly to the FADEC, and nothng else ?.

Yes. Other aircraft systems get the information through the FADECs (including the DFDRs) but the FADECs itself are isolated including independent alternators (PMG). There are two FADECs per engine and each has it's own throttle position sensor. That was explained by tdracer at some point in the old thread.

Thanks for the clarification.

Surely that's not quite right? If the center tank has fuel, both engines will be fed from the center tank. Only once/if the center tank doesn't have fuel, will the engines be fed from their respective wing tanks.

​​​​​​​Agree. Ban them, mods. Maintain Prune's high standard.

In his reply to your question above, EDML said that tdracer explained this specific wiring in a comment of the old thread (I had missed this detail too), and indeed, this is what he said:

For reference, this is the permalink of the said comment .

I'm afraid that this reconstituted thread is more polluted worse than the original as mods try to hold back this flood of sewage. While there are multiple examples of air disasters caused solely by astonishingly egregious malfeasance by pilots, I see absolutely no point in unsupported speculation about such things. I can't ever say "no professional aircrew would ever do that" but spouting off random theories with no evidence and no practical experience or knowledge of the actual operations involved is really annoying and pointless. If you are a GA pilot, SLF with an engineering degree or a sim enthusiast then maybe, just maybe, you can manage to ask an intelligent question--preferrably one that hasn't already been asked and answered five times already. But please keep your inane hypotheses and conclusions to yourself for now. There's no prize for guessing correctly!

While I disagree with the arrogance of the post generating the conflagration (and the \x91here\x92s how it went down\x92) if one rephrases and softens up the language a bit (and considering how many other low probability scenarios have been posted) the point has some validity.

In jet aircraft how many systems related dual engine flameouts have occurred at low altitude ? Excluding FOD \x97 birds and ice (which presumably aren\x92t a factor here) how many systems caused dual engine flameouts have occurred ?

As opposed to how many engine failures, thrust losses, or shutdowns have been caused by crew members grabbing at improper levers under stress or setting wrong data (I\x92ll include Air Florida in that).

Not meant to be self - indicting by any means but if one is looking at probabilities and far-fetched scenarios you can\x92t exclude crew actions as a part of that.

Yes, there's another snag in the million dollar Q for the explanation. If the MN4 microprocessor can run amok, so could perhaps the TCMA not exactly act as intended. But I take in both your pertinent comments and will (as per the mods advice) from now on sit on my hands and only read until the prelim report hopefully soon!

BR, D Bru

Actually that's not quite true. Thrust far higher than what's being commanded by the thrust lever - it doesn't have to be at idle. But even with a CPU failure commanding high thrust (relative to TL position), the odds of that happening to two engines at the same time is astronomical.
BTW, I don't know if there is any 'crosstalk' of TCMA activation between engines on the 787. I know we don't do any crosstalk of other engines info on the 747-8, but the 787 is far more integrated, and the amount of data that can put on that ethernet based data bus is massive.
My knee jerk is that they wouldn't crosstalk TCMA status between engines, but the reality is I really don't know.

Could you please elaborate on that?

FR24 did do that raw ADS-B data comparison. Remember the GPS position and barometric altitude are sent by the aircraft itself. The altitude is sent in 25 ft intervals, so a shallow curve that is smooth in reality looks janky in the data, due to the rounding of the numbers. From https://www.flightradar24.com/blog/f...rom-ahmedabad/ :
The red line is the accident flight, and it covers approximately 4.3 seconds.
Obviously the altitudes are all uncorrected for barometric pressure, which would've varied with the weather on that day; you kind of have to mentally shift the lines vertically downward. Now I looked for, but couldn't find, the post in the old thread where the rotation was triangulated\xb9, but I remember that it was near the turnoff to the high-speed taxiway, so a few seconds ahead of this ADS-B capture. We only have the video to show us what occurred then.

That means the ADS-B data doesn't really tell us whether the first few seconds of the climb were normal or not.

When we compare the red line to the blue lines, the data tells us the climb rate had already decayed significantly before the accident aircraft passed over the end of the runway, because the red flight path is much more shallow than the blue flight paths.

Please correct me if I'm wrong: to my eye, the data alone does not show that the engines must have failed after rotation, because the data does not demonstrate a normal climb rate.

But likewise, the engines can't have failed much before rotation:
For completeness' sake: you can look at the CCTV video, consider the 787's wingspan a flying 200 ft yardstick, and hopefully agree that the aircraft did not get much higher than 200 ft AAL, if that.

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\xb9 I found one of them, anyway. The reference is the CCTV video:

Yes. That is what I have read here, that is my assumption, that is how Airbus does it, that is what makes sense .

But I am being told elsewhere by someone with an A&P badge that that is not quite the whole story, and that the FADEC PMGs do double-duty as the flight control PMGs.

I am hoping for some documentation to confirm/refute that.

On the other hand, the guy with the A&P badge has to do diagnostics and trace faults across various systems and subsystems (and fix them where there's a repair procedure available).
They get to look into all of the various write-ups from the pilots when the aircraft and its systems don't work quite as they are expected to.
Let's not dismiss that kind of input without due consideration for what it looks like from the point of view of someone whose task it is to keep things working.
Pilots run into similar oddities - well, it's supposed to do this, per the manual, but it's doing something differently - now and again, right?

Never do math in public. You are correct. The center tank should have had a significant amount of fuel at takeoff. Probably at least 40,000 lbs.