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AAKEE
2025-06-12T13:05:00 permalink Post: 11899189 |
12hPa = 324 feet overstated altitude. Airport 189 feet. Sum = Should show 513feet on ground so 500 or 525 from the ADS-B. Max altitude shown = 650 feet. FR24 Shows zero on ground but adopts to ADS-B atitude after takeoff. Subjects: ADSB FlightRadar24 1 user liked this post. |
AAKEE
2025-06-19T17:34:00 permalink Post: 11906213 |
But the thing is, we do not have many clues/cues for why (supposedly) the engines did shut down. This opens for a worm can of possibilities that all have very low probability. But with not much or no clues, its not even worth continue to guess and find new even more improbable reasons. The extremely low probability seems to trigger non (professional) pilot to guess for reasons that almost can be disregarded right away. For example vapor lock might be a probable possibility for a avgas driven cessna with suction pump only but in this case, maybe not impossible but very close to. Just like about all other reasons a double eng failure should be almost improbable. I guess the highest probability is the unthinkable, and that because of lack for any information pointing anywhere we just might stand back and wait. (This is not my normal call. Usually we have information and cues that can make for a good thread with a lot of learning.) Subjects: None 1 user liked this post. |
AAKEE
2025-06-21T06:00:00 permalink Post: 11907507 |
This probably makes the theory of the TCMA halt a little? Gear up would be inhibited from not being in air. Subjects: Gear Retraction MLG Tilt TCMA (All) 1 user liked this post. |
AAKEE
2025-06-22T07:08:00 permalink Post: 11908310 |
The gear tilt position is not definitive evidence crew had selected gear up. I've speculated another cause for this non-normal gear tilt is that C hydraulics failed around time of rotation. This would explain the gear remaining in the forward tilt position. There are reasons why the crew may have not selected gear up,
see earlier post.
Therefore we cannot determine wow or air/ground logic from an assumed gear retraction.
Another point pointing to that the aircraft did consider itself being \x94In Air\x94 is the ADS-B data sending Altitude from the first 575 feet at 08:08:46.55 until at least 08:50.87\x85? I would think the sub systems like TCMA would use the same In Air / On Ground logic as the aircraft normally use? I come from an FBW aircraft with a Air/Ground logic that seems rather bullet proof and would guess the 787 wouldn\x92t use a less solid logic which probably, in doubt would consider it being \x94In Air\x94? It would be \x94logic\x94 for the TCMA to use this logic? Subjects: ADSB FBW Gear Retraction MLG Tilt TCMA (Air-ground Logic) TCMA (All) TCMA (Logic) 5 users liked this post. |
AAKEE
2025-06-22T08:01:00 permalink Post: 11908343 |
Qualified guess: You cannot certify a system that affects safety (TCMA for example) without considering failure of inputs etc. As the TCMA seems to be widely used it should not have been able to fly under the radar like the MCAS sort of did. Subjects: TCMA (All) 2 users liked this post. |
AAKEE
2025-06-22T11:24:00 permalink Post: 11908460 |
MCAS wasn't "under the radar". The designers thought:
* all MCAS can do is affect the trim * if something goes wrong with the trim, the crew works the "runaway trim" checklist * this cuts MCAS off from the trim * therefore, MCAS failure of any sort is going to be contained Anyway, I think we agree here. I cannot se TCMA logic flying under the Boeing radar in this case? TCMA is a logic nuilt in the EEC/FADEC by the Engine manufacturer I guess? TCMA was motivated by a similar observation: that crews can fail to shut down an engine that no longer follows command input. So the FAA requires aircraft to detect that condition and do it automatically when on the ground, where an engine running at significant thrust is a danger to people and movable objects in the vicinity. The safety consideration here is, if you're on the ground and the thrust reverser is not deployed, you're not going to need the engine that badly. (I think there are actually two more conditions that I don't remember right now.) In safety, you kinda need to weigh the consequences of having this system (with a chance that it might malfunction) vs not having it. Also consider that the benefit of having it, all of the occasions where it correctly shuts an engine off, don't get reported in the press. If a TCMA bug caused this accident, the investigation will find out. But right now, we don't have any evidence that that's what happened. With extremely little data for us to use I think people are grabbing anything as a cause. TCMA as a cause has been interresting, learning. But it should be designed safe. Can we find a data point that takes us away from TCMA or can\x92t we? Subjects: FAA TCMA (All) TCMA (Logic) |
AAKEE
2025-06-28T13:13:00 permalink Post: 11912486 |
I suspect both recorders will contain the same data. Given the radio transmission after the loss of thrust the aircraft still had at least the emergency electrical bus powered. This should have kept both recorders online. It is however possible given the 10 minute battery backup that Boeing chose to put the the recorders on another bus but that\x92s not the norm.
CVR and FDR, och combined such is not needed for survival. I would state that in general the CVR/FDR is shedded when on emergency electricity. Its clear from earlier posts that the front EAFR have a battery backup for this reason and the aft has not. 3 users liked this post. |
AAKEE
2025-06-28T18:19:00 permalink Post: 11912613 |
Not useless
much netter than\x85nothing. Thats most certainly the background to the new regulations to battery backup. Subjects: Parameters RIPS |
AAKEE
2025-06-29T16:25:00 permalink Post: 11913116 |
Murlidhar Mohol Interviewed (Civil aviation minister)
This is some news:
we will be able to ascertain if it was an engine problem or fuel supply issue or why both the engines had stopped functioning.
Subjects: Fuel (All) Fuel Pumps |
AAKEE
2025-06-29T17:18:00 permalink Post: 11913139 |
A slightly less sensationalised version of the same conversation reported in The Sun (posted above), with
Minister of State For Civil Aviation Murlidhar Mohol, though unsurprisingly it doesn't really tell us anything new.
The potential for sabotage is clearly a valid line of investigation in the absence - so far - of any clear evidence of more prosaic malfunction or errors, but I doubt it is anything more than one of dozens of lines of attention. I did not dig very deep into that though. Subjects: None |
AAKEE
2025-06-29T20:45:00 permalink Post: 11913220 |
Some thrust from idle and up would normally keep generators online. Subjects: Generators/Alternators RAT (All) 3 users liked this post. |
AAKEE
2025-07-01T08:26:00 permalink Post: 11914098 |
I've heard of conspiracy theories, but thinking that Boeing and the FAA have allowed the 787 to be certified with a non-compliant fuel system operation is going a bit far. And what about EASA? Plenty of European operators of 787s; EASA must agree it's compliant. "A320/737 does this" is totally irrelevant.
EASA 787-8 TC The FAR/CS 25 doesn\x92t seem to require fuel from separate tanks during takeoff. Subjects: FAA |
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