AAKEE
June 12, 2025, 13:05:00 GMT
permalink Post: 11899189

Quote:

Originally Posted by EK380

Needs to be corrected for a QNH of 997; so barely a few hundred feet AAL.

QNH, 1001, right?

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 (links are to this post in the relevant subject page so that this post can be seen in context): ADSB FlightRadar24

AAKEE
June 19, 2025, 17:34:00 GMT
permalink Post: 11906213

Quote:

Originally Posted by cloudhawke

Does anyone here think it is getting close to the point where all technical explanations are exhausted?

Not really.

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

AAKEE
June 21, 2025, 06:00:00 GMT
permalink Post: 11907507

Quote:

Originally Posted by Aerospace101

The 787-8 gear goes through the following movements on TO:

3. When the pilot commands gear up, the gear retraction sequence begins, specific to the 787-8, the gear trucks tilt forwards first, instantly followed by the gear doors opening.

I might have missed the thing, but as the gear up sequence did start we can be quite sure that the WoW logic had the aircraft \x94in air\x94 (not on ground).

This probably makes the theory of the TCMA halt a little? Gear up would be inhibited from not being in air.

Subjects: None

AAKEE
June 22, 2025, 07:08:00 GMT
permalink Post: 11908310

Quote:

Originally Posted by Aerospace101

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.

Without knowing the 787-8 gear system, we know that is is supposed to be hydraulically moved from \x94nose up\x94 to nose down as the first step in the gear up sequence. But do we know that it would end up \x94nose down\x94 without hyd pressure?

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

AAKEE
June 22, 2025, 08:01:00 GMT
permalink Post: 11908343

Quote:

Originally Posted by Musician

Not quite.

When the aircraft is on the ground (or on the water), it does not transmit altitude.

Thats right, and (guessing here), it would be better to use the solid logic In Air / On Ground than grab a single WoW sensor specially for things that could go very wrong if that sensor start showing a false value.

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: None

AAKEE
June 22, 2025, 11:24:00 GMT
permalink Post: 11908460

Quote:

Originally Posted by Musician

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

\x94Designers thought\x94 = MCAS flying under the radar from Boeing themself.

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?

Quote:

Originally Posted by Musician

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.

Yes. and whe\x92re discussing scenarios here.

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

AAKEE
June 28, 2025, 13:13:00 GMT
permalink Post: 11912486

Quote:

Originally Posted by Sailvi767

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.

I didn\x92t really find a clear reference for other posts (trying to avoid the hamster wheel to over-rev) but in general the emergency busses only support equipment needed for survival.
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.

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

AAKEE
June 28, 2025, 18:19:00 GMT
permalink Post: 11912613

Not useless

Quote:

Originally Posted by D Bru

Even the 10 min RIPS is useless if there's no data sent from electrically shut off systems.

As there of corse will not be any data from shutoff systems, there still will be from systems not shut down. Basic flight parameters, I guess.
much netter than\x85nothing. Thats most certainly the background to the new regulations to battery backup.

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

AAKEE
June 29, 2025, 16:25:00 GMT
permalink Post: 11913116

Murlidhar Mohol Interviewed (Civil aviation minister)

This is some news:

Quote:

we will be able to ascertain if it was an engine problem or fuel supply issue or why both the engines had stopped functioning.

Civil Aviation Murlidhar Mohol interviewed

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

AAKEE
June 29, 2025, 17:18:00 GMT
permalink Post: 11913139

Quote:

Originally Posted by za9ra22

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 read several articles but NDTV sounded like the origin, that actually spoke to the minister?
I did not dig very deep into that though.

Subjects: None

AAKEE
June 29, 2025, 20:45:00 GMT
permalink Post: 11913220

Quote:

Originally Posted by Tailspin Turtle

suggests that the engines were providing some thrust in order for it to get as far as it did.

I guess that that would not normally match the assumption that the generators disconnected (all four) and activated the RAT?
Some thrust from idle and up would normally keep generators online.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Generators/Alternators RAT (All)

AAKEE
July 01, 2025, 08:26:00 GMT
permalink Post: 11914098

Quote:

Originally Posted by Capn Bloggs

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.

No exemption or deviation in the EASA type certificate for shared fuel:
EASA 787-8 TC

The FAR/CS 25 doesn\x92t seem to require fuel from separate tanks during takeoff.

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

AAKEE
July 12, 2025, 08:19:00 GMT
permalink Post: 11920333

Quote:

Originally Posted by tdracer

Wow, 5 hours from tread initiation to hamster wheel type repeating of the same theories over and over again (some already discounted by knowledgeable people).

That must be some sort of record...

Hamster wheel Type Rating is cheaper than the 788 TR?

Subjects: None

AAKEE
July 12, 2025, 09:16:00 GMT
permalink Post: 11920400

Quote:

Originally Posted by AIMINGHIGH123

I can\x92t see how 2 switches can be moved within 1 second. Not with 1 hand.

Just performed three flights and looked at the chrono\x92 when shutting down both after parking, it was more or less exactly 1s between both switches was set to OFF, both when I did it and my cop did it. 1s is a very probable time between moving two switches of this type.

Subjects: None

AAKEE June 12, 2025, 13:05:00 GMT permalink Post: 11899189	Quote: Originally Posted by EK380 Needs to be corrected for a QNH of 997; so barely a few hundred feet AAL. QNH, 1001, right? 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 (links are to this post in the relevant subject page so that this post can be seen in context): ADSB FlightRadar24
AAKEE June 19, 2025, 17:34:00 GMT permalink Post: 11906213	Quote: Originally Posted by cloudhawke Does anyone here think it is getting close to the point where all technical explanations are exhausted? Not really. 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
AAKEE June 21, 2025, 06:00:00 GMT permalink Post: 11907507	Quote: Originally Posted by Aerospace101 The 787-8 gear goes through the following movements on TO: 3. When the pilot commands gear up, the gear retraction sequence begins, specific to the 787-8, the gear trucks tilt forwards first, instantly followed by the gear doors opening. I might have missed the thing, but as the gear up sequence did start we can be quite sure that the WoW logic had the aircraft \x94in air\x94 (not on ground). This probably makes the theory of the TCMA halt a little? Gear up would be inhibited from not being in air. Subjects: None
AAKEE June 22, 2025, 07:08:00 GMT permalink Post: 11908310	Quote: Originally Posted by Aerospace101 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. Without knowing the 787-8 gear system, we know that is is supposed to be hydraulically moved from \x94nose up\x94 to nose down as the first step in the gear up sequence. But do we know that it would end up \x94nose down\x94 without hyd pressure? 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 (links are to this post in the relevant subject page so that this post can be seen in context): ADSB FBW
AAKEE June 22, 2025, 08:01:00 GMT permalink Post: 11908343	Quote: Originally Posted by Musician Not quite. When the aircraft is on the ground (or on the water), it does not transmit altitude. Thats right, and (guessing here), it would be better to use the solid logic In Air / On Ground than grab a single WoW sensor specially for things that could go very wrong if that sensor start showing a false value. 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: None
AAKEE June 22, 2025, 11:24:00 GMT permalink Post: 11908460	Quote: Originally Posted by Musician 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 \x94Designers thought\x94 = MCAS flying under the radar from Boeing themself. 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? Quote: Originally Posted by Musician 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. Yes. and whe\x92re discussing scenarios here. 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 (links are to this post in the relevant subject page so that this post can be seen in context): FAA
AAKEE June 28, 2025, 13:13:00 GMT permalink Post: 11912486	Quote: Originally Posted by Sailvi767 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. I didn\x92t really find a clear reference for other posts (trying to avoid the hamster wheel to over-rev) but in general the emergency busses only support equipment needed for survival. 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. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CVR EAFR FDR
AAKEE June 28, 2025, 18:19:00 GMT permalink Post: 11912613	Not useless Quote: Originally Posted by D Bru Even the 10 min RIPS is useless if there's no data sent from electrically shut off systems. As there of corse will not be any data from shutoff systems, there still will be from systems not shut down. Basic flight parameters, I guess. much netter than\x85nothing. Thats most certainly the background to the new regulations to battery backup. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Parameters RIPS
AAKEE June 29, 2025, 16:25:00 GMT permalink Post: 11913116	Murlidhar Mohol Interviewed (Civil aviation minister) This is some news: Quote: we will be able to ascertain if it was an engine problem or fuel supply issue or why both the engines had stopped functioning. Civil Aviation Murlidhar Mohol interviewed Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All)
AAKEE June 29, 2025, 17:18:00 GMT permalink Post: 11913139	Quote: Originally Posted by za9ra22 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 read several articles but NDTV sounded like the origin, that actually spoke to the minister? I did not dig very deep into that though. Subjects: None
AAKEE June 29, 2025, 20:45:00 GMT permalink Post: 11913220	Quote: Originally Posted by Tailspin Turtle suggests that the engines were providing some thrust in order for it to get as far as it did. I guess that that would not normally match the assumption that the generators disconnected (all four) and activated the RAT? Some thrust from idle and up would normally keep generators online. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Generators/Alternators RAT (All)
AAKEE July 01, 2025, 08:26:00 GMT permalink Post: 11914098	Quote: Originally Posted by Capn Bloggs 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. No exemption or deviation in the EASA type certificate for shared fuel: EASA 787-8 TC The FAR/CS 25 doesn\x92t seem to require fuel from separate tanks during takeoff. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FAA
AAKEE July 12, 2025, 08:19:00 GMT permalink Post: 11920333	Quote: Originally Posted by tdracer Wow, 5 hours from tread initiation to hamster wheel type repeating of the same theories over and over again (some already discounted by knowledgeable people). That must be some sort of record... Hamster wheel Type Rating is cheaper than the 788 TR? Subjects: None
AAKEE July 12, 2025, 09:16:00 GMT permalink Post: 11920400	Quote: Originally Posted by AIMINGHIGH123 I can\x92t see how 2 switches can be moved within 1 second. Not with 1 hand. Just performed three flights and looked at the chrono\x92 when shutting down both after parking, it was more or less exactly 1s between both switches was set to OFF, both when I did it and my cop did it. 1s is a very probable time between moving two switches of this type. Subjects: None

Posts by user "AAKEE" [Posts: 14 Total up-votes: 0 Pages: 1]