Xeptu
2025-06-13T10:14:00
permalink Post: 11900293

Quote:

Originally Posted by bbofh

Rotation +33s
Mayday call +44s, circa 300 ft altitude (ADS-B)
Peak altitude +49s, 625 ft (Flightradar24)
Impact +58s, crash site 1.6 km from runway

If those numbers are correct about 120kts then. Interesting

Subjects: ADSB FlightRadar24 Mayday

Xeptu
2025-06-13T11:53:00
permalink Post: 11900411

Assumptions
30 secs to 100 kts from TO power set.and 200 kts after 60 seconds
Impact occurred 30 secs after Vr 1 nm out, so about 120 kts and no more than 300ft
The gear was not or could not be retracted.
Without doubt the crew knew impact was inevitable at least 10 seconds prior to impact noted by body angle change in video evidence
whether a Mayday Call was in fact made or not.

I think that the only thing that would matter for any of us in that 20 seconds would be THRUST and everything it's got.
Which occurred first, the loss of thrust on both engines causing all generators to go offline or a total electrical failure that caused flight Idle thrust.

Subjects: Electrical Failure Generators/Alternators Mayday

Xeptu
2025-06-13T13:18:00
permalink Post: 11900511

Quote:

Originally Posted by sSquares

I was thinking the same thing.

The "gear-up" places additional load on the hydraulic pumps and the result of that is step increase of load on the generators. Was this the trigger of the failures?

The gear is required to be retracted within 12 seconds even on one engine. The fact that it wasn't means it was either not selected or there wasn't engine driven hydraulic pressure to do it.
Out of interest about when did the RAT include a hydraulic pump, not that it would be sufficient to retract the gear anyway.

Subjects: Generators/Alternators Hydraulic Failure (All) Hydraulic Pumps RAT (All)

Xeptu
2025-06-13T13:50:00
permalink Post: 11900540

I think flap setting for takeoff is not in the equation because the aircraft became airborne and was seen in the video climbing away, the takeoff is over.
retracting the flap instead of the gear is a high possibility, yes there would be sink but the aircraft would still be accelerating, distance over time says an impact speed of about 120 kts.
where it would have been 200 kts in this scenario. I also think it would be unmistakeable to those on the ground if the engines were at go around thrust at impact.

Subjects: Flap Setting Flaps (All)

1 user liked this post.

Xeptu
2025-06-14T03:06:00
permalink Post: 11901102

Quote:

Originally Posted by appruser

Nose down would be to get best glide - longest time in the air and max distance. Raising the nose up leads to a stall and brings the aircraft down faster than best glide. It's counter-intuitive, hence the tendency to pull the nose up in a stall or loss of power has to be trained out of pilots.

LoL have a think about what you just said. Below 200 feet normally in transition to flare, such a rafical body angle change is the very thing that had to be trained out of pilots, it's fatal.

Subjects: None

2 users liked this post.

Xeptu
2025-06-15T01:53:00
permalink Post: 11902043

Quote:

Originally Posted by SpaceQuality

Also a newcomer here, but an experienced private pilot, Software Engineer with a degree in Aerospace Computer Science and former Head of Quality for Satellites and Interplanetary Missions. We have already seen bad software solutions and the results thereof in the 737 MAX accidents, which makes me wonder, if the TCMA can reach a state, where unintended engine shutdown is possible.

There is one system implemented in the 787, that has the authority to shut down the engines, based on software subsystem decision. Interestingly - according to the description in the patent below - the same TCMA software package determines the shutdown decision, in both redundant subsystems.

Excerpt from the Patent:
"Malfunctions in aircraft power plant thrust control systems can result in uncontrollable high engine power levels that are potentially hazardous or catastrophic for aircraft operation. A particularly hazardous situation is when a thrust control system failure results in one of the aircraft's engines continuing to operate at a high power condition and not responding to a throttle command to reduce power during takeoff, approach or landing. Typically, when this failure mode occurs, the actual thrust either increases to a significantly higher than commanded thrust and/or remains at a high level when the thrust levers are set for low thrust....

In one preferred embodiment the present invention is directed to a system and method for detecting and correcting a thrust control malfunction in an aircraft engine. The system includes an electronic engine control (EEC) unit that includes a first processing subsystem and a second processing subsystem, and a thrust control malfunction accommodation (TCMA) circuit included in the first processing subsystem and the second processing subsystem. Additionally, the system includes a TCMA software package executed by the first processing subsystem and the second processing subsystem, thereby providing redundant execution of the TCMA software package.

The method of the present invention compares the engine's actual power level with a threshold contour defined by the TCMA software package. When the TCMA software package determines that a thrust control malfunction has occurred, based on the engine's power level exceeding the threshold contour, the engine is shut down by the TCMA circuit.
The present invention is still further directed to an electronic engine control (EEC) unit configured to detect and correct an aircraft engine thrust control malfunction using an active-active functionality. The EEC includes a first processing subsystem for unilaterally monitoring engine operation and shutting down the engine when a thrust control malfunction occurs, and a second processing subsystem for unilaterally monitoring engine operation and shutting down the engine when a thrust control malfunction occurs."

Just my 20 cents

It's been troubling a few of us for some time. To translate all that for the layperson, a momentary electrical event triggered at V1 (still on the ground) and restored after rotation before gear up is selected.(in flight)

Subjects: Engine Failure (All) Engine Shutdown TCMA (All) V1

2 users liked this post.

Xeptu
2025-06-15T02:57:00
permalink Post: 11902067

Quote:

Originally Posted by grumpyoldgeek

I've read your cite four times and could not find anything implying that " a momentary electrical event triggered at V1 (still on the ground) and restored after rotation before gear up is selected." I guess you need to explain it to me like I was eight.

Sorry about that. The reply was aimed at the OP. from a software writers perspective, as you rightly point out it does not imply an electrical event actually occurred. As you raised that query writing software routines (programming) is no different and that's what we're looking for.

Subjects: Gear Retraction V1

Xeptu
2025-06-15T10:28:00
permalink Post: 11902330

Are we all forgetting the fact that the gear did not retract and so therefore didn't make it into the second segment, did it make it to 400 feet, probably not, regardless of what happened next whether the engines rolled back/stopped or some other butt squeezing distraction, there is only 15 seconds to impact remaining.
Now what was the crew doing, the same as any other crew maybe max thrust but mostly just waiting for impact, despite what you think you would do that's pretty much how it pans out in the sim too.

Subjects: None

Xeptu
2025-06-16T06:59:00
permalink Post: 11903160

Quote:

Originally Posted by OldnGrounded

I'm still looking for identification of the relevant inputs for TCMA on the GEnx-1B. If anyone has suggestions, please share.

Don't quote me but I think it closes the firewall shut off valves (wing root) not the high pressure shutoff valves (engine) and it sources it's information from the EEC

Subjects: TCMA (All)

Xeptu
2025-06-17T13:12:00
permalink Post: 11904292

Quote:

Originally Posted by tdracer

I was in this business long enough to know that you 'never say never', it would take a pretty gross error in the TCMA logic for it to have activated without a large thrust lever movement.

especially when your talking Megawatts of Energy over multipe buses in a confined space after 10 years. There are 4 things that electronics don't like, heat, water, dust and power surge.

Subjects: TCMA (All) TCMA (Logic)

3 users liked this post.

Xeptu
2025-06-17T14:39:00
permalink Post: 11904356

Quote:

Originally Posted by JRBarrett

But, if a similar protection against immediate shutdown does exist in the 787, would the engines keep running for a period of time (in the air) even if the fuel control switch was accidentally or deliberately moved to \x93off\x94?

Like pulling a fire handle, shuts the firewall shutoff valve (wing root) and hydraulics on that side.At takeoff thrust not immediately but less than 10 seconds.

Subjects: Fuel (All) Fuel Cutoff

2 users liked this post.

Xeptu
2025-06-17T15:39:00
permalink Post: 11904404

Quote:

Originally Posted by Piper.Classique

There are several videos of the survivor being interviewed in India, all of them as one might expect, in the language of the country, with English subtitles. As Mr Ramesh is a British national, many years in the UK, I did wonder if there have been any interviews in English, in which I expect he is fluent. That might/should eliminate errors in translation and make his testimony more clear. I can't find any on the net.

I don't think it will make any difference, english still isn't his first language and the bang he heard could be anything from a tail strike, load shift, catastrophic engine failure, rat deployment, initial strike/ impact. He is the luckiest guy on earth, lottery ticket stuff.

Subjects: Engine Failure (All)

Xeptu
2025-06-18T04:28:00
permalink Post: 11904891

Quote:

Originally Posted by dragon6172

The landing gear is run off of the center hydraulic system which is pressurized by electric pumps. The left and right hydraulic systems run their respective thrust reversers and some flight controls, and that is it.

Thankyou I didn't know that and I'm not questioning you. I guess it doesn't matter electrically driven or engine driven, they cannot share the same power supply the gear must be retracted within 12 seconds. this in my opinion improves the argument for total electrical failure. Unless of course gear up was never selected..There must also have been a substantial loss of thrust on at least one engine.

Subjects: Electrical Failure Gear Retraction Hydraulic Failure (All) Hydraulic Pumps

Xeptu
2025-06-18T23:09:00
permalink Post: 11905607

I need to correct one of my previous posts, I was going down the path of a mismanaged engine failure after V1, however it's been demonstrated to me that this aircraft will fly away on one engine even with the gear down with better than minimum climb gradient requirement. Quite astonishing actually.
That just leaves deliberate act not necessarily intentional, fuel vapour lock and automatically commanded engine shutdown.
I hope the rat is found soon so we know for sure if both engines were in fact lost.

Subjects: Engine Failure (All) Engine Shutdown Gear Retraction V1

3 users liked this post.

Xeptu
2025-06-19T12:57:00
permalink Post: 11906003

Quote:

Originally Posted by Capn Bloggs

That is not a Boeing Fuel switch.

That's a Beechcraft Kingair starter switch

Subjects: Fuel (All) Fuel Cutoff

Xeptu
2025-06-20T23:34:00
permalink Post: 11907393

It sure is a head scratcher and when you think you're on the right track "BOOM"
I'm of the view that this was most likely a commanded shutdown of both engines that occurred at or between liftoff and gear up selection.
That in the case of automatically that the conditions on the list of criteria were met and that one or more of those conditions was in opposite sense, weight on wheels would most likley be one of them.
I believe that in at least the first 10 seconds from Vr the crew would have continued to do exactly what they were trained to do without deviation.

For example
Both Engines at Takeoff Thrust
TL Position, Thrust Command, unknown or last known flight idle
Gear Selector, Overriden UP

Last edited by Xeptu; 21st Jun 2025 at 01:37 . Reason: extended

Subjects: Weight on Wheels

Xeptu
2025-06-21T22:20:00
permalink Post: 11908113

Quote:

Originally Posted by JustusW

So when people say "the FADEC software" (ie TCMA) has "failed" or "has a bug" what they're really saying is:

The conditions that were experienced in the real world by the system were incorrectly assessed in the system requirements and lead to an undesired output state when taking into account the real world result we would have preferred.

A bit of a mouth full, granted, but an important mouth full. This simply wouldn't be someone missing a semicolon somewhere in a thousand lines of code.

Regards,
Justus

Found It
Truth Table Line 101 = Service Terminated (licence agreement expired please contact your service provider)

Subjects: FADEC TCMA (All)

6 users liked this post.

Xeptu 2025-06-13T10:14:00 permalink Post: 11900293	Quote: Originally Posted by bbofh Rotation +33s Mayday call +44s, circa 300 ft altitude (ADS-B) Peak altitude +49s, 625 ft (Flightradar24) Impact +58s, crash site 1.6 km from runway If those numbers are correct about 120kts then. Interesting Subjects: ADSB FlightRadar24 Mayday
Xeptu 2025-06-13T11:53:00 permalink Post: 11900411	Assumptions 30 secs to 100 kts from TO power set.and 200 kts after 60 seconds Impact occurred 30 secs after Vr 1 nm out, so about 120 kts and no more than 300ft The gear was not or could not be retracted. Without doubt the crew knew impact was inevitable at least 10 seconds prior to impact noted by body angle change in video evidence whether a Mayday Call was in fact made or not. I think that the only thing that would matter for any of us in that 20 seconds would be THRUST and everything it's got. Which occurred first, the loss of thrust on both engines causing all generators to go offline or a total electrical failure that caused flight Idle thrust. Subjects: Electrical Failure Generators/Alternators Mayday
Xeptu 2025-06-13T13:18:00 permalink Post: 11900511	Quote: Originally Posted by sSquares I was thinking the same thing. The "gear-up" places additional load on the hydraulic pumps and the result of that is step increase of load on the generators. Was this the trigger of the failures? The gear is required to be retracted within 12 seconds even on one engine. The fact that it wasn't means it was either not selected or there wasn't engine driven hydraulic pressure to do it. Out of interest about when did the RAT include a hydraulic pump, not that it would be sufficient to retract the gear anyway. Subjects: Generators/Alternators Hydraulic Failure (All) Hydraulic Pumps RAT (All)
Xeptu 2025-06-13T13:50:00 permalink Post: 11900540	I think flap setting for takeoff is not in the equation because the aircraft became airborne and was seen in the video climbing away, the takeoff is over. retracting the flap instead of the gear is a high possibility, yes there would be sink but the aircraft would still be accelerating, distance over time says an impact speed of about 120 kts. where it would have been 200 kts in this scenario. I also think it would be unmistakeable to those on the ground if the engines were at go around thrust at impact. Subjects: Flap Setting Flaps (All) 1 user liked this post.
Xeptu 2025-06-14T03:06:00 permalink Post: 11901102	Quote: Originally Posted by appruser Nose down would be to get best glide - longest time in the air and max distance. Raising the nose up leads to a stall and brings the aircraft down faster than best glide. It's counter-intuitive, hence the tendency to pull the nose up in a stall or loss of power has to be trained out of pilots. LoL have a think about what you just said. Below 200 feet normally in transition to flare, such a rafical body angle change is the very thing that had to be trained out of pilots, it's fatal. Subjects: None 2 users liked this post.
Xeptu 2025-06-15T01:53:00 permalink Post: 11902043	Quote: Originally Posted by SpaceQuality Also a newcomer here, but an experienced private pilot, Software Engineer with a degree in Aerospace Computer Science and former Head of Quality for Satellites and Interplanetary Missions. We have already seen bad software solutions and the results thereof in the 737 MAX accidents, which makes me wonder, if the TCMA can reach a state, where unintended engine shutdown is possible. There is one system implemented in the 787, that has the authority to shut down the engines, based on software subsystem decision. Interestingly - according to the description in the patent below - the same TCMA software package determines the shutdown decision, in both redundant subsystems. Excerpt from the Patent: "Malfunctions in aircraft power plant thrust control systems can result in uncontrollable high engine power levels that are potentially hazardous or catastrophic for aircraft operation. A particularly hazardous situation is when a thrust control system failure results in one of the aircraft's engines continuing to operate at a high power condition and not responding to a throttle command to reduce power during takeoff, approach or landing. Typically, when this failure mode occurs, the actual thrust either increases to a significantly higher than commanded thrust and/or remains at a high level when the thrust levers are set for low thrust.... In one preferred embodiment the present invention is directed to a system and method for detecting and correcting a thrust control malfunction in an aircraft engine. The system includes an electronic engine control (EEC) unit that includes a first processing subsystem and a second processing subsystem, and a thrust control malfunction accommodation (TCMA) circuit included in the first processing subsystem and the second processing subsystem. Additionally, the system includes a TCMA software package executed by the first processing subsystem and the second processing subsystem, thereby providing redundant execution of the TCMA software package. The method of the present invention compares the engine's actual power level with a threshold contour defined by the TCMA software package. When the TCMA software package determines that a thrust control malfunction has occurred, based on the engine's power level exceeding the threshold contour, the engine is shut down by the TCMA circuit. The present invention is still further directed to an electronic engine control (EEC) unit configured to detect and correct an aircraft engine thrust control malfunction using an active-active functionality. The EEC includes a first processing subsystem for unilaterally monitoring engine operation and shutting down the engine when a thrust control malfunction occurs, and a second processing subsystem for unilaterally monitoring engine operation and shutting down the engine when a thrust control malfunction occurs." Just my 20 cents It's been troubling a few of us for some time. To translate all that for the layperson, a momentary electrical event triggered at V1 (still on the ground) and restored after rotation before gear up is selected.(in flight) Subjects: Engine Failure (All) Engine Shutdown TCMA (All) V1 2 users liked this post.
Xeptu 2025-06-15T02:57:00 permalink Post: 11902067	Quote: Originally Posted by grumpyoldgeek I've read your cite four times and could not find anything implying that " a momentary electrical event triggered at V1 (still on the ground) and restored after rotation before gear up is selected." I guess you need to explain it to me like I was eight. Sorry about that. The reply was aimed at the OP. from a software writers perspective, as you rightly point out it does not imply an electrical event actually occurred. As you raised that query writing software routines (programming) is no different and that's what we're looking for. Subjects: Gear Retraction V1
Xeptu 2025-06-15T10:28:00 permalink Post: 11902330	Are we all forgetting the fact that the gear did not retract and so therefore didn't make it into the second segment, did it make it to 400 feet, probably not, regardless of what happened next whether the engines rolled back/stopped or some other butt squeezing distraction, there is only 15 seconds to impact remaining. Now what was the crew doing, the same as any other crew maybe max thrust but mostly just waiting for impact, despite what you think you would do that's pretty much how it pans out in the sim too. Subjects: None
Xeptu 2025-06-16T06:59:00 permalink Post: 11903160	Quote: Originally Posted by OldnGrounded I'm still looking for identification of the relevant inputs for TCMA on the GEnx-1B. If anyone has suggestions, please share. Don't quote me but I think it closes the firewall shut off valves (wing root) not the high pressure shutoff valves (engine) and it sources it's information from the EEC Subjects: TCMA (All)
Xeptu 2025-06-17T13:12:00 permalink Post: 11904292	Quote: Originally Posted by tdracer I was in this business long enough to know that you 'never say never', it would take a pretty gross error in the TCMA logic for it to have activated without a large thrust lever movement. especially when your talking Megawatts of Energy over multipe buses in a confined space after 10 years. There are 4 things that electronics don't like, heat, water, dust and power surge. Subjects: TCMA (All) TCMA (Logic) 3 users liked this post.
Xeptu 2025-06-17T14:39:00 permalink Post: 11904356	Quote: Originally Posted by JRBarrett But, if a similar protection against immediate shutdown does exist in the 787, would the engines keep running for a period of time (in the air) even if the fuel control switch was accidentally or deliberately moved to \x93off\x94? Like pulling a fire handle, shuts the firewall shutoff valve (wing root) and hydraulics on that side.At takeoff thrust not immediately but less than 10 seconds. Subjects: Fuel (All) Fuel Cutoff 2 users liked this post.
Xeptu 2025-06-17T15:39:00 permalink Post: 11904404	Quote: Originally Posted by Piper.Classique There are several videos of the survivor being interviewed in India, all of them as one might expect, in the language of the country, with English subtitles. As Mr Ramesh is a British national, many years in the UK, I did wonder if there have been any interviews in English, in which I expect he is fluent. That might/should eliminate errors in translation and make his testimony more clear. I can't find any on the net. I don't think it will make any difference, english still isn't his first language and the bang he heard could be anything from a tail strike, load shift, catastrophic engine failure, rat deployment, initial strike/ impact. He is the luckiest guy on earth, lottery ticket stuff. Subjects: Engine Failure (All)
Xeptu 2025-06-18T04:28:00 permalink Post: 11904891	Quote: Originally Posted by dragon6172 The landing gear is run off of the center hydraulic system which is pressurized by electric pumps. The left and right hydraulic systems run their respective thrust reversers and some flight controls, and that is it. Thankyou I didn't know that and I'm not questioning you. I guess it doesn't matter electrically driven or engine driven, they cannot share the same power supply the gear must be retracted within 12 seconds. this in my opinion improves the argument for total electrical failure. Unless of course gear up was never selected..There must also have been a substantial loss of thrust on at least one engine. Subjects: Electrical Failure Gear Retraction Hydraulic Failure (All) Hydraulic Pumps
Xeptu 2025-06-18T23:09:00 permalink Post: 11905607	I need to correct one of my previous posts, I was going down the path of a mismanaged engine failure after V1, however it's been demonstrated to me that this aircraft will fly away on one engine even with the gear down with better than minimum climb gradient requirement. Quite astonishing actually. That just leaves deliberate act not necessarily intentional, fuel vapour lock and automatically commanded engine shutdown. I hope the rat is found soon so we know for sure if both engines were in fact lost. Subjects: Engine Failure (All) Engine Shutdown Gear Retraction V1 3 users liked this post.
Xeptu 2025-06-19T12:57:00 permalink Post: 11906003	Quote: Originally Posted by Capn Bloggs That is not a Boeing Fuel switch. That's a Beechcraft Kingair starter switch Subjects: Fuel (All) Fuel Cutoff
Xeptu 2025-06-20T23:34:00 permalink Post: 11907393	It sure is a head scratcher and when you think you're on the right track "BOOM" I'm of the view that this was most likely a commanded shutdown of both engines that occurred at or between liftoff and gear up selection. That in the case of automatically that the conditions on the list of criteria were met and that one or more of those conditions was in opposite sense, weight on wheels would most likley be one of them. I believe that in at least the first 10 seconds from Vr the crew would have continued to do exactly what they were trained to do without deviation. For example Both Engines at Takeoff Thrust TL Position, Thrust Command, unknown or last known flight idle Gear Selector, Overriden UP Last edited by Xeptu; 21st Jun 2025 at 01:37 . Reason: extended Subjects: Weight on Wheels
Xeptu 2025-06-21T22:20:00 permalink Post: 11908113	Quote: Originally Posted by JustusW So when people say "the FADEC software" (ie TCMA) has "failed" or "has a bug" what they're really saying is: The conditions that were experienced in the real world by the system were incorrectly assessed in the system requirements and lead to an undesired output state when taking into account the real world result we would have preferred. A bit of a mouth full, granted, but an important mouth full. This simply wouldn't be someone missing a semicolon somewhere in a thousand lines of code. Regards, Justus Found It Truth Table Line 101 = Service Terminated (licence agreement expired please contact your service provider) Subjects: FADEC TCMA (All) 6 users liked this post.

Posts by user "Xeptu" [Posts: 17 Total up-votes: 19 Pages: 1]