July 11, 2025, 20:40:00 GMT
permalink Post: 11919772
The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42
UTC and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned
from RUN to CUTOFF position one after another with a time gap of 01 sec. The Engine N1
and N2 began to decrease from their take-off values as the fuel supply to the engines was cut
off.
In the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff.
The other pilot responded that he did not do so.
The CCTV footage obtained from the airport showed Ram Air Turbine (RAT) getting deployed
during the initial climb immediately after lift-off (fig. 15). No significant bird activity is observed
in the vicinity of the flight path. The aircraft started to lose altitude before crossing the airport
perimeter wall.
As per the EAFR, the Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN at about
08:08:52 UTC. The APU Inlet Door began opening at about 08:08:54 UTC, consistent with
the APU Auto Start logic. Thereafter at 08:08:56 UTC the Engine 2 fuel cutoff switch also
transitions from CUTOFF to RUN. When fuel control switches are moved from CUTOFF to
RUN while the aircraft is inflight, each engines full authority dual engine control (FADEC)
automatically manages a relight and thrust recovery sequence of ignition and fuel introduction.
The EGT was observed to be rising for both engines indicating relight. Engine 1’s core
deceleration stopped, reversed and started to progress to recovery. Engine 2 was able to
relight but could not arrest core speed deceleration and re-introduced fuel repeatedly to
increase core speed acceleration and recovery. The EAFR recording stopped at 08:09:11
UTC
As per the EAFR data both engines N2 values passed below minimum idle speed, and the
RAT hydraulic pump began supplying hydraulic power at about 08:08:47 UTC.
RAT in extended position
15
As per the EAFR, the Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN at about
08:08:52 UTC. The APU Inlet Door began opening at about 08:08:54 UTC, consistent with
the APU Auto Start logic. Thereafter at 08:08:56 UTC the Engine 2 fuel cutoff switch also
transitions from CUTOFF to RUN. When fuel control switches are moved from CUTOFF to
RUN while the aircraft is inflight, each engines full authority dual engine control (FADEC)
automatically manages a relight and thrust recovery sequence of ignition and fuel introduction.
The EGT was observed to be rising for both engines indicating relight. Engine 1’s core
deceleration stopped, reversed and started to progress to recovery. Engine 2 was able to
relight but could not arrest core speed deceleration and re-introduced fuel repeatedly to
increase core speed acceleration and recovery. The EAFR recording stopped at 08:09:11
UTC
At about 08:09:05 UTC, one of the pilots transmitted “MAYDAY MAYDAY MAYDAY”.
UTC and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned
from RUN to CUTOFF position one after another with a time gap of 01 sec. The Engine N1
and N2 began to decrease from their take-off values as the fuel supply to the engines was cut
off.
In the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff.
The other pilot responded that he did not do so.
The CCTV footage obtained from the airport showed Ram Air Turbine (RAT) getting deployed
during the initial climb immediately after lift-off (fig. 15). No significant bird activity is observed
in the vicinity of the flight path. The aircraft started to lose altitude before crossing the airport
perimeter wall.
As per the EAFR, the Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN at about
08:08:52 UTC. The APU Inlet Door began opening at about 08:08:54 UTC, consistent with
the APU Auto Start logic. Thereafter at 08:08:56 UTC the Engine 2 fuel cutoff switch also
transitions from CUTOFF to RUN. When fuel control switches are moved from CUTOFF to
RUN while the aircraft is inflight, each engines full authority dual engine control (FADEC)
automatically manages a relight and thrust recovery sequence of ignition and fuel introduction.
The EGT was observed to be rising for both engines indicating relight. Engine 1’s core
deceleration stopped, reversed and started to progress to recovery. Engine 2 was able to
relight but could not arrest core speed deceleration and re-introduced fuel repeatedly to
increase core speed acceleration and recovery. The EAFR recording stopped at 08:09:11
UTC
As per the EAFR data both engines N2 values passed below minimum idle speed, and the
RAT hydraulic pump began supplying hydraulic power at about 08:08:47 UTC.
RAT in extended position
15
As per the EAFR, the Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN at about
08:08:52 UTC. The APU Inlet Door began opening at about 08:08:54 UTC, consistent with
the APU Auto Start logic. Thereafter at 08:08:56 UTC the Engine 2 fuel cutoff switch also
transitions from CUTOFF to RUN. When fuel control switches are moved from CUTOFF to
RUN while the aircraft is inflight, each engines full authority dual engine control (FADEC)
automatically manages a relight and thrust recovery sequence of ignition and fuel introduction.
The EGT was observed to be rising for both engines indicating relight. Engine 1’s core
deceleration stopped, reversed and started to progress to recovery. Engine 2 was able to
relight but could not arrest core speed deceleration and re-introduced fuel repeatedly to
increase core speed acceleration and recovery. The EAFR recording stopped at 08:09:11
UTC
At about 08:09:05 UTC, one of the pilots transmitted “MAYDAY MAYDAY MAYDAY”.
08:08:42 Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position.
One of the pilots asks the other why did he cutoff.
The other pilot responded that he did not do so.
08:08:52 Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN
08:08:56 Engine 2 fuel cutoff switch also transitions from CUTOFF to RUN
Who (or what?) operated the cutoff switches?
Last edited by Engineless; 11th July 2025 at 20:53 .
July 11, 2025, 20:52:00 GMT
permalink Post: 11919778
Ready to talk about the current Embraer method of respective throttle must be at idle to allow the fuel cutoff switch to send a cutoff signal?
That's where I was going in the last page of the last, closed thread.
Wear and tear, off by mistake, off by ill-will, off by cockpit FOD flying about at rotation, no effect with throttle forward.
That's where I was going in the last page of the last, closed thread.
Wear and tear, off by mistake, off by ill-will, off by cockpit FOD flying about at rotation, no effect with throttle forward.
Last edited by moosepileit; 11th July 2025 at 21:09 .
July 11, 2025, 21:16:00 GMT
permalink Post: 11919815
"The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42 UTC and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec."
Does anyone know what the sampling frequency of the data is? If we get one readout per second, then it's possible that a one second difference could only be a millisecond difference in real life, which doesn't necessarily rule out an accidental bump.
If there truly was a second of difference, there aren't many other options than an intentional act. Not necessarily with the purpose of crashing the plane though (confusion, hallucination, distraction, ..)
July 11, 2025, 21:17:00 GMT
permalink Post: 11919817
I remember the SAIB. I assessed it as “recommended” to all our customers and all agreed. I then raised work orders to check all fuel cut-off switches for the missing locking bar conditions. None were found defective. The preliminary report says the switches were found in the Run position. There is no mention of whether the locking mechanism is correctly in place. We need to wait for the full report for that, as this matter is still under investigation.
July 11, 2025, 21:24:00 GMT
permalink Post: 11919826
What the hell happened in the cockpit?
08:08:42 Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position.
One of the pilots asks the other why did he cutoff.
The other pilot responded that he did not do so.
08:08:52 Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN
08:08:56 Engine 2 fuel cutoff switch also transitions from CUTOFF to RUN
Who (or what?) operated the cutoff switches?
08:08:42 Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position.
One of the pilots asks the other why did he cutoff.
The other pilot responded that he did not do so.
08:08:52 Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN
08:08:56 Engine 2 fuel cutoff switch also transitions from CUTOFF to RUN
Who (or what?) operated the cutoff switches?
Does the FDR actually have some input of the physical position of the switches or is it just measuring the output signal voltage
which might be changed by a momentary short from liquid or swarf.
Both signals go to cutoff within 1 second but then one recovers four seconds after the other.
Surely a pilot discovering a turned off switch would have both back on in less than four seconds.
July 11, 2025, 21:48:00 GMT
permalink Post: 11919852
The Fuel Cut Off switches on a 787 have to be pulled up (out of \x91run\x92) and whilst held up, they are then moved backwards to the \x91cut off\x92 position. They are designed this way so loose objects
can not
move them to cut off. They can only be selected to cut-off by pulling and moving rearward in the same movement.
July 11, 2025, 21:50:00 GMT
permalink Post: 11919854
Agreed, it's most unfortunate that that the preliminary report hasn’t closed off speculation, it's simply created opportunity for more.
It confirms that both fuel cutoff switches were moved to OFF at Vr, within a one second interval which is as extreme and inexplicable as it gets. Then it gives us a CVR quote that’s so neutered, "Why did you cut off?” / “I didn’t”, that it raises more questions than it answers. If the goal was to reassure or clarify, it’s had the opposite effect.
It confirms that both fuel cutoff switches were moved to OFF at Vr, within a one second interval which is as extreme and inexplicable as it gets. Then it gives us a CVR quote that’s so neutered, "Why did you cut off?” / “I didn’t”, that it raises more questions than it answers. If the goal was to reassure or clarify, it’s had the opposite effect.
July 11, 2025, 22:00:00 GMT
permalink Post: 11919868
Agreed, it's most unfortunate that that the preliminary report hasn\x92t closed off speculation, it's simply created opportunity for more.
It confirms that both fuel cutoff switches were moved to OFF at Vr, within a one second interval which is as extreme and inexplicable as it gets. Then it gives us a CVR quote that\x92s so neutered, "Why did you cut off?\x94 / \x93I didn\x92t\x94, that it raises more questions than it answers. If the goal was to reassure or clarify, it\x92s had the opposite effect.
It confirms that both fuel cutoff switches were moved to OFF at Vr, within a one second interval which is as extreme and inexplicable as it gets. Then it gives us a CVR quote that\x92s so neutered, "Why did you cut off?\x94 / \x93I didn\x92t\x94, that it raises more questions than it answers. If the goal was to reassure or clarify, it\x92s had the opposite effect.
As to the report not closing off speculation, that isn't it's purpose. It is there to report the facts as they are found. It must also be said that speculation is not in any place but the eye of the beholder.
July 11, 2025, 22:06:00 GMT
permalink Post: 11919878
Out of interest, hypothetically if the captain was an instructor, is there a possibility that any kind of muscle memory from simulated failures in the simulator may have been triggered?
Let\x92s say that you are having to retrain another pilot on v1 cut handling whilst you occupy the P1 seat. Temptation may be to use the fuel cut off switches to save time rather than going back to the sim operator panel to reprogram the failure.
Let\x92s say that you are having to retrain another pilot on v1 cut handling whilst you occupy the P1 seat. Temptation may be to use the fuel cut off switches to save time rather than going back to the sim operator panel to reprogram the failure.
July 11, 2025, 22:08:00 GMT
permalink Post: 11919884
I know it's not a popular opinion around here but it seems like a flight deck camera would be quite useful right about now to determine whether either pilot's hands strayed near the fuel cutoff switches at the recorded time.
July 11, 2025, 22:09:00 GMT
permalink Post: 11919886
Seconds count:
Time was spent with the verbal exchange, and then perhaps each pilot expected the other to put the switch back?
Anyway, the preliminary report also establishes that the aircraft had only 3-4 seconds of powered flight. (Would the gear lever be operated that early?) Everyone who saw that from the CCTV video, pat yourselves on the back.
Mayday call, dual engine failure, RAT deployment all confirmed.
TCMA was a red herring, the aircraft was firmly in air mode as the accident unfolded, and the thrust levers were at takeoff thrust the whole time.
As per the EAFR, the Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN at about
08:08:52 UTC. The APU Inlet Door began opening at about 08:08:54 UTC, consistent with the APU Auto Start logic. Thereafter at 08:08:56 UTC the Engine 2 fuel cutoff switch also transitions from CUTOFF to RUN. When fuel control switches are moved from CUTOFF to RUN while the aircraft is inflight, each engines full authority dual engine control (FADEC) automatically manages a relight and thrust recovery sequence of ignition and fuel introduction. The EGT was observed to be rising for both engines indicating relight.
Engine 1's core deceleration stopped, reversed and started to progress to recovery.
Engine 2 was able to relight but could not arrest core speed deceleration and re-introduced fuel repeatedly to increase core speed acceleration and recovery. The EAFR recording stopped at 08:09:11 UTC.
That was with 10 seconds delay vs. 13 seconds for engine 2.
Time was spent with the verbal exchange, and then perhaps each pilot expected the other to put the switch back?
Anyway, the preliminary report also establishes that the aircraft had only 3-4 seconds of powered flight. (Would the gear lever be operated that early?) Everyone who saw that from the CCTV video, pat yourselves on the back.
Mayday call, dual engine failure, RAT deployment all confirmed.
TCMA was a red herring, the aircraft was firmly in air mode as the accident unfolded, and the thrust levers were at takeoff thrust the whole time.
July 11, 2025, 22:12:00 GMT
permalink Post: 11919889
Spoiler
I wouldn't put too much significance in the "01 second" since this still is close enough for an unintentional cause.
No matter what: The design and position of the fuel cut off switches is potentially prone for mishaps.
July 11, 2025, 22:13:00 GMT
permalink Post: 11919892
There are two options. The fuel cut off was accidental or it was deliberate. The question from one of the pilots is why did you do that? The other pilot denied it.
The fuel was cut off but restored too late.
The 'why did you do that' question is significant. It wasn't 'What happened?' or 'How did that happen'
Of course it could have happened accidentally. 757 pilots might have input.
The fuel was cut off but restored too late.
The 'why did you do that' question is significant. It wasn't 'What happened?' or 'How did that happen'
Of course it could have happened accidentally. 757 pilots might have input.
July 11, 2025, 22:17:00 GMT
permalink Post: 11919895
Background
The Boeing Company (Boeing) received reports from operators of Model 737 airplanes that the fuel control switches were installed with the locking feature disengaged. The fuel control switches (or engine start switches) are installed on the control stand in the flight deck and used by the pilot to supply or cutoff fuel to the engines. The fuel control switch has a locking feature to prevent inadvertent operation that could result in unintended switch movement between the fuel supply and fuel cutoff positions. In order to move the switch from one position to the other under the condition where the locking feature is engaged, it is necessary for the pilot to lift the switch up while transitioning the switch position. If the locking feature is disengaged, the switch can be moved between the two positions without lifting the switch during transition, and the switch would be exposed to the potential of inadvertent operation. Inadvertent operation of the switch could result in an unintended consequence, such as an in-flight engine shutdown.
...The table below identifies the affected airplane models and related part numbers (P/Ns) of the fuel control switch, which is manufactured by Honeywell.
...787-8, -9, and -10
The Boeing Company (Boeing) received reports from operators of Model 737 airplanes that the fuel control switches were installed with the locking feature disengaged. The fuel control switches (or engine start switches) are installed on the control stand in the flight deck and used by the pilot to supply or cutoff fuel to the engines. The fuel control switch has a locking feature to prevent inadvertent operation that could result in unintended switch movement between the fuel supply and fuel cutoff positions. In order to move the switch from one position to the other under the condition where the locking feature is engaged, it is necessary for the pilot to lift the switch up while transitioning the switch position. If the locking feature is disengaged, the switch can be moved between the two positions without lifting the switch during transition, and the switch would be exposed to the potential of inadvertent operation. Inadvertent operation of the switch could result in an unintended consequence, such as an in-flight engine shutdown.
...The table below identifies the affected airplane models and related part numbers (P/Ns) of the fuel control switch, which is manufactured by Honeywell.
...787-8, -9, and -10
Last edited by 13 others; 12th July 2025 at 01:40 . Reason: Bold emphasis mine, fixed link
July 11, 2025, 22:17:00 GMT
permalink Post: 11919896
There are two options. The fuel cut off was accidental or it was deliberate. The question from one of the pilots is why did you do that? The other pilot denied it.
...
The 'why did you do that' question is significant. It wasn't 'What happened?' or 'How did that happen'
...
The 'why did you do that' question is significant. It wasn't 'What happened?' or 'How did that happen'
July 11, 2025, 22:18:00 GMT
permalink Post: 11919901
Agreed, it's most unfortunate that that the preliminary report hasn\x92t closed off speculation, it's simply created opportunity for more.
It confirms that both fuel cutoff switches were moved to OFF at Vr, within a one second interval which is as extreme and inexplicable as it gets. Then it gives us a CVR quote that\x92s so neutered, "Why did you cut off?\x94 / \x93I didn\x92t\x94, that it raises more questions than it answers. If the goal was to reassure or clarify, it\x92s had the opposite effect.
It confirms that both fuel cutoff switches were moved to OFF at Vr, within a one second interval which is as extreme and inexplicable as it gets. Then it gives us a CVR quote that\x92s so neutered, "Why did you cut off?\x94 / \x93I didn\x92t\x94, that it raises more questions than it answers. If the goal was to reassure or clarify, it\x92s had the opposite effect.
Action slip
SAIB NM-18-33
Intentional.
July 11, 2025, 22:18:00 GMT
permalink Post: 11919902
There are two options. The fuel cut off was accidental or it was deliberate. The question from one of the pilots is why did you do that? The other pilot denied it.
The fuel was cut off but restored too late.
The 'why did you do that' question is significant. It wasn't 'What happened?' or 'How did that happen'
Of course it could have happened accidentally. 757 pilots might have input.
The fuel was cut off but restored too late.
The 'why did you do that' question is significant. It wasn't 'What happened?' or 'How did that happen'
Of course it could have happened accidentally. 757 pilots might have input.
In the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff.
The other pilot responded that he did not do so.
The other pilot responded that he did not do so.
July 11, 2025, 23:14:00 GMT
permalink Post: 11919977
The report states that
"the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec"
. It doesn't say at the start of the paragraph but if following from the previous paragraph then this information is sensed from the data recorder.
Again, from the report "As per the EAFR, the Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN at about 08:08:52 UTC. The APU Inlet Door began opening at about 08:08:54 UTC, consistent with the APU Auto Start logic. Thereafter at 08:08:56 UTC the Engine 2 fuel cutoff switch also transitions from CUTOFF to RUN.". Again this is sensed from the data recorder.
I would be interested to know whether sounds consistent with the actual fuel control switch being moved have been picked up on the voice recorder.
Again, from the report "As per the EAFR, the Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN at about 08:08:52 UTC. The APU Inlet Door began opening at about 08:08:54 UTC, consistent with the APU Auto Start logic. Thereafter at 08:08:56 UTC the Engine 2 fuel cutoff switch also transitions from CUTOFF to RUN.". Again this is sensed from the data recorder.
I would be interested to know whether sounds consistent with the actual fuel control switch being moved have been picked up on the voice recorder.
July 11, 2025, 23:22:00 GMT
permalink Post: 11919986
to add
In my airline (we don\x92t fly the 787 but our engine masters are in a near identical position on our jet) we have had *multiple* incidents of engine masters being manipulated accidentally in flight. This has involved both flight deck and cabin crew. This has meant a re-emphasis on SOPs regarding the centre pedestal but you still routinely see this broken on the line in minor and major ways from time to time
In my airline (we don\x92t fly the 787 but our engine masters are in a near identical position on our jet) we have had *multiple* incidents of engine masters being manipulated accidentally in flight. This has involved both flight deck and cabin crew. This has meant a re-emphasis on SOPs regarding the centre pedestal but you still routinely see this broken on the line in minor and major ways from time to time
I don't think it's ridiculous to suggest that perhaps one crew intended to manipulate a different control (stab trim cutout?) and flipped the fuel cutoff instead, maybe not even realizing what has happened. Sure, unlikely, but essentially every aspect of airline accidents is unlikely.
July 11, 2025, 23:26:00 GMT
permalink Post: 11919991
Speculations laid to rest
I am going by the list in the excellent post here:
Air India Ahmedabad accident 12th June 2025 Part 2
Anyway, here goes:
A. Misconfiguration or wrong takeoff data — OUT : 5 tons under MTOW, flaps 5, takeoff roll uneventful
B. Flaps retracted post-takeoff instead of gear — OUT : flaps 5 still set at crash
C. Low-altitude capture — OUT : throttle was at take-off thrust the whole time
D. Loss of both engines at or shortly after rotation — IN: confirmed to have occurred 3-4 seconds after liftoff
I. Bird strike/FOD — OUT
II.Fuel-related
1. Loss of electric fuel pumps — OUT
2. Fuel contamination — as good as OUT , but lab work is ongoing
3. Vapour lock — OUT
III. Improper maintenance — mostly OUT , switches might have been defective
IV. Large-scale electrical fault (e.g. due to water in E&E bay) — OUT . This would have been obvious from the flight recorder.
V. Shutdown of engines by TCMA — OUT . Conditions not met (not on ground, throttle not at idle)
VI. (Inadvertent) shutdown by flight crew
1. Spontaneous execution of memory items (fuel control switches OFF, then ON; deploy RAT) due to assumed engine malfunction — OUT from CVR
2. No indications whatsoever of an intentional shutdown for nefarious reasons — IN but unsupported
VII. Malfunction/mishandling of the fuel cutoff switches (most recent)
1. Wear or improper operation of the switches, so that they do not lock but can shift back into the OFF position. — IN
Read the previous post to this by 9 lives and reconsider VII.1
Senior Pilot
2. Spilled drink leading to short in the wiring — IN (barely) , 8 separate switch contacts must be affected in just the right way
If you never supported any of the theories that are now out, pat yourself on the back!
Anyway, here goes:
A. Misconfiguration or wrong takeoff data — OUT : 5 tons under MTOW, flaps 5, takeoff roll uneventful
B. Flaps retracted post-takeoff instead of gear — OUT : flaps 5 still set at crash
C. Low-altitude capture — OUT : throttle was at take-off thrust the whole time
D. Loss of both engines at or shortly after rotation — IN: confirmed to have occurred 3-4 seconds after liftoff
I. Bird strike/FOD — OUT
II.Fuel-related
1. Loss of electric fuel pumps — OUT
2. Fuel contamination — as good as OUT , but lab work is ongoing
3. Vapour lock — OUT
III. Improper maintenance — mostly OUT , switches might have been defective
IV. Large-scale electrical fault (e.g. due to water in E&E bay) — OUT . This would have been obvious from the flight recorder.
V. Shutdown of engines by TCMA — OUT . Conditions not met (not on ground, throttle not at idle)
VI. (Inadvertent) shutdown by flight crew
1. Spontaneous execution of memory items (fuel control switches OFF, then ON; deploy RAT) due to assumed engine malfunction — OUT from CVR
2. No indications whatsoever of an intentional shutdown for nefarious reasons — IN but unsupported
VII. Malfunction/mishandling of the fuel cutoff switches (most recent)
1. Wear or improper operation of the switches, so that they do not lock but can shift back into the OFF position. — IN
Read the previous post to this by 9 lives and reconsider VII.1
Senior Pilot
2. Spilled drink leading to short in the wiring — IN (barely) , 8 separate switch contacts must be affected in just the right way
If you never supported any of the theories that are now out, pat yourself on the back!
Last edited by Senior Pilot; 12th July 2025 at 03:40 . Reason: added comment