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, 21:51:00 GMT
permalink Post: 11919857
The phrase in the report is "switches transitioned from RUN to CUTOFF position".
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.
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, 21:52:00 GMT
permalink Post: 11919860
Actually, why are switches that are only really required on the ground or in an engine shut down event where they are? Embraer's have the switches out of the way on an overhead panel and as well as detent locked, have a protective guard, one has to physically lift. If the PF had to physically carry out the engine shut down on an Embraer, he would have to raise his arm. Would be obvious to the PnF.
Last edited by Saab Dastard; 11th July 2025 at 21:55 . Reason: Deleted post quote removed
July 11, 2025, 21:54:00 GMT
permalink Post: 11919862
So, yes, switches.
either
1/deliberately cut off by someone in the cockpit, or
2/placed in an intermediate gate position possible due to wear or wrong installation, happens during engine start, and then vibrates or bumps to cut-off during the take off roll or
3/some kind of liquid or other contamination in the LRU shorting both and cycling them after 8 seconds brought them electrically back to RUN.
Anyone got other ideas?
either
1/deliberately cut off by someone in the cockpit, or
2/placed in an intermediate gate position possible due to wear or wrong installation, happens during engine start, and then vibrates or bumps to cut-off during the take off roll or
3/some kind of liquid or other contamination in the LRU shorting both and cycling them after 8 seconds brought them electrically back to RUN.
Anyone got other ideas?
I would have thought a pilot would notice the engines spooling down, and comment on that. To immediately jump to the cutoff switches as the cause rather implies something drew attention to the switches.
Then there is a 10+ second gap before the switches are set to run again. I can't think of any good reason why the PNF would have taken so long to correct an accidental or deliberate manipulation of the switches.
July 11, 2025, 21:55:00 GMT
permalink Post: 11919864
One item in the report is the position of the LG Lever - Down.
Given the lack of a full transcript, and in trying to defend the crewmembers intentions , Is it possible that at the point of "Positive Rate - Gear Up" - PM Brain farted, and performed a different muscle memory action? Thus they would deny moving the Switches - and take a few seconds to compute what they just did?
Given the lack of a full transcript, and in trying to defend the crewmembers intentions , Is it possible that at the point of "Positive Rate - Gear Up" - PM Brain farted, and performed a different muscle memory action? Thus they would deny moving the Switches - and take a few seconds to compute what they just did?
July 11, 2025, 21:57:00 GMT
permalink Post: 11919867
It can only know their electrical, not mechanical positions. Think about it, how would that work?
Would love to see some kind of accelerometer reading of the moment the switches went to cut off. Or even cockpit area audio.
They will figure it out.
Would love to see some kind of accelerometer reading of the moment the switches went to cut off. Or even cockpit area audio.
They will figure it out.
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, 22:04:00 GMT
permalink Post: 11919872
The landing gear lever is forward and up on the centre instrument panel, adjacent to the PFD. The two fuel control switches are aft and low, on the thrust pedestal. There's no reasonable way to confuse one for the other in terms of position, hand movement or 'muscle memory'.
July 11, 2025, 22:04:00 GMT
permalink Post: 11919873
The phrase in the report is "switches transitioned from RUN to CUTOFF position".
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.
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, 22:04:00 GMT
permalink Post: 11919874
The landing gear lever is forward and up on the centre instrument panel, adjacent to the PFD. The fuel control switches are aft and low, on the thrust pedestal. There's no reasonable way to confuse one for the other in terms of position, hand movement or 'muscle memory'.
July 11, 2025, 22:04:00 GMT
permalink Post: 11919875
Actually, why are switches that are only really required on the ground or in an engine shut down event where they are? Embraer's have the switches out of the way on an overhead panel and as well as detent locked, have a protective guard, one has to physically lift. If the PF had to physically carry out the engine shut down on an Embraer, he would have to raise his arm. Would be obvious to the PnF.
July 11, 2025, 22:05:00 GMT
permalink Post: 11919876
The landing gear lever is forward and up on the centre instrument panel, adjacent to the PFD. The two fuel control switches are aft and low, on the thrust pedestal. There's no reasonable way to confuse one for the other in terms of position, hand movement or 'muscle memory'.
July 11, 2025, 22:06:00 GMT
permalink Post: 11919877
In the case of (2) or (3), would the expected response be "Why did you cutoff"?
I would have thought a pilot would notice the engines spooling down, and comment on that. To immediately jump to the cutoff switches as the cause rather implies something drew attention to the switches.
Then there is a 10+ second gap before the switches are set to run again. I can't think of any good reason why the PNF would have taken so long to correct an accidental or deliberate manipulation of the switches.
I would have thought a pilot would notice the engines spooling down, and comment on that. To immediately jump to the cutoff switches as the cause rather implies something drew attention to the switches.
Then there is a 10+ second gap before the switches are set to run again. I can't think of any good reason why the PNF would have taken so long to correct an accidental or deliberate manipulation of the switches.
You need to take the audio together with the switch data, not in isolation.
The two combined would appear to rule out a lot of options that the data alone would leave possible.
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, 22:07:00 GMT
permalink Post: 11919881
A douple-pole switch. One pole used for FDR signal for the physcial switch position. The other pole for the electrical switching circuit.
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, 22:12:00 GMT
permalink Post: 11919891
Folks, it appears that the message isn't getting through.
There were two professional pilots on that flight deck.
It is not acceptable to effectively accuse both of a criminal act, because there is no evidence to identify which hand - if either - moved the fuel switches, or for what purpose or reason.
Unless and until any such evidence is published by the relevant authorities, kindly desist from doing so out of respect for your professional colleagues.
There were two professional pilots on that flight deck.
It is not acceptable to effectively accuse both of a criminal act, because there is no evidence to identify which hand - if either - moved the fuel switches, or for what purpose or reason.
Unless and until any such evidence is published by the relevant authorities, kindly desist from doing so out of respect for your professional colleagues.
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.