July 12, 2025, 19:23:00 GMT
permalink Post: 11920770
This
video
takes the trouble of going through the preliminary report in some detail, and picks up on the inclusion of a psychologist in the investigation team, which I don't think has been mentioned here yet.
Is there anything professional pilots would take exception to in the explanation by the pilot in this video?
Is there anything professional pilots would take exception to in the explanation by the pilot in this video?
July 12, 2025, 19:35:00 GMT
permalink Post: 11920778
This
video
takes the trouble of going through the preliminary report in some detail, and picks up on the inclusion of a psychologist in the investigation team, which I don't think has been mentioned here yet.
Is there anything professional pilots would take exception to in the explanation by the pilot in this video?
Is there anything professional pilots would take exception to in the explanation by the pilot in this video?
Preliminary Air India crash report published
July 12, 2025, 19:39:00 GMT
permalink Post: 11920781
This
video
takes the trouble of going through the preliminary report in some detail, and picks up on the inclusion of a psychologist in the investigation team, which I don't think has been mentioned here yet.
Is there anything professional pilots would take exception to in the explanation by the pilot in this video?
Is there anything professional pilots would take exception to in the explanation by the pilot in this video?
July 12, 2025, 21:15:00 GMT
permalink Post: 11920836
Check your switches
At this stage of the investigation, where the preliminary report is limited to
facts and evidence
, there may be insufficient knowledge to warrant urgent safety action.
However, some national regulators might choose to reiterate the FAA SAIB: NM-18-33, requiring that all switches must be checked i.e. not optional.
Additionally, and independently, pilots might check the switches preflight (nice to know): - note the range of different types of aircraft and variants which could be affected - fleet size, number of switches exposed to the condition.
Regulators might also enquire of the FAA how many 'non locking' switches were identified by the SAIB - what was reported; and 'non FAA' operators recheck their inspection results and action taken.
… and how many operators did not check.
If errant switches were identified, then was the original safety assessment reconsidered (FAA/Boeing), if so what arguments were made against inadvertent simultaneous operation.
https://static-gi.asianetnews.com/co...nm-18-33-1.pdf
However, some national regulators might choose to reiterate the FAA SAIB: NM-18-33, requiring that all switches must be checked i.e. not optional.
Additionally, and independently, pilots might check the switches preflight (nice to know): - note the range of different types of aircraft and variants which could be affected - fleet size, number of switches exposed to the condition.
Regulators might also enquire of the FAA how many 'non locking' switches were identified by the SAIB - what was reported; and 'non FAA' operators recheck their inspection results and action taken.
… and how many operators did not check.
If errant switches were identified, then was the original safety assessment reconsidered (FAA/Boeing), if so what arguments were made against inadvertent simultaneous operation.
https://static-gi.asianetnews.com/co...nm-18-33-1.pdf
Last edited by Pilot DAR; 12th July 2025 at 21:19 . Reason: typo
July 12, 2025, 21:42:00 GMT
permalink Post: 11920857
Like I said,
if you take the preliminary report version of cockpit dialog at face value
, then if the fuel cutoff toggles were never physically turned off maybe they were not physically turned back on. Immediately prior to this flight the pilots reported a STAB master caution, which was investigated but 'no fault' was found. Intermittent electrical fault? Software/logic problem? Stranger things have happened. At least one maintenance engineer would have been in the cockpit immediately prior to this flight. The actions taken by this person(s) should also be part of the investigation.
July 12, 2025, 22:25:00 GMT
permalink Post: 11920886
1 second delay
Again, you can not conclude that from the report.
Different inputs are sampled at different rates. Some very basic info here:
It's highly likely switch positions are only sampled at 1Hz, and not at 100 Hz. For engine parameters you'll likely want a higher sample rate, as the whole engine could go from perfectly fine to exploded in less than a second.
If you had something like:
08:08:42.96 UTC: cut off switch 1
08:08:43.01 UTC: cut off switch 2
It would likely be recorded as:
08:08:42 UTC: cut off switch 1
08:08:43 UTC: cut off switch 2
Leading you to believe there was one second between these 2 actions, whereas it was actually only 50ms.
Different inputs are sampled at different rates. Some very basic info here:
It's highly likely switch positions are only sampled at 1Hz, and not at 100 Hz. For engine parameters you'll likely want a higher sample rate, as the whole engine could go from perfectly fine to exploded in less than a second.
If you had something like:
08:08:42.96 UTC: cut off switch 1
08:08:43.01 UTC: cut off switch 2
It would likely be recorded as:
08:08:42 UTC: cut off switch 1
08:08:43 UTC: cut off switch 2
Leading you to believe there was one second between these 2 actions, whereas it was actually only 50ms.
Last edited by AK1969; 13th July 2025 at 00:41 .
July 12, 2025, 22:46:00 GMT
permalink Post: 11920900
It seems to me that there must have been further dialogue after the bland "I didn't". To have nothing reported after that two-line exchange, until the MAYDAY at 08:09:05, is a highly suspect omission from the interim report. In a two-crew cockpit, facing a sudden dual engine rollback just after rotation, I find it very hard to believe that this two-line exchange was the only interaction captured.
Although published a little later than expected, it has now narrowed the speculator's focus from the wilder theories to the fuel switches.
Air India is not grounded, Boeing engines are not grounded and there are no recommended actions to engine operators and manufacturers.
Although a full verbatim transcript of the CVR could have been published, or even the recording itself, a decision has been made by the investigators not to do so. All we have is two bland paraphrases 'One of the pilots is heard asking the other why did he cutoff' (not even gramatically correct). 'The other pilot responded that he did not do so'.
Sometimes reports are more about what is not in them rather than was is in them.
It seems to me that the missing sections from the recording which would have revealed exact voice timings, language, tone, inflection and urgency which would have answered a lot of the questions on here have been deliberately withheld either temporarily or permanently. It is for the reader to infer why that might be. The investigators know much more but have chosen not to publicise it. I suspect they have more pieces of the jigsaw than we can see but probably not the full picture yet.
Last edited by T28B; 12th July 2025 at 23:06 . Reason: Formatting for ease of reading and pulling out key points
July 12, 2025, 23:37:00 GMT
permalink Post: 11920930
Reminder: the prelim report didn't say exactly what the pilots said, and I also think it's unlikely that they said it in English anyway.
So there's no value in wondering what motivated one pilot to say "why did you cutoff" because we don't know if that's what was said.
The exact wording in the report is:
Given the need to couch the report's wording in neutral/diplomatic terms (expletives?), and almost certainly to translate the conversation from another language, the inferences being drawn from those lines in the report are going wildly beyond what is reasonable.
So there's no value in wondering what motivated one pilot to say "why did you cutoff" because we don't know if that's what was said.
The exact wording in the report is:
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 12, 2025, 23:46:00 GMT
permalink Post: 11920938
The preliminary report has provided sufficient information about what happened (in general terms). It has also explained what didn\x92t happen - and hence no need for an AD or groundings etc.
The information from the FDR is quite detailed. That from the CVR is conspicuously less so.
it has likely been decided that other investigative bodies need to be brought in to answer the who and why.
The information from the FDR is quite detailed. That from the CVR is conspicuously less so.
it has likely been decided that other investigative bodies need to be brought in to answer the who and why.
July 12, 2025, 23:54:00 GMT
permalink Post: 11920939
My take is there is a lot of significant info purposely left out of the preliminary report. For instance, the status of the fuel cutoff switches was not mentioned. Maybe that is the info being sort by “stakeholders” and the “components of interest” that were “quarantined” were the fuel cutoff switches. “Initial leads” is also interesting.
July 13, 2025, 03:02:00 GMT
permalink Post: 11920998
Basically, the preliminary report has narrowed down the cause of the disaster and discounted a few earlier theories such as flaps up instead of gear up, but there are a lot of questions still to be answered. We need to know; who, how and why.
The switches could have been set to cut off in error even though this was denied on the CVR. However anyone with experience in this part of the world knows that owning up to mistakes isn't a common practice.
I'd rule out a suicide attempt because if the pilot doing it had moved to switches to cut off and the other pilot had put them back on, a hard push forward on the control column at that height would have settled the matter.
I'm not yet convinced that the aircraft isn't responsible due to a technical fault or improper maintenance.
The switches could have been set to cut off in error even though this was denied on the CVR. However anyone with experience in this part of the world knows that owning up to mistakes isn't a common practice.
I'd rule out a suicide attempt because if the pilot doing it had moved to switches to cut off and the other pilot had put them back on, a hard push forward on the control column at that height would have settled the matter.
I'm not yet convinced that the aircraft isn't responsible due to a technical fault or improper maintenance.
July 13, 2025, 07:18:00 GMT
permalink Post: 11921078
The Action Slip scenario
What is an action slip?
There's a possible scenario we're discussing here that fits all of the available evidence. It proposes that one of the pilots operated the switches in an unconscious action called an "action slip". This is a rote action that we do without conscious thought when we're distracted: we mean to do something, and then we get our signals crossed and do something else. To learn more, search for "action slip" or "cerebellum" on this thread; I hope paulross adds the keyword to the next build of his excellent index at https://paulross.github.io/pprune-th...171/index.html .
How would this scenario play out?
We don't have enough evidence to pin down the exact sequence, so there are some assumptions here that I hope you find plausible. (And obviously it's not the only scenario that fits the evidence.) We especially do not know who did what and why, so that is all guesswork on my part. The times are taken from the preliminary report. The report places the verbal exchange among the pilots where I put it.
———
8:08:39 The 787 becomes airborne. The F/O is pilot flying (PF), with both hands on the yoke. The Captain is PNF (not flying).
8:08:42 The PNF unconsciously flips both fuel switches to CUT OFF, one after the other. This is a rote action performed after each flight, or as training captain in the simulator.
The action cuts power to the engines; they stop delivering thrust almost immediately, and the turbines start slowing down.
The 787 systems disconnect the electrical generators in advance of them failing. The right side
(Captain's side)
of the cockpit l oses power to most instruments. With all 4 generators offline, the RAT deploys to provide emergency power.
The PF feels the cessation of thrust. He looks at the display to see an ENGINES SHUT OFF message. He assumes the PNF shut them off, and asks him why he shut them off. This is the lowest "probe" level on the PACE assertiveness scale; see e.g. https://psychsafety.com/pace-graded-assertiveness/ or search for "probe alert" on pprune if you wish to know more. The highest level of assertiveness, E for "emergency", would have the F/O put the switches back himself immediately, but that would have required a high degree of confidence in the face of the older Captain that may have been difficult to achieve.
Since the action was unconscious, the PNF replies that he did not do that.
8:08:47 The RAT starts delivering hydraulic power, the engines decelerate past idle.
The PNF realizes that engine power is in fact cut. Eventually he checks the switches he thinks he did not touch, sees the engine 1 switch first and flips it back to RUN at 8:08:52. He then thinks to check the second switch and flips it up at 8:08:56.
The accident sequence ensues.
There's really not much the PNF can do at this point. At 8:09:05, he transmits a MAYDAY.
———
Obviously there are variations to this, for example it could have been the PF who put the fuel switches back. (In the above scenario, the PF is focused on flying—aviate!—and never turns his head to see the switches.) My goal was simply to set out a possible sequence, to see whether it feels plausible. Remember, as you see other scenarios put forth, that any issues a person could wrestle with would also be distracting. While both pilots would be very focused during the takeoff run, the moment the aircraft lifted off, the PNF could well have mentally relaxed a little, opening an opportunity for the action slip.
Thoughts?
Edit: I got the roles mixed up; in a fixed scenario, either the Captain was the PF (and may have set the switches to cutoff), or flight control changed over at the power failure.
There's a possible scenario we're discussing here that fits all of the available evidence. It proposes that one of the pilots operated the switches in an unconscious action called an "action slip". This is a rote action that we do without conscious thought when we're distracted: we mean to do something, and then we get our signals crossed and do something else. To learn more, search for "action slip" or "cerebellum" on this thread; I hope paulross adds the keyword to the next build of his excellent index at https://paulross.github.io/pprune-th...171/index.html .
How would this scenario play out?
We don't have enough evidence to pin down the exact sequence, so there are some assumptions here that I hope you find plausible. (And obviously it's not the only scenario that fits the evidence.) We especially do not know who did what and why, so that is all guesswork on my part. The times are taken from the preliminary report. The report places the verbal exchange among the pilots where I put it.
———
8:08:39 The 787 becomes airborne. The F/O is pilot flying (PF), with both hands on the yoke. The Captain is PNF (not flying).
8:08:42 The PNF unconsciously flips both fuel switches to CUT OFF, one after the other. This is a rote action performed after each flight, or as training captain in the simulator.
The action cuts power to the engines; they stop delivering thrust almost immediately, and the turbines start slowing down.
The 787 systems disconnect the electrical generators in advance of them failing. The right side
The PF feels the cessation of thrust. He looks at the display to see an ENGINES SHUT OFF message. He assumes the PNF shut them off, and asks him why he shut them off. This is the lowest "probe" level on the PACE assertiveness scale; see e.g. https://psychsafety.com/pace-graded-assertiveness/ or search for "probe alert" on pprune if you wish to know more. The highest level of assertiveness, E for "emergency", would have the F/O put the switches back himself immediately, but that would have required a high degree of confidence in the face of the older Captain that may have been difficult to achieve.
Since the action was unconscious, the PNF replies that he did not do that.
8:08:47 The RAT starts delivering hydraulic power, the engines decelerate past idle.
The PNF realizes that engine power is in fact cut. Eventually he checks the switches he thinks he did not touch, sees the engine 1 switch first and flips it back to RUN at 8:08:52. He then thinks to check the second switch and flips it up at 8:08:56.
The accident sequence ensues.
There's really not much the PNF can do at this point. At 8:09:05, he transmits a MAYDAY.
———
Obviously there are variations to this, for example it could have been the PF who put the fuel switches back. (In the above scenario, the PF is focused on flying—aviate!—and never turns his head to see the switches.) My goal was simply to set out a possible sequence, to see whether it feels plausible. Remember, as you see other scenarios put forth, that any issues a person could wrestle with would also be distracting. While both pilots would be very focused during the takeoff run, the moment the aircraft lifted off, the PNF could well have mentally relaxed a little, opening an opportunity for the action slip.
Thoughts?
Edit: I got the roles mixed up; in a fixed scenario, either the Captain was the PF (and may have set the switches to cutoff), or flight control changed over at the power failure.
Last edited by Musician; 13th July 2025 at 08:03 .
July 13, 2025, 07:36:00 GMT
permalink Post: 11921087
What is an action slip?
There's a possible scenario we're discussing here that fits all of the available evidence. It proposes that one of the pilots operated the switches in an unconscious action called an "action slip". This is a rote action that we do without conscious thought when we're distracted: we mean to do something, and then we get our signals crossed and do something else. To learn more, search for "action slip" or "cerebellum" on this thread; I hope paulross adds the keyword to the next build of his excellent index at https://paulross.github.io/pprune-th...171/index.html .
How would this scenario play out?
We don't have enough evidence to pin down the exact sequence, so there are some assumptions here that I hope you find plausible. (And obviously it's not the only scenario that fits the evidence.) We especially do not know who did what and why, so that is all guesswork on my part. The times are taken from the preliminary report. The report places the verbal exchange among the pilots where I put it.
\x97\x97\x97
8:08:39 The 787 becomes airborne. The F/O is pilot flying (PF), with both hands on the yoke. The Captain is PNF (not flying).
8:08:42 The PNF unconsciously flicks both fuel switches to CUT OFF, one after the other. This is a rote action performed after each flight, or as training captain in the simulator.
The action cuts power to the engines; they stop delivering thrust almost immediately, and the turbines start slowing down.
The 787 systems disconnect the electrical generators in advance of them failing. The right side (Captain's side) of the cockpit loses power to most instruments. With all 4 generators offline, the RAT deploys to provide emergency power.
The PF feels the cessation of thrust. He looks at the display to see an ENGINES SHUT OFF message. He assumes the PNF shut them off, and asks him why he shut them off. This is the lowest "probe" level on the PACE assertiveness scale; see e.g. https://psychsafety.com/pace-graded-assertiveness/ or search for "probe alert" on pprune if you wish to know more. The highest level of assertiveness, E for "emergency", would have the F/O put the switches back himself immediately, but that would have required a high degree of confidence in the face of the older Captain that may have been difficult to achieve.
Since the action was unconscious, the PNF replies that he did not do that.
8:08:47 The RAT starts delivering hydraulic power, the engines decelerate past idle.
The PNF realizes that engine power is in fact cut. Eventually he checks the switches he thinks he did not touch, sees the engine 1 switch first and flips it back to RUN at 8:08:52. He then thinks to check the second switch and flips it up at 8:08:56.
The accident sequence ensues.
There's really not much the PNF can do at this point. At 8:09:05, he transmits a MAYDAY.
\x97\x97\x97
Obviously there are variations to this, for example it could have been the PF who put the fuel switches back. (In the above scenario, the PF is focused on flying\x97aviate!\x97and never turns his head to see the switches.) My goal was simply to set out a possible sequence, to see whether it feels plausible. Remember, as you see other scenarios put forth, that any issues a person could wrestle with would also be distracting. While both pilots would be very focused during the takeoff run, the moment the aircraft lifted off, the PNF could well have mentally relaxed a little, opening an opportunity for the action slip.
Thoughts?
There's a possible scenario we're discussing here that fits all of the available evidence. It proposes that one of the pilots operated the switches in an unconscious action called an "action slip". This is a rote action that we do without conscious thought when we're distracted: we mean to do something, and then we get our signals crossed and do something else. To learn more, search for "action slip" or "cerebellum" on this thread; I hope paulross adds the keyword to the next build of his excellent index at https://paulross.github.io/pprune-th...171/index.html .
How would this scenario play out?
We don't have enough evidence to pin down the exact sequence, so there are some assumptions here that I hope you find plausible. (And obviously it's not the only scenario that fits the evidence.) We especially do not know who did what and why, so that is all guesswork on my part. The times are taken from the preliminary report. The report places the verbal exchange among the pilots where I put it.
\x97\x97\x97
8:08:39 The 787 becomes airborne. The F/O is pilot flying (PF), with both hands on the yoke. The Captain is PNF (not flying).
8:08:42 The PNF unconsciously flicks both fuel switches to CUT OFF, one after the other. This is a rote action performed after each flight, or as training captain in the simulator.
The action cuts power to the engines; they stop delivering thrust almost immediately, and the turbines start slowing down.
The 787 systems disconnect the electrical generators in advance of them failing. The right side (Captain's side) of the cockpit loses power to most instruments. With all 4 generators offline, the RAT deploys to provide emergency power.
The PF feels the cessation of thrust. He looks at the display to see an ENGINES SHUT OFF message. He assumes the PNF shut them off, and asks him why he shut them off. This is the lowest "probe" level on the PACE assertiveness scale; see e.g. https://psychsafety.com/pace-graded-assertiveness/ or search for "probe alert" on pprune if you wish to know more. The highest level of assertiveness, E for "emergency", would have the F/O put the switches back himself immediately, but that would have required a high degree of confidence in the face of the older Captain that may have been difficult to achieve.
Since the action was unconscious, the PNF replies that he did not do that.
8:08:47 The RAT starts delivering hydraulic power, the engines decelerate past idle.
The PNF realizes that engine power is in fact cut. Eventually he checks the switches he thinks he did not touch, sees the engine 1 switch first and flips it back to RUN at 8:08:52. He then thinks to check the second switch and flips it up at 8:08:56.
The accident sequence ensues.
There's really not much the PNF can do at this point. At 8:09:05, he transmits a MAYDAY.
\x97\x97\x97
Obviously there are variations to this, for example it could have been the PF who put the fuel switches back. (In the above scenario, the PF is focused on flying\x97aviate!\x97and never turns his head to see the switches.) My goal was simply to set out a possible sequence, to see whether it feels plausible. Remember, as you see other scenarios put forth, that any issues a person could wrestle with would also be distracting. While both pilots would be very focused during the takeoff run, the moment the aircraft lifted off, the PNF could well have mentally relaxed a little, opening an opportunity for the action slip.
Thoughts?
July 13, 2025, 07:41:00 GMT
permalink Post: 11921093
What is an action slip?
There's a possible scenario we're discussing here that fits all of the available evidence. It proposes that one of the pilots operated the switches in an unconscious action called an "action slip". This is a rote action that we do without conscious thought when we're distracted: we mean to do something, and then we get our signals crossed and do something else. To learn more, search for "action slip" or "cerebellum" on this thread; I hope paulross adds the keyword to the next build of his excellent index at https://paulross.github.io/pprune-th...171/index.html .
How would this scenario play out?
We don't have enough evidence to pin down the exact sequence, so there are some assumptions here that I hope you find plausible. (And obviously it's not the only scenario that fits the evidence.) We especially do not know who did what and why, so that is all guesswork on my part. The times are taken from the preliminary report. The report places the verbal exchange among the pilots where I put it.
———
8:08:39 The 787 becomes airborne. The F/O is pilot flying (PF), with both hands on the yoke. The Captain is PNF (not flying).
8:08:42 The PNF unconsciously flicks both fuel switches to CUT OFF, one after the other. This is a rote action performed after each flight, or as training captain in the simulator.
The action cuts power to the engines; they stop delivering thrust almost immediately, and the turbines start slowing down.
The 787 systems disconnect the electrical generators in advance of them failing. The right side (Captain's side) of the cockpit loses power to most instruments. With all 4 generators offline, the RAT deploys to provide emergency power.
The PF feels the cessation of thrust. He looks at the display to see an ENGINES SHUT OFF message. He assumes the PNF shut them off, and asks him why he shut them off. This is the lowest "probe" level on the PACE assertiveness scale; see e.g. https://psychsafety.com/pace-graded-assertiveness/ or search for "probe alert" on pprune if you wish to know more. The highest level of assertiveness, E for "emergency", would have the F/O put the switches back himself immediately, but that would have required a high degree of confidence in the face of the older Captain that may have been difficult to achieve.
Since the action was unconscious, the PNF replies that he did not do that.
8:08:47 The RAT starts delivering hydraulic power, the engines decelerate past idle.
The PNF realizes that engine power is in fact cut. Eventually he checks the switches he thinks he did not touch, sees the engine 1 switch first and flips it back to RUN at 8:08:52. He then thinks to check the second switch and flips it up at 8:08:56.
The accident sequence ensues.
There's really not much the PNF can do at this point. At 8:09:05, he transmits a MAYDAY.
———
Obviously there are variations to this, for example it could have been the PF who put the fuel switches back. (In the above scenario, the PF is focused on flying—aviate!—and never turns his head to see the switches.) My goal was simply to set out a possible sequence, to see whether it feels plausible. Remember, as you see other scenarios put forth, that any issues a person could wrestle with would also be distracting. While both pilots would be very focused during the takeoff run, the moment the aircraft lifted off, the PNF could well have mentally relaxed a little, opening an opportunity for the action slip.
Thoughts?
There's a possible scenario we're discussing here that fits all of the available evidence. It proposes that one of the pilots operated the switches in an unconscious action called an "action slip". This is a rote action that we do without conscious thought when we're distracted: we mean to do something, and then we get our signals crossed and do something else. To learn more, search for "action slip" or "cerebellum" on this thread; I hope paulross adds the keyword to the next build of his excellent index at https://paulross.github.io/pprune-th...171/index.html .
How would this scenario play out?
We don't have enough evidence to pin down the exact sequence, so there are some assumptions here that I hope you find plausible. (And obviously it's not the only scenario that fits the evidence.) We especially do not know who did what and why, so that is all guesswork on my part. The times are taken from the preliminary report. The report places the verbal exchange among the pilots where I put it.
———
8:08:39 The 787 becomes airborne. The F/O is pilot flying (PF), with both hands on the yoke. The Captain is PNF (not flying).
8:08:42 The PNF unconsciously flicks both fuel switches to CUT OFF, one after the other. This is a rote action performed after each flight, or as training captain in the simulator.
The action cuts power to the engines; they stop delivering thrust almost immediately, and the turbines start slowing down.
The 787 systems disconnect the electrical generators in advance of them failing. The right side (Captain's side) of the cockpit loses power to most instruments. With all 4 generators offline, the RAT deploys to provide emergency power.
The PF feels the cessation of thrust. He looks at the display to see an ENGINES SHUT OFF message. He assumes the PNF shut them off, and asks him why he shut them off. This is the lowest "probe" level on the PACE assertiveness scale; see e.g. https://psychsafety.com/pace-graded-assertiveness/ or search for "probe alert" on pprune if you wish to know more. The highest level of assertiveness, E for "emergency", would have the F/O put the switches back himself immediately, but that would have required a high degree of confidence in the face of the older Captain that may have been difficult to achieve.
Since the action was unconscious, the PNF replies that he did not do that.
8:08:47 The RAT starts delivering hydraulic power, the engines decelerate past idle.
The PNF realizes that engine power is in fact cut. Eventually he checks the switches he thinks he did not touch, sees the engine 1 switch first and flips it back to RUN at 8:08:52. He then thinks to check the second switch and flips it up at 8:08:56.
The accident sequence ensues.
There's really not much the PNF can do at this point. At 8:09:05, he transmits a MAYDAY.
———
Obviously there are variations to this, for example it could have been the PF who put the fuel switches back. (In the above scenario, the PF is focused on flying—aviate!—and never turns his head to see the switches.) My goal was simply to set out a possible sequence, to see whether it feels plausible. Remember, as you see other scenarios put forth, that any issues a person could wrestle with would also be distracting. While both pilots would be very focused during the takeoff run, the moment the aircraft lifted off, the PNF could well have mentally relaxed a little, opening an opportunity for the action slip.
Thoughts?
Seeing that the gear remained down after liftoff, there was CVR confusion after the event, and there was an attempt to rectify the situation…. I’m now thinking aviation is witnessing its most bizarre action-slip it’s ever seen and we’ll learn that the human automatic system is capable of making the most inappropriate and illogical responses to a given situation. I suspect fatigue and the captains sim experience of flicking switches plays a part.
As a result of this, I think we’ll see a renewed interest in slowing down actions at all times…touch a control, look at it, pause, consciously think about what you are touching before you execute it. This needs to be habitual, especially on LH fleets where fatigue inevitably plays into the operation.
We’ll also be discouraging the “insta-pilot” trend of showing how slick you are (usually on A320) where your hands flick round the flight deck at lightning speed. Even in more benign scenarios like shutdown flows etc, this isn’t a good habit.
July 13, 2025, 07:45:00 GMT
permalink Post: 11921095
Why don't they publish CVR recordings?
The short answer is that we wouldn't have CVR recordings if that was possible.
Basically, the cockpit voice recorder records the pilots incriminating themselves. It was only possible to get pilots to agree to have a CVR in the cockpit by assuring them it would only be used in accident investigations. For example, on the 787's EAFR you can read out the data on a laptop connected to the onboard network, but you can't read out the CVR unless you physically access the device.
Air accident investigations must safeguard that status. Their success depends on the guarantee that the investigation results can't be used to incriminate the pilots legally. But while courts cannot subpoena the CVR recording from the accident investigation, they wouldn't have to if the board released a full recording or even just a full transcript.
In my opinion, that is why this preliminary report is vague on who said what, and what exactly was said.
The CVR must not become a constant "anything you say can and will be used against you in a court of law" in the cockpit.
I'd be happy if any lawyers in the thread (e.g. WillowRun 6-3 ) could correct or confirm.
Basically, the cockpit voice recorder records the pilots incriminating themselves. It was only possible to get pilots to agree to have a CVR in the cockpit by assuring them it would only be used in accident investigations. For example, on the 787's EAFR you can read out the data on a laptop connected to the onboard network, but you can't read out the CVR unless you physically access the device.
Air accident investigations must safeguard that status. Their success depends on the guarantee that the investigation results can't be used to incriminate the pilots legally. But while courts cannot subpoena the CVR recording from the accident investigation, they wouldn't have to if the board released a full recording or even just a full transcript.
In my opinion, that is why this preliminary report is vague on who said what, and what exactly was said.
The CVR must not become a constant "anything you say can and will be used against you in a court of law" in the cockpit.
I'd be happy if any lawyers in the thread (e.g. WillowRun 6-3 ) could correct or confirm.
July 13, 2025, 08:33:00 GMT
permalink Post: 11921133
The short answer is that we wouldn't have CVR recordings if that was possible.
Basically, the cockpit voice recorder records the pilots incriminating themselves. It was only possible to get pilots to agree to have a CVR in the cockpit by assuring them it would only be used in accident investigations. For example, on the 787's EAFR you can read out the data on a laptop connected to the onboard network, but you can't read out the CVR unless you physically access the device.
Air accident investigations must safeguard that status. Their success depends on the guarantee that the investigation results can't be used to incriminate the pilots legally. But while courts cannot subpoena the CVR recording from the accident investigation, they wouldn't have to if the board released a full recording or even just a full transcript.
In my opinion, that is why this preliminary report is vague on who said what, and what exactly was said.
The CVR must not become a constant "anything you say can and will be used against you in a court of law" in the cockpit.
I'd be happy if any lawyers in the thread (e.g. WillowRun 6-3 ) could correct or confirm.
Basically, the cockpit voice recorder records the pilots incriminating themselves. It was only possible to get pilots to agree to have a CVR in the cockpit by assuring them it would only be used in accident investigations. For example, on the 787's EAFR you can read out the data on a laptop connected to the onboard network, but you can't read out the CVR unless you physically access the device.
Air accident investigations must safeguard that status. Their success depends on the guarantee that the investigation results can't be used to incriminate the pilots legally. But while courts cannot subpoena the CVR recording from the accident investigation, they wouldn't have to if the board released a full recording or even just a full transcript.
In my opinion, that is why this preliminary report is vague on who said what, and what exactly was said.
The CVR must not become a constant "anything you say can and will be used against you in a court of law" in the cockpit.
I'd be happy if any lawyers in the thread (e.g. WillowRun 6-3 ) could correct or confirm.
I understand, to some extent, the reasoning for not publishing the actual recording as a general rule, but from my perspective the usual outcome is speculation that can be just as critical of the actions and skills of the crew, and be just as inviting to 'ambulance chasers' keen on litigation, as ripping the band aide off the sore and dealing with the truth. I remain of the view that the least bad way to get to the awful truth - whatever it may be in the circumstances of this tragedy - includes publication of the raw recordings of the cockpit and ATC. As many have already pointed out - correctly in my view - so much depends on the nuances of the language spoken, who said what, in what order, the cultural or other status of those in the conversation, the other sounds in the environment, all assessed in the context of the timeline of flight data recorded.
All one needs to do is consider the different meanings of "yeah nah" or "yeah right" in the Australian vernacular, which meanings depend, crucially, on context and tone and inflection and emphasis. Without that level of detail, paraphrasing or even quotes in transcripts are more often the source of increased speculation rather than the resolution of uncertainty.
July 13, 2025, 08:59:00 GMT
permalink Post: 11921157
It\x92s not great that they mention the SAIB in the Preliminary Report but don\x92t give any details to the state of the particular switches of this airplane.
The metal parts of the switches seem intact in the picture, so it would be easy to check if the \x93lobes\x94 in the movable and stationary parts of the switches were there. A close-up picture would lay this topic to rest.
This omission is causing a lot of speculation online.
The metal parts of the switches seem intact in the picture, so it would be easy to check if the \x93lobes\x94 in the movable and stationary parts of the switches were there. A close-up picture would lay this topic to rest.
This omission is causing a lot of speculation online.
July 13, 2025, 09:02:00 GMT
permalink Post: 11921159
It\x92s not great that they mention the SAIB in the Preliminary Report but don\x92t give any details to the state of the particular switches of this airplane.
The metal parts of the switches seem intact in the picture, so it would be easy to check if the \x93lobes\x94 in the movable and stationary parts of the switches were there. A close-up picture would lay this topic to rest.
This omission is causing a lot of speculation online.
The metal parts of the switches seem intact in the picture, so it would be easy to check if the \x93lobes\x94 in the movable and stationary parts of the switches were there. A close-up picture would lay this topic to rest.
This omission is causing a lot of speculation online.
July 13, 2025, 10:13:00 GMT
permalink Post: 11921202
Not sure if this is helpful for anyone or not but I thought a visual view of the timeline of events might be useful, in seconds since V1.
I've assumed 1Hz for the switch sampling rate and >1Hz for everything else (could be wrong) to give windows for the switch state changes.
I've also added in the ADS-B relevant data, although made no attempt to work out whether these timestamps are synchronised or not, so take them as you will.
I have assumed the cutoff is in chronological order from the report, albeit I have ignored the RAT supply timestamp in terms of chronology from the CVR recording, as that statement in the report at that time may just be due to contextual nature of the statement, rather than it happening prior to the RAT power supply. This gives a window for potentially when that statement was made (assuming also that it was made prior to reversing cutoff).
Don't think it neccessarily adds anything for me, other than:
- Would we expect ADS-B data to stop on engine transition to run? Note that ADS-B data was received between 08:08:43 and 08:08:51, so apparently only received in the time window that the switches were in "cutoff"
- The window between the switches being shut off and moved to run could be as short as 8 seconds, and the window between engine 1 and engine 2 being moved to run could be as short as 2 seconds
- The statement on the CVR could be a wide range of timepoints.
The ADS-B data is in my view odd, albeit this might be my lack of understanding. Yes, not synchronised, but unless the timestamps are way out (like 10 seconds out, and given the timestamp of max altitude, this feels incredibly unlikely), ADS-B data was transmitted without issue during phase 2 (both engines off, no RAT), and phase 3 (both engines off, RAT)...but NOT phase 4 (both engines firing back up, presumably still with RAT?). Bear in mind that phase 4 is almost half of the short flight. Also it would appear no data during phase 1 (both engines on), including during takeoff, despite receiving data during taxi?
*EDIT* - having looked into some other historical ADS-B data for this airport, albeit a bit cursory, it definitely appears that the lack of data in "phase 1" that I've outlined above is solely a coverage issue, with no other flights I can see having coverage in that area either. It's harder to determine the "phase 4" element as obviously no airplanes in a normal mode are in that geographical region at the altitude in question, but it does appear to be a reasonably safe bet that the missing datapoints are coverage related.
Last edited by Mrshed; 13th July 2025 at 11:47 .
July 13, 2025, 10:23:00 GMT
permalink Post: 11921207
Not sure if this is helpful for anyone or not but I thought a visual view of the timeline of events might be useful, in seconds since V1.
I've assumed 1Hz for the switch sampling rate and >1Hz for everything else (could be wrong) to give windows for the switch state changes.
I've also added in the ADS-B relevant data, although made no attempt to work out whether these timestamps are synchronised or not, so take them as you will.
I have assumed the cutoff is in chronological order from the report, albeit I have ignored the RAT supply timestamp in terms of chronology from the CVR recording, as that statement in the report at that time may just be due to contextual nature of the statement, rather than it happening prior to the RAT power supply. This gives a window for potentially when that statement was made (assuming also that it was made prior to reversing cutoff).
Really highlights how knowing precisely when the why did you cutoff" question was asked might have provided more clarity and less speculation as to how those fateful seconds played out
And it would have helped to know if Positive rate / Gear Up was called ... and when
Last edited by unworry; 13th July 2025 at 12:19 .