June 15, 2025, 19:24:00 GMT
permalink Post: 11902747
The biggest news site in Greece claims to have the results of a kind of preliminary report from India AAIB which say that as the plane rotated, the pilot's seat malfunctioned (broken pin) and went suddenly far back forcing the captain to accidentally lower the thrust lever as he already had his hand on it and despite the co-pilots effort to help increase the thrust it was already to late to avoid the stall. I dont believe they would have posted something as serious as this without any credible source cause they are supposed to be a serious news outlet but you never know when stupidity takes over validity. Source is the protothema dot gr site
July 11, 2025, 20:30:00 GMT
permalink Post: 11919765
From the Report:
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.
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.
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, 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, 21:24:00 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: 11919851
Again, you can not conclude that from the report.
Different inputs are sampled at different rates. Some very basic info here: https://scaledanalytics.com/2023/04/...uses-767-data/
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: https://scaledanalytics.com/2023/04/...uses-767-data/
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.
July 11, 2025, 22:16:00 GMT
permalink Post: 11919894
From the report, there is no indicated time stamp identifying the point when one pilot asked the other "why did you cut off"
This could explain the the assumption that it took ten seconds to reverse the switch positions.
Cut off could have been noticed at any point later than 08:08:42 but before 08:08:52.
This could explain the the assumption that it took ten seconds to reverse the switch positions.
Cut off could have been noticed at any point later than 08:08:42 but before 08:08:52.
July 11, 2025, 23:43:00 GMT
permalink Post: 11920013
10 seconds
Baffled, as probably all of us. But 10 seconds between \x93cut-off\x94 and \x93run\x94 is not excessive imo:
08:08:42 - max speed
08:08:43 - cut-off eng 1
08:08:44 - cut-off eng 2; run-down eng 1
08:08:45 - run-down eng 2
08:08:46 - startle moment
08:08:47-48 - instruments, levers and switch scan
08:08:49-50 interrogate other pilot why he moved switches
08:08:51: other pilot denies
08:08:52: eng 1 fuel switch to \x93run\x94
08:08:53: it\x92s both fuel switches that were cut off
08:08:56: eng 2 fuel switch to \x93run\x94
08:08:42 - max speed
08:08:43 - cut-off eng 1
08:08:44 - cut-off eng 2; run-down eng 1
08:08:45 - run-down eng 2
08:08:46 - startle moment
08:08:47-48 - instruments, levers and switch scan
08:08:49-50 interrogate other pilot why he moved switches
08:08:51: other pilot denies
08:08:52: eng 1 fuel switch to \x93run\x94
08:08:53: it\x92s both fuel switches that were cut off
08:08:56: eng 2 fuel switch to \x93run\x94
July 12, 2025, 00:08:00 GMT
permalink Post: 11920029
Timeline of known events with source attribution from the preliminary report:
08:07:33 ATC: Takeoff clearance
08:07:37 A-SMGCS: Aircraft starts rolling
08:08:33 EAFR: V1 153kts
08:08:35 EAFR: Vr 155kts
08:08:39 EAFR: Gnd-Air mode transition
08:08:42 EAFR: Max IAS 180kts, Eng 1/2 Cutoff switches activate within 1 second of each other
08:08:42 CVR: "Why did you cut off", "I did not" (exact time not specified)
08:08:42 A-SMGCS: RAT deployed (exact time not specified)
08:08:47 EAFR: Both engine N2 below min idle. RAT hyd pwr commences
08:08:52 EAFR: Eng 1 cutoff to RUN
08:08:54 EAFR: APU inlet door opens (auto start logic)
08:08:56 EAFR: Eng 2 cutoff to RUN
08:09:05 ATC: Mayday call
08:09:11 EAFR recording stops
Fuel cutoff switches operated within 1 second of each other suggests to me that the locking mechanism wasn't working as per (SAIB) No. NM-18-33. Any loose item could have accidentally (or not) operated the switches (including hands).
08:07:33 ATC: Takeoff clearance
08:07:37 A-SMGCS: Aircraft starts rolling
08:08:33 EAFR: V1 153kts
08:08:35 EAFR: Vr 155kts
08:08:39 EAFR: Gnd-Air mode transition
08:08:42 EAFR: Max IAS 180kts, Eng 1/2 Cutoff switches activate within 1 second of each other
08:08:42 CVR: "Why did you cut off", "I did not" (exact time not specified)
08:08:42 A-SMGCS: RAT deployed (exact time not specified)
08:08:47 EAFR: Both engine N2 below min idle. RAT hyd pwr commences
08:08:52 EAFR: Eng 1 cutoff to RUN
08:08:54 EAFR: APU inlet door opens (auto start logic)
08:08:56 EAFR: Eng 2 cutoff to RUN
08:09:05 ATC: Mayday call
08:09:11 EAFR recording stops
Fuel cutoff switches operated within 1 second of each other suggests to me that the locking mechanism wasn't working as per (SAIB) No. NM-18-33. Any loose item could have accidentally (or not) operated the switches (including hands).
Last edited by physicus; 12th July 2025 at 00:24 .
July 12, 2025, 01:28:00 GMT
permalink Post: 11920070
Can someone with the engineering knowledge build a timeline/timeframe for fuel cutoff switch RUN to CUTOFF -> fuel stops -> engine flameout -> N2 drops to ? -> VFSGs quit -> RAT deployment starts -> RAT full power -> APU deployment start?
Does the RAT really start providing power in 4 seconds from the E2 fuel cutoff switch RUN -> CUTOFF?
Timeline from AAIB and the public CCTV video:
08:08:33 v1 153 kts
.
08:08:35 vr 155 kts
.
.
.
08:08:39 Liftoff, A/G Air Mode, rotation at 00:18 in public CCTV video
.
.
08:08:42 E1 Fuel Cutoff Switch RUN -> CUTOFF, 180 kts
08:08:43 E2 Fuel Cutoff Switch RUN -> CUTOFF
.............? N1 N2 begin to decrease
.............? "Why did you cutoff", "I didn't"
.............? Airport CCTV shows RAT
.............? N2 < idle speed
08:08:47 RAT hydraulic power
.
08:08:49 Public CCTV video: visible loss of thrust, Alt < 200ft using wingspan
.
.
08:08:52 E1 Fuel Cutoff Switch CUTOFF -> RUN, CCTV video: visible descent
.
08:08:54 APU inlet door begins opening
.
08:08:56 E2 Fuel Cutoff Switch CUTOFF -> RUN
08:09:05 MAYDAY
08:09:11 EAFR Recording stops
08:14:44 Crash Fire Tender leaves airport
Does the RAT really start providing power in 4 seconds from the E2 fuel cutoff switch RUN -> CUTOFF?
Timeline from AAIB and the public CCTV video:
08:08:33 v1 153 kts
.
08:08:35 vr 155 kts
.
.
.
08:08:39 Liftoff, A/G Air Mode, rotation at 00:18 in public CCTV video
.
.
08:08:42 E1 Fuel Cutoff Switch RUN -> CUTOFF, 180 kts
08:08:43 E2 Fuel Cutoff Switch RUN -> CUTOFF
.............? N1 N2 begin to decrease
.............? "Why did you cutoff", "I didn't"
.............? Airport CCTV shows RAT
.............? N2 < idle speed
08:08:47 RAT hydraulic power
.
08:08:49 Public CCTV video: visible loss of thrust, Alt < 200ft using wingspan
.
.
08:08:52 E1 Fuel Cutoff Switch CUTOFF -> RUN, CCTV video: visible descent
.
08:08:54 APU inlet door begins opening
.
08:08:56 E2 Fuel Cutoff Switch CUTOFF -> RUN
08:09:05 MAYDAY
08:09:11 EAFR Recording stops
08:14:44 Crash Fire Tender leaves airport
Last edited by appruser; 12th July 2025 at 01:29 . Reason: readability
July 12, 2025, 01:43:00 GMT
permalink Post: 11920081
What happened before this to cause the engines to run down, resulting in the crew trying the documented procedure of turning the switches off then on to restart ?
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.
July 12, 2025, 01:47:00 GMT
permalink Post: 11920083
Spoiler
It seems like people are jumping to conclusions about the pilots and letting Boeing off the hook without proper investigation. Instead of providing a professional, detailed transcript of the cockpit voice recorder (CVR), we’re just getting casual comments about what the pilot allegedly said. Critical information—like the timing of transmissions, the checklist items completed before takeoff, and other key details that should be on the CVR—are essential for understanding what happened in the cockpit, especially since the crash occurred so soon after takeoff. In my view, the preliminary report feels too convenient for certain parties involved.
Examining the before-takeoff checklists seems like it would be akin to examining the re-arrangement of the deckchairs before the titanic even hit the iceberg.
The engines were switched off. Unlike Embraer, B & A have no protections stopping you switching an engine off inadvertently. From everything in the report, everything operated exactly as designed. I am not certain of how long the relight window is without windmilling speed, but +- 10 seconds seems entirely reasonable.
The outstanding question that presumably requires much more in-depth investigation of the wreckage items and CVR audio is whether:
- the cutoff switches were operated deliberately (and by who)
- the cutoff switches were operated inadvertently (and by who)
- the cutoff switches were bumped (by what) and the guards failed or weren't installed
- some electrical failure perfectly mimicked both many-pole switches being operated, then being operated again (seems unlikely)
July 12, 2025, 02:39:00 GMT
permalink Post: 11920112
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?
What observation(s) would or could have alerted either pilot to the fact that the fuel cutoff switches had been set to CUTOFF?
July 12, 2025, 03:22:00 GMT
permalink Post: 11920141
The Vr speed (155 kts) was achieved as per the EAFR at 08:08:35
UTC. The aircraft air/ground sensors transitioned to air mode, consistent with liftoff at 08:08:39 UTC.
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.
UTC. The aircraft air/ground sensors transitioned to air mode, consistent with liftoff at 08:08:39 UTC.
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.
July 12, 2025, 07:42:00 GMT
permalink Post: 11920296
Timeline of known events with source attribution from the preliminary report:
08:07:33 ATC: Takeoff clearance
08:07:37 A-SMGCS: Aircraft starts rolling
08:08:33 EAFR: V1 153kts
08:08:35 EAFR: Vr 155kts
08:08:39 EAFR: Gnd-Air mode transition
08:08:42 EAFR: Max IAS 180kts, Eng 1/2 Cutoff switches activate within 1 second of each other
08:08:42 CVR: "Why did you cut off", "I did not" (exact time not specified)
08:08:42 A-SMGCS: RAT deployed (exact time not specified)
08:08:47 EAFR: Both engine N2 below min idle. RAT hyd pwr commences
08:08:52 EAFR: Eng 1 cutoff to RUN
08:08:54 EAFR: APU inlet door opens (auto start logic)
08:08:56 EAFR: Eng 2 cutoff to RUN
08:09:05 ATC: Mayday call
08:09:11 EAFR recording stops
Fuel cutoff switches operated within 1 second of each other suggests to me that the locking mechanism wasn't working as per (SAIB) No. NM-18-33. Any loose item could have accidentally (or not) operated the switches (including hands).
08:07:33 ATC: Takeoff clearance
08:07:37 A-SMGCS: Aircraft starts rolling
08:08:33 EAFR: V1 153kts
08:08:35 EAFR: Vr 155kts
08:08:39 EAFR: Gnd-Air mode transition
08:08:42 EAFR: Max IAS 180kts, Eng 1/2 Cutoff switches activate within 1 second of each other
08:08:42 CVR: "Why did you cut off", "I did not" (exact time not specified)
08:08:42 A-SMGCS: RAT deployed (exact time not specified)
08:08:47 EAFR: Both engine N2 below min idle. RAT hyd pwr commences
08:08:52 EAFR: Eng 1 cutoff to RUN
08:08:54 EAFR: APU inlet door opens (auto start logic)
08:08:56 EAFR: Eng 2 cutoff to RUN
08:09:05 ATC: Mayday call
08:09:11 EAFR recording stops
Fuel cutoff switches operated within 1 second of each other suggests to me that the locking mechanism wasn't working as per (SAIB) No. NM-18-33. Any loose item could have accidentally (or not) operated the switches (including hands).
Last edited by sorvad; 12th July 2025 at 08:03 . Reason: Clarification
July 12, 2025, 08:17:00 GMT
permalink Post: 11920331
Timing of Query Re Cut Off Switches
From the report, there is no indicated time stamp identifying the point when one pilot asked the other "why did you cut off"
This could explain the the assumption that it took ten seconds to reverse the switch positions.
Cut off could have been noticed at any point later than 08:08:42 but before 08:08:52.
This could explain the the assumption that it took ten seconds to reverse the switch positions.
Cut off could have been noticed at any point later than 08:08:42 but before 08:08:52.
July 12, 2025, 10:43:00 GMT
permalink Post: 11920474
SLF: I have a small observation but I'm not sure what it means or if it has any relevance to the accident.
Previously I had assumed that the ADS-B data cut out at the same time as power was lost, so I imagined that whatever caused the fairly clear loss of thrust would have happened not too long before. But this report throws a bit of a wrench in my understanding of that.
According to the report, the fuel cutoff switches transition from RUN to CUTOFF at or very shortly after 08:08:42 UTC. Both engines' N2 values pass below minimum idle speed and the RAT begins supplying hydraulic power at about 08:08:47. Does this not imply that the generators have already been lost? With the APU also being off (the APU inlet door is noted to start opening at 08:08:54), I would have expected ADS-B data to cut out at or before 08:08:47. But curiously FlightRadar24 at least claims to have received data frames from the aircraft until 08:08:51.640970, almost five seconds later and almost ten seconds after the transition to CUTOFF (though the last frame containing coordinates comes at 08:08:50.871005).
Could anyone with relevant experience confirm how long it would take for AC power to be lost in this situation? Also, is it usual/unusual for a preliminary report like this to mention if/when the flight recorder switched to its independent power supply? I imagine it would definitely be in the final report, but I'd hoped it would be easily observable enough to be in this one.
Beyond idle curiosity I'm asking because the report also says the no. 1 engine's cutoff switch transitioned from CUTOFF to RUN at "about 08:08:52", which oddly coincides with the last ADS-B data frame at 08:08:51.640970, and that seems important somehow. Or more likely I'm just ignorant of some quirk of the 787's electrical system.
For reference FR24's CSV containing all ADS-B frames supposedly received from the aircraft can be found in their post here: https://www.flightradar24.com/blog/f...rom-ahmedabad/
Previously I had assumed that the ADS-B data cut out at the same time as power was lost, so I imagined that whatever caused the fairly clear loss of thrust would have happened not too long before. But this report throws a bit of a wrench in my understanding of that.
According to the report, the fuel cutoff switches transition from RUN to CUTOFF at or very shortly after 08:08:42 UTC. Both engines' N2 values pass below minimum idle speed and the RAT begins supplying hydraulic power at about 08:08:47. Does this not imply that the generators have already been lost? With the APU also being off (the APU inlet door is noted to start opening at 08:08:54), I would have expected ADS-B data to cut out at or before 08:08:47. But curiously FlightRadar24 at least claims to have received data frames from the aircraft until 08:08:51.640970, almost five seconds later and almost ten seconds after the transition to CUTOFF (though the last frame containing coordinates comes at 08:08:50.871005).
Could anyone with relevant experience confirm how long it would take for AC power to be lost in this situation? Also, is it usual/unusual for a preliminary report like this to mention if/when the flight recorder switched to its independent power supply? I imagine it would definitely be in the final report, but I'd hoped it would be easily observable enough to be in this one.
Beyond idle curiosity I'm asking because the report also says the no. 1 engine's cutoff switch transitioned from CUTOFF to RUN at "about 08:08:52", which oddly coincides with the last ADS-B data frame at 08:08:51.640970, and that seems important somehow. Or more likely I'm just ignorant of some quirk of the 787's electrical system.
For reference FR24's CSV containing all ADS-B frames supposedly received from the aircraft can be found in their post here: https://www.flightradar24.com/blog/f...rom-ahmedabad/
July 12, 2025, 10:51:00 GMT
permalink Post: 11920482
"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."
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 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 .