July 13, 2025, 10:32:00 GMT
permalink Post: 11921213
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?
- 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?
Assuming the 787 is similar, perhaps the aircraft was broadcasting ADS-B for the full flight (with the transponder running off main battery/RAT power) but the reception was marginal, resulting in no reception until just after liftoff and no reception once they start to sink again.
July 13, 2025, 10:35:00 GMT
permalink Post: 11921214
I think in the Jeju thread, it was noted that one of the transponders was on an AC bus and the other was on the standby bus. If they had been using the other transponder (swapped each flight), then we would have had ADS-B for the full flight.
Assuming the 787 is similar, perhaps the aircraft was broadcasting ADS-B for the full flight (with the transponder running off main battery/RAT power) but the reception was marginal, resulting in no reception until just after liftoff and no reception once they start to sink again.
Assuming the 787 is similar, perhaps the aircraft was broadcasting ADS-B for the full flight (with the transponder running off main battery/RAT power) but the reception was marginal, resulting in no reception until just after liftoff and no reception once they start to sink again.
July 13, 2025, 18:03:00 GMT
permalink Post: 11921493
Electrical effects of engine rollback
As I understand it from previous discussions, without the APU, all electrical power except for that DC power provided by battery to essential systems would have been lost.
With the copilot as PF, would he have lost his instrument displays? If so, possibly additional startle effect and workload for him.
Why did the ADS-B information keep going on for so long? My understanding from previous threads was that loss of ADS-B was considered an indication of loss of electrical power.
What else would be expected with loss of power?
Some general speculation: I find it hard to understand the long delay from what must have been the onset of obvious issues to the time the first engine is set to "RUN". I wonder if much more cockpit dialog intervened, e.g. PF requesting PM to turn the fuel switches back on (since he had his hands full), and eventually operating the switches himself, with the delay and time gap between the two switches being turned to "RUN" being attributable to being preoccupied with flying the aircraft under trying conditions.
July 13, 2025, 18:39:00 GMT
permalink Post: 11921522
I would like to raise a subject that I don't believe has been discussed here since the Preliminary Report was published, namely what happened to the aircraft's electrical systems as a consequence of the dual engine rollback and thereafter (RAT deployment, partial engine recovery, etc.). Apologies if I've missed posts on this topic here, but I have tried to review all of this thread quickly after previously reading most of it in detail.
As I understand it from previous discussions, without the APU, all electrical power except for that DC power provided by battery to essential systems would have been lost.
With the copilot as PF, would he have lost his instrument displays? If so, possibly additional startle effect and workload for him.
Why did the ADS-B information keep going on for so long? My understanding from previous threads was that loss of ADS-B was considered an indication of loss of electrical power.
What else would be expected with loss of power?
Some general speculation: I find it hard to understand the long delay from what must have been the onset of obvious issues to the time the first engine is set to "RUN". I wonder if much more cockpit dialog intervened, e.g. PF requesting PM to turn the fuel switches back on (since he had his hands full), and eventually operating the switches himself, with the delay and time gap between the two switches being turned to "RUN" being attributable to being preoccupied with flying the aircraft under trying conditions.
As I understand it from previous discussions, without the APU, all electrical power except for that DC power provided by battery to essential systems would have been lost.
With the copilot as PF, would he have lost his instrument displays? If so, possibly additional startle effect and workload for him.
Why did the ADS-B information keep going on for so long? My understanding from previous threads was that loss of ADS-B was considered an indication of loss of electrical power.
What else would be expected with loss of power?
Some general speculation: I find it hard to understand the long delay from what must have been the onset of obvious issues to the time the first engine is set to "RUN". I wonder if much more cockpit dialog intervened, e.g. PF requesting PM to turn the fuel switches back on (since he had his hands full), and eventually operating the switches himself, with the delay and time gap between the two switches being turned to "RUN" being attributable to being preoccupied with flying the aircraft under trying conditions.
There seems to be a period around second 12/13 post V1 where engines are (or should) be likely below idle, but prior to RAT power generation.
Note that the report explicitly states the RAT started providing hydraulic power 5 seconds after engine shutdown commenced. It doesn't reference electrical power. So we don't know whether this was at the same time - others may clarify re: RAT operation.
But either way, it would appear there would be a gap in power (which, incidentally, would tie in with the survivor commentary). But yet ADS data continued.
If in fact there was a momentary loss of power then that would contribute heavily to the startle and "delay" in refiring (although comments here make me think there wasn't really such a delay anyway).
(And incidentally would make what appears to be a really rather valiant attempt to save the aircraft even more impressive)
July 13, 2025, 18:44:00 GMT
permalink Post: 11921524
The ADS-B data collected by FR24 leave the aircraft at 172 knots
Please tell me how recoverable that is, with hypothetical 95% thrust on both engines
edit: reviewed fr24 data and adjusted time covered; I think it did decelerate to approximately 155 knots in 10 seconds, based on -3knots/second.
July 13, 2025, 19:29:00 GMT
permalink Post: 11921564
Yes.
The ADS-B data collected by FR24 leave the aircraft at 172 knots
8 seconds
4 seconds into the outage. Vr was 155 knots per the report. The preliminary report also says it crashed at 8⁰ nose-up attitude, which was after the "flare".
Please tell me how recoverable that is, with hypothetical 95% thrust on both engines
2
6 seconds later.
edit: reviewed fr24 data and adjusted time covered; I think it did decelerate to approximately 155 knots in 10 seconds, based on -3knots/second.
The ADS-B data collected by FR24 leave the aircraft at 172 knots
Please tell me how recoverable that is, with hypothetical 95% thrust on both engines
edit: reviewed fr24 data and adjusted time covered; I think it did decelerate to approximately 155 knots in 10 seconds, based on -3knots/second.
Beware of comparing the speeds from ADS-B, which are groundspeeds, with those from the report, which are IAS.
July 13, 2025, 21:06:00 GMT
permalink Post: 11921654
Thank you for your reply! I'm aware you know more about ADS-B than I do, and I'm happy to learn.
As you know, I'm referring to the map view and data on https://www.flightradar24.com/blog/f...rom-ahmedabad/ .
That's what I thought at first, based on the time stamps.
08:08:50.87 last full ADS-B message (172 kts)
08:08:54 APU inlet door starts to open, per the report.
My problem here is that the report also says that the maximum speed was 180 knots IAS at about 08:08:42. And we have
2025-06-12T08:08:46.550875Z,8005ec,23.069138,72.625871,575
associated with 184 kts as the first ADS-B message in the sequence.
Given that the clocks of ADS-B receivers are sometimes off, I think this might actually represent the moment of maximum speed; but then the AFS-B clock would be 4 seconds fast.
And that's why I adjusted my times.
A way to cross-check would be to track the aircraft position over time from the point of rotation, or to use the new photo in the report that shows the RAT over the runway to triangulate where that was.
Yes.
Would low pressure and high temperature make IAS lower than ground speed, even with the 7 knot headwind?
Either way, if they were decelerating at approximately 3 knots per second, then they would've ended up at about 150 knots IAS, which is less than Vr.
When I look at the CCTV video, 13 seconds into the flight, the aircraft is just "over the hump" and starts descending, so that tracks.
At this point, I don't know what having the engines spool up instead of being dead weight would've done to that flight path; and how successfully the aircraft could've been recovered from that.
Maybe they had only 4 seconds to flip those switches, instead of 5 seconds?
Still, the best bet is to not ask questions, but flip these switches back ASAP, no?
As you know, I'm referring to the map view and data on https://www.flightradar24.com/blog/f...rom-ahmedabad/ .
08:08:50.87 last full ADS-B message (172 kts)
08:08:54 APU inlet door starts to open, per the report.
My problem here is that the report also says that the maximum speed was 180 knots IAS at about 08:08:42. And we have
2025-06-12T08:08:46.550875Z,8005ec,23.069138,72.625871,575
associated with 184 kts as the first ADS-B message in the sequence.
Given that the clocks of ADS-B receivers are sometimes off, I think this might actually represent the moment of maximum speed; but then the AFS-B clock would be 4 seconds fast.
And that's why I adjusted my times.
A way to cross-check would be to track the aircraft position over time from the point of rotation, or to use the new photo in the report that shows the RAT over the runway to triangulate where that was.
Beware of comparing the speeds from ADS-B, which are groundspeeds, with those from the report, which are IAS.
Would low pressure and high temperature make IAS lower than ground speed, even with the 7 knot headwind?
Either way, if they were decelerating at approximately 3 knots per second, then they would've ended up at about 150 knots IAS, which is less than Vr.
When I look at the CCTV video, 13 seconds into the flight, the aircraft is just "over the hump" and starts descending, so that tracks.
At this point, I don't know what having the engines spool up instead of being dead weight would've done to that flight path; and how successfully the aircraft could've been recovered from that.
Maybe they had only 4 seconds to flip those switches, instead of 5 seconds?
Still, the best bet is to not ask questions, but flip these switches back ASAP, no?
Last edited by Musician; 13th July 2025 at 21:36 .
July 13, 2025, 21:15:00 GMT
permalink Post: 11921667
Thank you for your reply! I'm aware you know more about ADS-B than I do, and I'm happy to learn.
As you know, I'm referring to the map view and data on https://www.flightradar24.com/blog/f...rom-ahmedabad/ .
That's what I thought at first, based on the time stamps.
08:08:50.87 last full ADS-B message (172 kts)
08:08:54 APU inlet door starts to open, per the report.
My problem here is that the report also says that the maximum speed was 180 knots IAS at about 808:08:42. And we have
2025-06-12T08:08:46.550875Z,8005ec,23.069138,72.625871,575
associated with 184 kts as the first ADS-B message in the sequence.
Given that the clocks of ADS-B receivers are sometimes off, I think this might actually represent the moment of maximum speed; but then the AFS-B clock would be 4 seconds fast.
And that's why I adjusted my times.
A way to cross-check would be to track the aircraft position over time from the point of rotation, or to use the new photo in the report that shows the RAT over the runway to triangulate where that was.
Yes.
Would low pressure and high temperature make IAS lower than ground speed, even with the 7 knot headwind?
Either way, if they were decelerating at approximately 3 knots per second, then they would've ended up at about 150 knots IAS, which is less than Vr.
When I look at the CCTV video, 13 seconds into the flight, the aircraft is just "over the hump" and starts descending, so that tracks.
At this point, I don't know what having the engines spool up instead of being dead weight would've done to that flight path; and how successfully the aircraft could've been recovered from that.
Maybe they had only 4 seconds to flip those switches, instead of 5 seconds?
Still, the best bet is to not ask questions, but flip these switches back ASAP, no?
As you know, I'm referring to the map view and data on https://www.flightradar24.com/blog/f...rom-ahmedabad/ .
That's what I thought at first, based on the time stamps.
08:08:50.87 last full ADS-B message (172 kts)
08:08:54 APU inlet door starts to open, per the report.
My problem here is that the report also says that the maximum speed was 180 knots IAS at about 808:08:42. And we have
2025-06-12T08:08:46.550875Z,8005ec,23.069138,72.625871,575
associated with 184 kts as the first ADS-B message in the sequence.
Given that the clocks of ADS-B receivers are sometimes off, I think this might actually represent the moment of maximum speed; but then the AFS-B clock would be 4 seconds fast.
And that's why I adjusted my times.
A way to cross-check would be to track the aircraft position over time from the point of rotation, or to use the new photo in the report that shows the RAT over the runway to triangulate where that was.
Yes.
Would low pressure and high temperature make IAS lower than ground speed, even with the 7 knot headwind?
Either way, if they were decelerating at approximately 3 knots per second, then they would've ended up at about 150 knots IAS, which is less than Vr.
When I look at the CCTV video, 13 seconds into the flight, the aircraft is just "over the hump" and starts descending, so that tracks.
At this point, I don't know what having the engines spool up instead of being dead weight would've done to that flight path; and how successfully the aircraft could've been recovered from that.
Maybe they had only 4 seconds to flip those switches, instead of 5 seconds?
Still, the best bet is to not ask questions, but flip these switches back ASAP, no?
July 13, 2025, 23:43:00 GMT
permalink Post: 11921782
Thank you for your reply! I'm aware you know more about ADS-B than I do, and I'm happy to learn.
As you know, I'm referring to the map view and data on https://www.flightradar24.com/blog/f...rom-ahmedabad/ .
That's what I thought at first, based on the time stamps.
08:08:50.87 last full ADS-B message (172 kts)
08:08:54 APU inlet door starts to open, per the report.
My problem here is that the report also says that the maximum speed was 180 knots IAS at about 08:08:42. And we have
2025-06-12T08:08:46.550875Z,8005ec,23.069138,72.625871,575
associated with 184 kts as the first ADS-B message in the sequence.
Given that the clocks of ADS-B receivers are sometimes off, I think this might actually represent the moment of maximum speed; but then the AFS-B clock would be 4 seconds fast.
And that's why I adjusted my times.
A way to cross-check would be to track the aircraft position over time from the point of rotation, or to use the new photo in the report that shows the RAT over the runway to triangulate where that was.
Yes.
Would low pressure and high temperature make IAS lower than ground speed, even with the 7 knot headwind?
Either way, if they were decelerating at approximately 3 knots per second, then they would've ended up at about 150 knots IAS, which is less than Vr.
When I look at the CCTV video, 13 seconds into the flight, the aircraft is just "over the hump" and starts descending, so that tracks.
At this point, I don't know what having the engines spool up instead of being dead weight would've done to that flight path; and how successfully the aircraft could've been recovered from that.
Maybe they had only 4 seconds to flip those switches, instead of 5 seconds?
Still, the best bet is to not ask questions, but flip these switches back ASAP, no?
As you know, I'm referring to the map view and data on https://www.flightradar24.com/blog/f...rom-ahmedabad/ .
That's what I thought at first, based on the time stamps.
08:08:50.87 last full ADS-B message (172 kts)
08:08:54 APU inlet door starts to open, per the report.
My problem here is that the report also says that the maximum speed was 180 knots IAS at about 08:08:42. And we have
2025-06-12T08:08:46.550875Z,8005ec,23.069138,72.625871,575
associated with 184 kts as the first ADS-B message in the sequence.
Given that the clocks of ADS-B receivers are sometimes off, I think this might actually represent the moment of maximum speed; but then the AFS-B clock would be 4 seconds fast.
And that's why I adjusted my times.
A way to cross-check would be to track the aircraft position over time from the point of rotation, or to use the new photo in the report that shows the RAT over the runway to triangulate where that was.
Yes.
Would low pressure and high temperature make IAS lower than ground speed, even with the 7 knot headwind?
Either way, if they were decelerating at approximately 3 knots per second, then they would've ended up at about 150 knots IAS, which is less than Vr.
When I look at the CCTV video, 13 seconds into the flight, the aircraft is just "over the hump" and starts descending, so that tracks.
At this point, I don't know what having the engines spool up instead of being dead weight would've done to that flight path; and how successfully the aircraft could've been recovered from that.
Maybe they had only 4 seconds to flip those switches, instead of 5 seconds?
Still, the best bet is to not ask questions, but flip these switches back ASAP, no?
July 14, 2025, 21:36:00 GMT
permalink Post: 11922527
This was posted sometime ago, but if anyone would still find it useful to pinpoint the location of the aircraft in the 'new' photo from the Preliminary Report (with RAT deployed) I made a crude attempt which placed it roughly midway between the two sets of identical touchdown zone markings, ~245m (803 ft) from the displaced threshold of RW05.
The deemed position of the CCTV camera is only an estimate, based on visual cues. I'm happy to share my workings, should anyone find it useful to cross-reference this with other data they are working on, but I will avoid cluttering up the thread any further until/unless it becomes relevant.
You're looking for the point where the LEFT of the two white lines intersects the runway (ignore the white dots):
The deemed position of the CCTV camera is only an estimate, based on visual cues. I'm happy to share my workings, should anyone find it useful to cross-reference this with other data they are working on, but I will avoid cluttering up the thread any further until/unless it becomes relevant.
You're looking for the point where the LEFT of the two white lines intersects the runway (ignore the white dots):
July 16, 2025, 01:55:00 GMT
permalink Post: 11923383
Since the preliminary report neglected including when the RAT deployment occurred, I've tried to estimate it based on the picture they did include:
Baro altitude should be around 150ft; using the public cctv video, I estimate this picture was taken between 4-7 seconds after rotation. A wide range, but that was the best estimate I could come up with. Maybe someone else could narrow it down further.
Baro altitude should be around 150ft; using the public cctv video, I estimate this picture was taken between 4-7 seconds after rotation. A wide range, but that was the best estimate I could come up with. Maybe someone else could narrow it down further.
1. ADSB readouts - according to FlightRadar24, the last ADSB transmission was at 71ft AGL. Is that significant given the RAT is seen already deployed at 150ft AGL per the estimate above? At 71ft AGL, the wheels are about 40-50ft off the ground, assuming aircraft attitude is unchanged between there and this image. Is that 1 or 2 seconds after rotation? Does this imply electrical issues?
1a. The timings for ADSB transmissions outlined by MrShed are not in sync with the estimates above - people have talked about a time shift in this thread. I do believe ADSB timestamps are by the receiving station.
2. The preliminary report timings from the EAFR for E2 fuel cutoff switch RUN -> CUTOFF to the RAT supplying hydraulic power disagree with the lower end of the 4-7s estimate above, and are only consistent if this picture was taken 6-7 seconds after rotation, in my opinion, because of the time (4-5s) it would take to cut off the fuel to E2, spool down to where the VFSGs stop providing AC power, and RAT deployment.
3. The Preliminary Report mentions that the RAT deployed "immediately after" lift-off. Again, I have to wonder, why didn't they provide the RAT deployment timestamp, even relative to rotation? If this is in fact the case, does this imply electrical issues, in line with the last ADSB altitude reading?
FR24 article https://www.flightradar24.com/blog/f...rom-ahmedabad/
Last edited by appruser; 16th July 2025 at 01:57 . Reason: Added link to FR24 blog post
July 16, 2025, 03:52:00 GMT
permalink Post: 11923409
This was posted sometime ago, but if anyone would still find it useful to pinpoint the location of the aircraft in the 'new' photo from the Preliminary Report (with RAT deployed) I made a crude attempt which placed it roughly midway between the two sets of identical touchdown zone markings, ~245m (803 ft) from the displaced threshold of RW05.
The deemed position of the CCTV camera is only an estimate, based on visual cues. I'm happy to share my workings, should anyone find it useful to cross-reference this with other data they are working on, but I will avoid cluttering up the thread any further until/unless it becomes relevant.
You're looking for the point where the LEFT of the two white lines intersects the runway (ignore the white dots):
The deemed position of the CCTV camera is only an estimate, based on visual cues. I'm happy to share my workings, should anyone find it useful to cross-reference this with other data they are working on, but I will avoid cluttering up the thread any further until/unless it becomes relevant.
You're looking for the point where the LEFT of the two white lines intersects the runway (ignore the white dots):
Generally don't think it's a good idea to reply to own posts, but in this case wanted to keep things in context. A few interesting items of note:
1. ADSB readouts - according to FlightRadar24, the last ADSB transmission was at 71ft AGL. Is that significant given the RAT is seen already deployed at 150ft AGL per the estimate above? At 71ft AGL, the wheels are about 40-50ft off the ground, assuming aircraft attitude is unchanged between there and this image. Is that 1 or 2 seconds after rotation? Does this imply electrical issues?
1a. The timings for ADSB transmissions outlined by MrShed are not in sync with the estimates above - people have talked about a time shift in this thread. I do believe ADSB timestamps are by the receiving station.
2. The preliminary report timings from the EAFR for E2 fuel cutoff switch RUN -> CUTOFF to the RAT supplying hydraulic power disagree with the lower end of the 4-7s estimate above, and are only consistent if this picture was taken 6-7 seconds after rotation, in my opinion, because of the time (4-5s) it would take to cut off the fuel to E2, spool down to where the VFSGs stop providing AC power, and RAT deployment.
3. The Preliminary Report mentions that the RAT deployed "immediately after" lift-off. Again, I have to wonder, why didn't they provide the RAT deployment timestamp, even relative to rotation? If this is in fact the case, does this imply electrical issues, in line with the last ADSB altitude reading?
FR24 article https://www.flightradar24.com/blog/f...rom-ahmedabad/
1. ADSB readouts - according to FlightRadar24, the last ADSB transmission was at 71ft AGL. Is that significant given the RAT is seen already deployed at 150ft AGL per the estimate above? At 71ft AGL, the wheels are about 40-50ft off the ground, assuming aircraft attitude is unchanged between there and this image. Is that 1 or 2 seconds after rotation? Does this imply electrical issues?
1a. The timings for ADSB transmissions outlined by MrShed are not in sync with the estimates above - people have talked about a time shift in this thread. I do believe ADSB timestamps are by the receiving station.
2. The preliminary report timings from the EAFR for E2 fuel cutoff switch RUN -> CUTOFF to the RAT supplying hydraulic power disagree with the lower end of the 4-7s estimate above, and are only consistent if this picture was taken 6-7 seconds after rotation, in my opinion, because of the time (4-5s) it would take to cut off the fuel to E2, spool down to where the VFSGs stop providing AC power, and RAT deployment.
3. The Preliminary Report mentions that the RAT deployed "immediately after" lift-off. Again, I have to wonder, why didn't they provide the RAT deployment timestamp, even relative to rotation? If this is in fact the case, does this imply electrical issues, in line with the last ADSB altitude reading?
FR24 article https://www.flightradar24.com/blog/f...rom-ahmedabad/
Note that the good folks at FR24 did not apply temperature correction to the barometric altitude (they corrected for air pressure and runway elevation); pilots on pprune have done the corrections themselves and arrived at slightly different values, so take those altitude numbers with a grain of salt. Note also that the 787 sends altitude in 25 ft. increments, and I don't know how these are rounded (up, down, nearest).
We do not know how long the RAT has been deployed in this photo, we only know it can't have been deployed later. I have learned on this thread that the CUTOFF switch will also cause the VFSGs to disconnect, i.e. the B787 systems will electrically isolate the engine from the power buses before it has spooled down. With a dual failure, this would leave the main buses unpowered in short order, so if all of this is correct, the RAT would have clonked into place very soon after the second engine was cut off. This would not depend on the turbine speed.
I personally do not know what items are logged on the flight recorder, but I imagine RAT deployment was not among them. If so, the conditions for its deployment would be logged, but it requires an analytical step to conclude it did, and a preliminary report typically has no analysis at all. Hydraulic pressure to the flight controls is likely logged, so the RAT delivering hydraulic power would be a matter of record.
Where is the RadAlt antenna on a 787? Is it in the nose, or further back between the main gears?
Last edited by Musician; 16th July 2025 at 04:02 .
July 16, 2025, 05:42:00 GMT
permalink Post: 11923437
The timestamps most certainly are not synced so the blue boxes on my image almost certainly need to move a little left or right, but actually when I looked at them before I think it's pretty close.
What is it that makes you think they are out (genuine question!).
July 16, 2025, 13:21:00 GMT
permalink Post: 11923732
I may be having a "brain fart" myself here, but do they definitely not?
The timestamps most certainly are not synced so the blue boxes on my image almost certainly need to move a little left or right, but actually when I looked at them before I think it's pretty close.
What is it that makes you think they are out (genuine question!).
The timestamps most certainly are not synced so the blue boxes on my image almost certainly need to move a little left or right, but actually when I looked at them before I think it's pretty close.
What is it that makes you think they are out (genuine question!).
As an aside, I have no knowledge of the software used by Flight Aware reporters, but I would be surprised if, at the very least, the computer involved was not set up with NTP (Internet Network Time Protocol) to synchronize its clock. This would set the computer's clock to within a small fraction of a second of correct time. For even greater accuracy, an inexpensive GPS device could be interfaced with the computer.
Last edited by andihce; 16th July 2025 at 13:42 . Reason: typo
July 16, 2025, 13:57:00 GMT
permalink Post: 11923742
As I've previously posted, there is the fact that the ADS-B data (in your diagram) continues long after electrical power from the engines would have been lost. Someone recently posted that the engines don't even need to run down for this to happen, saying that operation of the FCS to cutoff would shut down the engine VFSG's.
https://fliphtml5.com/quwam/qhdw/Boo...cs_Electrical/ (page 96)
I don't know if the transponder is on the captain's instrument bus, but if so, it would have power from the main battery while the RAT is being deployed.
We are definitely seeing the loss of thrust in the ADS-B data.
July 16, 2025, 14:20:00 GMT
permalink Post: 11923758
As I've previously posted, there is the fact that the ADS-B data (in your diagram) continues long after electrical power from the engines would have been lost. Someone recently posted that the engines don't even need to run down for this to happen, saying that operation of the FCS to cutoff would shut down the engine VFSG's.
As an aside, I have no knowledge of the software used by Flight Aware reporters, but I would be surprised if, at the very least, the computer involved was not set up with NTP (Internet Network Time Protocol) to synchronize its clock. This would set the computer's clock to within a small fraction of a second of correct time. For even greater accuracy, an inexpensive GPS device could be interfaced with the computer.
As an aside, I have no knowledge of the software used by Flight Aware reporters, but I would be surprised if, at the very least, the computer involved was not set up with NTP (Internet Network Time Protocol) to synchronize its clock. This would set the computer's clock to within a small fraction of a second of correct time. For even greater accuracy, an inexpensive GPS device could be interfaced with the computer.
So in the diagram (can't modify right now but I will), the blue bar starts at 5 and ends at 13, max altitude marker at 8.
That would tie in with loss of power.
It would put, interestingly, engine cutoffs right at the earliest opportunity within the window available with sampling etc.
(Incidentally an apology to Musician who I incorrectly told earlier that such a movement would be inconsistent with max altitude record, I can see clearly now this isn't the case!).
July 18, 2025, 00:25:00 GMT
permalink Post: 11924773
So I've looked again and I think that basically the ADS-B data is 5 seconds out.
So in the diagram (can't modify right now but I will), the blue bar starts at 5 and ends at 13, max altitude marker at 8.
That would tie in with loss of power.
It would put, interestingly, engine cutoffs right at the earliest opportunity within the window available with sampling etc.
(Incidentally an apology to Musician who I incorrectly told earlier that such a movement would be inconsistent with max altitude record, I can see clearly now this isn't the case!).
So in the diagram (can't modify right now but I will), the blue bar starts at 5 and ends at 13, max altitude marker at 8.
That would tie in with loss of power.
It would put, interestingly, engine cutoffs right at the earliest opportunity within the window available with sampling etc.
(Incidentally an apology to Musician who I incorrectly told earlier that such a movement would be inconsistent with max altitude record, I can see clearly now this isn't the case!).
I think for various reasons the ADSB data's absolute values are offset by some amount, for possibly all of the parameters. But there should be consistency in the deltas for the timestamp (by receiving station), the raw baro altitude, the Flightradar24 AGL values, and the airspeed. Flightradar24 themselves note that for altitude " ... the data is not above ground level, but it is consistent to itself."
08:08:46.55 ... 575ft ... 21ft ... 184kt
08:08:48.14 ... 600ft ... 46ft ... 179kt
08:08:48.61 ... 600ft ... 46ft ... 177kt
08:08:49.01 ... 600ft ... 46ft ... 177kt
08:08:49.46 ... 625ft ... 71ft ... 177kt
08:08:49.92 ... 625ft ... 71ft ... 174kt
08:08:50.39 ... 625ft ... 71ft ... 174kt
08:08:50.87 ... 625ft ... 71ft ... 172kt
From the Preliminary Report's airport cctv picture, the RAT was seen deployed at, by my estimate here , 150ft baro altitude, between 4-7 seconds after rotation. So the ADSB readings have to be prior to that.
What's interesting is that the ADSB data covers:
- 4-5 seconds of time (let's approximate 4 seconds from 46.55 to 50.55, ignoring the 0.32s for the moment)
- 50ft of altitude gain
- Declining airspeed from the 1st reading to the last in this final segment from the runway.
Big questions in my mind:
1. If the loss of ADSB corresponds to the E1/E2Fuel Cutoff switches being moved from RUN -> CUTOFF, why is the airspeed declining for the prior 4 seconds?
2. In 4 seconds, why is there only 50ft of altitude gain? that seems odd.
3. To account for only 50ft of alt gain, if we assume the 1st reading is on the runway just before rotation, the intermediate +25ft alt gain is at rotation (Nose up but MLG still on the runway), and the last 4 readings are in the air (nose up an additional 25ft), that means that 1 second or less after lift-off, ADSB was lost - this is before E1/E2 FCO RUN-> CUTOFF.
It's just weird .
Last edited by appruser; 18th July 2025 at 00:41 . Reason: added a comma for clarity
July 18, 2025, 01:32:00 GMT
permalink Post: 11924794
Apologies for the delay in responding to your posts. I see that you and others have stepped in, thanks.
I think for various reasons the ADSB data's absolute values are offset by some amount, for possibly all of the parameters. But there should be consistency in the deltas for the timestamp (by receiving station), the raw baro altitude, the Flightradar24 AGL values, and the airspeed. Flightradar24 themselves note that for altitude " ... the data is not above ground level, but it is consistent to itself."
08:08:46.55 ... 575ft ... 21ft ... 184kt
08:08:48.14 ... 600ft ... 46ft ... 179kt
08:08:48.61 ... 600ft ... 46ft ... 177kt
08:08:49.01 ... 600ft ... 46ft ... 177kt
08:08:49.46 ... 625ft ... 71ft ... 177kt
08:08:49.92 ... 625ft ... 71ft ... 174kt
08:08:50.39 ... 625ft ... 71ft ... 174kt
08:08:50.87 ... 625ft ... 71ft ... 172kt
From the Preliminary Report's airport cctv picture, the RAT was seen deployed at, by my estimate here , 150ft baro altitude, between 4-7 seconds after rotation. So the ADSB readings have to be prior to that.
What's interesting is that the ADSB data covers:
- 4-5 seconds of time (let's approximate 4 seconds from 46.55 to 50.55, ignoring the 0.32s for the moment)
- 50ft of altitude gain
- Declining airspeed from the 1st reading to the last in this final segment from the runway.
Big questions in my mind:
1. If the loss of ADSB corresponds to the E1/E2Fuel Cutoff switches being moved from RUN -> CUTOFF, why is the airspeed declining for the prior 4 seconds?
2. In 4 seconds, why is there only 50ft of altitude gain? that seems odd.
3. To account for only 50ft of alt gain, if we assume the 1st reading is on the runway just before rotation, the intermediate +25ft alt gain is at rotation (Nose up but MLG still on the runway), and the last 4 readings are in the air (nose up an additional 25ft), that means that 1 second or less after lift-off, ADSB was lost - this is before E1/E2 FCO RUN-> CUTOFF.
It's just weird .
I think for various reasons the ADSB data's absolute values are offset by some amount, for possibly all of the parameters. But there should be consistency in the deltas for the timestamp (by receiving station), the raw baro altitude, the Flightradar24 AGL values, and the airspeed. Flightradar24 themselves note that for altitude " ... the data is not above ground level, but it is consistent to itself."
08:08:46.55 ... 575ft ... 21ft ... 184kt
08:08:48.14 ... 600ft ... 46ft ... 179kt
08:08:48.61 ... 600ft ... 46ft ... 177kt
08:08:49.01 ... 600ft ... 46ft ... 177kt
08:08:49.46 ... 625ft ... 71ft ... 177kt
08:08:49.92 ... 625ft ... 71ft ... 174kt
08:08:50.39 ... 625ft ... 71ft ... 174kt
08:08:50.87 ... 625ft ... 71ft ... 172kt
From the Preliminary Report's airport cctv picture, the RAT was seen deployed at, by my estimate here , 150ft baro altitude, between 4-7 seconds after rotation. So the ADSB readings have to be prior to that.
What's interesting is that the ADSB data covers:
- 4-5 seconds of time (let's approximate 4 seconds from 46.55 to 50.55, ignoring the 0.32s for the moment)
- 50ft of altitude gain
- Declining airspeed from the 1st reading to the last in this final segment from the runway.
Big questions in my mind:
1. If the loss of ADSB corresponds to the E1/E2Fuel Cutoff switches being moved from RUN -> CUTOFF, why is the airspeed declining for the prior 4 seconds?
2. In 4 seconds, why is there only 50ft of altitude gain? that seems odd.
3. To account for only 50ft of alt gain, if we assume the 1st reading is on the runway just before rotation, the intermediate +25ft alt gain is at rotation (Nose up but MLG still on the runway), and the last 4 readings are in the air (nose up an additional 25ft), that means that 1 second or less after lift-off, ADSB was lost - this is before E1/E2 FCO RUN-> CUTOFF.
It's just weird .
The widely watched video shows a very normal initial rotation and climb.
July 18, 2025, 03:43:00 GMT
permalink Post: 11924815
I am not sure why 50 feet in 4 seconds seems odd right after liftoff in a heavy aircraft. That corresponds to 750 FPM. Seems entirely normal to me. The rate would have been increasing as the timeline advanced. I would also point out that RAT deployment verses the rat coming online fully are two different times. When that RAT is singled to deploy it bangs out nearly instantly. It begins producing its rated electrical and hydraulic power sometime after deployment.
The widely watched video shows a very normal initial rotation and climb.
The widely watched video shows a very normal initial rotation and climb.
Since the preliminary report states E2 cutoff after 3-4 seconds after lift-off, if that cutoff corresponds to ADSB interruption and which itself was only transmitting for 4 seconds, then 50ft after liftoff is a bit anemic?
But if we include the first 25ft after rotation but before lift-off, then, because the ADSB duration is only 4 seconds, it means that ADSB was interrupted before the E2 FCO operation. I don't know if there is a sliding window - part after rotation, part after lift-off that might meet all of these constraints.
That still leaves unexplained the declining airspeed seen in the ADSB data... did prior discussions on the ADSB data cover this? is there a good explanation?
Last edited by appruser; 18th July 2025 at 04:03 . Reason: fixed heights
July 18, 2025, 05:07:00 GMT
permalink Post: 11924844
Apologies for the delay in responding to your posts. I see that you and others have stepped in, thanks.
I think for various reasons the ADSB data's absolute values are offset by some amount, for possibly all of the parameters. But there should be consistency in the deltas for the timestamp (by receiving station), the raw baro altitude, the Flightradar24 AGL values, and the airspeed. Flightradar24 themselves note that for altitude " ... the data is not above ground level, but it is consistent to itself."
08:08:46.55 ... 575ft ... 21ft ... 184kt
08:08:48.14 ... 600ft ... 46ft ... 179kt
08:08:48.61 ... 600ft ... 46ft ... 177kt
08:08:49.01 ... 600ft ... 46ft ... 177kt
08:08:49.46 ... 625ft ... 71ft ... 177kt
08:08:49.92 ... 625ft ... 71ft ... 174kt
08:08:50.39 ... 625ft ... 71ft ... 174kt
08:08:50.87 ... 625ft ... 71ft ... 172kt
From the Preliminary Report's airport cctv picture, the RAT was seen deployed at, by my estimate here , 150ft baro altitude, between 4-7 seconds after rotation. So the ADSB readings have to be prior to that.
What's interesting is that the ADSB data covers:
- 4-5 seconds of time (let's approximate 4 seconds from 46.55 to 50.55, ignoring the 0.32s for the moment)
- 50ft of altitude gain
- Declining airspeed from the 1st reading to the last in this final segment from the runway.
Big questions in my mind:
1. If the loss of ADSB corresponds to the E1/E2Fuel Cutoff switches being moved from RUN -> CUTOFF, why is the airspeed declining for the prior 4 seconds?
2. In 4 seconds, why is there only 50ft of altitude gain? that seems odd.
3. To account for only 50ft of alt gain, if we assume the 1st reading is on the runway just before rotation, the intermediate +25ft alt gain is at rotation (Nose up but MLG still on the runway), and the last 4 readings are in the air (nose up an additional 25ft), that means that 1 second or less after lift-off, ADSB was lost - this is before E1/E2 FCO RUN-> CUTOFF.
It's just weird .
I think for various reasons the ADSB data's absolute values are offset by some amount, for possibly all of the parameters. But there should be consistency in the deltas for the timestamp (by receiving station), the raw baro altitude, the Flightradar24 AGL values, and the airspeed. Flightradar24 themselves note that for altitude " ... the data is not above ground level, but it is consistent to itself."
08:08:46.55 ... 575ft ... 21ft ... 184kt
08:08:48.14 ... 600ft ... 46ft ... 179kt
08:08:48.61 ... 600ft ... 46ft ... 177kt
08:08:49.01 ... 600ft ... 46ft ... 177kt
08:08:49.46 ... 625ft ... 71ft ... 177kt
08:08:49.92 ... 625ft ... 71ft ... 174kt
08:08:50.39 ... 625ft ... 71ft ... 174kt
08:08:50.87 ... 625ft ... 71ft ... 172kt
From the Preliminary Report's airport cctv picture, the RAT was seen deployed at, by my estimate here , 150ft baro altitude, between 4-7 seconds after rotation. So the ADSB readings have to be prior to that.
What's interesting is that the ADSB data covers:
- 4-5 seconds of time (let's approximate 4 seconds from 46.55 to 50.55, ignoring the 0.32s for the moment)
- 50ft of altitude gain
- Declining airspeed from the 1st reading to the last in this final segment from the runway.
Big questions in my mind:
1. If the loss of ADSB corresponds to the E1/E2Fuel Cutoff switches being moved from RUN -> CUTOFF, why is the airspeed declining for the prior 4 seconds?
2. In 4 seconds, why is there only 50ft of altitude gain? that seems odd.
3. To account for only 50ft of alt gain, if we assume the 1st reading is on the runway just before rotation, the intermediate +25ft alt gain is at rotation (Nose up but MLG still on the runway), and the last 4 readings are in the air (nose up an additional 25ft), that means that 1 second or less after lift-off, ADSB was lost - this is before E1/E2 FCO RUN-> CUTOFF.
It's just weird .