June 14, 2025, 15:02:00 GMT
permalink Post: 11901554
Of course one taking off would have a different signature. If anyone can point point to one taking off with the rat out we could compare.
What I find interesting is that I don’t see any evidence in the audio of the engine spooling down, which would leave a recogniseable pattern in the audio one should think. So either it is down so much that the fan rpm is down to windmilling already, or it is simply low enough in volume to be already masked by the ambience.
So taking this and moving into speculative territory for a moment, I think I read somewhere that the video with audio starts 17 seconds after the wheels left the ground.
Provided the engines were windmilling the video audio since I haven't been able to find any obvious spool down, can anyone say anything meaningful on how long it takes for the engines to spool down to windmilling rpm?
we can then backtrack from the point the video starts. How does that timing then coincide with the ADS-B data ceasing to transmit, for instance?
Putting back in the more strictly data-driven hat, I am not prepared to say so far anything about the engine working or not. You guys know more anout why the rat is out.
Last edited by Kraftstoffvondesibel; 14th June 2025 at 15:33 .
June 14, 2025, 15:17:00 GMT
permalink Post: 11901567
It\x92s the elephant in the room regarding the audio, isn\x92t it, but I am not prepared to say either way. There simply is too much city background noise/ambience to discern this from the engine noise from a landing 787.
Of course one taking off would have a different signature. If anyone can point point to one taking off with the rat out we could compare.
What I find interesting is that I don\x92t see any evidence in the audio of the engine spooling down, which would leave a recogniseable pattern in the audio one should think. So either it is down so much that the fan rpm is down to windmilling already, or it is simply low enough in volume to be already masked by the ambience.
So taking this and moving into speculative territory for a moment, I think I read somewhere that the video with audio starts 17 seconds after the wheels left the ground.
Provided the engines were windmilling the video audio since I haven\x92t been able to find any obvious spool down, can anyone say anything meaningful on how long it takes for the engines to spool down to windmilling rpm?
we can then backtrack from the point the video starts. How does that timing then coincide with the ADS-B data ceasing to transmit, for instance?
Putting back in the more strictly data-driven hat, I am not prepared to say so far anything about the engine working or not. You guys know more anout why the rat is out.
Of course one taking off would have a different signature. If anyone can point point to one taking off with the rat out we could compare.
What I find interesting is that I don\x92t see any evidence in the audio of the engine spooling down, which would leave a recogniseable pattern in the audio one should think. So either it is down so much that the fan rpm is down to windmilling already, or it is simply low enough in volume to be already masked by the ambience.
So taking this and moving into speculative territory for a moment, I think I read somewhere that the video with audio starts 17 seconds after the wheels left the ground.
Provided the engines were windmilling the video audio since I haven\x92t been able to find any obvious spool down, can anyone say anything meaningful on how long it takes for the engines to spool down to windmilling rpm?
we can then backtrack from the point the video starts. How does that timing then coincide with the ADS-B data ceasing to transmit, for instance?
Putting back in the more strictly data-driven hat, I am not prepared to say so far anything about the engine working or not. You guys know more anout why the rat is out.
June 14, 2025, 15:33:00 GMT
permalink Post: 11901579
It\x92s the elephant in the room regarding the audio, isn\x92t it, but I am not prepared to say either way. There simply is too much city background noise/ambience to discern this from the engine noise from a landing 787.
Of course one taking off would have a different signature. If anyone can point point to one taking off with the rat out we could compare.
What I find interesting is that I don\x92t see any evidence in the audio of the engine spooling down, which would leave a recogniseable pattern in the audio one should think. So either it is down so much that the fan rpm is down to windmilling already, or it is simply low enough in volume to be already masked by the ambience.
So taking this and moving into speculative territory for a moment, I think I read somewhere that the video with audio starts 17 seconds after the wheels left the ground.
Provided the engines were windmilling the video audio since I haven\x92t been able to find any obvious spool down, can anyone say anything meaningful on how long it takes for the engines to spool down to windmilling rpm?
we can then backtrack from the point the video starts. How does that timing then coincide with the ADS-B data ceasing to transmit, for instance?
Putting back in the more strictly data-driven hat, I am not prepared to say so far anything about the engine working or not. You guys know more anout why the rat is out.
Of course one taking off would have a different signature. If anyone can point point to one taking off with the rat out we could compare.
What I find interesting is that I don\x92t see any evidence in the audio of the engine spooling down, which would leave a recogniseable pattern in the audio one should think. So either it is down so much that the fan rpm is down to windmilling already, or it is simply low enough in volume to be already masked by the ambience.
So taking this and moving into speculative territory for a moment, I think I read somewhere that the video with audio starts 17 seconds after the wheels left the ground.
Provided the engines were windmilling the video audio since I haven\x92t been able to find any obvious spool down, can anyone say anything meaningful on how long it takes for the engines to spool down to windmilling rpm?
we can then backtrack from the point the video starts. How does that timing then coincide with the ADS-B data ceasing to transmit, for instance?
Putting back in the more strictly data-driven hat, I am not prepared to say so far anything about the engine working or not. You guys know more anout why the rat is out.
June 14, 2025, 16:03:00 GMT
permalink Post: 11901607
I did read and search this thread, but I found nothing about ADS-B loss just before the end of the runway and at 71 ft high, according to FR24. ADS-B coverage is poor on the ground on the north-east part of the airfield (hence the fake news about taking off from the intersection) but I don't think it would be lost once airborne, except if it has been shut off... electrical failure ?
more precisely, loss of the two Main AC buses (ADS-B not powered by Standby AC)
more precisely, loss of the two Main AC buses (ADS-B not powered by Standby AC)
June 14, 2025, 16:07:00 GMT
permalink Post: 11901611
I did read and search this thread, but I found nothing about ADS-B loss just before the end of the runway and at 71 ft high, according to FR24. ADS-B coverage is poor on the ground on the north-east part of the airfield (hence the fake news about taking off from the intersection) but I don't think it would be lost once airborne, except if it has been shut off... electrical failure ?
But certainly loss of engines or electrics that caused deployment of the RAT (if that was the case) would be accompanied by a bunch of load-shedding, which would in all likelihood include the transponder.
Edit: Your own reply beat me to it ...
June 14, 2025, 16:37:00 GMT
permalink Post: 11901634
I did read and search this thread, but I found nothing about ADS-B loss just before the end of the runway and at 71 ft high, according to FR24. ADS-B coverage is poor on the ground on the north-east part of the airfield (hence the fake news about taking off from the intersection) but I don't think it would be lost once airborne, except if it has been shut off... electrical failure ?
more precisely, loss of the two Main AC buses (ADS-B not powered by Standby AC)
more precisely, loss of the two Main AC buses (ADS-B not powered by Standby AC)
I guess you have to make a post on just this one item to get it noticed!
But I agree that this piece of data deserves close attention, and is potentially confirmatory of certain scenarios which lead to electrical power loss.
I'm no expert on Flight Aware's ADS-B data, but other posts here show other flights taking off on this runway happily reporting data further down the runway and (well) after takeoff.
How else do you explain the cessation of ADS-B data from this flight from shortly after takeoff until the crash?
June 14, 2025, 17:35:00 GMT
permalink Post: 11901681
What concerns me a little bit is if indeed AC power is lost, would the suction feed inlets in the wing tanks provide enough fuel flow to maintain TO thrust?
I know the system is designed to achieve this in a situation where all of the AC powered boost pumps are lost. But what about in a real situation...
Could this cause a degradation of thrust? Even the slightest decrease..
I know the system is designed to achieve this in a situation where all of the AC powered boost pumps are lost. But what about in a real situation...
Could this cause a degradation of thrust? Even the slightest decrease..
I did read and search this thread, but I found nothing about ADS-B loss just before the end of the runway and at 71 ft high, according to FR24. ADS-B coverage is poor on the ground on the north-east part of the airfield (hence the fake news about taking off from the intersection) but I don't think it would be lost once airborne, except if it has been shut off... electrical failure ?
more precisely, loss of the two Main AC buses (ADS-B not powered by Standby AC)
more precisely, loss of the two Main AC buses (ADS-B not powered by Standby AC)
There's a list of equipment operable on battery/RAT here, but I'm not sure which (if any) is the transponder (26:10):
If you had gear pins and an engine loss, I could maybe see climb rate being zero or slightly negative. Not the brick impression we see here.
There have been a couple comments regarding the tilt of the bogies not corresponding to the landing configuration which have taken this as an indicator for an attempted (but failed) retraction.
I don't think anybody has so far confirmed which of the two positions the bogie would have without hydraulic pressure, but I would strongly think it is the one used in the retraction/extension cycle and not the landing configuration, for the simple reason that otherwise the gravity drop would potentially not work (I assume it is tilted for the stowing because it would otherwise not fit).
Maybe someone with concrete knowledge can confirm this?
This would then only confirm that the bogies were unpressurized (likely because of loss of hydraulics, but of course could also still be a partial retraction that stopped for some reason)
I don't think anybody has so far confirmed which of the two positions the bogie would have without hydraulic pressure, but I would strongly think it is the one used in the retraction/extension cycle and not the landing configuration, for the simple reason that otherwise the gravity drop would potentially not work (I assume it is tilted for the stowing because it would otherwise not fit).
Maybe someone with concrete knowledge can confirm this?
This would then only confirm that the bogies were unpressurized (likely because of loss of hydraulics, but of course could also still be a partial retraction that stopped for some reason)
June 14, 2025, 18:27:00 GMT
permalink Post: 11901706
1. there are multiple frames of the video showing ' something' at the position where the RAT is located under the fuselage
2. the sound in the video which is very similar to a deployed RAT
3. the sound analysis posted here by multiple people
last but not least
4. the aircraft stopped transmitting ADSB data shortly after the rotating. This indicates an electrical failure. Other aircraft ADSB data was picked up by FR24 receivers indication there is a good reception of the signal in that area.
June 14, 2025, 19:20:00 GMT
permalink Post: 11901748
This FR24 recording of AI171
https://www.flightradar24.com/data/f.../ai171#3ac3097
only consists of 4 unique ADS-B data messages. The first two were on the apron/taxiway. Then one at the runway intersection. And the fourth and last one just after the aircraft became airborne. That's all.
The two last ADS-B data messages are more than 4 minutes apart. It was 8:04 UTC when they entered the runway at the intersection. The next and last data point was received at 8:08 UTC.
The map view connects these dots, so it looks like a proper track. But in reality the ADS-B receiver barely received anything. It's therefore silly to argue the aircraft stopped transmitting ADS-B data based on this poor recording. The only thing you can say with certainty is that FR24's ADS-B receiver at Ahmedabad has really, really poor coverage...
June 14, 2025, 19:36:00 GMT
permalink Post: 11901758
People really need to stop using FR24 data if they don't understand it.
The map view connects these dots, so it looks like a proper track. But in reality the ADS-B receiver barely received anything. It's therefore silly to argue the aircraft stopped transmitting ADS-B data based on this poor recording. The only thing you can say with certainty is that FR24's ADS-B receiver at Ahmedabad has really, really poor coverage...
The map view connects these dots, so it looks like a proper track. But in reality the ADS-B receiver barely received anything. It's therefore silly to argue the aircraft stopped transmitting ADS-B data based on this poor recording. The only thing you can say with certainty is that FR24's ADS-B receiver at Ahmedabad has really, really poor coverage...
June 14, 2025, 19:59:00 GMT
permalink Post: 11901780
1stSpotter: Your point #4 is well taken. I had seen a graph higher up in this that that showed altitude and evidence of ADSB transmissions but then as you noted the transmissions stopped soon after rotation. Well spotted suggesting some kind of electrical supply interruption. The engines can still run in this situation but I don't know for how long.
June 14, 2025, 20:00:00 GMT
permalink Post: 11901782
People really need to stop using FR24 data if they don't understand it.
This FR24 recording of AI171
https://www.flightradar24.com/data/f.../ai171#3ac3097
only consists of 4 unique ADS-B data messages. The first two were on the apron/taxiway. Then one at the runway intersection. And the fourth and last one just after the aircraft became airborne. That's all.
This FR24 recording of AI171
https://www.flightradar24.com/data/f.../ai171#3ac3097
only consists of 4 unique ADS-B data messages. The first two were on the apron/taxiway. Then one at the runway intersection. And the fourth and last one just after the aircraft became airborne. That's all.
Not sure how permanent the content at this URL is, but here's a link to FR24's update which has a CSV with all frames received https://www.flightradar24.com/blog/f...rom-ahmedabad/
Last edited by nachtmusak; 14th June 2025 at 20:04 . Reason: Added a link to the more extensive ADS-B data
June 14, 2025, 20:03:00 GMT
permalink Post: 11901785
June 14, 2025, 20:08:00 GMT
permalink Post: 11901790
People really need to stop using FR24 data if they don't understand it.
This FR24 recording of AI171
https://www.flightradar24.com/data/f.../ai171#3ac3097
only consists of 4 unique ADS-B data messages. The first two were on the apron/taxiway. Then one at the runway intersection. And the fourth and last one just after the aircraft became airborne. That's all.
The two last ADS-B data messages are more than 4 minutes apart. It was 8:04 UTC when they entered the runway at the intersection. The next and last data point was received at 8:08 UTC.
The map view connects these dots, so it looks like a proper track. But in reality the ADS-B receiver barely received anything. It's therefore silly to argue the aircraft stopped transmitting ADS-B data based on this poor recording. The only thing you can say with certainty is that FR24's ADS-B receiver at Ahmedabad has really, really poor coverage...
This FR24 recording of AI171
https://www.flightradar24.com/data/f.../ai171#3ac3097
only consists of 4 unique ADS-B data messages. The first two were on the apron/taxiway. Then one at the runway intersection. And the fourth and last one just after the aircraft became airborne. That's all.
The two last ADS-B data messages are more than 4 minutes apart. It was 8:04 UTC when they entered the runway at the intersection. The next and last data point was received at 8:08 UTC.
The map view connects these dots, so it looks like a proper track. But in reality the ADS-B receiver barely received anything. It's therefore silly to argue the aircraft stopped transmitting ADS-B data based on this poor recording. The only thing you can say with certainty is that FR24's ADS-B receiver at Ahmedabad has really, really poor coverage...
While those still have the 4\xbd minute gap while the aircraft was presumably backtracking, they resume during the latter part of the takeoff roll where reception is clearly better.
There is little doubt that when they abruptly cease after the aircraft is airborne it's because the plane has stopped transmitting.
June 14, 2025, 20:13:00 GMT
permalink Post: 11901794
https://www.flightradar24.com/blog/f...rom-ahmedabad/
June 14, 2025, 20:19:00 GMT
permalink Post: 11901798
People really need to stop using FR24 data if they don't understand it.
This FR24 recording of AI171
https://www.flightradar24.com/data/f.../ai171#3ac3097
only consists of 4 unique ADS-B data messages. The first two were on the apron/taxiway. Then one at the runway intersection. And the fourth and last one just after the aircraft became airborne. That's all.
The two last ADS-B data messages are more than 4 minutes apart. It was 8:04 UTC when they entered the runway at the intersection. The next and last data point was received at 8:08 UTC.
The map view connects these dots, so it looks like a proper track. But in reality the ADS-B receiver barely received anything. It's therefore silly to argue the aircraft stopped transmitting ADS-B data based on this poor recording. The only thing you can say with certainty is that FR24's ADS-B receiver at Ahmedabad has really, really poor coverage...
This FR24 recording of AI171
https://www.flightradar24.com/data/f.../ai171#3ac3097
only consists of 4 unique ADS-B data messages. The first two were on the apron/taxiway. Then one at the runway intersection. And the fourth and last one just after the aircraft became airborne. That's all.
The two last ADS-B data messages are more than 4 minutes apart. It was 8:04 UTC when they entered the runway at the intersection. The next and last data point was received at 8:08 UTC.
The map view connects these dots, so it looks like a proper track. But in reality the ADS-B receiver barely received anything. It's therefore silly to argue the aircraft stopped transmitting ADS-B data based on this poor recording. The only thing you can say with certainty is that FR24's ADS-B receiver at Ahmedabad has really, really poor coverage...
June 14, 2025, 20:59:00 GMT
permalink Post: 11901827
Flightradar24 published the CSV with all received data. It had EIGHT datapoints of the aircraft after its rotation showing its altitude.
https://www.flightradar24.com/blog/f...rom-ahmedabad/
June 14, 2025, 21:21:00 GMT
permalink Post: 11901849
What don't you believe in the published data?
June 15, 2025, 08:08:00 GMT
permalink Post: 11902212
A thrust reduction is not an engine failure. Engine shutdown due to an action of crew (or inaction) is not a failure.
There is no evidence of an electrical failure. What evidence? A surviving passenger thought he saw flickering lights? Give me a break.
The word evidence in English has a very specific meaning.
Look for the simplest explanation here and then ask why the worldwide B787 fleet is still flying with no urgent inspection requirements from Boeing or GE. Think about that "evidence".
There is no evidence of an electrical failure. What evidence? A surviving passenger thought he saw flickering lights? Give me a break.
The word evidence in English has a very specific meaning.
Look for the simplest explanation here and then ask why the worldwide B787 fleet is still flying with no urgent inspection requirements from Boeing or GE. Think about that "evidence".
If the aircraft had flaps deployed (the crash site photos look like it), flight controls working (no indications they weren't), and the thrust levers pushed full forwards, there is very very little that will cause it to sink other than lack of thrust.
For the team pointing to the RAT out as a failure indicator, it could have been deployed by the crew after the initial reduction in climb performance. I am not convinced it is deployed but it really does not make a convincing argument for any type of failure.
For the children on holiday, yes I fly transport category jets, current on two types.
In general, I think it's looking like dual engine failure/shutdown cutting electrics. I agree that why it occurred is very unclear. Outside chance of total electrical failure causing dual engine failure rather than the other way around, but that would perhaps be even more concerning a design failure.
Similar to Jeju, we also have what is looking increasingly like a loss of ADS-B data at the moment things went wrong, not just a loss of coverage.
That gives:
- Sound of RAT
- Visible RAT
- (edit: APU door open implies APU autostart)
- Loss of ADS-B out
- Near-total loss of thrust.
- A/T rolled engines back
- Crew interpreted this as dual engine failure
- Crew didn't push throttles forward
- Crew did switch each engine off & on again and maybe deployed RAT manually as well.
I think it has been suggested that the upload only happens every 30 minutes or so.
Last edited by Someone Somewhere; 15th June 2025 at 08:21 .
June 15, 2025, 10:27:00 GMT
permalink Post: 11902329
Correcting for QNH 1001? gives an altitude of 290 ft approx.
Less 189 ft airfield elevation gives a height AGL of 100 feet.
But that was based on last ADS-B return. From the video it looks like they reached closer to 200\x92 AGL using wingspan for scale.