June 14, 2025, 12:43:00 GMT
permalink Post: 11901451
Even though there is no point speculating about the cause of this accident, it is the nature of the beast to have questions. As pilots (most of us at least), we do have an inquiring mindset.
My initial thoughts were an inadvertent flap retraction. But with the ‘evidence’ that has been presented over the last 48 hours, I think we can safely discard that option.
What we think we know is:
- RAT was deployed (highly possible)
- Gear was selected up, but did not operate (bogey tilted, doors remained closed)
- APU was ‘on’ (APU door open on after crash pictures)
- Flight path
Any of these observations, alone, would mean very little. However, in combination, they all point to a dual engine flameout just at/after the rotation. The aircaft has enough kinetic energy to reach roughly 150ft altitude, end then starts a shallow descent at ‘alpha max’ into the buildings ahead. The RAT deployed, APU attempted auto-start, gear was unable to retract.
I only wonder why the engines spooled down. Bird strike seems to be out of the question, so that leaves us with only a very few options, which include a software bug or a suicidal pilot (not a popular option, I understand, but we have to take all options into account).
What I don’t believe is incorrect FCU selections, since that would not explain the high AOA on impact. It also would not explain the RAT, no gear retraction or the APU inlet flap open. Another thing that is highly unlikely is any switching done by the pilots, especially RAT etc.. These airborne time is just too little, pilots usually don’t take any action below approximately 400ft, and these switches are so ‘underused’ that a pilot would not find them instantaneously in a high stress situation.
For me, a dual engine flameout seems the only possible explanation, now we only have to wait for its cause.
My initial thoughts were an inadvertent flap retraction. But with the ‘evidence’ that has been presented over the last 48 hours, I think we can safely discard that option.
What we think we know is:
- RAT was deployed (highly possible)
- Gear was selected up, but did not operate (bogey tilted, doors remained closed)
- APU was ‘on’ (APU door open on after crash pictures)
- Flight path
Any of these observations, alone, would mean very little. However, in combination, they all point to a dual engine flameout just at/after the rotation. The aircaft has enough kinetic energy to reach roughly 150ft altitude, end then starts a shallow descent at ‘alpha max’ into the buildings ahead. The RAT deployed, APU attempted auto-start, gear was unable to retract.
I only wonder why the engines spooled down. Bird strike seems to be out of the question, so that leaves us with only a very few options, which include a software bug or a suicidal pilot (not a popular option, I understand, but we have to take all options into account).
What I don’t believe is incorrect FCU selections, since that would not explain the high AOA on impact. It also would not explain the RAT, no gear retraction or the APU inlet flap open. Another thing that is highly unlikely is any switching done by the pilots, especially RAT etc.. These airborne time is just too little, pilots usually don’t take any action below approximately 400ft, and these switches are so ‘underused’ that a pilot would not find them instantaneously in a high stress situation.
For me, a dual engine flameout seems the only possible explanation, now we only have to wait for its cause.
Last edited by Senior Pilot; 14th June 2025 at 19:08 . Reason: Double posting of image
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): APU Fuel (All) Fuel Cutoff Fuel Cutoff Switches RAT (All) RAT (Deployment)
June 14, 2025, 16:08:00 GMT
permalink Post: 11901612
Indeed. All theories remain on the table until falsified - including the unpalatable ones. However, you may be overlooking Murphy's Law which tells us to expect this.
To me, it makes sense to focus on testing out theories that fit within the ambit of Murphy's Law. There is no way of knowing which of us will turn out to be right. Possibly none of us...
To me, it makes sense to focus on testing out theories that fit within the ambit of Murphy's Law. There is no way of knowing which of us will turn out to be right. Possibly none of us...
AI 171 may prove to also have a totally unpredicted cause.
Subjects: None
June 15, 2025, 16:06:00 GMT
permalink Post: 11902592
Trying to keep an open mind, but\x85.
Is no one surprised the lone survivor remembers a bang just before impact, and other things like apparently emergency lights, but has not mentioned the power going from takeoff power to nothing. Even the power change at thrust reduction altitude is often very noticeable in the cabin, so it surprises me nothing about the noise (and startle/panic) of full-power to no-power has been mentioned. I think we are getting into absurd scenarios trying to make the scenario of a simultaneous double engine failure just after liftoff fit, based on perhaps not the best evidence.
Is no one surprised the lone survivor remembers a bang just before impact, and other things like apparently emergency lights, but has not mentioned the power going from takeoff power to nothing. Even the power change at thrust reduction altitude is often very noticeable in the cabin, so it surprises me nothing about the noise (and startle/panic) of full-power to no-power has been mentioned. I think we are getting into absurd scenarios trying to make the scenario of a simultaneous double engine failure just after liftoff fit, based on perhaps not the best evidence.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Dual Engine Failure Engine Failure (All)
June 18, 2025, 14:50:00 GMT
permalink Post: 11905306
It could equally refer to the APU which some have suggested either started or was in the process of starting.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): APU Generators/Alternators RAT (All)
June 20, 2025, 11:17:00 GMT
permalink Post: 11906850
Remote Diagnostics
This engine health monitoring is incorporated GE Aerospace’s self-service customer web portals, where customers can find technical updates and analysis of key engine performance trends such as oil usage, gas temperatures, vibration, rotor speed, fuel flow and more. In addition, Customer Notification Reports (CNRs) issued to GE Aerospace customers identify potential engine issues with recommended maintenance actions. The comprehensive service includes dedicated consultations for analysis of key engine performance trends to optimize fleet operations as well customized insights and maintenance recommendations.
https://www.geaerospace.com/commerci...ital-solutions
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All)
June 20, 2025, 14:59:00 GMT
permalink Post: 11907036
In the CCTV footage the aircraft's flight path appears to be a parabola. If there was any thrust remaining following rotation it would be very different.
Last edited by Saab Dastard; 20th June 2025 at 15:27 . Reason: Quote of deleted post removed
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CCTV
June 20, 2025, 15:21:00 GMT
permalink Post: 11907053
Not very scientific I'm afraid. I made it into a loop that runs at 4x speed forwards from take-off to just before it disappears and then reverses. It looks parabolic as the height gain is the same as the descent.
Last edited by OPENDOOR; 20th June 2025 at 15:40 .
Subjects: None
June 20, 2025, 17:21:00 GMT
permalink Post: 11907147
On each engine It is fail-safed to close off fuel-feed flows by a spring that is held
open
by a solenoid.
Subjects: None
June 21, 2025, 15:04:00 GMT
permalink Post: 11907825
In the coming weeks, as black box data is analysed and preliminary findings emerge, the world will l... Read more at:
https://english.mathrubhumi.com/news...fails-rkswjyay
https://english.mathrubhumi.com/news...fails-rkswjyay
Subjects: None
June 21, 2025, 15:29:00 GMT
permalink Post: 11907844
787 EAFR unit
The Enhanced Airborne Flight Recorder (EAFR) fitted in the forward and aft locations are interchangeable and appear to be able to record video.
As their power requirements are 28 VDC and just 20.5 watts it seems strange that only the forward mounted unit should have a battery backup.
https://www.geaerospace.com/sites/de...rder-3254F.pdf
As their power requirements are 28 VDC and just 20.5 watts it seems strange that only the forward mounted unit should have a battery backup.
T he Image Recorder growth function is used to record visual images of the flight deck instruments, flight deck, the aircraft structures, and engines as required. The Image Recorder function is capable of receiving a digital 10/100 Mbit Ethernet data stream of cockpit images and stores this data in the Crash Protected Memory in a separate partition. Even though the image recording duration will be governed by regulations, the EAFR Crash Protected Memory capacity has the storage capacity for two hours of image data recording per EUROCAE ED-112 requirements. Data in the Image Recording Crash Protected Memory partition can only be downloaded when the EAFR is off the aircraft.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): DFDR EAFR
June 21, 2025, 15:56:00 GMT
permalink Post: 11907869
The tail seemed to be intact from many post crash pictures and one would assume the boxes are there?
I don't understand why we are told they were badly damaged.
I don't understand why we are told they were badly damaged.
Subjects: None
June 21, 2025, 18:11:00 GMT
permalink Post: 11907957
It consumes 20.5 watts so a ten minute power supply should not only be easy to integrate but also already exists and is certificated for the forward mounted unit.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CVR RIPS
June 22, 2025, 14:57:00 GMT
permalink Post: 11908601
Enhanced Airborne Flight Recorders (EAFR)
Whilst we wait for any announcements from the crash investigators can anybody suggest the logic behind providing the front mounted Enhanced Airborne Flight Recorders (EAFR) with a
Recorder Independent Power Supply (RIPS) but not giving the identical aft mounted EAFR unit the same protection where it is less likely to suffer damage?
The RIPS unit is a certificated device that just has to supply 20.5 watts for ten minutes so cost cannot be a consideration.
Another debate that should now be had is real time telemetry. Given the number of airlines contracting with Starlink for internet services onboard their fleets uploading the data stream fed to FDR's wouldn't put a dent on the available bandwidth and the search and recovery process for FDR's would be a thing of the past.
The RIPS unit is a certificated device that just has to supply 20.5 watts for ten minutes so cost cannot be a consideration.
Another debate that should now be had is real time telemetry. Given the number of airlines contracting with Starlink for internet services onboard their fleets uploading the data stream fed to FDR's wouldn't put a dent on the available bandwidth and the search and recovery process for FDR's would be a thing of the past.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): DFDR EAFR RIPS
June 22, 2025, 15:40:00 GMT
permalink Post: 11908632
If it has no power it won't record anything at all, like the fact that multiple electrical systems are U/S but as a limited power supply from the RAT or APU comes on-line it would have something to record. It seems to me absurd that it is not powered at all times.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): APU RAT (All) RIPS
July 14, 2025, 17:55:00 GMT
permalink Post: 11922396
A few years ago I'd have agreed with you but with many airlines now installing Starlink terminals on their fleet it is a relatively tiny amount of data to add.
There is no reason the data stream fed to the FDR's couldn't also be encrypted and sent to the operator for long term storage. It might prove very useful and not just after accidents.
Subjects: None
July 17, 2025, 20:53:00 GMT
permalink Post: 11924657
Subjects: None