Page Links: Index Page
| MR8
2025-06-14T12:31:00 permalink Post: 11901444 |
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, and 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.. The 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. Subjects: APU Bird Strike Flap Retraction Flaps (All) Gear Retraction RAT (All) RAT (Deployment) 16 users liked this post. |
| MR8
2025-06-14T17:52:00 permalink Post: 11901692 |
It's approximately 1km glide from where the aircraft was at roughly 200ft, not 2 km. 1km equals about 3000ft, so that is a glide ratio of 15. Taking into account a bit of excess speed to bleed off before reaching alpha max, this sounds very feasible to me. Subjects: None 9 users liked this post. |
| MR8
2025-06-14T18:07:00 permalink Post: 11901701 |
That leads to the next question.. Is there any system on the 787 that CAN shutdown the engines. We know there is at least one... But the A/C needs to be ground mode. However, if would not be the 1st time a system that should not deploy when the A/C is airborne, does! LaudaAir out from BKK is one example...
My guess is that the glitch occurred during the transition from ground to air mode for some reason... Subjects: None 2 users liked this post. |
| MR8
2025-06-14T18:51:00 permalink Post: 11901728 |
Could a debris strike on the airfield cause this accident? The Concorde crash (Air France flight 4590) comes to mind... Has anyone mentioned this already?
I agree that the takeoff appears "normal", on a low quality video. But it does not exclude that something potentially catastrophic happened prior to rotation, which we cannot see. No, an apparent symmetrical loss of engine thrust can not be explained by FOD. Also, even though the videos are not the highest quality, it is evident that the engines don't seem damaged. There is no smoke, flames or apparent engine stalls (audible) on the video. Subjects: None 1 user liked this post. |
| MR8
2025-06-15T12:07:00 permalink Post: 11902414 |
Altitude reached AAL
No, they did not climb that high. Latest FR24 ADS-B report was indeed 625 ft, but that is based on 1013 (STD). With the local QNH being 1000, that 625ft becomes roughly 300ft MSL. Corrected for airport elevation, this is just above 100ft. The last recorded altitude of the aircraft was roughly 100ft AGL, which does not mean it didn\x92t climb a bit higher, but the aircraft reaching 400ft is pure speculation.
Subjects: ADSB FlightRadar24 2 users liked this post. |
| MR8
2025-06-15T15:24:00 permalink Post: 11902551 |
On Aviation Herald it is stated that "Government Officials reported the aircraft had a longer than normal takeoff run and used up almost all of the 3905 meters / 1499 feet runway". That would perhaps explain the dust on one of the videos as it passed across usually undisturbed areas. However it also would fit in with the theory in post #1433 that the thrust levers may have been pulled back and hence the aircraft had a period of deceleration before the levers were the quickly pushed forward and confused the TCMA.. It could be that the accident occurred due to what happened on the runway, not the overall config thereafter.
Additionally, ADS-B data and the triangulation of the video showing the takeoff would lead you to a different conclusion. Subjects: ADSB TCMA (All) |
| MR8
2025-06-15T17:54:00 permalink Post: 11902671 |
Regarding the 'pack issue'.
As mentioned before, the packs are electrical. What might have happened is that during the engine start sequence, the packs are not working, similar to a conventional bleed system. In an environment of 40˚C, a full cabin heats up very quickly and will take some time to cool down again. This might be conceived by passengers as "the airco isn't working". I am not a 787 driver, so this is just an educated guess based on my own experience operating in hot temperatures. Any 787 drivers in the know, please back me up or shoot me down if I'm talking nonsense. Subjects: None |
| MR8
2025-06-15T19:54:00 permalink Post: 11902776 |
Fuel temperature is not the issue. Max Fuel temperature on our Airbus is 53˚C, the B787 will have a similar limitation. Summer in the Middle East is hotter than this without any issue.
Subjects: None 3 users liked this post. |
Page Links: Index Page