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| Xeptu
2025-06-15T02:57:00 permalink Post: 11902067 |
Sorry about that. The reply was aimed at the OP. from a software writers perspective, as you rightly point out it does not imply an electrical event actually occurred. As you raised that query writing software routines (programming) is no different and that's what we're looking for.
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| Tailspin Turtle
2025-06-15T03:47:00 permalink Post: 11902079 |
IMO
In the CCTV video, the aircraft stops climbing at 00:28. 3 seconds after, it starts visibly descending. At peak altitude, using the 197ft wingspan as a measure, the altitude is around 200ft or below. The fireball is at 00:48, 17s after descent starts visibly. Per google maps and the impact location mapped at avherald, the impact point is ~3990ft from the airport boundary road and about 4200ft from the midpoint of the runway threshold and the airport boundary road. 16:1 to 25:1 is what I could find for the 787 glide ratio range (unpowered) with main landing gear down and flaps 5. So the aircraft could cover 16 to 25 ft horizontally for every 1 ft of descent. With a starting altitude of 200ft, that would imply it could have covered 3200ft.to 5000ft during unpowered descent. The actual distance covered, around 4000ft, certainly seems to suggest that the descent was unpowered. 1 user liked this post. |
| Compton3fox
2025-06-15T06:48:00 permalink Post: 11902156 |
Do not discount the mistaken early flap retraction scenario too easily. Mull on this:
PF commanded gear up on attaining positive rate of climb, fixating on the HUD. PM mistakenly raise flap lever from 5 to Flap 1 gate. Thrust reduced to Climb Thrust. Landing gear remained deployed. Massive loss of lift misidentified as loss of thrust. If any one pilot just had a dual engine failure scenario on a recent sim ride, brain and muscle memory would jump to loss of thrust in dual engine, prompting them to accomplish the recall memory items which called for both engine fuel switches to OFF and then RUN, and physically deployed the RAT. There would be immediate loss of thrust with the engine taking time to recover , if at all, at such low airspeed! The rest is left for Ppruners’ imagination.😖🥴😬 However, I think their reaction would likely be to apply more power. I know mine would be. But anything is possible! |
| Chuck Canuck
2025-06-15T08:22:00 permalink Post: 11902223 |
Do not discount the mistaken early flap retraction scenario too easily. Mull on this:
PF commanded gear up on attaining positive rate of climb, fixating on the HUD. PM mistakenly raise flap lever from 5 to Flap 1 gate. Thrust reduced to Climb Thrust. Landing gear remained deployed. Massive loss of lift misidentified as loss of thrust. If any one pilot just had a dual engine failure scenario on a recent sim ride, brain and muscle memory would jump to loss of thrust in dual engine, prompting them to accomplish the recall memory items which called for both engine fuel switches to OFF and then RUN, and physically deployed the RAT. There would be immediate loss of thrust with the engine taking time to recover , if at all, at such low airspeed! The rest is left for Ppruners’ imagination.😖🥴😬 This is a very plausible scenario. Above 400 ‘ AGL, memory items. 4 users liked this post. |
| das Uber Soldat
2025-06-15T08:34:00 permalink Post: 11902234 |
Could be that the gear is quite clearly in the forward tilt position (indicating initial gear retraction has commenced), but then the gear never goes up. How does that occur? The gear in the 787 is driven in retraction by the center hydraulic system. How is the center hydraulic system powered? Electrically, via C1 and C2 EMP's. How are those EMP's supplied with power? Engine 1 and 2 (via a bootstrap from L1/2 R1/2 gens). The rat also connects to the center hydraulic system, but importantly, it does not supply hydraulic power to the gear. Only a select number of flight control surfaces. So, my question to you is, given you're claiming there is zero evidence of electrical failure, how did the gear move into the forward tilt position, but then not retract? 4 users liked this post. |
| amsm01
2025-06-15T08:54:00 permalink Post: 11902253 |
Do not discount the mistaken early flap retraction scenario too easily. Mull on this:
PF commanded gear up on attaining positive rate of climb, fixating on the HUD. PM mistakenly raise flap lever from 5 to Flap 1 gate. Thrust reduced to Climb Thrust. Landing gear remained deployed. Massive loss of lift misidentified as loss of thrust. If any one pilot just had a dual engine failure scenario on a recent sim ride, brain and muscle memory would jump to loss of thrust in dual engine, prompting them to accomplish the recall memory items which called for both engine fuel switches to OFF and then RUN, and physically deployed the RAT. There would be immediate loss of thrust with the engine taking time to recover , if at all, at such low airspeed! The rest is left for Ppruners\x92 imagination.😖🥴😬 Am slightly puzzled as to why if flap reduction triggering climb thrust is part of the standard logic (and presumably clean-up technique) then partial dual thrust loss wouldn\x92t be immediately recognised as the classic symptom of gear / flap retraction handling error? I presume Boeing pilots / air India are just as aware of this it as everyone else, strikes me as odd that one would immediately go into full dual EF mode. My instinctive reaction without knowing the Boeing would be to firewall both TLs, would this have worked in the early flap retraction logic scenario? Many thanks all |
| Aerospace101
2025-06-15T11:42:00 permalink Post: 11902398 |
I see the YouTube influencers are now shifting their speculation to the RAT deployment and loss of thrust theory.
we have to look at the limited evidence and stop speculating on things that have no evidence yet (like the flaps). Aside from RAT deployment the other red flag here is the partial gear retraction. On the 787-8 the bogey will tilt forwards first, before gear doors opens. Not to be confused with the -9 and -10 variants where the gear doors automatically open after liftoff. This is an important distinction because the Center hydraulics which is solely electrically pump driven (not engine) only had enough power to tilt the bogey, not open the doors. so the question is, did the electrical failure (and loss of Center hydraulics power) happen before or after loss of thrust? 4 users liked this post. |
| sorvad
2025-06-15T12:39:00 permalink Post: 11902431 |
So for those getting in the weeds with one in several trillion (or lower) probabilities of systems failures have you considered that that improper RTOW (with or without improper flap setting), flap retraction / climb thrust trigger, is of much higher probability and has actually happened ?
Anyway I think we’ll find out soon if a systems failure was involved. The FLCH Hold thing (Asiana) was never an issue and well known (at least on our line). And for a crew of 3 (or 4) to press a destabilized approach getting 40-ish knots too slow (!) isn’t a systems problem — it’s a breach of basic airmanship. |
| fox niner
2025-06-15T12:51:00 permalink Post: 11902439 |
777/787 driver here.
Reading a few posts about an APU-to-pack takeoff, or a packs off takeoff on a 787, because of the hot weather, makes me shake my head. There is no bleed air on the 787. A packs off takeoff, or an apu to pack takeoff, is never done. There isn’t a procedure in the fcom to describe it. It is also pointless. The packs are electrical. Then the gear. When you lift off the runway, the gear doors open REGARDLESS of gear lever position. If you do not raise the gear within 30 seconds, the gear doors close again and you keep the gear down as you apparently desire. In the video, the gear doors are closed again as the airplane flies into the suburb. This requires normal hydraulics in system C, which was apprently available as the doors are closed again. takeoff performance: I entered all relevant weather parameters into my performance tool for Ahmedabad VAAH, rwy 23, 42 degrees C and no wind, qnh 1005. It comes up with flaps 10 as optimum, albeit for a 787-9 (don’t have the possibility to calculate for the 787-8) But even the 787-9 is able to depart with flaps 5 in those conditions. Max tow around 230tons. 14 users liked this post. |
| EGPI10BR
2025-06-15T13:00:00 permalink Post: 11902445 |
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| DaveReidUK
2025-06-15T13:06:00 permalink Post: 11902449 |
Then the gear.
When you lift off the runway, the gear doors open REGARDLESS of gear lever position. If you do not raise the gear within 30 seconds, the gear doors close again and you keep the gear down as you apparently desire. In the video, the gear doors are closed again as the airplane flies into the suburb. This requires normal hydraulics in system C, which was apprently available as the doors are closed again. Are you saying that they are wrong? 6 users liked this post. |
| Ted633
2025-06-15T13:13:00 permalink Post: 11902456 |
The 787-8 doesn\x92t have the early doors feature (i.e. the main gear doors open automatically after take off). The -9 & -10 both have this feature. Later -8 may also do it (unknown if it was introduced on later production models), but as this is an early -8 that is irrelevant.
3 users liked this post. |
| Roo
2025-06-15T13:14:00 permalink Post: 11902457 |
777/787 driver here.
Then the gear. When you lift off the runway, the gear doors open REGARDLESS of gear lever position. If you do not raise the gear within 30 seconds, the gear doors close again and you keep the gear down as you apparently desire. In the video, the gear doors are closed again as the airplane flies into the suburb. This requires normal hydraulics in system C, which was apprently available as the doors are closed again.. 10 users liked this post. |
| galaxy flyer
2025-06-15T13:22:00 permalink Post: 11902463 |
777/787 driver here.
Reading a few posts about an APU-to-pack takeoff, or a packs off takeoff on a 787, because of the hot weather, makes me shake my head. There is no bleed air on the 787. A packs off takeoff, or an apu to pack takeoff, is never done. There isn\x92t a procedure in the fcom to describe it. It is also pointless. The packs are electrical. Then the gear. When you lift off the runway, the gear doors open REGARDLESS of gear lever position. If you do not raise the gear within 30 seconds, the gear doors close again and you keep the gear down as you apparently desire. In the video, the gear doors are closed again as the airplane flies into the suburb. This requires normal hydraulics in system C, which was apprently available as the doors are closed again. takeoff performance: I entered all relevant weather parameters into my performance tool for Ahmedabad VAAH, rwy 23, 42 degrees C and no wind, qnh 1005. It comes up with flaps 10 as optimum, albeit for a 787-9 (don\x92t have the possibility to calculate for the 787-8) But even the 787-9 is able to depart with flaps 5 in those conditions. Max tow around 230tons. 2 users liked this post. |
| D Bru
2025-06-15T15:31:00 permalink Post: 11902557 |
777/787 driver here.
When you lift off the runway, the gear doors open REGARDLESS of gear lever position. If you do not raise the gear within 30 seconds, the gear doors close again and you keep the gear down as you apparently desire. In the video, the gear doors are closed again as the airplane flies into the suburb. This requires normal hydraulics in system C, which was apprently available as the doors are closed again. 1. 787-8 LG retraction: boogies tilt forward, doors open, boogies tilt inward: Last edited by D Bru; 16th Jun 2025 at 04:24 . Reason: Following pertinent comments EXDAC & Roo (thanks!) 4 users liked this post. |
| Shep69
2025-06-15T15:32:00 permalink Post: 11902560 |
I do concur if it was a major systems breakdown without crew mistakes being made we will know shortly through emergency ADs. |
| EXDAC
2025-06-15T16:00:00 permalink Post: 11902588 |
1 user liked this post. |
| Roo
2025-06-15T16:36:00 permalink Post: 11902616 |
This yt video is somewhat cheesy, but it should make the -9 “early open” MLG door process clear to you, in a normal gear retraction. Unless you think this clown selected gear up on the ground. They cycle open before gear is selected up (& even if gear is left down as you observed). Whereas on the -8 MLG doors will not budge until gear is selected up. Last edited by Roo; 15th Jun 2025 at 16:47 . 1 user liked this post. |
| sorvad
2025-06-15T17:19:00 permalink Post: 11902647 |
After hours of reading I conclude that so far nobody has the slightest clue about what happened.
1: Flaps were down 2: The RAT story is based on a single unsharp video frame. Earlier frames were much sharper but the RAT could not be seen (although there was a sound). 3. Lack of evidence I could be wrong, in that case please link QUALITY evidence so that we can learn something new. This way thousands of people are wasting countless hours. Last edited by sorvad; 15th Jun 2025 at 17:35 . 14 users liked this post. |
| Furr
2025-06-15T17:27:00 permalink Post: 11902651 |
Glide range compatible with total loss of thrust?
IMO
In the CCTV video, the aircraft stops climbing at 00:28. 3 seconds after, it starts visibly descending. At peak altitude, using the 197ft wingspan as a measure, the altitude is around 200ft or below. The fireball is at 00:48, 17s after descent starts visibly. Per google maps and the impact location mapped at avherald, the impact point is ~3990ft from the airport boundary road and about 4200ft from the midpoint of the runway threshold and the airport boundary road. 16:1 to 25:1 is what I could find for the 787 glide ratio range (unpowered) with main landing gear down and flaps 5. So the aircraft could cover 16 to 25 ft horizontally for every 1 ft of descent. With a starting altitude of 200ft, that would imply it could have covered 3200ft.to 5000ft during unpowered descent. The actual distance covered, around 4000ft, certainly seems to suggest that the descent was unpowered. 3 users liked this post. |
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