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| Magplug
June 12, 2025, 12:11:00 GMT permalink Post: 11899141 |
Like most Boeings, on the 787 you are prevented from selecting the flaps/slats all the way up in one go by the gate at flap 1. If this was a mis-selection by one of the pilots, they would have been prevented from selecting ALL the high lift devices up in one go by the flap 1 gate. Even if you manage to get the lever to the Flaps Up position then below 225kts you should get Slat-Gap protection which maintains MOST of the lift. I have never tried it personally but that's the operation as advertised by Boeing. Would that provide enough lift to save them...... that is really a matter of debate.
The aircraft may have suffered a power loss of one or both engines possibly by bird strike. I have to say that the B787 is the very easiest aircraft I have ever flown when handling an engine failure above V1. The flight path vector and the flight director in the head up display make finessing an engine failure absolute child's play. Having said that the Boeing 787 performance is calculated right to the limits of legal requirement, so there is no scope for mis-handling. If they failed to select the landing gear up, not due to a flap lever mis-selection, but some another distraction, like an engine failure, then the aircraft would struggle to accelerate to V2 to safely climb away. The B787 derates are calculated to give an acceptable Vmca in the event of an engine failure. That is to say, if you apply any more power asymmetricly the Vmca criteria of up to 5deg of bank towards the live engine will require more control input resulting in more control drag. Our SOP was - If you need it - Use It! Thankfully I never had to find out. By way of illustration, on the B747-400, leaving the gear down following an engine failure had the same effect as failing two of the four engines. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Engine Failure (All) V1 V2 |
| Magplug
June 13, 2025, 22:13:00 GMT permalink Post: 11900963 |
Speaking as a B787 Captain..... There is so much rubbish and stupid suggestion being written here.
This aircraft was airborne for a grand total of 22 seconds, half of which was climbing to no more than 150' aal. - No Flaps? Due to the setup of the ECL it is physically impossible to go down the runway without some sort of take-off flap set. The T/o config warning would have been singing it's head off. Despite assertions to the contrary I have seen no video clear enough to detect a lack of flaps. - RAT out? Almost impossible, I have seen no quality footage that definitively witnesses the RAT being out. Those who think they car hear a RAT type noise might be listening to a motorcycle passing or similar. It takes a triple hydraulic failure or a double engine failure to trigger RAT deploment. They happily went through V1 without a hint of rejected take off so as they rotated the aircraft was serviceable. These are big engines, they take a long time to wind down when you shut them down. I have never tried it however engine failure detection takes 30s or for the aircraft to react and they were not even airborne that long. - Flaps up instead of gear? The B787 flaps are slow both in and out. Given that the 'Positive rate' call is not made the second the wheels leave the ground, a mis-selection of flaps up would not cause any loss of lift for at least 20 seconds, by which time they had already crashed. I believe the gear remained down not because of mis-selection but because of a major distraction on rotate. Discounting the impossible, two hypotheses remain: 1. Invalid derate set through incorrect cross-checking. Trundling down the runway takes very little power to reach Vr. It is only when you rotate that you create more drag and discover that you do not have sufficient thrust vs. drag to sustain a climb. Or.... 2. Put 200' as the altitude target in the FCU. Immediate ALT capture and all the power comes off. PF is still hand flying trying to increase pitch but is already way behind the aircraft. It could be after this that Boeing are forced to review the B787 practice of exploring the very edges of the performance envelope. 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) Engine Failure Detection Time Hydraulic Failure (All) RAT (All) RAT (Deployment) V1 |
| Magplug
June 14, 2025, 13:45:00 GMT permalink Post: 11901502 |
B787 skipper again..... Many thanks for your kind comments and PMs about the post previously known as #867. Due to mods weeding of posts it is now
HERE
.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Thread Moderation |
| Magplug
June 13, 2025, 22:13:00 GMT permalink Post: 11903713 |
Speaking as a B787 Captain..... There is so much rubbish and stupid suggestion being written here.
This aircraft was airborne for a grand total of 22 seconds, half of which was climbing to no more than 150' aal. - No Flaps? Due to the setup of the ECL it is physically impossible to go down the runway without some sort of take-off flap set. The T/o config warning would have been singing it's head off. Despite assertions to the contrary I have seen no video clear enough to detect a lack of flaps. - RAT out? Almost impossible, I have seen no quality footage that definitively witnesses the RAT being out. Those who think they car hear a RAT type noise might be listening to a motorcycle passing or similar. It takes a triple hydraulic failure or a double engine failure to trigger RAT deploment. They happily went through V1 without a hint of rejected take off so as they rotated the aircraft was serviceable. These are big engines, they take a long time to wind down when you shut them down. I have never tried it however engine failure detection takes 30s or for the aircraft to react and they were not even airborne that long. - Flaps up instead of gear? The B787 flaps are slow both in and out. Given that the 'Positive rate' call is not made the second the wheels leave the ground, a mis-selection of flaps up would not cause any loss of lift for at least 20 seconds, by which time they had already crashed. I believe the gear remained down not because of mis-selection but because of a major distraction on rotate. Discounting the impossible, two hypotheses remain: 1. Invalid derate set through incorrect cross-checking. Trundling down the runway takes very little power to reach Vr. It is only when you rotate that you create more drag and discover that you do not have sufficient thrust vs. drag to sustain a climb. Or.... 2. Put 200' as the altitude target in the FCU. Immediate ALT capture and all the power comes off. PF is still hand flying trying to increase pitch but is already way behind the aircraft. It could be after this that Boeing are forced to review the B787 practice of exploring the very edges of the performance envelope. 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) Engine Failure Detection Time Hydraulic Failure (All) RAT (All) RAT (Deployment) V1 |
| Magplug
June 14, 2025, 13:45:00 GMT permalink Post: 11903722 |
B787 skipper again..... Many thanks for your kind comments and PMs about the post previously known as #867. Due to mods weeding of posts it is now
HERE
Last edited by Magplug; 17th June 2025 at 16:24 . Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Thread Moderation |
| Magplug
June 17, 2025, 17:01:00 GMT permalink Post: 11904468 |
B787 Skipper.... No longer able to sit on my hands!
The joker that published one or other of the fictional accident reports before the dead are even identified needs stringing up by the thumbs.... Well done mods. OK, some of these theories, just bearing in mind the the flight recorder (there is only one FDR + CVR combined) was in the intact section of the undamaged tail and has been with the authorities for almost five days...... - All you guys who are rushing down the TCMA rabbit hole: If it was established that a software error drove both engines to idle without warning, after rotate.... Don't you think the worldwide fleet of B787s would have been grounded by now? Such a glaring failure would be absolutely inescapable on the FDR. Whatever was wrong with this aircraft was present at rotate, unbeknown to the crew. The fact that no ADs or notices to operators have been issued usually means that the cause is known and the aircraft was serviceable. The statement from a prominent Indian Captain about the skill and tenacity of the crew, right up to the last minute is absolutely laudable. However, the cynic in me says that the way is being paved for some bad news and by that I mean news that will do Air India reputational damage. Expect more management of expectation in the coming days. I'm still going with a) Incorrect derate + low Vspeeds or b) Low altitude capture Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CVR DFDR FDR Thread Moderation |
| Magplug
June 18, 2025, 10:17:00 GMT permalink Post: 11905107 |
Boeing will safeguard Boeing's interests, the NTSB will safeguard American interests. If the Indian AAIB start dragging their feet over publishing their initial report in an effort to protect Indian interests then Boeing and the NTSB will make a joint press release to the effect that the aircraft was serviceable right up to the point of impact. They have done it before.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All) AAIB (India) NTSB |
| Magplug
June 18, 2025, 15:54:00 GMT permalink Post: 11905352 |
I'd like to stick my neck out and say what I think I know. And I do mean "know", not what I think "likely" or "possible".
1. The aircraft reached an altitude AGL rather more than one wingspan. This can be clearly seen in the still from the CCTV video posted by Cape Bloggs on 2025-06-18 at 0401. The 787-8 wingspan is 197+ ft. So it got at least 200 feet up in the air. (Info from CCTV screen shot.) 2. (a) Ground effect on lift essentially disappears on TO when the wheels are at screen height. (Info from an eminent colleague who performed the analysis.) I believe it follows that (b) he didn't get up to 200 ft by performing a zoom climb on unstick. It further follows that (c) there must have been some initially adequate lift out of GE to establish for a few seconds positive RoC. 3. The FR24 graphic posted by Musician shows that the aircraft became initially airborne "as usual", compared with other TO profiles. (Info from FR24.) 4. The aircraft lacked adequate thrust even to maintain altitude shortly after unstick. 5. Flaps 5 is minimal for TO. If you don't set it, you are told very clearly that you are misconfigured, well before TO roll. (Info from others.) 6. At Flaps 5 and likely loading (fuel, PAX, token sum for baggage) and in the atmospheric conditions pertaining, there is more than enough nominal thrust available to establish positive RoC. That obviously also holds for Flaps-more-than-5. (Info from others.) I am not au fait with audio spectral analysis so, unlike some others here, including some whose views and experience I value highly, I am agnostic at this point about the RAT. (This is neither to deprecate those who performed this analysis, nor the views of those who know more about practical spectral analysis than I do and are convinced by it.) Now for my personal inference so far from this. Items 2 and 3 above suggest to me that the aircraft was adequately configured to conduct a normal TO and initially establish positive RoC for a second or two. For me, the big question is: why wasn't there adequate thrust to maintain that? (We've been talking about those possibilities for some days now - I won't attempt to summarise.) PBL But you ask..... How can an aircraft possibly get airborne with a stalled wing? Look at Air France 7775 . At rotate the wing was already stalled (albeit for different reasons) but the airborne profile of the aircraft was rather similar to Air India. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CCTV FlightRadar24 RAT (All) TOGA V2 |
| Magplug
June 18, 2025, 17:19:00 GMT permalink Post: 11905411 |
Capn Bloggs
We shall see!
A mate tried gear/flap scenario in the sim earlier. Selecting flaps up (all the way) instead of the gear did not predjudice the flight path at all. They selected flaps up at normal gear retraction height and punched the AP in. The Slats remained out until 225kts (as per my post about 50 pages ago) and the aircraft climbed happily away clearing all obstacle by a good margin. Last edited by Saab Dastard; 18th June 2025 at 18:30 . Reason: Unwarranted speculation Subjects: None |
| Magplug
June 18, 2025, 18:09:00 GMT permalink Post: 11905436 |
They used a ZFW typical of DEL-LHR (which we do) with a full house and some typical freight. The met details are publicly known. Using all of that data fed into the EFB it decided upon an appropriate derate and flap. There is no reason to assume the AI EFB would have come up with any different data.
Subjects: None |
| Magplug
June 19, 2025, 08:38:00 GMT permalink Post: 11905832 |
Originally Posted by
Capn Bloggs
Come on, people. If it went into altitude hold, yes, the power probably would come off, but only to maintain the current airspeed. It would very quickly start powering back up as the aircraft attempted to sink and was countered by the PF. But the power didn't come back up, that being obvious from the increasing AOA during the descent.
In any case, there wouldn't be a sudden level-off because the PF is still l hand flying below 200ft. Do you think he'd blindly just jam the stick forward to follow the FD at such a low altitude? As stated before, if even only one of those engines was running, there's no way it would have descended, slowing down, as it did. Just after rotate is a very busy time for your scan. The FMA modes are in the HUD for both pilots to see, however did they have time to read and digest rapidly changing autoflight modes? I have way more experience flying the B744 than the B788 but I can see this happening on either type. How many times were you reminded to RTF FMA! Subjects (links are to this post in the relevant subject page so that this post can be seen in context): V1 |
| Magplug
June 19, 2025, 17:43:00 GMT permalink Post: 11906222 |
Had a play with this scenario in the sim today and learnt a few things:
1) Incorrect performance data... It has to be a VERY significant perf shortfall and depending on the startle factor versus reaction time is still in my view a possibility. 2) Low altitude capture. The HUD is very compelling and there is no visualisation of power demanded versus power set in the symbology. The speed tape has a 10 second speed trend arrow and the FPV has avery sensitive inertial speed trend arrow. Again recovery was possible but by this time the guys were ready for it. 3) I remain agnostic about the RAT deployment. However, aside from punching out the RAT on the overhead panel there was only one method we could find to deploy the RAT in this very short timescale. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): RAT (All) RAT (Deployment) |
| Magplug
June 19, 2025, 18:37:00 GMT permalink Post: 11906256 |
Difficult to put a number to it as the guys were getting better at it after the 1st attempt. Using 40-50T below ATOW was pretty impossible due no lift on rotate. This is definitely test-pilot territory.
Subjects: None |
| Magplug
June 19, 2025, 20:34:00 GMT permalink Post: 11906348 |
Sadly we don't have a better investigative tool. Certainly a lot better than some of the theories espoused here.
Subjects: None |
| Magplug
July 09, 2025, 14:45:00 GMT permalink Post: 11918435 |
As a 787 operator I can observe a couple of things......
Deliberately cycling the Engine Cutoff switches just after rotate, in response to a dual power loss is inconceivable. You are way too low and slow for it to have any effect and your attention is better devoted to aiming for the flattest area ahead to crash into. Commencing the Dual Eng Fail/Stall checklist memory items is conditional upon both engines being at sub-idle and the aircraft being within the in-flight relight envelope. Neither of those conditions existed. The flight recorder will witness what came first - Power loss or Start Switches to Cutoff? It seems the 'Third Contingency' that I alluded to about a thousand posts ago, sadly now seems likely. Given the iron-grip that the government appears to have over the media, one wonders how the truth will ever surface? Subjects (links are to this post in the relevant subject page so that this post can be seen in context): DFDR Fuel (All) Fuel Cutoff Switches Memory Items Relight |
| Magplug
July 09, 2025, 16:17:00 GMT permalink Post: 11918490 |
Originally Posted by
za9ra22
With all due respect, do you have any idea how a large scale investigation of this kind actually works, because it would appear not so much.
Not only are there agencies and personnel from outside governmental influence directly involved in the investigation, and playing an active as well as observational role, which makes it almost impossible to hide or obscure critical pieces of information or data, but other than a frenzy of any-nonsense-goes in the name of hits, clicks and ad revenue, the media play no role whatsoever in any part of the investigation. The team itself will operate largely within a bubble, and team members don't talk to media or politicians - however much the media or politicians still need to flap their jaws because to both classes, silence is anathema. Furthermore, everyone who does this kind of work is a professional, well aware that any unofficial commentary is capable of severely compromising the investigation and other members of the team. Subjects: None |
| Magplug
July 09, 2025, 16:57:00 GMT permalink Post: 11918527 |
Propellerhead
You are correct, a low level altitude capture would back off the throttles as the FMA goes into ALT. However the FD would drop unexpectedly as would the engine noise as the throttles rolled back..... So in what world would that prompt you to call for the dual engine failure checklist rather than firewalling the throttles? This was discussed about 75 pages ago.... It makes good reading
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) |
| Magplug
July 10, 2025, 08:59:00 GMT permalink Post: 11918849 |
A couple of points if I may......
I don't see it written in the 787 FCOM but I have always been told that the action of resetting the Engine Cutoff switches in the event of a dual engine failure, is merely backing up what the FADECs have already done. If there is an 'engine event' the FADECs will manage ignition and fuel-flow to restore the thrust that was demanded before the event. If that management has failed then the manual resetting may be more successful. (The same holds true for the RAT, manual selection is merely backing up the auto-deployment). Any airline pilot will tell you that executing an in-flight relight on a big engine, no matter if it is by electric start, windmilling RPM or cross-bleed assisted, can take between 1 and 3 minutes to restore power. This aircraft was airborne for less that 30 seconds. No pilot in his right mind would prioritise an in-flight relight procedure, in a situation where they had neither the time, the height nor the speed for it to succeed. I have no doubt the crew focussed entirely on pointing the aircraft at the clearest area they could see, to mitigate what would inevitably follow. 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) FCOM Fuel (All) Fuel Cutoff Switches RAT (All) Relight |
| Magplug
July 10, 2025, 14:12:00 GMT permalink Post: 11919049 |
Originally Posted by
"Capn Bloggs
So, we have a Memory Drill with a non-numbered thing you have to remember first, being sub-idle, and an FCTM that pumps the idea of getting those switches off and on ASAP, before the revs drop off too much, at any speed or altitude.
Great. Notwithstanding what it says in the B787 FCOM and FCTM, I don't think Boeing ever envisaged the dual engine failure procedure being required 10 seconds after rotate. There are many pilots in civil aviation who live and die by what is written in the manuals without thinking past the text. There are times when what is written is sensible and appropriate, and there are times when application is just plain daft. This is why a man is in charge, not a machine. For those thinking about a SEF followed by an incorrect shutdown..... In the event of a SEF you control the aircraft, take the gear up and engage the autopilot. You then sit on your hands until 400' AGL. If an engine is on fire - You let it burn until 400'. No procedure is actioned until the problem is confirmed between you, and you are safely climbing away. To deviate from that would be very unprofessional and highly dangerous. 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) FCOM |
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