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KSINGH
2025-06-13T23:51:00 permalink Post: 11901008 |
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. the ALT capture is what caught EK\x92s 777 out in DBX right? I still can\x92t think of a logical reason why they continued to allow ALT capture below thrust reduction height (depending on your operator 400-1000 AGL), that seems like a latent threat. |
Blake777
2025-06-14T00:52:00 permalink Post: 11901042 |
Couldn't agree more - never understood this - got to say, calling a mayday seconds into an event (particularly when still down in the dirt) does my head in - nobody is coming up to help. I think you need to keep the focus completely on the task at hand. In an emergency, external distractions destroy checklist SOPs, crew coordination etc etc - I try and keep ATC, company maintenance, etc etc disruptions out of the cockpit until everything is under control.
4 users liked this post. |
Toruk Macto
2025-06-14T02:39:00 permalink Post: 11901091 |
Are you thinking of the EK A340 that departed with a 100 ton descepancy entered in the box resulting in incorrect thrust derate and under cooked V speeds? That aircraft was saved by the flight crew that fire walled the thrust leavers with about 600M remaining. Tail strike and destroyed the LOC antenta, but was able to get Airbourne then return for landing at YMML. Is this a possibility? 100 ton gross error, resulting in incorrect thrust, speeds and flap setting? Pilot mistakes lack of thrust for partial engine failure? The confusion and startle factor as the aircraft is rotating with a surprising lack of thrust and the runway end fast approaching may account for the gear not being selected up. If there were a gross error in the weight entered in the FMC, no takeoff config warning. 40 degrees C, flaps 5 instead of flaps 15 or similar? Hopefully some initial data from the FDR may be a pretty good indication.
If RAT out ??? That tells a lot . Not long to wait now ? condolences to family\x92s and loved ones ! Last edited by Toruk Macto; 14th Jun 2025 at 04:30 . |
Sisiphos
2025-06-14T06:53:00 permalink Post: 11901175 |
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. 1) The flap retraction would immediately result in progressive less lift, not only after full retraction . The time in the air could have been longer than your estimate, maybe enough time for full retraction 2) if 200 feet in MCP, why would that lead to a descent? Shouldn't that result in level flight? 3) wrong TOW / too low power setting sounds like a plausible event.Happened before. But with full power / TOGA set in the air ( which surely must have happened)I would expect at least a longer struggle rather than the constant descent. Just a gut feeling though, busdriver, no experience on 787. Maybe already in a power on stall. The only problem with this hypothesis is that it does not explain the gear down since there definitely was positive rate after rotation. 4) double engine failure too remote, no signs of flames etc. Forget it, agreed. My guess remains inadvertant flaps retraction for what it's worth. 1 user liked this post. |
aeo
2025-06-14T14:05:00 permalink Post: 11901513 |
I agree it is helpful to seek a consensus on some of these matters.
The most productive responses would be along the lines of:- (1) I too have read all previous posts and agree that your summary reflects the current consensus, (2) I too have read all previous posts and agree your summary reflects the consensus HOWEVER I challenge that consensus because... [ [i]EITHER (a) reference to previous post that merits greater credence, OR (b) new evidence supplied], (3) I too have read all previous posts but I do NOT agree your summary reflects the consensus [explanation required]. It is not necessary for everyone who thinks (1) to say it (although some initial feedback would be useful!). However, if any of the more experienced and informed PPRuNers are thinking either (2) or (3) then it would be instructive to hear that. FWIW, yours strikes me as a reasonable summary of the best consensus I have been able to discern (as of ~30 minutes ago). There are multiple caveats to each line item, but I presume you've deliberately left those out for the sake of readability, so I'll do the same! The only comments I would add are:- - It's a stretch to say the RAT is seen or heard "conclusively". Doubts have been expressed about the video quality and there are dissenting views regarding the audio. If a few more people were able to wade in on the audio point in particular, this could be very beneficial in moving the discussion forward because the presence or otherwise of the RAT is significant to several competing theories. - On the subject of audio, I am surprised there has not been more discussion regarding engine noise. In the primary eye witness video the (alleged) RAT can be heard distinctly, as can the sounds of distant impact. If the engines were working as expected when overflying the camera and then flying directly away from it, do we really not think the engine noise would be more conclusive, i.e. louder (notwithstanding quiet engines and derated takeoffs)? Whichever way readers are leaning in the flaps versus power loss debate, surely these two points are pivotal, and we have actual evidence available to discuss? - Gear bogies: I'm not sure a consensus has yet been reached regarding the angle of the bogies. (I am not personally qualified to comment on this - I am purely saying I don't see a clear consensus just yet among those who are) - Mayday call: I don't recall seeing a confirmed source for the widely reported mayday. Others have brought this up in the thread but nobody appears to be able to confirm one way or the other. If accurate, its contents are informative. Am I right to presume that you have left it out of your summary due to a lack of confirmation? - The bogie could be explained by the Flap/Slat priority valve giving priority to the flaps if the PM suddenly realised his mistake and quickly put the flap lever back to the TO position and then selected the gear lever to UP. Those systems are both heavy hitters and would\x92ve sucked the life out of the CTR hydraulic system pumps. - There is no way loss of AC (alleged RAT deployment) could've caused a spool down of both engines. Think QF A380 incident in SIN - The entire #1 engine wiring harness in the wing was completely severed and yet it continued (by design) to run at its previous thrust setting. They had to shut it down using a fire truck! - History and design would dictate that a big 180 minutes ETOP\x92s twin such as the 787 having a dual engine failure or significant power loss at such a critical phase of flight would be a billion to one chance at best. Only the Airbus A400 had a software issue causing all 4 engine fuel shutoff valves to close causing it to crash killing the flight test crew - But this was during its development and flt testing. - Wide body twin\x92s delivering in the region of 60,000 to 115,000 lbs of thrust at TO rarely , if at all, flame out from multiple bird strike(s) like the baby Bus\x92s and Boeing\x92s. If anyone has seen the frozen chickens at TO power video would know what I\x92m talking about. And the Fan Blade being \x91blown off\x92 as well. In both cases the engine was was able to maintain full TOGA thrust for significantly longer than the AI aircraft. But it\x92s early days and anything could happen. And nothing surprises me anymore. 3 users liked this post. |
njc
2025-06-14T15:06:00 permalink Post: 11901555 |
- The bogie could be explained by the Flap/Slat priority valve giving priority to the flaps if the PM suddenly realised his mistake and quickly put the flap lever back to the TO position and then selected the gear lever to UP. Those systems are both heavy hitters and would’ve sucked the life out of the CTR hydraulic system pumps.
- There is no way loss of AC (alleged RAT deployment) could've caused a spool down of both engines. Think QF A380 incident in SIN - The entire #1 engine wiring harness in the wing was completely severed and yet it continued (by design) to run at its previous thrust setting. They had to shut it down using a fire truck! - History and design would dictate that a big 180 minutes ETOP’s twin such as the 787 having a dual engine failure or significant power loss at such a critical phase of flight would be a billion to one chance at best. Only the Airbus A400 had a software issue causing all 4 engine fuel shutoff valves to close causing it to crash killing the flight test crew - But this was during its development and flt testing. - Wide body twin’s delivering in the region of 60,000 to 115,000 lbs of thrust at TO rarely , if at all, flame out from multiple bird strike(s) like the baby Bus’s and Boeing’s. If anyone has seen the frozen chickens at TO power video would know what I’m talking about. And the Fan Blade being ‘blown off’ as well. In both cases the engine was was able to maintain full TOGA thrust for significantly longer than the AI aircraft. As for history and design making a dual-engine failure a billion to one chance: I'd be more inclined to agree that it's unlikely to be what happened if the actual manufacturing of planes (Boeings in particular) and the maintenance procedures were both carried out "by the book" at all times by the manufacturer and the airlines... This is clearly not the case though. Last edited by Saab Dastard; 14th Jun 2025 at 19:35 . Reason: reference to deleted posts removed |
MLHeliwrench
2025-06-14T16:39:00 permalink Post: 11901637 |
The complex software.
Can anyone familiar with the 787 built in overspeed protections comment on what could possibly override a pilots TOGA button command or fire walling the throttles?
I am presuming that at some point just prior to the mayday call the pilots would have just commanded \x91full\x92 thrust and received no or a significantly mild response. I don\x92t think fuel contamination, birds or anything else external to the aircraft affected this crash. There is no evidence of it. could some combination of already MEL items and one or more faulty inputs to the computers cause the aircraft to \x91protect\x92 itself into the ground? Regardless of throttle position? I am thinking - ground/air logic, faulty airspeed sense, faulty AoA sense or other. |
Compton3fox
2025-06-15T07:34:00 permalink Post: 11902190 |
No evidence of engine failure
No evidence of RAT deployment from a poor image. No evidence of electrical failure. The teams of lawyers in the UK representing 53 grieving families will be working over the weekend to sign up said families to a class action. This is going to get messy. No evidence of RAT deployment from a poor image . - You can argue Not from the Image but...: 2 independent audio analysis of the video audio shows the sound comes from a deployed RAT plus JB's video. Plus the guys who live in SEA having heard 100's of RATs deployed during test flight have stated that the sound is a RAT. No evidence of electrical failure . - Not true. Reported cabin emergency lights going off, FR24 feed stopped just as in the 737 South Korea incident in December. APU intake door partially open at crash scene, suggesting an APU autostart. Now you can call into question the above evidence but to state there is none, is simply not true. Last edited by Compton3fox; 15th Jun 2025 at 08:23 . 12 users liked this post. |
Squawk7700
2025-06-17T10:28:00 permalink Post: 11904180 |
Perhaps?
"LNAV" - "VNAV" or "FLCH SPD" To ensure:
2 users liked this post. |
TURIN
2025-06-17T11:12:00 permalink Post: 11904212 |
Perhaps?
"LNAV" - "VNAV" or "FLCH SPD" To ensure:
|
McDoo
2025-06-17T12:50:00 permalink Post: 11904275 |
What if?
Perhaps?
"LNAV" - "VNAV" or "FLCH SPD" To ensure:
altitude was set on the FGP? Suppose they had left it at zero prior to final departure briefing? Not 787 rated but is it possible that they selected FLCH after take off and the aircraft targeted the zero altitude selection? Doesn\x92t explain the RAT deployment but I have a feeling there maybe more than one hole in this Swiss cheese\x85 3 users liked this post. |
Capn Bloggs
2025-06-17T14:17:00 permalink Post: 11904336 |
Originally Posted by
Squawk7700
Perhaps?
Originally Posted by
Squawk7700
"LNAV" - "VNAV" or "FLCH SPD" To ensure:
VNAV or FLCH was NOT engaged
after liftoff.
Pilot assumed A/T was managing thrust, but it wasn’t.
Pilot assumed A/T was managing thrust, but it wasn’t.
Thrust stayed fixed or decayed (if levers were moved).
​​​​​​​Speed decayed, aircraft climbed too steeply, energy bled off.
​​​​​​​Pilot assumed engine failure due to poor climb response.
Boeing SOPs typically include a callout at 400 ft like:
"LNAV" - "VNAV" or "FLCH SPD" To ensure:
You're clearly implying a complete ballsup by the crew, making multiple serious mistakes or errors of omission. Last edited by T28B; 17th Jun 2025 at 15:40 . Reason: formatting clean up 9 users liked this post. |
Shep69
2025-06-18T01:18:00 permalink Post: 11904818 |
I wouldn't be surprised.
The speed should be at least at V2 and probably higher. Why would the ATS not just hold that speed, albeit being a shock to the crew. Within a few seconds I'll bet the throttles would end up back in the forward position as the ATS says "hey, we're slowing down fast here!". It would be ugly but I can't see that the jet's going to drop out of the sky. The throttles aren't going to come right back and stay right back. From one of the previous scenarios if capture at a way low altitude occurred they`d (IIRC correctly) engage in SPD mode resulting in a significant loss of thrust as they attempted to maintain speed assuming a level off. Presumably after this when the PF continued a climb (regardless of flight director) they`d come forward after this loss of thrust to attempt to meet commanded speed—V2 or V2+15 or whatever—but there`d be a lag. But I`ve never misset the MCP to a way low altitude in flight or the sim (not a holier than thou thing) so I`m not entirely sure how how the autothrottles would behave. More than one crew has failed to push them to the stops when things went south. And the reverse is true; when the second MCAS accident happened IIRC the autothrottles stayed in THR REF due to task saturation by the crew. Exacerbating the condition and ultimately resulting in an accident. 3 users liked this post. |
Capn Bloggs
2025-06-18T01:26:00 permalink Post: 11904824 |
Originally Posted by
Shep69
Because they are in `hold` after the takeoff thrust is set by engaging the TOGA levers. VNAV will engage at 400` AGL and set them at THR REF — referencing takeoff or climb thrust as programmed.
|
Magplug
2025-06-18T15:54:00 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. 1 user liked this post. |
Capn Bloggs
2025-06-18T16:11:00 permalink Post: 11905368 |
Originally Posted by
Magplug
It is quite probable that this aircraft rotated below a suitable Vr speed for the weight and ambient conditions and was unable to establish a stable climb due lack of applied power.
Originally Posted by
Magplug
Big engines take time to spool up, your immediate future depends on how late you recognise the situation and go for TOGA.
13 users liked this post. |
Sailvi767
2025-06-19T11:08:00 permalink Post: 11905928 |
I have to agree with you
PBL
. It is amazing that people are still arguing about the height the aircraft reached during the first 11s of the flight. It is almost measurable to the metre from the aircraft wingspan on the video. Do not mistake the power required to reach Vr within in the TORA with the power required to maintain a stable climb at V2 to V2+10 in the second and third segments. They are very different numbers, that's why Perf A is one of the dark arts of aviation! It is quite probable that this aircraft rotated below a suitable Vr speed for the weight and ambient conditions and was unable to establish a stable climb due lack of applied power. Big engines take time to spool up, your immediate future depends on how late you recognise the situation and go for TOGA.
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. 3 users liked this post. |
LGB
2025-06-19T11:18:00 permalink Post: 11905939 |
THR REF/VNAV SPD
Does a Boeing 787 go from HOLD TO/GA to THR REF/VNAV SPD at 400' AGL/AAE, like older versions of the Boeing?
If so, what if the WoW stayed in ground mode, for whatever reason, how would that affect 1) Retraction of the landing gear (it didn't retract, as obvious in videos released) 2) The transition from HOLD to THR/REF at 400' (they reached just barely over 400' AGL before leveling, then descending) I am also thinking that Air India would follow Boeing procedures in that the left seat pilot will move their right hand away from the thrust levers at V1, and thus, at 400', the thrust levers are not guarded or monitored? Even if thrust levers were pushed forward, is there some kind of logic related to FMC and-or FADEC or other involved systems, which regardless of thrust lever position commands IDLE thrust to the engine? Remember that Airbus accident where the aircraft thought it was landing, while the pilots wanted full thrust, and they crashed into a small forest because some kind of idle is all they were afforded by the system? If the engines of this 787 thought it was in the rollout or final part of the flare, it might also command thrust levers to idle? This does not explain the RAT, though, unless there is some weird combination of software working against each others logic. Had the engines failed by some really random, odd reason, like birds, fuel contamination-vapor-starvation or such, wouldn't there be at least a slight bit of roll or yaw visible? Even with TAC or whatever they have on the 787, I would think even a 1 second difference in thrust reduction between the engines, a hint of yaw or roll should be visible ... Thoughts, especially by someone who flies the 787? Last edited by LGB; 19th Jun 2025 at 11:36 . Reason: Updates and more thinking .. 1 user liked this post. |
Musician
2025-06-20T19:32:00 permalink Post: 11907237 |
\x95 The crew pushed TOGA, but it didn't take, because the aircraft had technically landed already. This delayed pushing the throttle forward. \x95 AI171, starting from 184 knots or more, had substantially more energy to work with. |
Zionstrat2
2025-06-20T21:33:00 permalink Post: 11907338 |
GA guy who's been reading the thread from the beginning..
I'm assuming my question is moot because I don't believe it's been mentioned in the entire thread, however is there any possible maintenance issue that could affect two engines over time? This is certainly happened before, I'm thinking of N334EA where all three engines were lost due to maintenance replacing all three chip detectors with defective detectors before the flight. Of course it took 40 something minutes before the first engine oil was drained and the other two engines failed at different times after that. So that pattern doesn't fit, but my question is are there other things that could be replaced on both engines that could theoretically take a relatively long time to fail but might do so under TOGA? In other words are there any devices that could have been changed on both engines before the previous flight that were defective and didn't fail until full power on both engines on take off on the accident flight? Obviously this is pure speculation, I don't claim to know anything and I'm just curious. 1 user liked this post. |