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PoacherNowGamekeeper
June 12, 2025, 13:16:00 GMT permalink Post: 11899201 |
Just for the record, there is no system on modern Boeing aircraft to prevent the accidental retraction of flaps when too low or slow when airborne. You wouldn't even get a warning on Boeing aircraft that is related to Flaps, you'd eventually get one related to Low Speed or Stall. The Airbus has a safety feature called "Alpha-Lock" which physically stops the Flaps from moving when the AoA or speed? is deemed too low. But that's not a safety net for all flap settings, just the lowest for takeoff. It will save the day in 95% of situations though Mr Boeing (hint hint)
Takeoff config warnings and checklists may not have helped if the flap setting was not enough given the weight and conditions. A good handling pilot could recover from an incorrect flap setting (providing there's no obstacles to deal with), by gently lowering the nose allowing the airspeed to build up before resuming the climb. However, various human factors such as startle and over reliance on automation (my thrust setting must be good) will not help the situation. In order of likelihood: 1.) Flaps moved instead of gear 2.) Incorrect Flap settings and inability of crew to recover from that 3.) Double engine failure 4.) Some electrical event that distracted them |
Propellerhead
June 12, 2025, 13:23:00 GMT permalink Post: 11899208 |
Main panel. And the handle is a rubber wheel. The flap lever is shaped like a flap. But that hasn\x92t stopped it happening multiple times in the past. The yellow and red lines on the speed tape will start to converge and should be an indication to PF. On all Boeing / Airbus that\x92s it\x92s happened on the pilots have recovered by re selcting flaps. Selecting F1 will save you. It\x92s a Boeing procedure written in the manual.
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nomess
June 13, 2025, 05:10:00 GMT permalink Post: 11900002 |
I think it\x92s normal for most, even those with time on type, to point to the flap or gear lever issue. It was the same with the MAX until all the software issues came to light, the software was not really something top of mind, these machines are built and designed with precision, the thought of software causing havoc is somewhat implausible.
I think the discussion is at a standstill until we get more clarity on the flap position, and the RAT. The latter will become an issue for Boeing if that was extended, and they will need to work around the clock to prevent future mishaps, and reassure many flight op departments, especially those with early build 787s, that this is a isolated event. |
Tu.114
June 13, 2025, 10:11:00 GMT permalink Post: 11900287 |
So what is known at the moment?
- The flight crew consisted of an experienced Captain and a First Officer with a little more than 1000 hours. Whether or not this flight was a training event appears not yet determined. - The aircraft departed from Ahmedabad, using full length of the runway, lifting off at an appropriate distance from the departure end and reaching an altitude of less than 1000ft before descending again to an impact. It therefore got out of ground effect. Also, the power selected for takeoff was sufficient to get the aircraft airborne within the constraints of the field. - The landing gear was left down much longer than usual and remained so for the whole duration of the flight. - Flaps appear to have been extended normally to a setting not triggering any pre-takeoff configuration warning. On the 787, extended TE flaps are not as obviously visible as on other types, especially with low quality pictures, but a gap between the flaps and the wing proper was visible, showing a glimpse of the engine nacelle through it. - Whether or not the RAT was out appears not entirely clear, although there are strong indicators of it being deployed. If this is confirmed, this seems to point to a major engine or electric issue. - Engine noise is surprisingly low on the available videos, either drowned out by environnmental noise (the 787 is not a noisy bird) or due to lack of power produced. - Descent was at a very high AOA and appears not intentional. The crew did not decide to push the nose down. - The aircraft appears to have been structurally intact with nothing issuing from it. No debris, smoke, fumes or liquids were in trail, no parts were observed to have been lost or dropped. - There seems to have been a mayday call from the aircraft, possibly indicating power issues. The crew seems to have found no reason to abort the takeoff before V1. Whatever befell them must have struck past that speed and given them cause not to retract the landing gear. Whether the lever was not moved or the systems did not react to it is not determined yet. The aircraft had enough energy to climb to about 600, in any case less than 1000ft altitude. Ahmedabad seems not to call for a specific NADP, but whether it was NADP1, 2, A or B that was flown, it is fairly safe to assume that its normal regime would have been takeoff power and takeoff flap settings at that time. Multiple other aircraft departed from or arrived at Ahmedabad before the accident, of which at least one must in all probability have taken onboard the fuel from the local bowsers in substantial amounts and used it without troubles, or else there would have been other flights in trouble due to this. I am awaiting the preliminary report from the authorities and the readout of the data recorders with much interest. Last edited by Tu.114; 13th June 2025 at 10:32 . |
AerocatS2A
June 13, 2025, 13:17:00 GMT permalink Post: 11900510 |
So - my question: If you look up the 787 cockpit layout (google, YT, your picture), how can Flaps Up instead of Gears Up be executed. It is a totally different activation of arm muscles, hand muscles, fingers even when not looking what you do ("three greens no red" anyone?). I mean, I totally understand the mishandlig of the switches and buttons on the Vilnius B737 - taking out hydraulics instead of Anti Ice. Switches are close, switches are same. But Gears and Flaps levers - I just dont understand why still many people here set this on the high probability list. I absolutely dont believe it. At least it would be on my possible causes on a list far, far down. Considering the deck layout on a 787. Do I miss some physiological/psychological human brain factors? Because some of the professionals seem to have written - "quite possible" in real stressfull world. Maybe on some GA aircraft where flaps select is also sometimes on the front panel. To answer your broader question though, how could such an error happen? It happens because us simple humans learn how to do actions to the point where we don\x92t have to think about them anymore. This allows us to effectively automate routine tasks and save our brains for more novel tasks. The problem arises when we trigger the wrong automatic action in response to a cue. You ask for gear up, I know I need to select the gear up, I know where the gear handle is and what it looks and feels like, yet something goes wrong in the wiring of my body and instead, the flap-up automatic action is run. It\x92s run before I have consciously thought about it. Sound far fetched? Well it has happened numerous times. I\x92ve seen someone do exactly that, select the flap instead of the gear, and there are incident reports publicly available. All modern passenger jets have a similar layout of the flap lever and the gear lever with the gear looking like a wheel and the flap looking like a wing, yet this error can still happen. Have you ever gone to put something in the fridge that should\x92ve been put in the cupboard? I\x92d bet that most people have made that weird error at some point in their lives, and yet the fridge doesn\x92t look like the cupboard and they\x92re nowhere near each other. |
smith
June 13, 2025, 14:35:00 GMT permalink Post: 11900575 |
that\x92s why the switches and levers are designed like this. The gear lever is round like a wheel and the flap lever is, well flap shaped. Mixing up switches was/is common. Happened to me in my training pulled the mixture full out instead of carb heat on my approach. Immediately realised the change in the engine and pushed it back in before it cut out completely and engine started up again. Change of underwear required.
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go-around flap 15
June 13, 2025, 15:40:00 GMT permalink Post: 11900638 |
Just a few examples:
https://assets.publishing.service.go...MAJS_01-12.pdf https://www.aeroinside.com/11716/eas...stead-gear-up# Also I remember a similar story in "Fate is the Hunter"... In an Airbus the flap lever is even further away from the gear lever than in any Boeing, yet still it happened! Action slips are just that and to blindy say that moving the flaps before gear is impossible, just because they are in a different location is incredibly naive. Next time you pour orange juice in your tea because you were thinking about something else and grabbed the wrong carton will you decry it impossible? To be as crystal clear: I am not saying this is how it happened, but it could be. Just as other things could be. |
xyze
June 13, 2025, 18:57:00 GMT permalink Post: 11900808 |
In the take off video I think there is a subtle yaw to the right at lift off (the moment it begins being obscured by the building in the foreground). There is then a massive blast of dust on the airfield on the left side of the aircraft as it lifts off. Later video audio suggests the engines were not at full power ( or even operating - just wind noise) and that the RAT was whirring. It also shows the fuselage wheel bogies were tilted forward - so wheels up has commenced - but the gear doors are not open.
Possible sequence: right engine failure at rotation, firewalling of left engine, lift off and positive rate, gear up lever activated, wheels tilt forward, left engine failure, RAT deployed, insufficient hydraulics to Open gear doors to complete gear up sequence, ongoing dual engine failure? |
appruser
June 13, 2025, 19:20:00 GMT permalink Post: 11900831 |
Firstly, I don\x92t think an inadvertent selection of flaps up caused this accident. I think it\x92s a red herring that seemed plausible initially but it is not consistent with the RAT being deployed, and the evidence for the RAT is strong.
To answer your broader question though, how could such an error happen? It happens because us simple humans learn how to do actions to the point where we don\x92t have to think about them anymore. This allows us to effectively automate routine tasks and save our brains for more novel tasks. The problem arises when we trigger the wrong automatic action in response to a cue. You ask for gear up, I know I need to select the gear up, I know where the gear handle is and what it looks and feels like, yet something goes wrong in the wiring of my body and instead, the flap-up automatic action is run. It\x92s run before I have consciously thought about it. Sound far fetched? Well it has happened numerous times. I\x92ve seen someone do exactly that, select the flap instead of the gear, and there are incident reports publicly available. All modern passenger jets have a similar layout of the flap lever and the gear lever with the gear looking like a wheel and the flap looking like a wing, yet this error can still happen. Have you ever gone to put something in the fridge that should\x92ve been put in the cupboard? I\x92d bet that most people have made that weird error at some point in their lives, and yet the fridge doesn\x92t look like the cupboard and they\x92re nowhere near each other. |
neila83
June 13, 2025, 20:50:00 GMT permalink Post: 11900886 |
We're all shouting each other down with two main different theories on why the aircraft lost lift so shortly after takeoff.
1) Incorrect flap retraction causing the aircraft to lose lift and unable to recover the energy in time. (Not unheard of and plenty of reports where this has happened - albeit usually not to a crash). 2) Loss of engine thrust backed up two potential pieces of evidence that back up the RAT was deployed (apparent RAT sound, potential RAT seen on low res video). It is impossible to know which of these is the case. Considering this summary of memory items is there the potential for a combination of both theories to have taken place? Inadvertant flap retraction by PNF leading the PF to sense a sink and loss of lift. Pushes the thrust levers forward to the firewall and still the aircraft sinks. PF looking through the HUD and so very much 'outside focused' and doesn't realise that PNF has instead moved the flaps. PF defaults to memory items for loss of thrust on both engines before PNF can realise or communicate to PF what they've done, start switches are cut off which drops the RAT and from that point they're only heading one way. This would satisfy the strongly held belief that the RAT was extended, whilst also following the more likely initial cause of an action slip by PNF starting the sequence, rather than a dual engine failure. As has been said many times as well, the landing gear retraction process appears to start as the bogies tilt, and then suddenly stops. Which rather suggests they did pull the gear lever. Based on the videos and the amount of speed the plane lost in the very brief sequence ovents, I'd say that the plane lost power a lot earlier than it would have in your theory. Last edited by neila83; 13th June 2025 at 21:03 . |
neila83
June 13, 2025, 21:58:00 GMT permalink Post: 11900955 |
Retracting the flaps would put them at the back of the power curve where drag increases with decreasing speed, causing the speed to reduce further!
The trouble seems to start at the exact moment the gear should have been raised, putting the flaps up, iso the gear, would cause the kind of loss of lift you see in the video. From there on, being at the back of the power curve, only firewalling the thrust levers and extending the flaps again could have saved them. We can see the landing gear retraction process begin. We see the bogies tilted in the second video. We can hear the RAT. We can see the RAT. We can see the flaps extended in the video and at the crash site. There isn't actually a single piece of evidence the flaps were raised, it's just a conclusion people jumped too before evidence began to emerge. The crazy thing is, when the report comes out and there is no mention of flaps none of the people who have been pushing the flap theory will self reflect or learn anything. They'll think those of us who didn't buy into it were just lucky, rather than it being down to use of fairly simple critical thinking. |
Right Way Up
June 13, 2025, 22:08:00 GMT permalink Post: 11900961 |
Yes indeed, the moment they pulled the gear lever, as we see the gear begin the retraction process, and then suddenly stop. Almost as if they suddenly lost power.
We can see the landing gear retraction process begin. We see the bogies tilted in the second video. We can hear the RAT. We can see the RAT. We can see the flaps extended in the video and at the crash site. There isn't actually a single piece of evidence the flaps were raised, it's just a conclusion people jumped too before evidence began to emerge. The crazy thing is, when the report comes out and there is no mention of flaps none of the people who have been pushing the flap theory will self reflect or learn anything. They'll think those of us who didn't buy into it were just lucky, rather than it being down to use of fairly simple critical thinking. |
fdr
June 13, 2025, 22:13:00 GMT permalink Post: 11900962 |
At this stage, at least two scenarios seem highly plausible:
1. Technical issue Airliners rely on air/ground logic , which is fundamental to how systems operate. There have been numerous crashes and serious incidents linked to this logic functioning incorrectly. Some engineering tests require the air/ground switch to be set in a particular mode. If it's inadvertently left in engineering mode—or if the system misinterprets the mode—this can cause significant problems.
2. Pilot misselection of fuel control switches to cutoff This is still a very real possibility. If it occurred, the pilot responsible may not have done it consciously—his mindset could have been in a different mode. There’s precedent: an A320 pilot once inadvertently shut down both engines over Paris. Fortunately, the crew managed to restart them. Afterward, the pilot reportedly couldn’t explain his actions. If something similar happened here, then when the pilots realized the engines had stopped producing thrust, pushing the levers forward would have had no effect. It’s easy to overlook that the fuel switches are in the wrong position—they're far from the normal scan pattern. And with the ground rushing up, the view outside would’ve been far more commanding. Speaking personally, when I shut down engines at the end of a flight, I consciously force myself to operate each fuel switch independently and with full attention. I avoid building muscle memory that might lead to switching off both engines in a fast, well-practiced habit. If this is a technical issue, I assume we’ll know soon enough. On item 2, the video shows no asymmetry at any time, so there is only a symmetric failure of the engines possible. Back on a B747 classic, you could chop all 4 engines at the same time with one hand, on a B737, also, not so much on a B777 or B787. I would doubt that anyone used two hands to cut the fuel at screen height. Note, there was a B744 that lost one engine in cruise when a clip board fell off the coaming. Didn't happen twice, and it only happened to one engine.
Yes indeed, the moment they pulled the gear lever, as we see the gear begin the retraction process, and then suddenly stop. Almost as if they suddenly lost power.
We can see the landing gear retraction process begin. We see the bogies tilted in the second video. We can hear the RAT. We can see the RAT. We can see the flaps extended in the video and at the crash site. There isn't actually a single piece of evidence the flaps were raised, it's just a conclusion people jumped too before evidence began to emerge. The crazy thing is, when the report comes out and there is no mention of flaps none of the people who have been pushing the flap theory will self reflect or learn anything. They'll think those of us who didn't buy into it were just lucky, rather than it being down to use of fairly simple critical thinking. Neila83 is correct, the gear tilt pre retraction is rear wheels low, and at the commencement of the selection of the retraction cycle (generally), There is enough in the way of anomalies here to end up with regulatory action, and airlines themselves should/will be starting to pore over their systems and decide if they are comfortable with the airworthiness of the aircraft at this moment. A latent single point of failure is not a comfortable place to be. Inhibiting TCMA might be a good interim option, that system could have been negated by having the ATR ARM switches....(Both)... ARM deferred to the before takeoff checks. The EAFR recovery should result in action within the next 24-48 hours. Boeing needs to be getting their tiger teams warmed up, they can ill afford to have a latent system fault discovered that is not immediately responded to, and the general corporate response of "blame the pilots" is not likely to win any future orders. I think we are about to have some really busy days for the OEM. Not sure that Neila83 is that far off the mark at all. Last edited by fdr; 14th June 2025 at 01:21 . Reason: corrected for B788 by Capt Bloggs! |
aeo
June 14, 2025, 14:05:00 GMT 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. |
njc
June 14, 2025, 15:06:00 GMT 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 June 2025 at 19:35 . Reason: reference to deleted posts removed |
cncpc
June 14, 2025, 23:00:00 GMT permalink Post: 11901935 |
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Lifer01
June 15, 2025, 01:29:00 GMT permalink Post: 11902033 |
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fox niner
June 15, 2025, 12:51:00 GMT 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. |
EGPI10BR
June 15, 2025, 13:00:00 GMT permalink Post: 11902445 |
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DaveReidUK
June 15, 2025, 13:06:00 GMT 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? |