Posts about: "Flap Setting" [Posts: 55 Pages: 3]

ahmetdouas
2025-06-12T18:05:00
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Post: 11899553
Originally Posted by JG1
Looking at the video of the takeoff roll, it seemed normal, normal rotation, normal initial climb. Other incidents with incorrect performance data or incorrect flap setting (especially flapless) resulted in an extended rotation phase, often with a tailstrike which doesn't seem to be the case here. So the flaps were probably set correctly.

This aircraft then climbed okay but then 3 things happened

1. They didn't raise the gear (maybe due distraction)
2. They apparently called a mayday for an engine problem
3. The aircraft started to sink and continued to do so until ground impact

The videos and the flight path don't seem to show lateral deviation or rudder application but if they called mayday for an engine problem we've got to go with that.

Perhaps the flaps were retracted early but I don't see any pitch change, just sink.

As the aircraft is certified to fly on a single engine, it should have done so. That it didn't seems to indicate that the other engine also stopped developing the required thrust.

Whether it was shut down unintentionally or damaged due to some environmental factor remains to be seen but my moneys on inadvertent shutdown.
nothing was normal the plane rotated right at the end of the runway far too late and barely climbed at all for 10 seconds before falling 20 seconds and finally crashing 30 seconds after take off.

The most obvious answer is low power/flaps setting if the engines were weird they would have probably aborted take off. Bird strike/engine issue during take off roll after v1? Super unlikely but never say never
Airboard
2025-06-12T23:50:00
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Post: 11899842
Wow love the theories. Ok why was the gear still down. Under all circumstances that comes up with positive rate. Can\x92t see the flaps but sure looks like they were retracted instead of gear coming up.

engine failure. Sure that would suck lift out but all parameters take thay into effect with the proper flap setting. And you can\x92t take off without the right flap setting per the performance data unless you ignore it.

Loss of lift. VNAV engages at 400 ft and targets airspeed in MCP.
T28B
2025-06-12T23:54:00
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Post: 11899847
Originally Posted by Airboard
Ok why was the gear still down. Under all circumstances that comes up with positive rate. Can’t see the flaps but sure looks like they were retracted instead of gear coming up.

engine failure. Sure that would suck lift out but all parameters take thay into effect with the proper flap setting. And you can’t take off without the right flap setting per the performance data unless you ignore it.

Loss of lift. VNAV engages at 400 ft and targets airspeed in MCP.
Airboard, do you fly the 787?
nomess
2025-06-13T05:10:00
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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.
aeo
2025-06-13T06:15:00
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Post: 11900048
I tend to agree. I taught ground school for the 744, 748, 777, 320 and 330. I used to tell my students the most critical phase of flight is the 3 minutes after 100 knots. That\x92s when critical TO inhibits occur and ADP\x92s (777) come online etc etc. But the elephant in the room for me is thrust reduction. On the Boeing it can be an altitude or a flap setting where the AT will reduce thrust from derated TO to CLB. For the Bus it\x92s an altitude and the crew are prompted to move the TL\x92s to the CLB detent. If at positive rate (or climb) the PM selected one or two units of flap up instead of gear up would the thrust reduction explain the aircraft\x92s response? This would startle any PF and he wouldn\x92t (muscle memory) manually move the levers back to TOGA while trying to follow the FD Bars to maintain V2 and RWY heading.

If the RAT deployment is indeed confirmed then my theory is out the window\x85.

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babybaby
2025-06-13T10:29:00
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Post: 11900315
FR24 data appears to stop shortly after airborne but well before impact.
That would seem to align with the significant loss of electrics as a result of loss of engine generators theory?
Flaps prematurely retracted shouldn\x92t be a cause of loss of electrical power to the transponder. If electrical power was normal then one would have expected data info until impact, regardless of flap position.

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Xeptu
2025-06-13T13:50:00
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Post: 11900540
I think flap setting for takeoff is not in the equation because the aircraft became airborne and was seen in the video climbing away, the takeoff is over.
retracting the flap instead of the gear is a high possibility, yes there would be sink but the aircraft would still be accelerating, distance over time says an impact speed of about 120 kts.
where it would have been 200 kts in this scenario. I also think it would be unmistakeable to those on the ground if the engines were at go around thrust at impact.

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nolimitholdem
2025-06-13T14:15:00
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Post: 11900554
Originally Posted by xetroV
Video evidence suggests at least the leading edge devices were extended:

https://youtu.be/oUFS2np0mKc?si=0f1Td6bQiqNOE4U-
LE devices extended on impact would correspond with the B787 auto-gap function that extends the slats in certain low-speed high AOA conditions for stall protection (aka "Autoslats"). Which this aircraft most certainly was in before impact.

Only to say, that LE devices seen extended on the crash a/c don't prove configuration on takeoff.

B777/787 rated/current/active pilot.

B787 FCOM:

The slat autogap function is only available in primary mode when the slats are in the middle position and the airspeed is below 225 KIAS. At a high angle of attack, autogap fully extends the slats to increase the wing camber, thus increasing the lift and margin to stall. The slats return to the middle position after the angle of attack decreases. The autogap trip threshold is a function of AOA, airspeed and flap position.

Last edited by T28B; 13th Jun 2025 at 16:58 . Reason: Formatting assistance

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pug
2025-06-13T20:30:00
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Post: 11900873
Originally Posted by go-around flap 15
It's tempting to think that, however one may also have made the case 'why doesn't Boeing install a system that prevents the nose getting too high on the 737 MAX? Then they won't have to retrain crews on handling differences'. We know how that worked out.

When designing anything you need to account for unintended consequences and the possibilities for that system adversely affecting safety if it were to malfunction. If you introduced a system designed to prevent flap retraction 20 to 30s after liftoff, what if failure in a channel of that system then prevents flap retraction required to achieve a MACG with critical terrain on departure. We could 'why don't they do this / why don't they do that' until eventually we end up with not flying at all.

On your point of integrated scales, there is a far easier way to cross check actual aicraft weight with calculated weight: a computer that cross references acceleration data on the takeoff run with known values from lookup tables based on specific environmental conditions and engine thrust settings. If you're not accelerating at a normal rate expected for the calculated thrust and weight a warning can be triggered. This was a recommendation echoed by the AAIB following the incident with a Jet2 aircraft getting airborne at only 70% thrust. I believe Airbus and Boeing are looking into the potential implementation of such a safety system.
This I believe is an option to retrofit. Can\x92t recall the supplier, Honeywell perhaps, not sure on the 737-MAX and whether it has anything fitted as standard.. Anyway the more cost effective option (for NG operators) is to amend SOPs where appropriate. However the U.K. CAA do apparently intend on creating a working group regarding such events. See also the TUI event at BRS.

https://asn.flightsafety.org/wikibase/388602

https://simpleflying.com/aaib-report...f-runway-10ft/

It\x92s worth noting that the acceleration rate was exceptionally low in the TUI event based on the average for that airport. I refer you to my initial post on this thread, it\x92s a risk that there is no config warning horn (to my knowledge) on the B737-800 that will alert the crew, upon selection of TOGA, that the performance solution entered into the FMC does not agree with the actual config. In the case of flap setting, it will only alert if a non standard take-off flap setting is selected. If in the unlikely event TOGA is not pressed at all then\x85..

Airbus have added something of an FWC to their 321NEO aircraft that will alert crew to this - something I\x92d heard from bus mates but wasn\x92t 100% certain on so thanks to those on here that confirmed.

Sorry for further thread derailment, however felt it might be of interest. 787 rated crew on this thread suggest this would form part of the electronic checklist on the aircraft so in the case of the event at hand a red herring.


Last edited by pug; 13th Jun 2025 at 21:29 .

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Sailvi767
2025-06-13T21:53:00
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Post: 11900949
Originally Posted by SpGo
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.
Even if they selected the flaps to the next higher flap position on a flight to London the 787 would have been able to power out of it. The deceleration rate and aircraft attitude don\x92t suggest to me an inadvertent flap retraction. I have done this exercise in the 767-300ER and it\x92s almost a non event unless extremely heavy.

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bogie30
2025-06-14T01:54:00
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Post: 11901072
If the Flaps were retracted instead of the gear then this would trigger a reduction of the Take Off Thrust to Climb thrust. With less thrust and a reducing Flap setting the aircraft would slowly loose lift and height.

Roo
2025-06-14T02:03:00
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Post: 11901073
Originally Posted by Sailvi767
There is no auto flap retract on the 787.


Flap/Slat Load Relief
In the primary mode, the flap load relief system protects the flaps from excessive air loads. If flap airspeed placard limits are exceeded with the flaps in the 15 through 30 position, LOAD RELIEF is displayed and the flaps automatically retract to a safe position appropriate to the airspeed. Load relief retraction is limited to flaps 5. When airspeed is reduced, the flaps automatically re–extend as airspeed allows. Re–extension is limited to the commanded flap position.

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Sailvi767
2025-06-14T02:17:00
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Post: 11901081
Originally Posted by Roo


Flap/Slat Load Relief
In the primary mode, the flap load relief system protects the flaps from excessive air loads. If flap airspeed placard limits are exceeded with the flaps in the 15 through 30 position, LOAD RELIEF is displayed and the flaps automatically retract to a safe position appropriate to the airspeed. Load relief retraction is limited to flaps 5. When airspeed is reduced, the flaps automatically re–extend as airspeed allows. Re–extension is limited to the commanded flap position.
Thats a load relief system for a flap over speed. It never retracts the slats and only moves the flaps to the next position. There was definitely no overspeed of the flaps in this accident.
Calldepartures
2025-06-14T02:17:00
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Post: 11901082
YMML EK?

Originally Posted by nachtmusak
Speaking of invalid derate, I sort of recall reading about an incident with a very heavy aircraft and some kind of mistake or fault (or maybe both?) leading to insufficient takeoff thrust on a hot day. Fortunately the crew was able to stabilise the aircraft and return safely to the airport, but unfortunately I don't remember any more details, and so finding it has been difficult.

Might that incident shed any light on this one, especially since that crew was able to recover?

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.

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Toruk Macto
2025-06-14T02:39:00
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Post: 11901091
Originally Posted by Calldepartures
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.
Hard to imagine if that mistake was made he\x92d get on the radio saying engines losing power with out pushing levers up first ? What ever happened had guy in left seat stunned ? My opinion only , if he was a training Capt he , like most guys in the left keep a good watch on where hands go . If an incorrect weight, chances are he\x92d know on runway and thrust to TOGA , those engines appear to be along way off producing thrust . If flap was raised by mistake , flap can be lowered just as quick . He\x92d not be on radio saying thrust decreasing while looking at flap up . If miss set alt hold he\x92d be calling modes and selecting higher altitude and changing climb mode thinking he\x92s got to remember to write a report on arrival . If engines turned off deliberately!! Big If , no need for radio calls , turn engines back on and protect them and try isolating flight controls, if possible .

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 .
KSINGH
2025-06-14T08:43:00
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Post: 11901266



I’m not a 787 driver so for fear of looking dumb in front of those that are this still confuses me. Even IF they’ve mis-selected the flap setting (I still don’t think it’s been cemented on here that there is in fact a FMS/flap setting disagreement warning but i believe there is), had the wrong de-rated take off settings, selected flaps instead of gear up the 787 with massive high bypass engines, FBW and full envelope protections surely cannot let itself be put in such a low energy/high alpha regime as we saw in the videos IF it has both fans functioning normally, surely?

the pilots may have messed up royally and numerous times so those holes lined up but the plane is the final block in the chain and a 21st century all digital entirely clean sheet design was sold as being immune to such catastrophic outcomes from a few minor (consequential yes) and fairly common errors- aren’t all the protections and our procedures designed after decades of mistakes?

im having a hard time squaring how a fully functioning modern bird like this could allow for this outcome and almost whatever the pilots did outside of unbelievable inputs and the pilots are are a bit of a red herring IMO


Dale Winsley
@Winsleydale
No. The LE slats are deployed therefore the flaps are as well. This is an automatic linkage. The flaps are set at Take-Off. Hard to see from the angle but they are...if slats are out (easy to see) then flaps are set. Looks like Flaps 5. Also, the 787 has the highest Thrust-to-Weight ratio of any airliner on Earth. The change in Alpha and lift is a trifling matter for it, at these settings (1-5). It will fly out of it easily, even at that density altitude. The attitude change is - in the circumstances I describe, consistent with a massive power loss (both sides). I believe based on probability that simultaneous mechanical failure is not the cause. Fuel contamination or starvation is likewise unlikely based on the 787 fuel system. The common element is the FADEC/Autothrottle/TOGO. However, each engine FADEC is dual redundant two channels. So any such common failure must happen further upstream. From a design perspective, that would be unthinkable. But this is Boeing. Given what I can see with my own eyes, I believe the flap issue is a non-starter. Also, re the landing gear: Clearly the Positive Rate challenge would be met based on normal rotation and fly-off at V2. But since we know the flaps were set correctly, that rules out an "oopsie" moment. Just as likely there was at the challenge moment an indication that something was amiss, and the Gear Up call was not made. They see both N1s unwinding and it takes a second to get past the WFT factor. They cross-check and see the airspeed also unwinding. Then they unload the Alpha and pitch to gear down Vy. And they had another 6 seconds. Whatever it was, it was not a flap, mechanical or fuel issue. We will know soon enough. But this is Boeing. My gut says "software". All 787s worldwide need to be grounded, now.
6:10 AM \xb7 Jun 14, 2025
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Last edited by Senior Pilot; 14th Jun 2025 at 09:04 . Reason: Add X quote
KSINGH
2025-06-14T08:52:00
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Post: 11901272
Originally Posted by KSINGH
https://x.com/winsleydale/status/193...230524974?s=46

I\x92m not a 787 driver so for fear of looking dumb in front of those that are this still confuses me. Even IF they\x92ve mis-selected the flap setting (I still don\x92t think it\x92s been cemented on here that there is in fact a FMS/flap setting disagreement warning but i believe there is), had the wrong de-rated take off settings, selected flaps instead of gear up the 787 with massive high bypass engines, FBW and full envelope protections surely cannot let itself be put in such a low energy/high alpha regime as we saw in the videos IF it has both fans functioning normally, surely?

the pilots may have messed up royally and numerous times so those holes lined up but the plane is the final block in the chain and a 21st century all digital entirely clean sheet design was sold as being immune to such catastrophic outcomes from a few minor (consequential yes) and fairly common errors- aren\x92t all the protections and our procedures designed after decades of mistakes?

im having a hard time squaring how a fully functioning modern bird like this could allow for this outcome and almost whatever the pilots did outside of unbelievable inputs and the pilots are are a bit of a red herring IMO
also to add, if it turns out that this was triggered by some procedural slips from the crew, if I was an airline I\x92d seriously consider my fleet choices going forward. I\x92ve never been on the anti-Boeing bandwagon, that has been the refuge of many ignorant people over the years, but I struggle to believe an Airbus would\x92ve got itself into that situation and we know for a fact they with their protections (narrow bodies mostly) have saved multiple crews (and their pax) in recent memory. The most modern Boeing around was meant to be as safe as possible and redundant

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directsosij
2025-06-14T11:55:00
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Post: 11901403
Originally Posted by KSINGH
https://x.com/winsleydale/status/193...230524974?s=46



I\x92m not a 787 driver so for fear of looking dumb in front of those that are this still confuses me. Even IF they\x92ve mis-selected the flap setting (I still don\x92t think it\x92s been cemented on here that there is in fact a FMS/flap setting disagreement warning but i believe there is), had the wrong de-rated take off settings, selected flaps instead of gear up the 787 with massive high bypass engines, FBW and full envelope protections surely cannot let itself be put in such a low energy/high alpha regime as we saw in the videos IF it has both fans functioning normally, surely?

the pilots may have messed up royally and numerous times so those holes lined up but the plane is the final block in the chain and a 21st century all digital entirely clean sheet design was sold as being immune to such catastrophic outcomes from a few minor (consequential yes) and fairly common errors- aren\x92t all the protections and our procedures designed after decades of mistakes?

im having a hard time squaring how a fully functioning modern bird like this could allow for this outcome and almost whatever the pilots did outside of unbelievable inputs and the pilots are are a bit of a red herring IMO
I don\x92t agree with either of those assessments at all. One strongly pushing the flap scenario and the other a software fault. The flap one has been done ad nauseam, I won\x92t repeat it. A sudden software glitch on a decade plus old model is a stretch and likewise a call to ground the entire fleet immediately.

of course like everyone else I have absolutely no idea what actually happened but I am willing to bet the explanation will be simpler than everyone is expecting.

I am not going to speculate further as I believe it is a waste of time without further information.

For the record I am not b787 rated but I do have Boeing and airbus narrow body and wide body time and i struggle to forsee a situation where the aircraft falls out of the sky at 200ft without a very serious error of some description.

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appruser
2025-06-14T17:21:00
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Post: 11901674
Originally Posted by Xeptu
LoL have a think about what you just said. Below 200 feet normally in transition to flare, such a rafical body angle change is the very thing that had to be trained out of pilots, it's fatal.
So I called a 787 Captain to ask him about this - in dual-engine fail, at 200ft or below, 170kts, flaps 5, does the PF push the nose down for best glide, do nothing, or push nose up in transition to flare?

This is what he said - the PF *has* to push the nose down to prevent a stall and keep the aircraft flying, and if the PF won't, the aircraft will do so to prevent a stall. How much depends on the flap setting.
Tech Guy
2025-06-14T19:49:00
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Post: 11901771
Originally Posted by appruser
So I called a 787 Captain to ask him about this - in dual-engine fail, at 200ft or below, 170kts, flaps 5, does the PF push the nose down for best glide, do nothing, or push nose up in transition to flare?

This is what he said - the PF *has* to push the nose down to prevent a stall and keep the aircraft flying, and if the PF won't, the aircraft will do so to prevent a stall. How much depends on the flap setting.
I would "suggest" when your only options are push the nose down to increase forwards velocity (and plough into the ground); or pull back, possibly stall and belly flop onto the ground. There must be a point when you are so low and slow that the latter becomes the better option?

It is also interesting to note that on Google maps, the crash location has been marked. If the aircraft flew another 300m, they would have crashed into the cities hospital. Could the pilot in his last moments have been trying to avoid that scenario?
https://maps.app.goo.gl/zSyU8Y6A7AMS9FWy5

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