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

Shep69
2025-06-14T19:55:00
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Post: 11901777
Originally Posted by zero/zero
Climb Power is programmed as an altitude in the FMC, usually 1000' but sometimes higher for noise abatement, which in this case they wouldn't have reached.

In some instances, the TO derate is so significant that the selection of climb power moves the thrust levers forward. AMD is sea level with a long runway, so can imagine it would be a fairly low power take off.
Flew the 777 assuming the FMS is similar. We would usually program the FMS to select climb power based on flap setting (F5 for a F15/20 TO; flaps 1 for a F5 takeoff). It could also be set to an altitude but our SOP was normally flap setting.

And yes with a takeoff with heavy derates CLB might be more than selected for TO (although IIRC CLB2 usually wasn`t when we were using TO2 with moderate AT).

Understand it`s a long runway but I wouldn’t assume heavy derates with a moderately long flight and full airplane (and hot day). But we don`t know yet.
Tu.114
2025-06-15T09:46:00
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Post: 11902300
Something rather relevant has not yet been shown on this thread: a performance calculation.

Could somebody with access to a 787 performance calculator please show realistic figures for this type out of Ahmedabads runway 23?

Weather at the time of the accident:

VAAH 120830Z 24003KT 6000 NSC 37/17 Q1000 NOSIG=
VAAH 120800Z 25007KT 6000 NSC 37/16 Q1001 NOSIG=

With 240 souls on board, a payload of 20-22 tons might be a ballpark figure, and a fuel load of about 50 tons was claimed as realistic in earlier posts.

An appropriate flap setting, a flex temperature, V1, Vr, V2, flap retraction and green dot speed (or its Boeing equivalent), a climb gradient after departure, and some distances might be of interest, I\xb4d think.

Last edited by Tu.114; 15th Jun 2025 at 10:50 .

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sorvad
2025-06-15T09:56:00
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Post: 11902306
Originally Posted by amsm01
(Sorry, Airbus here and not familiar with Boeing) Flap 5 to 1 reduction on the Boeing triggers autothrust reduction, is that correct? If so, are there any other conditions that need to be met for this to happen like being in some kind of takeoff mode? Just thinking whether this would have potential otherwise in other regimes to cause issues, discontinued approach perhaps.

Am slightly puzzled as to why if flap reduction triggering climb thrust is part of the standard logic (and presumably clean-up technique) then partial dual thrust loss wouldn’t be immediately recognised as the classic symptom of gear / flap retraction handling error? I presume Boeing pilots / air India are just as aware of this it as everyone else, strikes me as odd that one would immediately go into full dual EF mode. My instinctive reaction without knowing the Boeing would be to firewall both TLs, would this have worked in the early flap retraction logic scenario? Many thanks all
Well I’m a triple driver so can’t be sure for the 78, but during the preflight we can programme thrust reduction either at and altitude or at flap 5 or 1. The company I’m with at the moment it’s an altitude, the one I was at before was usually at a flap setting. I’m not sure it’s got anything to do with this accident though. I guess you could enter 150ft instead of 1500ft in the FMC for the thrust reduction which would be alarming when it happened for sure but doesn’t explain the RAT or the gear observations….. unless someone did something like the memory items in response to what they perceived to be a double engine failure, but at that altitude, with no confirmation of any failure? I wouldn’t have thought so but never say never.

Last edited by sorvad; 15th Jun 2025 at 10:15 .

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Shep69
2025-06-15T11:32:00
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Post: 11902384
So for those getting in the weeds with one in several trillion (or lower) probabilities of systems failures have you considered that that improper RTOW (with or without improper flap setting), flap retraction / climb thrust trigger, is of much higher probability and has actually happened ?

Anyway I think we’ll find out soon if a systems failure was involved.

The FLCH Hold thing (Asiana) was never an issue and well known (at least on our line). And for a crew of 3 (or 4) to press a destabilized approach getting 40-ish knots too slow (!) isn’t a systems problem — it’s a breach of basic airmanship.

Last edited by Senior Pilot; 15th Jun 2025 at 11:49 . Reason: Edit

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sorvad
2025-06-15T12:39:00
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Post: 11902431
Originally Posted by Shep69
So for those getting in the weeds with one in several trillion (or lower) probabilities of systems failures have you considered that that improper RTOW (with or without improper flap setting), flap retraction / climb thrust trigger, is of much higher probability and has actually happened ?

Anyway I think we’ll find out soon if a systems failure was involved.

The FLCH Hold thing (Asiana) was never an issue and well known (at least on our line). And for a crew of 3 (or 4) to press a destabilized approach getting 40-ish knots too slow (!) isn’t a systems problem — it’s a breach of basic airmanship.
Have you considered that what you have described won’t deploy the rat, initiate the gear retraction sequence or cause the auto start of the APU, all of which there is a fair bit of compelling evidence for?
87guy
2025-06-15T14:35:00
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Post: 11902509
My first post here...I feel I need to, due to some posts I have read. As a 787 pilot who has flown Embraer, Airbus, 767 and the 787-8/-9, I am saddened by many of the posts on this thread.

Some of you should be ashamed.

Blaming the pilots before anyone has any idea what transpired.Short takeoff, improper flap/no flap setting, retracting the flaps instead of the gear, shutting down the wrong engine. In ANY other situation these actions would be laughable, and an insult to proffessional pilots the world over. Some commenting about the flaps even after pictures have shown that the flaps are extended. Also numerous people posting regarding shutting the wrong engine being shut down without any evidence to back this up. Videos clearly showing that the RAT was extended indicates that something very serious/catastrophic happened prior to this hull loss. People...this is the Proffessional Pilot's Rumour Network...Not the National Enquirer!!! I would urge everyone to WAIT for the report. Unbelievable.

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JustusW
2025-06-16T09:42:00
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Post: 11903330
Originally Posted by Burnt Fishtrousers
Im a layman who knows nothing and am just a PPL and am fascinated by the technicals.So does the computer store the recommended flap setting given all the information entered and then decide whether the actual setting used is appropriate and spits out a warning of checklist complete?what would happen if use of the full runway was entered into the computer, but actually they entered at an intersection, surely the info would be wrong ?...
The 787 in particular has a system that is fully automated for takeoff calculation. That includes Takeoff Distance, all relevant airspeeds, etc and uses combined sensor data to make pilot error in calculations exceedingly unlikely.

In addition the valid settings for takeoff flaps simply begin at 5\xb0, so anything less isn't even offered. The corresponding alarms will thus always trigger if you don't have at least 5\xb0 flaps set upon setting takeoff thrust, possibly requiring a higher setting depending on the calculated takeoff configuration. As mentioned before in this thread the loading of the accident aircraft should have been far below its maximums, so a 5\xb0 flaps takeoff is quite ordinary, and the aircraft left the runway well short of its end.

Also the aircraft used the entire runway after backtracking along it since there are no taxiways going that far. This information has been corrected by FR24 a while ago and stems from the incomplete GPS positional data that is inherent in ADS-B tracking, especially on the ground.

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Roo
2025-06-14T02:03:00
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Post: 11903883
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.
KSINGH
2025-06-14T08:43:00
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Post: 11903718



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
\xb7
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KSINGH
2025-06-14T08:52:00
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Post: 11903719
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
JustusW
2025-06-16T09:42:00
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Post: 11903756
Originally Posted by Burnt Fishtrousers
Im a layman who knows nothing and am just a PPL and am fascinated by the technicals.So does the computer store the recommended flap setting given all the information entered and then decide whether the actual setting used is appropriate and spits out a warning of checklist complete?what would happen if use of the full runway was entered into the computer, but actually they entered at an intersection, surely the info would be wrong ?...
The 787 in particular has a system that is fully automated for takeoff calculation. That includes Takeoff Distance, all relevant airspeeds, etc and uses combined sensor data to make pilot error in calculations exceedingly unlikely.

In addition the valid settings for takeoff flaps simply begin at 5\xb0, so anything less isn't even offered. The corresponding alarms will thus always trigger if you don't have at least 5\xb0 flaps set upon setting takeoff thrust, possibly requiring a higher setting depending on the calculated takeoff configuration. As mentioned before in this thread the loading of the accident aircraft should have been far below its maximums, so a 5\xb0 flaps takeoff is quite ordinary, and the aircraft left the runway well short of its end.

Also the aircraft used the entire runway after backtracking along it since there are no taxiways going that far. This information has been corrected by FR24 a while ago and stems from the incomplete GPS positional data that is inherent in ADS-B tracking, especially on the ground.
Capn Bloggs
2025-06-17T00:38:00
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Post: 11903892
Originally Posted by M.Mouse
this vey situation happened to a good friend of mine, former Tornado pilot with 25 years on airliners, as a captain and PF on a B777. In his words he was initially totally confused why the aircraft stopped climbing. He engaged the autopilot and quickly realised the problem but they came very close to stalling.

I would not like to place money on how quickly I would recognise the, highly unusual, situation of flaps being retracted with the gear remaining down and react appropriately.
It's interesting how good design ideas don't migrate between aircraft; I haven't flown the 777 or the 787, but in my last steed, the 717, at the bottom left corner of the PFD was the flap position, together with a little arrow that showed what they were doing. It was a simple exercise to glance there, when you told the PF to do something with the flaps/slats, to make sure it was happening (or not). The big one was when calling for Flap Zero. If you saw "Slats" appear, you would start yelling. I don't see such an indication of flap/slat position on the PFD on any 777 or 787 screen images I can find on the 'net.

While this didn't happen in this case, I suppose it is a good reminder to make a conscious effort to be aware of what your other half is doing. It's not difficult when you get used to it. As a side note, one outfit I worked for had a "Selected, three reds" response to "Gear Up".

Last edited by Senior Pilot; 17th Jun 2025 at 00:47 . Reason: Quote

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M.Mouse
2025-06-18T00:23:00
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Post: 11904796
In any case the autopilot wouldn’t have been in at such a low altitude and the PF would have been hand flying. Most of the min engagement altitudes for autopilots is 400’ AGL.
Minimum autopilot engagement height on the B787 is 200'.

767 pilot here, on the 767 it would capture the altitude, but more importantly, it would freeze the airspeed at whatever speed the alt capture occurred at. So the thrust levers would retard to maintain the much slower speed at the point of capture. This could be a possible scenario, especially if the crew was slow to realize what happened, AND the 787 has a similar low altitude capture issue.
On the B787 if VNAV is engaged and the aircraft captures an altitude below the programmed acceleration height then the vertical mode transitions to VNAV ALT and commences acceleration to the current flap setting limit speed -5 knots.

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Shep69
2025-06-18T01:33:00
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Post: 11904829
Originally Posted by M.Mouse
Minimum autopilot engagement height on the B787 is 200'.



On the B787 if VNAV is engaged and the aircraft captures an altitude below the programmed acceleration height then the vertical mode transitions to VNAV ALT and commences acceleration to the current flap setting limit speed -5 knots.
Assuming then that VNAV in the 78 engages at 200` AGL vice the 400` of the 777 ?
Sailvi767
2025-06-19T11:08:00
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Post: 11905928
Originally Posted by Magplug
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.
The rotation in the video appears normal and tail clearance is normal as well. That suggests VR was correct as well as the flap setting.

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