Posts about: "Flaps (All)" [Posts: 165 Pages: 9]

If decrease in thrust not by transition to climb thrust due to early inadvertent flap retraction and pilot action on fuel control switches from accomplishing dual engine failure memory items, then fuel cavitation /fuel fumes lock may be a cause. Just saying.

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.

Yes. But I have not flown this scenario in the sim. Way too many protection to take off without proper configuration which leads me to believe loss of lift due to flap retraction. 1100 hr FO ……..

I\x92ll reply to my own post in light of the RAT deployment. If true then this opens up to a lot more. And simply guessing with grainy video a fools game. All I saw was gear down to high Into the climb. This should not happen under any circumstance . Dual engine failure would explain the loss of lift obviously. Early flap retraction also. One would hope it\x92s not a simple as that: cheers

On item 1, the TCMA issue should have been fixed, it does fit the sort of issue that occurred here. TDRACER can talk to that, and has done in 2019 and again in post 792. As to flap auto retraction, the B787 like all Boeings has a gated flap lever, and the flaps are only able to move independent of the lever by flap load relief. That would not have caused a loss of thrust, and in this case it is evident that the event is a thrust loss not a CL loss.

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.


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Neila83 is correct, the gear tilt pre retraction is rear wheels low, and at the commencement of the selection of the retraction cycle (generally), the first thing that happens is the inboard MLG doors start to open below the wheel well and then the bogie is driven to front wheels low. (There is also an option that the inboard gear doors start to open early as a result of WOW sensing to improve the SSL climb limit). [my bad, for the B788 Capt Bloggs informs us the gear door sequence is after the tilt, not before, the B789 has the before tilt, the option for the door open at rotate is separate]

The inboard doors do not appear to have opened in this case, yet, the gear is forward wheels down. This appears to be out of sequence. TD may have better knowledge on the options that exist with the B788, but this is not looking good at this time.

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.

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.

I have to agree with everything here except your assertion about engine shutdown.
Even though these are big engines with plenty of inertia, when you select engine shut off they spool down very quickly if on load. IE, The generators, two per engine and hydraulic pumps, etc, being driven by the (relatively) small mass of the N2 rotor will drag the speed down very quickly, the gennies will trip offine in seconds, the pumps will quickly reduce flow and pressure.
As for what went wrong.
If the engines have stopped working there has to be a common failure mode, fuel is one but as has been said, no other aircraft has had a problem, as far as we know. FOD? It would have to be something major to shut down two GeNX engines and there would be debris all over the runway, we would know by now.
I have no idea if the RAT has deployed, I can't see it in the video and the noise could be something else.
We shall see.
There is compelling evidence that flaps are set correctly and not retracted inadvertently.
I await further evidence.
Edit to add. LAE 40 years, type rated on 737 to 787 with lots of others in between.

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.

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

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

Every airline training course I have had stressed never touching a critical item below 400 feet. That was later changed to 1000 feet at my airline. . I can\x92t conceive of the crew shutting a engine down in the first 8 seconds of flight.

"I might see a small puff of smoke and a smoke-ring just before they pass the shed."

I originally wondered about that ... until an old colleague sent me this short clip of a triple kicking up dust rotating in the same location

For your consideration: (20 second clip)

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.

Thanks as always TDR for your excellent professional input. It is therefore so much more perplexing that even you cant logic our way out of this impasse. That is, the assumption that the aircraft experienced a double engine failure (supported by a reasonably convincing argument that the RAT deployed), and yet no plausible reason (that we can see) for such an event. So some then collectively slip into the tired and lazy theories of intentional or unintentional crew actions that 1. beggar belief (intentional), 2. defy physics (flaps instead of gear despite clear evidence to the contrary) and call into question the professionalism of a very experienced Captain and crew as well as the aircraft manufacturer (because...well its Boeing so it must be software ).

Yet, the answer must be simpler and staring us in the face since logic and experience (everything you have offered TDR), tell us that modern airliner engines generally do not just suddenly quit flying at the same time. In this regard we can recall several instances of double engine failure associated with bird strikes generally involving large birds or large flocks or both. But it seems we have discounted this theory very early in discussion. Why? Because we cant see any birds, or flocks of birds or engine flames/surges or puffs of smokes from the engines which would support this. Really?

I have read all the 100's of posts (sadly) and while some very early posters tried to analyze the imagery, I suspect the very poor quality eventually discouraged most from seeing anything of interest. However, smattered throughout this discussion from the beginning to the end there have about four posts that describe seeing something where others have not. At least two of these were related to possible smoke but which were probably just the dust blown outwards by the wingtip vortices. Two others however have mentioned possible flames and puffs of smoke.

The video of course is very poor. There should be a special place in hell for people who subject us to looking at a video with continuous zooming in and out, inability to retain focus on the subject (it was just a CCTV monitor, not the actual aircraft they had to focus on) and constant camera shake. A video of a video, and then the resolution probably reduced for social media upload. This all results in a very unwatchable record of the aircrafts departure. The only immediate information gleaned seems to be some idea of how far down the runway the aircraft was at takeoff and the parabolic curve as it very clearly described the aircrafts flight path.




Air India Flight 171 on departure
But take a look at this frame. The right engine shows an artifact (pixelation if you like) that might represent a surge flame. I can almost see a puff of smoke just inboard of the aileron that may be associated with that too.

Am I just seeing distortion? Am I just seeing some smoke because that's where I would expect to see it?
We are all very used to seeing everything in 4K today but back in the day when everything was low res we used to join the dots. If pixels existed then something was there. If they didn't, it wasn't.
So if it's just pixels caused by distortion then they have coincidentally appeared in the tailpipe of an aircraft that crashed shortly after takeoff with a presumed double engine failure.

But surely we would see the birds? Well, not in this video. You cant even see the registration number on the side of the aircraft and that is much bigger than a bird. Haze, distortion, focus and low res, and each individual bird wouldn't even make up a pixel.

So make of this what you will, but this problem may have started on the ground. Birds strikes are very common according to Some AI pilots who interviewed for this following article but I have no idea of the authenticity of this report:

https://www.rediff.com/news/report/a...h/20250613.htm "The Air India pilots also added that Ahmedabad airport has long been known for bird activity near the runway, which could have contributed to the incident.

"This issue (of the excessive presence of birds) has been flagged multiple times," a third Air India pilot said, asking not to be named."
Of course, a single engine failure would not have brought this aircraft down, nor would it have deployed the RAT, but we can't see what happened on the left engine when the aircraft slipped behind the radio antenna building.

While these high bypass engines are designed and certified to keep running after experiencing certain types of bird strike, the effect on two engines concerns have been voiced about the contribution of certification to the mitigation of the risk hazardous bird strike in the two engine case.

This from Sky Library:
https://skybrary.aero/articles/aircr...nue%20to%20fly .

" A number of concerns have been quite widely voiced about the contribution of certification to the mitigation of the risk of hazardous bird strikes:

• The case of bird ingestion into more than one engine at the same time is not addressed directly and it is clearly extremely difficult to meaningfully estimate the probability of such an occurrence. However, it has been observed that, since some of the current standards only require that a damaged engine can be safely shut down, this circumstance should be more fully considered when determining the acceptable outcome of ingestion into single engines, especially for the twin engine case.
• It has been noted that the potential effects of bird strikes on modern electronic flight control systems and flight deck instrument displays have not yet been fully assessed.

Maybe someone can do some video enhancing of this image as others have done with the audio enhancement to give strong probability of RAT deployment.

If my suggestion can be corroborated at all, then the question of what happened next becomes somewhat easier to answer. Perhaps neither engine stopped running but they did so with limited thrust? If anything from the pilots mayday call can believed, it wasn't engines shut down..it was no thrust. So why did the RAT deploy? Cant answer that. And, I cant imagine it would be manually deployed if both engines were still running.
However, TDR did say.

"On the 767 and 747-400, when you shutdown an engine and the IDG goes offline, there is a momentary 'glitch' in the electrical power system as it reconfigures for the available power source - this is why you see the flight deck displays flicker and return, and the cabin lights momentarily flicker."

Startle factor that electrically systems were about to fail? Manually deploy RAT?

Edit: I might add, they would have found remains on the runway if this did indeed happen. But we have heard anything from anybody?

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".

Very unlikely IMO as it's difficult to imagine even a low time pilot making this error--not impossible of course.

If you are correct and early flap retraction instead of gear.....why was the rat out? It is almost assuredly deployed. Why did the video not indicate high thrust on the engines? The are silent. Pulling the flaps too early won't cause an engine failure(s) ans won't cause the rat to deploy.

Even if inexperienced FO retracts flaps early certainly a senior captain who is also per some reports a training captain.....certainly he would have gone for max thrust and lowered the nose to try and fly out of it. Certainly he would have raised the gear?!?!?!

Still not making sense....unless....and I posted this earlier.....was it intentional?!?!?

Do we know for certain there was a mayday? If yes, do we know for certain is was the captain? Could the captain have possibly become incapacitated around VR and low time FO totally unprepared and froze?

I am always amazed how foreign airlines put super low time FOs in biiiiig planes.....scary. i chatted up an early 20 somthing Ryanair FO and she was excited bc she just hit 300 hrs. I said oh 300 on type (737)?? She says no.....300 hrs...total time. And she's flying internationally!!!!!!

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 ?

Capn Bloggs We shall see!

A mate tried gear/flap scenario in the sim earlier. Selecting flaps up (all the way) instead of the gear did not predjudice the flight path at all. They selected flaps up at normal gear retraction height and punched the AP in. The Slats remained out until 225kts (as per my post about 50 pages ago) and the aircraft climbed happily away clearing all obstacle by a good margin.

Was that using the same aircraft weight, same flaps, same ambient temperature and with the same de-rate(s) as the accident flight? Presumably he had inside information to find the appropriate numbers?