Posts about: "Gear Retraction" [Posts: 243 Pages: 13]

The video seems to show the aircraft descending from a few 100ft altitude to an impact. The landing gear appears down, flaps are harder to make out.

How does a 787 react to low speed? What are the protections on this type?

Exactly what I was thinking, landing gear still down at a height it would normally be retracted and the wing clean before normal acceleration altitude suggests just that. F/O with 1100 hours total time might make a mistake like that, although no one is immune.

Not video, shows a live feed?

Not familiar with the Dreamliner, but IF correct, it reportedly took off without backtracking, resulting in a TODA of app 1900m.. That sounds very marginal for a heavy 787 embarking on a 9+hr flight.
The horrifying video (IF legit) also suggests the aircraft is seriously on the backside of the power curve with gear down / flaps up..... Speculation: too early rotation due to rwy end approaching (too) fast-then mistakenly retracts flaps instead of raising the gear.... That would result in what we saw in the video... Pure speculation in this rumour network. A sad day indeed...

Plenty of engine noise on the video. Aircraft appears stable, wings level, not stalled. Gear down, flaps clearly up.

+1

​​​​​​​They only had half the runway. Flight Radar shows the track.

video is legit

Looks like a tragic tragic lack of lift and thrust. PF seems to combat sink (or lack of climb rate) by simply pulling back nto deeper draggy stall.
Were flaps up at start of roll? or subsequently after marginal liftoff ? Unfamiliar with 787s interlocks and take-off protections but undercarriage should have been up.or going up in that state at a minimum

Talking head on BBC speculating that it may be a case of retracted flaps instead of landing gear. Seems plausible

And PF's reaction being to pull back and stall into the ground rather than lower the nose, select TOGA and call for gear up (or do it himself)....

Stupid question: What is backtracking in this context?

Landing gear down when the aircraft struggles to climb is a key factor in this accident. It points to a \xabgear up\xbb but flaps incorrectly selected up instead. It has happened before several times, but without tragic results.

No speculation as to what caused the crash, but a couple of points. If there was an inadvertent retraction of flaps instead of gear, this could potentially be remedied by reselecting flaps promptly once recognised. Whether the startle factor would allow it is another thing.

If the RAT is indeed out and there was some sort of powerplant issue, ie. double engine failure, I don't think I would be in a hurry to retract the gear either. In fact it may well have been put down again in that scenario.

Regardless, awful footage to watch. RIP.

Boeing 744 logic results in acceleration and thrust reduction if flap retraction commences before programmed acceleration height. Lots of the B744 FMC /Autoflight logic seems to have made its way into the 787. If flaps were retracted in lieu of gear and this logic was so, could explain the lack of noise?

Like most Boeings, on the 787 you are prevented from selecting the flaps/slats all the way up in one go by the gate at flap 1. If this was a mis-selection by one of the pilots, they would have been prevented from selecting ALL the high lift devices up in one go by the flap 1 gate. Even if you manage to get the lever to the Flaps Up position then below 225kts you should get Slat-Gap protection which maintains MOST of the lift. I have never tried it personally but that's the operation as advertised by Boeing. Would that provide enough lift to save them...... that is really a matter of debate.

The aircraft may have suffered a power loss of one or both engines possibly by bird strike. I have to say that the B787 is the very easiest aircraft I have ever flown when handling an engine failure above V1. The flight path vector and the flight director in the head up display make finessing an engine failure absolute child's play. Having said that the Boeing 787 performance is calculated right to the limits of legal requirement, so there is no scope for mis-handling. If they failed to select the landing gear up, not due to a flap lever mis-selection, but some another distraction, like an engine failure, then the aircraft would struggle to accelerate to V2 to safely climb away.

The B787 derates are calculated to give an acceptable Vmca in the event of an engine failure. That is to say, if you apply any more power asymmetricly the Vmca criteria of up to 5deg of bank towards the live engine will require more control input resulting in more control drag. Our SOP was - If you need it - Use It! Thankfully I never had to find out.

By way of illustration, on the B747-400, leaving the gear down following an engine failure had the same effect as failing two of the four engines.

For an aircraft that will likely have TOGA pressed and be at a high power setting (plus the RAT deployed) it sounds awfully quiet.
Perhaps the gear was down because they knew they were going to force land due to lack of thrust.
(Only a 738 driver), but the electric pumps to drive the hydraulics is much slower than the engine driven pumps and so flap selection / re-selection could be not as expected.

RIP to all involved.

787 gear and flaps/slats are both on the centre system, powered by 2x big electric pumps and no EDPs, so retraction should be minimally impacted by engine failure assuming electric power was still available and reconfiguration worked. Note the 787 has two generators per engine so generator failure is also unlikely to contribute, unless both engines failed taking out all four generators (and presumably no APU running).

From that thread, I believe it was discussed that on most/all other large transports, deploying the RAT re-powers the CVR/FDR. The 737 didn't have that happen because no RAT. You may still get a few second gap while the RAT deploys.

The 787 has 2x Enhanced Airborne Flight Recorders (EAFR), which each record both cockpit voice and flight data. I expect they are also fitted with the dedicated batteries that the Jeju was a year or two too early to require. Per the NTSB , the forward recorder has a 10-minute backup battery.

Hopefully flight data is not going to be an issue for this investigation.

The suggestion is that the buzzsaw/propeller sound is the RAT; it does sound a bit like an interference pattern, but you don't get the engine roar with it.

It's also maybe visible in a few stills (e.g. post 64).

Ok, nobody mentioned this or at least I can't see this. If the brakes are very hot due to use during taxying the landing gear is often left down longer than usual to cool the brakes to a safe temperature before retraction (see Swissair 306) It was also very hot on the ground today
Comments ? I'll get my coat...

Not a big or busy airport. Taxi time would've been minimal. Aircraft was on the ground for around 2 hours from the previous flight which is enough in most cases. It's every so slightly possible though.

Extremely unlikely imho.

If pre-planned, it would apply a serious (commercially costly) weight penalty on take off. If not pre-planned it would invalidate all the normal take-off performance figures. I have no idea what the cause of this tragic accident is but I am sure the investigators will be at least considering the gear and flap positions and associated selections.