View Full Version : 777 Flare Compensation

16th May 2004, 12:24

Im a Licenced Eng. currently on a 777 type course, on the PFCS they describe a mode called flare compensation that puts in a nose DOWN command to the elevators at 50ft RA on Landing, to counter act the ground effect. Was just intrested on what that would feel like to you guys? is it even that noticable? it seems really strange to me, but its there!


17th May 2004, 04:35
I find that would be quite "wierd" (couldn't find a better word) for the 777 to have such a compansator. Never heard any of the 777 pilots i know talk about this "flare compensator". To my opinion I would find that a little on the unsafe side especially when aborting a landing, like I said that's my opinion.
I'll ask them soon and ill get back to you on this.

Nil defects
17th May 2004, 05:58
I woud assume this is part of the autoland system.

There is definitely no strange feeling when landing the aeroplane manually, apart from a huge amount of ground effect due to the large wing area.

It is probably the easiest jet to make consistent good landings. Just flare 2 degrees at 20-30 feet rad alt and hold the attitude. It will paint itelf on every time.

17th May 2004, 16:28
Thanks guys,

It must be very subtle then, is a normal mode of the PFCS nothing to do with autoland.

The ground effect must be the reason, maybe something to do with the lack of proper feel due to fly-by-wire.

Its a very clever aircraft im finding out!


17th May 2004, 19:24
Its a very clever aircraft im finding out!Obviously.... Shame this was copied from Airbus <G>:

.... As Ac descends thru' 30R.. system reduces pitch attitude... by 2deg Nose Down over 8 seconds... means takes gentle nose-up action by pilot to flare aircraft.

This is for A320 series. I believe was not present on A340 etc... Having flown both 320 and 340, cannot say I notice it, so suspect it's a clever feature that makes the FBW feel more realistic where required.


18th May 2004, 05:43
Ground Effect Compensation

All depends how it is done.
Expect that if the TPs have done their jobs properly then there will be insignificant feel of the compensation input by the pilot especially if the controls are FBW.

Used to fly a heavy delta which had auto mach trim from 0.88 Mach No through to 0.98. No movement of the stick and nothing felt as the elevators were progressively adjusted to take out an increasing nose down pitch.

It's difficult to feel the onset of ground effect as it comes in gradually. Most pilots call it float and handle it instinctively following experience on type.