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avionneta
2nd Dec 2008, 17:31
hello,
does anybody know what is the usefulness of the white cross appearing on PFD (on A320 at least) until rotation, linked to the movement of the stick ?

rich_g85
2nd Dec 2008, 17:44
I'm not an airline pilot, but the first thing that springs to my mind is so that you can verify that the sidestick is generating the correct inputs, before you find out in the air?

I'm sure someone 'in the know' will be along shortly to correct/confirm!

Double Hydco
2nd Dec 2008, 17:57
It's to enable the non-handling pilot to see what control inputs are being made during the takeoff, since the sidesticks are not connected.

The control checks on taxi out, check that both sidesticks are working in the correct sense, and that the surfaces have full and free movement.

DH

SILENT_BADGER
2nd Dec 2008, 18:13
The main usefulness is in the take off roll when you put half deflection pitch down to keep the nosewheel down until the control blends out more in favour of the rudder.

During the control check on the ground you would look more at the ECAM flight controls page to check that the actual correct control surfaces move as you would expect.

Cardinal
2nd Dec 2008, 18:37
Also a technique for into wind aileron, should you desire it. Keep the white cross touching the box and you get a bit of aileron without any spoiler deployment.

avionneta
2nd Dec 2008, 19:22
cardinal, which box to touch ?

VRSCSE2
3rd Dec 2008, 10:21
The white cross only indicates the sum of both sidestick orders.
It is used to check for full sidestick movement before takeoff.
The 4 corner white indices show max sidestick deflection.
It does not indicate free and full travel of the flight controls....that has to be checked on the ecam page.

VRSC :ok:

Cardinal
3rd Dec 2008, 20:57
"referring to the box which is the centre of the aeroplane symbol on the artificial horizon"

Yep, that is the box I meant, should have been more specific.