Birky
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A320 Flight Directors On Or Off?

Mon Aug 25, 2008 9:57 am

Perhaps you can help...?

If, as my A320 type rating instructors tell me, you are best advised to have the FDs either both ON or both OFF, why haven't Airbus designed the FD engagement procedure with just ONE pushbutton in the centre of the FCU?

Perhaps more to the point, when would you ever want to deliberately fly with one FD ON and the other OFF?

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wilco737
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RE: A320 Flight Directors On Or Off?

Mon Aug 25, 2008 10:40 am



Quoting Birky (Thread starter):
Perhaps more to the point, when would you ever want to deliberately fly with one FD ON and the other OFF?

I don't know about the airbus, but we on the MD11F has as well 2 switches for the FD. And when I switch my off, the captain leaves his on, so he can check what I am doing and cross check it with the calculated commands of the FD.

For CAT III approchaes with autoland both FD needs to be fully operational as well.

WILCO737 (MD11F)
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RE: A320 Flight Directors On Or Off?

Tue Aug 26, 2008 11:59 am

In 737 we also used to do exactly what WILCO explains. You want to keep your skills sharp while the other pilot crosschecks.But here on The Bus the book says both FD's On and OFF at the same time.Not because it can not be used as explained above but because its airbus,everything has to be different  Smile
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Jetlagged
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RE: A320 Flight Directors On Or Off?

Wed Aug 27, 2008 10:54 am

I suppose there may be occasions where on pilot may need to switch their FD off. With AP on there is no real problem in having one FD off. The weakness in the design became clear after the Bangalore A3e20 crash. After that, caused partly by one FD being on while the other was off, the FMA annunciation for FD was modifed to show the status of the other pilot's FD as well. So although your FD is off, you can see that the other is on and so affecting the mode the autothrottle is operating in.
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PhilSquares
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RE: A320 Flight Directors On Or Off?

Wed Aug 27, 2008 11:44 am



Quoting Birky (Thread starter):
If, as my A320 type rating instructors tell me, you are best advised to have the FDs either both ON or both OFF, why haven't Airbus designed the FD engagement procedure with just ONE pushbutton in the centre of the FCU?

Can't speak for all operators, but all I have been associated with have a SOP of either both on or both off. In reality, you will either have the FD on both sides, TK/FPA or the bird.
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