Re: Airbus A320 flight controls

From:         faurecm@halcyon.com (C. Marin Faure)
Organization: Northwest Nexus Inc.
Date:         06 Feb 96 14:15:38 
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In article <airliners.1996.105@ohare.Chicago.COM>, rdd@netcom.com (Robert
Dorsett) wrote:

> In article <airliners.1996.43@ohare.Chicago.COM> "P. Wezeman"
<pwezeman@blue.weeg.uiowa.edu> writes:
> >   In a recent exchange of postings in rec.travel.air several people have
> >mentioned conplaints of a lack of proper force feedback in the Airbus A320
> >sidestick control. Could someone who is familiar with the system please
> >describe it briefly?

> The joystick is not coupled.  That means that the two joysticks are com-
> pletely independent critters.  Their inputs are algebraically added.  If
> one pilot pulls full-left and the other full-right, nothing will happen.

I had heard the left-plus-right-equals-nothing formula was the case on the
original version of the system, but that it has subsequently been
changed.  Imagine this scenario: both pilots suddenly become aware of
another airplane rapidly approaching on a collision course.  The
instinctive reaction of most pilots is to turn toward the window that is
next to him.  The captain slams his stick left, the first officer slams
his stick right.  Result: the plane continues straight ahead into the
collision.  I believe the very real possibility of something like this
occuring caused Airbus to have the stick authority software rewritten, but
I don't know how the priorities are assigned, if they have, in fact,
changed it.

C. Marin Faure
author, Flying A Floatplane