Re: Airbus safety (was Re: TWAs Status)

From:         palmer@icat.larc.nasa.gov (Michael T. Palmer)
Organization: NASA Langley Research Center, Hampton, VA  USA
Date:         11 Dec 92 17:42:32 PST
References:   1 2 3 4
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rdd@cactus.org (Robert Dorsett) writes:

>I would also note that in fighter aircraft, there isn't the issue of 
>two-pilot "peers" having to quickly and instinctively figure out who is
>flying the airplane.  On the A320, there is no interconnect between the
>sidesticks: the captain can command a full-left in an emergency evasive
>maneuver, the F/O full-right, and the net result will be an algebraically
>added "zero."  

I believe this is incorrect, though I don't have the documentation here
right now.  My understanding is that whenever one of the sticks reaches
a critical percentage of deflection (say, 75%), it becomes automatically
the selected input device.  At this point, the other control stick is
ignored.  So it's a race.  Whoever slams their stick to the stops first
wins, and the only way for the other crewmember to override is to physically
attack the winner.  Neat, huh?

I'm not sure how sub-critical deflections are handled - they may indeed
be algebraically summed.  If any Airbus people can provide the straight
scoop, I'd appreciate it.

In the sidestick implementations used at NASA, the sticks are interconnected
("logically", really, since they are hydraulically back-driven) so that,
like in current cockpits, whoever is strongest (i.e., most scared-to-death)
wins.

-- 
Michael T. Palmer, M/S 152, NASA Langley Research Center, Hampton, VA 23681
Voice: 804-864-2044,   FAX: 804-864-7793,   Email: m.t.palmer@larc.nasa.gov
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