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 17:42:30 PST
References:   1 2 3 4
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rdd@cactus.org (Robert Dorsett) writes:

>Seriously, this is a tremendously conservative industry.  What isn't broken,
>doesn't get fixed.  However, when a better mouse-trap is invented, it is
>almost always adopted, universally.  The fact that no other manufacturer
>is rushing to repeat Airbus' example suggests the arbitrariness of the
>use of the sidesticks: if there were even minor operational or material
>advantages in using them (and modified control laws) as interfaces to the
>EFCS, you could bet your last dollar every other manufacturer would be doing 
>so, not least as the result of airline demand.   We don't see that.

>This isn't one of them.  We aren't operating in a vacuum: NASA, as one example,
>has been running a lot of research (over, and over) over the last 20 years, 
>addressing precisely these issues: the Airbus implementation is arguably on
>the weaker of a variety of choices available.

My contacts at Boeing agree - Boeing Flight Deck Research has been looking
at sidestick controllers for a long time.  They have decided that until they
develop an airplane that is flown *differently* they will continue to use
the column/yoke arrangement.  Now, what I mean by differently really refers
to switching from ATTITUDE control laws to VELOCITY VECTOR control laws.
Mr Dorsett is correct; NASA Langley has decades of experience with sidestick
controllers in our B-737 aircraft (it has TWO cockpits - standard in front,
and an aft research cab from which you can fly the entire flight profile
including landing).

The sidestick control has been shown to be best when commanding velocity
vector changes instead of attitude changes.  This is an interesting way of
using automation to ease the burden on the pilot while allowing him to
also remain in the loop, since the automation configures the control
surfaces to maintain the commanded direction of flight, but the pilot
still "flies" the airplane (when not in full-autopilot).  The velocity
vector control-stick steering mode is by far the mode of choice of the
pilots we bring in for experiments.

Based on the work here and their own efforts, Boeing has decided that until
they build a velocity vector airplane (hint: High-Speed Civil Transport)
they will not provide a totally different way to fly an airplane designed
with attitude control laws in mind.

Please note that I am neither a Boeing employee nor spokesman, and I neither
(officially) recommend nor approve of actions taken by them.  All the info
provided here (about Boeing's position) was provided to me personally by
Boeing employees, though, so I have no reason to doubt it.  It would be nice
if some of you lurking Boeing people jumped in to correct any mistakes I
have made.  :-)

-- 
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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