Re: FLY-BY-WIRE (AIRBUS vs. BOEING)

From:         Steve Lacker <slacker@arlut.utexas.edu>
Organization: applied research laboratories
Date:         01 Jun 95 05:00:53 
References:   1 2
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"peter (p.j.) ashwood-smith" <petera@bnr.ca> wrote:
>pilot has full control of the plane. There are two problems with the Airbus
>approach. First is that the "proper flight envelope" is determined by a host
>of sensors and God help you if you if they give off false signals. A faulty
>AOA indicator starts to have deadly consequences. Second is that sometimes,
>just sometimes the improper flight envelope is what saves your ass. Who
>knows, perhaps stalling the plane with the gear up 10 feet off the ground
>is the best anybody could do but the software would prevent it ...

I would add another: the lack of tactile feedback to tell the pilot what the
automatic systems are doing. I find it strange that in an era when the auto
companies are castrating power steering and power brakes to give drivers a
better "road feel", aircraft manufacturers are isolating the pilot from the
airframe more than ever! I've talked to a pilot who said things like 'Yes, the
MD-80 is nice and  quiet, but in the 727 I could *hear* all three engines spool
up when I pushed the throttles...' Now, I personally think that the middle
ground is where we should be: I hate modern cars that have power steering but
feel like they don't, and I would prefer an airplane that is not exhausting to
ride in or fly because it has automated systems. In both cases, automated
systems should work *with* the operator and ease his load, not do everything
for him or make him do everything.

As an example of *excessive* insulation of the pilot from what the airplane is
doing, my understanding is that Airbus chose *not* to move the throttles when
the autothrottle changes power settings, whereas Boeing does move the
throttles. To me, as an engineer who currently spends a lot of time designing
man/machine interfaces, this looks like a fundamental mistake on the part of
Airbus.

--
Steve Lacker	/	Applied Research Laboratories, The University of Texas
512-835-3286	/	PO Box 8029, Austin TX 78713-8029
slacker@arlut.utexas.edu