From: rdd@cactus.org (Robert Dorsett)
Subject: Re: Airline Safety Review
Organization: Capital Area Central Texas UNIX Society, Austin, Tx
Date: Fri, 31 Jul 1992 05:45:50 GMT

In article <1992Jul30.083502.20964@praxis.co.uk> mct@praxis.co.uk (Martyn Thomas) writes:
>andy@raft.spider.co.uk (Andy Davis) writes:
>: The snag is that an aircraft flight deck
>:is not the place to be cluttered with computers saying "Are you sure?"
>:to every command input.  An even more insidious implication is that the
>:computer only has to say "are you sure?" to the commands which seem
>:implausible or dangerous to it - now, the machine is making decisions to
>:question things on a basis which is non-obvious to the pilot.

On my first A310 simulator ride, I was struck by how *frequently* the
system displays cautions (non-critical warnings).  Forget something
simple, like waiting a few extra seconds to raise the gear, while lowering
the nose a bit *too* much for second-stage climb-out, and you'll get a 
caution.  A real pain.  All the glass cockpits use something similar: they
have to, given the "consolidated" systems interface.  I can see how it's
very easy to learn to filter out cautions.

(A caution is (a) a chime, (b) a little light on the glareshield, and 
(c) a system synoptic on an ECAM display, indicating what the computer's
concerned about--it requires a head to be lowered, eyesight refocused, 
brain orientation shifted, and the display read, in order to be processed 
and acted on or ignored.  A warning also chimes, turns on a *red* light,
has the synoptic, and deals with an emergency item).


>The A320 "knew" the intended destination. It's systems "knew" the location
>of the aircraft. It therefore "knew" that the chosen descent mode would lead
>to terrain impact some distance from the runway. It also "knew" how soon
>that would happen.

The A320 knew none of that.  The typical database in an FMS is around 200K;
that's just about enough for the route structure, plausible diversions,
and navaids, plus a bit of performance info.  Besides, the FMS was OFF (in
Bangalore and Habsheim, not Strasbourg--a lot of the comments aren't
properly identifying what they're referring to).  Or, more precisely, the
airplane was being flown with the flight control unit (glareshield inter-
face), not the "stored" flight-plan; the FMS was "on" in all three cases,
just not pre-emptive.

Which raises the question: *why* doesn't the A320 (or any airplane) have
a detailed topographic database?  Instead of relying on GPWS, why not
have a "smart" system, which takes altitude and position, and sounds a 
warning?  The technology lags a little bit behind what's necessary to make
this work (mainly in the precision of location info), but it's certainly an 
interesting idea.


>An alert co-pilot would wait long enough to be sure that this wasn't a
>temporary maneuver, then ask the pilot what (s)he was doing. If the
>automatics are taking the degree of control they currenmtly have, is it too
>much to ask that they behave like an alert co-pilot?

Because in modern cockpits, the "complementary" cockpit paradigm often gets
abandoned, resulting in "single-pilot" operations.  The pilot flying,
flies; the pilot not flying often has his nose in a display.  Even if an
emergency arises, it can take a few seconds for the PNF to get back in
the loop.




---
Robert Dorsett
rdd@cactus.org
...cs.utexas.edu!cactus.org!rdd
Newsgroups: rec.aviation