From: ericg@jeeves.ucsd.edu (Eric Geerdes)
Newsgroups: sci.aeronautics
Subject: A320/automation...
Keywords: A320, 747-400, FMS
Date: 25 Jul 92 15:48:37 GMT


My eyeballs are falling out after reading all the postings on the 
A320 et.al. for the last few weeks.

Just spent the last 9 months doing flight deck research in a
CogSci lab here at UCSD.  The work centered on video tapes of
recent simulated 747-400 flights by senior (non-company) pilots at
Boeing's hi-fi simulators.  The process of transcribing the 6+ hours 
of video brought us quite close to some of the issues raised in the
recent A320 thread.

A few bits of info:

A few months ago our lab folk got to crawl around the cockpits
of a Northwest A320 and a 757 one night.  Both planes had FMS
systems still powered up, so we got to play around with the 
A320 FMS-CDU and ND (nav display), as well as some other Flight
Director stuff (A320 is much like the 747-400 w.r.t. FMS and
much of the other glass).  

Did you know the A320 uses a few of its annunciators (little 
windows that display numbers) on the Mode Control Panel for more 
than one mode?  A combination of V/S and FPA (Vert.spd,flight path
angle) modes share a single annunciator.  This means the number 
you dial in means quite different things to the FD depending on the
current mode.  This is one example of where visual feedback, aka
visability, of the current state of the FD is very important. If 
you are depending on the automated systems, you must be able
to *see* what its doing.  (The A320 mode annunciator for V/S and 
FPA is small--my observation).

Many times I've heard pilots say, "...what is the damm thing 
doin'...".  Or, the plane will begin a *pre-planned* descent while 
in VNAV, (vert nav autopilot mode), and the pilot-flying will quickly 
cut into the control loop thinking the FD went crazy.

On the accident in Germany...Did you here the one about the difference
between a chain saw and an A320?...  ABOUT 400 feet per second!
(I don't mean to pick on the A320, but I heard this one and thought
slightly funny.)

Did you realize that the FD and the Fly-By-Wire on that A320 may 
well have saved the lives of the passengers and crew?  Because the 
pilot may have thought his new A320 gave him *complete* envelope
protection, he did a manuver that was nearly un-recoverable.  He was
running around after the accident claiming the FBW system caused the
accident.  He showed a plot of the positions of the throttles and the 
pitch controls over time.  He got the "fire-wall-thrust" he asked for,
but his full-back-on-the-yoke_(joystick) input was over-ridden by the FBW
system and it didn't give him the stick he wanted, = crash.  
So he's right?...NOT!

Add one more curve on the plot--airspeed.  Would you all agree that a
"nice" semi-level belly crash is less lethal than a nose-into-the-ground
type?  If the system would have given him the stick he wanted, the 
combination of rotational force caused by two under-wing-and-forward
engines at max thrust, and his stick input would have given an angle
of attack that would stall the plane.  The man was too low and slow.
The system may have saved his butt--but his perception of the system's
envelope protection may have help put him there in the first place..

This and the other stuff above seem to point up the need for: 

-pilots to try harder to adapt (well) to the growing 
automation--understand the systems you have, while we try to make 
them better.

-flight deck designers to make the automated tasks more visible to the 
crew. How about another display where they can get a window into
the tasks that are going on out of their reach. The A320 sure has room!

Bye
-Eric

Newsgroups: sci.astro