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From: wolit@alice.UUCP (Jan Wolitzky)
Newsgroups: net.aviation
Subject: Re: China Airlines 747
Message-ID: <3442@alice.UUCP>
Date: Thu, 7-Mar-85 09:17:59 EST
Article-I.D.: alice.3442
Posted: Thu Mar  7 09:17:59 1985
Date-Received: Fri, 8-Mar-85 04:32:53 EST
Organization: Bell Labs, Murray Hill
Lines: 32

> The airliner is on autopilot and the crew is flying with brains disengaged.
> Power is lost on one of the outer engines.  The obedient autopilot maintains
> altitude by raising the nose.  Air speed drops, plane stalls.  The asymmetric
> thrust rolls it into a spin.  Plane drops, goes transonic in the dive.  The
> plane reaches denser air and the autopilot pulls it out if the dive at 9500
> feet.  During the pull out, the G force drops the gear and the doors fly off
> and hit the tail.  After the pull out, the crew finally gets their act 
> together and disengages the autopilot.

Interesting possibility, but 747's are generally equipped with
autothrottles as well.  It's true, though, that at 40,000 feet the
margin between maximum cruise speed and stall speed isn't very wide --
maybe 20 - 40 kts or so.  Maybe the autothrottles are programmed not
to exceed a certain thrust level during cruise (remember that the Air
Florida 737 that went into the Key Bridge in DC did so mainly because
the crew refused to put the throttles to the firewall because of a
faulty high thrust readout, even when their fate was obvious,
a mistake no new student pilot would ever make).  At any rate, some of
these planes are also equipped not only with stick shakers, which literally
start shaking your hand (if you have them on the yoke, of course) when
you're approaching a stall, but with stick pushers that actually push
the stick forward if you get close enough to one.  No, given the
redundant systems and just plain nice flying characteristics (from
what I've read) of a 747, I'd guess that "benign neglect" would not
have been enough to cause what happened on the China Airlines flight:
sheer stupidity seems to have been necessary.  Maybe deploying some
slats or dropping gear at Mach 0.8 (gear doors fly off FIRST, hit
tail, knock off much of horizontal stabilizer and some of elevators,
with resulting loss of pitch authority), when you meant to push in the
cigarette lighter or something...
-- 
Jan Wolitzky, AT&T Bell Laboratories, Murray Hill, NJ; (201) 582-2998