Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site alice.UUCP Path: utzoo!watmath!clyde!burl!ulysses!allegra!alice!wolit 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