Newsgroups: sci.aeronautics.airliners Path: news From: raveling@Unify.com (Paul Raveling) Subject: Re: hydraulic problems with DC-10's?? X-Submission-Date: Tue, 8 Dec 92 20:18:22 GMT References: Message-ID: Approved: kls@ohare.Chicago.COM Organization: Unify Corporation (Sacramento) X-Submission-Message-Id: Sender: kls@ohare.Chicago.COM Date: 08 Dec 92 15:51:12 PST In article , drinkard@bcstec.ca.boeing.com (Terrell D. Drinkard) writes: > In article weiss@turing.SEAS.UCLA.EDU (Michael Weiss) writes: > > > >>Flight AA 191 lost the slats on the left hand > >>wing (if memory serves) because of Douglas' failure to include mechanical > >>lockouts on the slat actuators. They were not required to certify the > >>airplane. I'd be inclined to phrase that a bit differently. The certification requirements were satisfield by demonstrating safe flight with asymmetric slats. The catch is that (a) flying safely in this configuration requires keeping airspeed above the minimum (or AOA below the maximum) needed with slats retracted and (b) the crew didn't have a sufficient indication to judge immediately that they had asymmetric slats. This fits in with a pattern that's shown up in virtually all breeds of airliners where the cockpit's 'human interface' fails to supply needed information. This shows up in a fair variety of accidents in various forms -- unloading the autopilot produces surprising gyrations, aircraft FBW control logic reacted to factors other than the pilot's directions and the pilot didn't anticipate it, etc. One human factors problem is how to best inform the crew of simultaneous failures that each can be critical. For this DC-10 accident, they experienced loss of an engine at low altitude, followed quickly by partial loss of hydraulics and asymmetric slats. Each of these three primary circumstances call for prompt attention, and cockpit warnings of these and other consequent failures can overload the crew with failure alarms, becoming more of a problem than a solution. Bottom line: IMHO human factors engineering in the cockpit is more a more important target than airframe engineering for risk reduction. ------------------ Paul Raveling Raveling@Unify.com