Re: Recoverable flight attitudes?

From:         shevell@leland.stanford.edu (Richard Shevell)
Organization: Stanford University, Dept. of Aero/Astro
Date:         09 Feb 95 18:50:03 
References:   1
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In article <airliners.1995.153@ohare.Chicago.COM>, Joe Diederichs
<joed@lsid.hp.com> wrote:

> So my question is, if an airliner somehow gets into an unusual attitude,
> say straight nose down, at a reasonable altitude, say 15,000 feet, is it
> recoverable, or is crash at that point the only possible outcome?

In general a transport airplane is recoverable from any attitude IF there
is enough altitude, IF the speed already attained is not too close to the
structural placard speed and IF all the controls are working.  USAir 427
had rolled 90 deg. after 13 seconds so pulling g's was not helping the rate
of descent.  It appears that the pilot was unable to stop the roll or even
diminish the roll rate.  Since the design lateral control power is large on
these aircraft and can overcome even a large rudder deflection, one must
conclude that either the aileron/spoiler system was not functioning
correctly, or something else input a large rolling moment, perhaps a left
wing stall due to ???? (perhaps a slat failure of some kind, a wild
speculation but the NTSB is not doing too well either).  Boeing says you
can recover because they want the airplane to be perfect; ALPA says you
cannot recover because they want the pilots to be blameless.  
Richard Shevell
Email: shevell@leland.stanford.edu