Recoverable flight attitudes?

From:         Joe Diederichs <joed@lsid.hp.com>
Date:         08 Feb 95 01:21:19 
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Aviation experts:

I would be interested in comments on the subject of airliners and their
safe flight envelope, in particular with regard to recoverable flight
attitudes.

I am not a full-size pilot, but have some experience with model
aircraft, which in general have much more relative power and control
authority than their full-size counterparts.  Originally I assumed,
without much thought, that airliners, given a reasonable altitude, were,
like models, recoverable from any flight attitude they happened to get
into.  Based on the sketchy technical details the public gets about
airliner crashes, I am starting to see that this may not be the case.
(Either the press wrongly assumes we aren't interested in the technical,
or they don't understand it well enough to write about it, but that's
another subject.)

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?
General comments about the recoverable flight envelope of airliners
would also be of interest, as would any knowledgeable comments relating
to this subject in any way.

In reading about the USAir 427 crash, in the January 30 Aviation Week,
an expert is quoted as saying, "the aircraft was unrecoverable" after
the left wing stalled about 13 seconds after the initial wake vortex
encounter.  Why was it "unrecoverable"?  Was it because it did not have
enough altitude to recover, or had it gotten into an attitude that,
assuming the rudder wasn't stuck and given any altitude, was out of its
recoverable flight envelope?

I have similar questions about the Lauda 767 on which the thrust reverser
deployed climbing at 24,000 feet.

Thanks in advance,

Joe Diederichs
joed@lsid.hp.com