Re: 727 deep stall (Re: tip vortices *do* exist!)

From:         greg@saltydog.dpsi.com (Gregory R. Travis)
Organization: Data Parallel Systems, Inc
Date:         31 Mar 93 01:15:09 PST
References:   1 2 3 4 5
Followups:    1
Next article
View raw article
  or MIME structure

In <airliners.1993.296@ohare.Chicago.COM> watson@win.tue.nl (Bruce W. Watson) writes:

>I didn't catch the original part of this 727 deep stall thread, but I _think_
>I remember a 727 deep stall accident (the following is entirely from memory,
>but I read about it some years ago in my Canadian aviation safety bulletin):
>   One some cargo flight, the Captain and FO decided to allow the (type-rated
>but rusty) FE flight the departure. As it turned out, they somehow forgot the
>pitot heat. During the climbout, the pitot iced up, and with the static source
>open the ASI began to act as an altimeter. With the airspeed ever-increasing,
>and passing through the structural limits for flaps extended, the FE (flying)
>continued to pitch up, while retarding the throttles. The end result was that,
>by the time someone had managed to cross-check, the wind noise had died down
>and they were indeed deeply stalled at a low throttle setting. I think the
>way it ended, was with only a partial recovery, killing all 3 aboard.
>   If anyone else knows the whole story (perhaps it was fiction ;-) I'd be
>happy to see the corrections.


The story is true, with some minor corrections: The FE was not flying and
the crew never realized that they were stalled.

As you say, the crew neglected the pitot heat resulting in an iced-over
pitot.  As they climbed into the night, the airspeed indicator acted
as an altimeter.  The pilot's response was to increasingly pull back
the stick in an attempt to arrest the speed.

At about 20,000 the airplane began a pre-stall shudder which the
crew misinterpreted as mach buffet.  The airplane subsequently stalled
as the pilot applied even MORE back pressure.

The pilot continued with back pressure and the airplane eventually began
to spin.  During the spin and subsequent attempt to recover, one of the
vertical stabilizers was torn from the airframe, making further attempts
at recovery futile.

There was no deep stall - had the crew realized the situation that they
were in, and had they applied typical stall-recovery techniques in time
(namely, lower the nose) they would have survived.

greg


--
Gregory Reed Travis				D  P  S  I
Data Parallel Systems Incorporated   greg@dpsi.com (For MX mailers only!)
Bloomington, IN			     greg@indiana.edu (For the others)