[NSRCA-discussion] 747 Snap Entry?

[Martin X. Moleski, SJ]

rcmaster199 at aol.com wrote:

> A few of us were discussing just such an occurrence recently which 
> apparently happened by accident and darned near crashed the plane. Dean 
> remembered the details which went something like this:

> The pilot of the 727 about 20 years ago had the plane trimmed as far aft 
> as possible and had inputed a bit of flap to use fuel most efficiently. 
> The co-pilot, soon after returning from a visit to the loo, saw the 
> trimmed flap and flipped the switch to return the flap to neutral. This 
> action immediately made the plane too tail heavy which made the plane do 
> a pretty violent half snap to inverted. ...

TWA Flight 841, 04 APR 1979.  Harvey G. "Hoot" Gibson.

The NTSB says one LE slat failed to retract fully, causing the
plane to roll to the right:

Final report:
http://aviation-safety.net/database/record.php?id=19790404-0

Accident report:
http://amelia.db.erau.edu/reports/ntsb/aar/AAR81-08.pdf

The Accident report notes that the pilot erased all of the
cockpit voice recorder data (CVR) after the plane landed
in Detroit.  Although the pilot and copilot denied actuating
the flaps, the NTSB concluded that they could not have
deployed by accident and suggests that the crew was trying
to get 2 degrees extension of the trailing edge flaps.

If all of the leading edge slats had retracted or if the
pilot had responded to the second roll to the right sooner,
there wouldn't have been a problem.

"After recognizing the right roll condition, the captain rolled the aircraft
to a near wings-level upright position; thereafter, through untimely use
of the flight controls, he permitted the aircraft to roll to the right into
an uncontrollable attitude. The captain probably was distracted
immediately after restoring the aircraft to near level flight by his
efforts in attempting to rectify the source of the control problem."

They went from 39,000 feet to 5,000 feet in 63 seconds.

Hmm.  I'm going to add these links to the Wikipedia article:
http://en.wikipedia.org/wiki/TWA_Flight_841_(1979).

				Marty