Dylan Smith wrote

On 2006-06-20, wrote:
Is it possible for an aircraft to stall and sink nose-up tail-down
instead of pitching nose-down? Or does aircraft design inherently
preclude that?

YES

Conventional light planes should not do that (i.e. certified, non-canard
designs). However, some rear engined T-tailed airliner designs WILL do
that. It is called a deep stall, and is irrecoverable.
http://en.wikipedia.org/wiki/Deep_stall

This Wikipedia article leaves a lot to be desired. Stick Shakers are not
related to the deep stall. Stall Warning devices which include stick
shakers are required because of a lack of sufficient natural stall warning
buffet in any airplane. The cure for the Deep Stall was the "Stick Pusher"
which prevented the aircraft from reaching the stalling AOA in the first
place.

has a diagram. Note that in a rear engined T tailed plane, the wash from
the wing will prevent appreciable thrust being made by the engines, so
you can't just 'power' out of it either.

Wing wash had nothing to do with engine power available, the extreamly high
AOA for the deep stall also put the engine cowls at an extream angle from
the relative wind resulting in compressor stalls.

Bob Moore