On Mon, 29 Dec 2014 15:58:50 -0500, "Mr. Luddite"
wrote:

On 12/29/2014 3:20 PM, wrote:
On Mon, 29 Dec 2014 13:40:19 -0600, Califbill
wrote:

Tim wrote:
They're not sure but the searchers are finding oily stuff floating. The
news is saying it's probably on the bottom of the ocean...

The air bus is mostly plastic, so should be a lot of floating debris.

I am sure they will turn up a debris field pretty soon and this is
relatively shallow water so getting the boxes will be easier to do as
soon as we get decent assets in the area.

The more we hear, the more this sounds like a departure stall and an
unrecoverable dive into the sea.
If these 3d world bozos maintained their boxes, they should have the
real answer pretty soon. Politics and the legal issues may determine
when it is actually announced to the public.


Not technically a "departure" stall, but similar if the pilot
was trying to climb at too steep of an angle of attack for speed.

Departure stalls are practiced all the time in flight school and
simulate a take-off with too steep of an angle of attack. Basically
you are trying to stand the airplane on it's tail at full throttle
while balancing it with the rudder. Eventually it stops flying and
drops, usually to one side which, if not corrected, can result in a spin.

===

If you closely read the Airworthiness Directive that Greg found, you
will notice that it is not an actual stall condition they are warning
about. Instead it is an instrumentation error that triggers the
flight automation system into an erroneous stall recovery mode. The
stall recovery automation does the text book solution by putting the
plane into a nose down dive to build airspeed and get the plane flying
again. The problem is that the plane was never in a stall to begin
with, and there is a special sequence that the pilots have to follow
to disable the automation and get the plane out of the dive. Scary
stuff if it takes the pilots by surprise and they are not carefully
trained.

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/210629d32e131bc986257daa007ccddb/$FILE/2014-25-51_Emergency.pdf

I quote:

-----------------------------------------

An occurrence was reported where an Airbus A321 aeroplane encountered
a blockage of two Angle of Attack (A of A) probes during climb,
leading to activation of the Alpha Protection (Alpha Prot) while the
Mach number increased. The flightcrew managed to regain full control
and the flight landed uneventfully. When Alpha Prot is activated due
to blocked A of A probes, the flight
control laws order a continuous nose down pitch rate that, in a worst
case scenario, cannot be stopped with backward sidestick inputs, even
in the full backward position. If the Mach number increases during a
nose down order, the A of A value of the Alpha Prot will continue to
decrease. As a result, the flight control laws will continue to order
a nose down pitch rate, even if the speed is above minimum selectable
speed, known as VLS.

This condition, if not corrected, could result in loss of control of
the aeroplane.

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