On 16 May, 13:25, James Robinson wrote:
Jessica wrote:

James Robinson wrote:

wrote:

Standard practice is to wait until you have a positive rate of climb
before raising the flaps. *Raising the flaps if the airplane was on
the verge of a stall would be a big mistake. *Lowering the nose and
applying full power would be the best course of action, and once a
positive rate of climb could be achieved, then the flaps could be
raised.

There is some debate about that. *For a wing stall, you are correct,
however, some have pointed out that the PIC's experience was recently
on Saabs, which can see tail stalls in icing conditions - the Q400
isn't subject to tail stalls. *A tail stall is most often first seen
when the flaps are extended, and the effect is for the nose to drop.
The reaction to a tail stall is to retract the flaps, and pull the
nose up. *Was that what the captain was reacting to?

Perhaps, but even that doesn't make sense either. *The airplane stall
warning system/ stick shaker was activating. *This would only indicate
a stall condition is imminent for the wing. *The stall warning system
does not indicate anything about the tail, so the only corrective
measure to take for a stick shaker would be a conventional wing stall
recovery, such as full available power, prop forward, pitch down,
don't bring up the flaps until a positive rate of climb is achieved.

The question is what to do when everything happens at the same time? *
That is, after the flap setting is increased, the stick shaker stall
warning fires, and the nose pitches down. What would you do then? *The
stick shaker is only an indication of an impending stall, and there are
probably a few MPH margin left, but the increased flap setting might have
started a tailplane stall, on aircraft that have that tendency.

Immediately retracting the flaps might be the best course, along with
either level flight with increased power or slightly pushing the nose
down to keep the speed up. Pulling on the control column likely wouldn't
be a good idea, unless the pitch down was extreme. I don't know.

I'm not familiar with the specific stall recovery for that type, but
you get the idea. *If the pilot pushed the stick over to recover from
a non-existent tail stall, that was a bad move. *I haven't seen
anything to suggest that happened however.

The FDR shows moderate backpressure (20 lb, 40 lbs total) momentarily
applied to the control columns on both sides in response to the stick
shaker.

If memory serves me correctly, from my reading of NTSB material
the two control column force
transducers are *not* representative of the forces on the
two pilots' control columns.

There are two force sensors but I interpreted the explanation
to mean that it cannot be determined how much force each pilot
was applying.

http://www.ntsb.gov/Dockets/Aviation...027/417236.pdf
3.5.4. Control Column Forces
"With the system operating normally (for example,
disconnect not pulled), there is no way to determine
if pilot, copilot or both are flying."

There is more in the original doc. Quite complex and hard to
follow.