In case of pitot related malfunction you can get all sorts of weird and conflicting instrument readouts. There was a case, i think in Chile, where the instruments were displaying warnings for overspeed while the stick shaker was activated. What is this you might ask?
Well, since these aircraft are usually fitted with fly by wire or otherwise assisted controls, the pilots don't have the same kind of tactile control feedback that simpler rod and linkage controls allow. In a cessna you can feel the stall because the stall buffet transfers through the control linkages to the yoke, in a fly by wire system you can't. So, these airliners have a feature that simulates this by shaking the control column when they near a stall, it's like force feedback.
Apply that knowledge to the above example and you'll see that a malfunctioning pitot system caused an overspeed warning on the caution lights panel at the same time that the stick was telling pilots they were stalling.
My point being, things are not that cut and dry. Especially at the speeds and altitudes these things fly where it's not that easy to judge airspeed by eyeballing it and simply looking at the ground, not to mention that the accident i'm talking about also happened at night.
Pilots are trained to reduce AoA when approaching a stall. Some might have botched this at times, but for the most part if a pilot is pulling up with a stall warning in place he's probably got a reason for it: conflicting information that forces him to make a choice between two completely opposite scenarios.
If you get simultaneous overspeed and stall warnings with no other reliable means to confirm which one is wrong what do you do? Well, if you're high enough and know you can recover the particular plane from a stall, i'd say go ahead and stall it mildly. If you're wrong you'll just loose a few thousand feet of altitude and then you know the overspeed is a false alarm that you can disregard from that point on, if you're right and you don't take any action however you'll overspeed it and have it disintegrate in mid-air.
In other words, it's all highly situational. In low altitude flight and provided some form of speed perception is available by looking out the window, i'd say avoid the stall first.
The problem (at least according to what an airliner pilot told me) is not so much why they did what they did, but the fact that too many young pilots in airliners are conditioned to go through the motions mechanically and rely a lot on automation, instead of flying the plane first and foremost.
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