Let's put this into perspective. Certification requirements, airplane systems design and airline pilot's training primarily seek to avoid stalling the airplane. Limiting myself to system design, there are first of all the various high-AoA protections in normal law. In the fairly remote failure condition of alternate law the only protection left is stall warning. Its function is to warn the pilot that AoA is exceeding a threshold close to AoA-stall, but sufficiently below it to allow the pilot to avoid stalling. At high Mach it is set to stay below the onset of buffet, which provides additional margin to the stall, and its function is amplified by the occurrence of aerodynamic buffet. In the words of the regulation (which doesn't apply in abnormal systems configurations) stall warning must continue until the AoA is reduced below the threshold at which it is triggered. It would seem that in almost all cases the system will do just that. The only case where it will not function as intended is when the stall warning is ignored, and nose-up commands are maintained, causing the AoA to increase to values (>40 degrees) at which the sensed airspeed is so corrupted that the AoA signal itself is considered unreliable or invalid.
P.S.
Originally Posted by grity
what can be a reason for UAS until the ice dedectors has no ise detected...
Ice detectors detect the formation of ice by freezing of liquid water, which in all probability was not present in the conditions of AF447. They work in cycles: unheated while collecting ice, heated to shed the ice. Ice particles do not adhere to non-heated surfaces, and are therefore not detected.