The point I was making is that the indicated airspeed was working. So that the pilot knew or should have known his stall speed. Let us say it was 100kts. Once you reach 100kts and there has been no stall warning and no auto recovery, then the conclusion is that it is not working and you do a normal stall recovery using the side stick. That would still be working. What it seems the pilot did was keep reducing the speed well below the known stall speed hoping that the automation would kick in. It did not. I will look for other threads on this since it is interesting but I have carried out perhaps 100 full stalls on 737 757 767 and approach to full stall on 744 and in every case we knew the expected stall speed and would recover if the stall warning system were to prove faulty.