Only thing I don't understand is how AOA display will prevent bizarre application of flight controls which created the need for all that? AF447 didn't have speed but five and half years later after learning everything about it in QZ8501 despite having everything the initial action that started the disaster and continued to the crash was exactly same. With introduction of BUSS you can survive without speed below FL250 provided you don't do something above 250 that makes BUSS irrelevant.