Quote HN39: I'm aware that the 'low speed awareness' markings are fundamentally different from Airbus' markings of 'characteristic speeds'.
Quote Clandestino: Not valid for all Airbus characteristic speeds. Valpha max and Wsw on Airbus are very similar to low speed cue. ADC/IR design, flight controls and display architecture are different yet displayed information is similar.
Reply:
AFAIK Valpha max is the '1g' stall speed and is not g-sensitive. It is not displayed in alternate law. Although Vsw is g-sensitive, it is calculated for the current weight and moves off-scale as the speed tape moves up to display 60 kts. As I understand low speed awareness (
see here), and you concurred in your post 467, it would maintain the 'Vsw' where it is on the display, while the speed tape moves.
Quote Clandestino in post#467: I strongly suspect your further line of thought, about showing wrong stall warning speed when IAS gets unreliable is correct ...
Quote FCOM 3.04.27 p.7: (Alternate Law) ValphaMax disappears ... Unlike VLS, which is stable, VSW (stall warning speed) is g sensitive so as to give additional margin in turns.
Quote HN39: But when airspeed has 'gone south' and in Alternate Law, may be the 'low speed awareness' is better?
Quote Clandestino: If airspeed is lost, how could we have possibly have low speed awareness? High alpha awareness is even better and is provided through aural stall warning.
Reply: The aural stall warning comes 'out of the blue' for the pilots, they do not see it coming, consider it 'inappropriate' and dismiss it as 'false'.
Quote HN39: It would have informed the pilots of the 'validity' of the first brief stall warnings, that they were transient and no reason for concern at that time
Quote Clandestino: At the cruise Mach, they were not 'valid', they were valid. They were transient as the aeroplane was jerked into climb at its max recommended cruise level and were reason to be very, very concerned.
Reply: Yes, they were valid, but partly due to turbulence, and therefore transient, and as such, not calling for immediate nose-down response.