Originally Posted by Clandestino
Basically, low speed awareness tapes are just alpha information superimposed on speed tape. (...) It's interesting to watch it bounce in turbulent approach or climb in turns, just as Alpha max red strip does on A320.
Originally Posted by Clandestino
It's wrong! Who wrote that? I did?!? Oh well... What I wrote was very simplified, and most probably oversimplified, illustration of the way low speed cues work on modern EFIS aeroplanes, without the need to know what's the actual weight. It was not meant to be taken literally as be-all and end-all definition of system operation. I strongly suspect your further line of thought, about showing wrong stall warning speed when IAS gets unreliable is correct and covers the reason why low speed cue gets shut off when IAS data is lost. BUSS is basically the same thing you are proposing: replacing IAS with AoA information.
Could we look at this more objectively? I'm aware that the 'low speed awareness' markings are fundamentally different from Airbus' markings of 'characteristic speeds'. But when airspeed has 'gone south' and in Alternate Law, may be the 'low speed awareness' is better? While the speed tape is faulty (maybe it should be 'greyed'), the 'low speed awareness' tape is valid, correctly displaying the stall margin. 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, and would have informed them of the approaching stall warning and stall later on.
Would it, by confirming the PNF's feeling that things were going 'the wrong way', have convinced him to step in with more determination?
It doesn't have the big drawbacks of the BUSS that you lose all three ADR's for the remainder of the flight, and that it is virtually useless above (IIRC) FL250.