Why can't those who are interested and concerned enough to voice opinions on the A320 systems at least go find an FCOM and read up on how it
actually works first? You don't have to be rated to do that; you don't even have to be a pilot. This is the 21st century; the relevant FCOM chapters are easily available on the internet.
The issue that intrigues me, is that every aviation regulatory body for every country in the world which allows Airbus to fly into it's airspace subscribes to the infallibility and redundancy of the Airbus Alpha floor protection system.
Otherwise the performance figures based on 1.12Vs (versus 1.3Vs of all standard flight control variants) wouldn't be accepted as the basis for the certified flight manual performance figures.
That is a misunderstanding that could have been avoided with a brief look in the FCOM. Where older aircraft used 1.3 Vs, the Airbus uses 1.23 Vs1G. Vs1G is the stall speed at 1G, whereas the traditional Vs was measured at less than 1G. The conversion factor used is Vs=0.94Vs1G, which is where the factor of 1.23 comes from.
This has nothing to do with FBW or maneuver limitations; modern non-FBW aircraft, like the ATR, also base their values on Vs1G, and thus have the 1.23 factor in their speed calculations.
The confusion arises when one assumes that "1.23Vs" refers to the old definition of Vs, not the new 1G one, which seems to imply that the new rules give lower maneuver margins. But the new rules give exactly the same maneuver margins as the old ones did.
The pilot's very probably had done hundreds of Alpha floor recoveries in the simulator and known at what stage of the deceleration the autotrim should have locked out and when alpha floor / TOGA lock kicks in. Why did they continue to decelerate below the paper VLS?
Good Q, but has nothing to do with FBW now does it?
Surely the FAC's would have a comparator logic to cross reference other flight parameters with the AoA vanes and not just rely on a single similar sensor cross check?
If it's proven that the stall protection system is deficient in it's certified abilities, does Airbus and all the operators of airbus variants have to amend the performance figures (read weights) of the aircraft?
The problem as I see it isn't that the maneuver was carried out at less than the described altitude, but that the system has proven to be fallible.
Where is the data that suggests something didn't work exactly as designed? What appears to have happened here is that the systems were fed poor data from malfunctioning AoA sensors; the systems eventually
did realize that, concluded that something must be wrong somewhere, and handed the situation to the pilots.
How else should the systems have reacted with such a malfunction? If the computers start trying to guess
which sensor is providing valid but erroneous data you really start getting interesting failure modes...
Another issue entirely is the number of incidents and accidents that have happened after an autotrimming systems puts the aircraft in a grossly out of trim situation, disconnects itself and suddenly dumps a mistrimmed aircraft into the laps of the unsuspecting pilots. But that is not an FBW issue; a 50 year old autopilot is just as capable of doing that.
Maybe what ought be remembered is this: At any time, and totally unexpectedly, a sufficient number of malfunctions could suddenly cause the Airbus FBW systems to revert to a behavior that is identical to an old-fashioned ("conventional") aircraft. It is unlikely, it is exceedingly rare, but it could happen. Thus,
don't do anything in an Airbus that you wouldn't do in a B737, 'cuz it could suddenly become a B737.
Which of course everybody already lived by. Except, it would seem, the Habsheim crew and the Perpignan crew.