Originally Posted by
Concours77
vilas... " Anyway it's too late to discuss unreliable speed as Airbus now has mathematically calculated airspeed which they call it digital back up speed. This doesn't require any anemometric input. This supervises the ADR calculations and in case of all ADRs going rogues their speed indications are replaced by the Digital Backup Speed. A350 does it automatically A320 does it through ECAM actions. " Is that BUSS? Back Up Speed Scale? An option on A330, which Air France took a pass on? Still goes to ALT LAW 2 B ?? Begs the question, should duff IAS have trIggered a change to ALT LAW ? Much ado about a condition that needs merely Pitch and Power? ALSO, AoA is the critical instrument? Where was the AoA instrument? Right, not equipped with one...How much money did Air France save on F-GCZP....?
What Air france delayed installing was not the BUSS because it was simply not deviced yet. Actually BUSS was thought of because of AF447. To my knowledge the pitot static equipment which was installed on AF was prone to icing and a better euipment became available which they delayed installing. Stall warning comes fro purely AoA speed has nothing to do with it. But the low speed stability in alternate law which pitches the nose down comes from speed. When speed is not available control laws change to alternate2 which looses the pitch down capability but stall warning remains available since it comes from AoA.