Originally Posted by
Concours77
" 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?
No! Backup speed scale is an older mod. It doesn't calculate speed just shows a green band like TCAS to fly based on AoA. That also came after 447 as a remedy. Digital back up speed is actual speed displayed on speed tape that pilot flies. It is calculated by injecting weight, load factor and AoA in lift equation. It has different indication for pilot to know it's calculated speed.