Originally Posted by A4
Double RA failure means you go from "normal law" to " direct law" when the gear is lowered. Usually the sequence is NORM-ALTN-DIRECT.
No, when gear is selected down, it will transition to flare law without the nose down bias.
Originally Posted by DC-ATE
I'm curious as to WHY, in the Airbus, a double radar altimeter failure causes the aircraft to change 'laws' ?!
If the FBW computers do not have their required inputs, they will automatically reconfigure laws. This is common on any FBW aircraft, including the 777/787.
Originally Posted by Rananim
IF I have dual RA fail on Boeing,its a total non-event.I fly the plane.No this law or that law.
The Boeing FBW types (777/787), they will drop out of "Normal Mode" if the FBW does not have the required inputs. You also get a noticeable increase in control responsiveness and loss of tail strike protection.
Boeings FBW aircraft have 3 flight control laws as well, normal, secondary, and direct.
Originally Posted by neville_nobody
And Qantas had the same failure in a 737 and it resulted in a normal landing because the pilots knew what they were doing and can actually hand fly an aeroplane. The issue at play here is the Airbus system and the change of flight laws in a very critical stage of flight.
Qantas has also had a dual RADALT failure on the A330, with no tail scrape either. Dual RADALT failures on a FBW aircraft does not mean a tail strike.