PPRuNe Forums - View Single Post - AF 447 Thread No. 12
View Single Post
Old 3rd Dec 2014, 16:22
  #806 (permalink)  
RetiredF4
 
Join Date: Jun 2009
Location: Germany
Age: 71
Posts: 776
Received 3 Likes on 1 Post
Again, this is something I've brought up before, but the Airbus (and later Boeing) FBW "hard" protections are not just about sparing the blushes of the flight crew, and while this aspect was emphasised to the general public (who in 1985 had seen one of the worst years for airline safety on record), the other equally important aspect was that the hard protections allowed the crew to deliberately use full control deflections in an emergency scenario without worrying about stalling/spiralling the aircraft or overstressing the airframe.
It was and still is a clever move to sell the flight envelope protections only as a device to protect the aircraft from the pilot inputs and to allow them to use maximum control imputs without thinking too much about stalling or overstressing the airframe. Those envelope protections are a necessary gadget to prevent the FCS in a flightpath stable setup from exiting the flightenvelope with no corrective intervention by autothrottle, autopilot or human pilot. It is probably a philosophical point which need was first, to implement a system which sets limits to the FCS and regains the necessary positive static stability at the edge of the flight envelope or to implement the system to aid in piloting the airframe at the borders of the flight envelope. Both purposes are served well. But without those protections the flightpath stable C* design would hardly have been certified by the authorities.
But I agree, the official version sells better.
RetiredF4 is offline