7 OUTLINE THE STRUCTURE OF RECOVERY BLOCK SOFTWARE TO COPE WITH THE...

17.7

Outline the structure of recovery block software to cope with the following situation.

A fly-by-wire aircraft is controlled by software. A normal algorithm calculates the opti-

mal speed and the appropriate control surface and engine settings. A safety module

checks that the calculated values are within safe limits. If they are not, it invokes an

alternative module that calculates some safe values for the settings. If, again, this

module fails to suggest safe values, the pilots are alerted and the aircraft reverts to

manual control.