FAC meaning in Computing ?

Fly-by-wire (FBW) is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. The movements of flight controls are converted to electronic signals transmitted by wires, and flight control computers determine how to move the actuators at each control surface to provide the ordered response. It can use mechanical flight control backup systems (like the Boeing 777) or use fully fly-by-wire controls.

Improved fully fly-by-wire systems interpret the pilot's control inputs as a desired outcome and calculate the control surface positions required to achieve that outcome; this results in various combinations of rudder, elevator, aileron, flaps and engine controls in different situations using a closed feedback loop. The pilot may not be fully aware of all the control outputs acting to effect the outcome, only that the aircraft is reacting as expected. The fly-by-wire computers act to stabilise the aircraft and adjust the flying characteristics without the pilot's involvement and to prevent the pilot operating outside of the aircraft's safe performance envelope.