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.