Apollo flight controller. Display and keyboard unit (DSKY) from the F-8 digital-fly-by-wire (DFBW) system used on the Apollo mission lunar modules. This formed the prototype of fly-by-wire systems. Fly-by-wire links the controls of an aircraft to a computer, which then effects the pilot's commands. It allows aircraft to dispense with heavy hydraulic systems, and the computer can control the aircraft's stability to a greater degree than a human. Fly-by-wire systems are used on the majority of military and commercial aircraft.