Fly-by-wire (FBW) replaces mechanical control cables with electronic signals sent from the cockpit to actuators at the control surfaces. Earlier fly-by-wire aircraft included the Avro Canada CF-105 Arrow (first flew 1958) and operational types such as the A-5 Vigilante; NASA's 1972 F-8 Crusader was the first digital fly-by-wire aircraft without mechanical backup, used for research in the Digital Fly-by-Wire program. The first commercial airliner with full FBW was the Airbus A320, introduced in 1988. The advantage is that computers can stabilize inherently unstable aircraft—like the F-117 Nighthawk, which could not be flown without its quadruple-redundant FBW system. FBW also enables envelope protection, preventing the pilot from exceeding the aircraft's structural or aerodynamic limits. Critics have raised concerns about "mode confusion," where pilots do not understand what the automation is doing. The Airbus A320 crash at Habsheim in 1988, where the aircraft entered alpha protection and the pilot could not override it, remains a case study in the design philosophy of "the computer knows best." Boeing's approach, by contrast, allows more pilot override authority. Both philosophies have advantages and risks.