Fault tolerant avionics for the Space Shuttle

The space shuttle uses a digital fly-by-wire control system. If this system were to fail, it would cause certain loss of personnel, payloads, and the vehicle itself. Consequently, an avionics architectural design was chosen that would withstand two failures in any particular subsystem and still provide adequate vehicle control. A total of four primary computers are used to provide safe control of the vehicle. Multiple copies of flight-critical sensors were installed. Software redundancy was also used