How is a fly-by-wire flight control computer architected for safety?

FBW flight control computers (FCCs) use multiple strategies for safety: Redundancy - typically 3-4 computers with independent channels, voting logic, and automated fault detection; Dissimilarity - different processor types, software teams, or algorithms to prevent common-mode failures; Partitioning - separation of functions with defined interfaces per DO-297 (IMA); Monitoring - Built-In Test (BIT), watchdog timers, self-checking pairs; Reversionary modes - graceful degradation maintaining control with failures. Architecture example (A320): 3 primary flight control computers (PRIM), 2 secondary computers (SEC), independent hydraulic actuators. Software certified to DO-178C DAL A. Extensive failure analysis, simulation testing, and flight test validation required for certification.