ABSTRACT

This chapter discusses the motivation for fault-tolerant designs and the many different design practices evolving to implement a fault-tolerant system. A fault-tolerant avionics system is a critical element of flight-critical architectures, which include the fault-tolerant computing system (hardware, software, and timing), sensors and their interfaces, actuators, aircrew, components, and data communication among the distributed components. The fault-tolerant avionics system ensures integrity of output data used to control the flight of the aircraft, whether operated by the pilot or by autopilot. The design of a dependable fault-tolerant avionics system must be based on proven systems engineering processes and tools. The designers must identify all of the functions and the information and data flow between processes that implement these functions. Voter comparators are very widely used in fault-tolerant avionics systems, and they are generally vital to the integrity and safety of the associated systems.