Fault - Tolerance in the advanced automation system

The Advanced Automation System is a distributed real-lime system under development by IBM's Systems Integration Division for the US Federal Aviation Administration, The system is intended to replace the present en-route and terminal approach US air traffc control computer systems over the next decade. High availability of air traffic control services is an essential requirement of the system. Hits paper discusses the general approach to fault-tolerance adopted in AAS, by reviewing some of the questions which were asked during the system design, various alternative solutions considered, and the reasons for the design choices made.