Formal requirements analysis of an avionics control system

The authors report on a formal requirements analysis experiment involving an avionics control system. They describe a method for specifying and verifying real-time systems with PVS. The experiment involves the formalization of the functional and safety requirements of the avionics system as well as its multilevel verification. First level verification demonstrates the consistency of the specifications whilst the second level shows that certain system safety properties are satisfied by the specification. They critically analyze methodological issues of large scale verification and propose some practical ways of structuring verification activities for optimizing the benefits.