Re-engineering fault tolerance requirements: a case study in specifying fault tolerant flight control systems

We present a formal specification of fault tolerance requirements for an analytical redundancy based fault tolerant flight control system. The development of the specification is driven by the performance and fault tolerance requirements contained in the US Air Force military specification MIL-F-9490D. The design constraints imposed to the system from adopting the analytical redundancy approach are captured within the specification. We draw some preliminary conclusions from our study.