Integrated safety analysis of requirements specifications

This paper describes an integrated approach to safety analysis of software requirements and demonstrates the feasibility and utility of applying the individual techniques and the integrated approach on the requirements specification of a guidance system for a high-speed civil transport being developed at NASA Ames. Each analysis found different types of errors in the specification; thus together the techniques provided a more comprehensive safety analysis than any individual technique. We also discovered that the more the analyst knew about the application and the model, the more successful they were in finding errors. Our findings imply that the most effective safety-analysis tools will assist rather than replace the analyst. A shorter version of this paper appeared in the Proceedings of the 3rd International Symposium on Requirements Engineering, Annapolis, Maryland, January 1997. The research described has been partly funded by NASA/Langley Grant NAG-1-1495, NSF Grant CCR-9396181, and the California PATH Program of the University of California