High Level Organization of Safety Arguments

摘要

The work presented in this paper has been conducted as part of the BAE Systems funded Dependable ComputingSystems Centre (DCSC). In this paper we build on previous Safety Case Architecture (SCA) work and introduce atechnique called Imaginative Anticipation and two quality characteristics to aid the development of a SCA.SCAs are used, in this paper, to facilitate the high level organisation of the safety case into argument modules. Asafety case presents a reasoned argument that uses identified evidence to justify the safety of a particular system in aparticular context. Therefore, the arrangement into argument modules is conducted to develop modular safety cases.In this paper we discuss reasons for why a modular safety case would be developed and how a SCA can be used tosupport the development.A process is introduced for creating SCAs. The process consists of four iterative phases: Knowledge gathering,proposition of SCAs, evaluation of proposed SCAs, and, selection of the most appropriate SCA. The four phasesare discussed and the process is demonstrated through a small example.