Fault mitigation in safety-critical software systems

Software hazard analysis involves identifying safety faults in software and mitigating their causes. Designing safe systems is a creative process and there are no systematic guidelines for generating safe designs. In this paper we present some patterns of safety fault mitigation in medical devices, which were identified from a case study at the Guidant Corporation. These patterns prescribe appropriate fault mitigation processes and techniques for different safety situations. The patterns are classified into two major categories, Process Patterns, and Technique Patterns. The process patterns are the patterns found in the process and decisions taken by engineers during safety analysis. The technique patterns are patterns found in the various mitigation techniques used to mitigate faults. The factors affecting the usage of these patterns and the process of mitigation are also discussed here.