Formal safety analysis and the software engineering process in the pacemaker industry

The increasing application of software-based systems to safety-critical processes has necessitated the integration of safety into the software-development process. An example from the cardiac pacemaker industry of this safety-oriented software design methodology is provided. Safety considerations begin on product description with the hazard analysis, whereby potential hazards are classified according to their criticality and qualitative probability of occurrence. The completed hazard analysis determines the software safety requirements, which specify what the system will not do. A system hazard cross-check matrix is defined that serves to direct the design team to those areas requiring more scrutiny. Finally, traceability matrices provide a verifiable link from safety requirements through design to the actual code. This methodology should serve to minimize hazards in the final software product.<>