Safety analysis of requirements for a product family

A safety analysis was performed on the software requirements for a family of flight instrumentation displays of commercial aircraft. First, an existing safety checklist was extended to apply to four-variable models and used to analyze the requirements models for representative members of the product family. The results were evaluated against an initial specification of the product family's required commonalities and variabilities. The safety checklist was found to be effective at analyzing the completeness of the product family requirements and at identifying additional variabilities and commonalities. Secondly, a forward and backward search for hazards was performed on representative members of the product family. Additional safety requirements for enhanced fault tolerance were derived from these searches. The safety analysis techniques used here appear to have applicability for enhancing the completeness and robustness of a product family's safety related software requirements.