Applying a single source of truth approach to the information needed for Functional Safety

The economics of the aerospace business often require engineers to develop systems either as product-lines or as derivatives of existing designs. When completing the system safety analyses of these individual variants, it is critical that the analyses be completed both for each specific application and to the standards of each end recipient. In the example of a military product-line, the purchasing governments may separately require documentation based on SAE ARP4761, Goal Structuring Notation, System Theoretic Process Analysis (STPA), various Mil-Std forms, or others. These separate deliverable requirements may cause a great amount of variant-specific work, despite the underlying data and analyses differing little between variants. This paper describes a pilot project completed by several partners to integrate system safety tools and processes into a common environment. The goal of this common environment is to define a “Single Source of Truth” across multiple systems and safety toolsets, simultaneously providing all required system safety artifacts and eliminating non-value added activities of transposing and replicating system safety data in multiple places. The paper discusses the successes of this “Single Source of Truth” approach in completing compliant system safety analyses and the associated documentation. It also explains the limitations, both technical and process-related that still present challenges. Finally, the paper details how a “Single Source of Truth” can also provide other safety process related feedback such as progress metrics or completeness checks.