Safety Analysis in Early Concept Development and Requirements Generation

Abstract

This paper shows how a new hazard analysis technique, STPA (System Theoretic Process Analysis), can be used to generate high-level safety requirements early in the concept development phase that canthenassist in the design of the system architecture. These general, system-level requirements can be refined using STPA as decisions are made. The process goes hand-in-hand with design and the rest of the lifecycle as STPA can be used to provide information to assist in decision-making throughout the development and even operations phases. STPA also fits into a model-based engineering process as it works on a model of the system (which is also refined as design decisions are made) although that model is different than the architectural models usually proposed for model-based system engineering today. The process promotes traceability throughout the development process so decisions and designs can be changed with minimum requirements for redoing previous analyses. Finally, while this paper describes the approach with respect to safety,it can be applied to any emergent system property.