A Proposal of Hazard Analysis Method Using Structured System Theoretical Process Analysis

System Theoretic Process Analysis (STPA) is a method for analyzing hazards caused by interactions between components of an industrial product. STPA is applied in the upper stream stages of the industrial product's development, and STPA detects hazards while referring to the whole configuration of the industrial product. Therefore, STPA generally does not deal with detailed information. Since the information on the industrial product is insufficient, it is difficult to clarify the factors of hazards, the occurrence procedure of factors, and the hazard causal factors. Therefore, the following methods were added to the conventional STPA; the method of describing the components of industrial products hierarchically, the method of clearly defining the behavior of each component, and the method of tracking the hazard occurrence procedure. As a result of applying the proposed method to the existing system, it was confirmed that the proposed method could detect more factors of hazards and create adequate hazard scenarios.