Handling Consistency Between Safety and System Models

Safety analyses are of paramount importance for the development of embedded systems. In order to perform these analyses, safety engineers use different modeling techniques, such as, for instance, Fault Trees or Reliability Block Diagrams. One of the industrial development process challenges today is to ensure the consistency between safety models and system architectures. Model Based Safety Analysis (MBSA) is one of the newest modeling methods, which promises to ease the exchange of information between safety engineers and system designers. The aim of this article is to discuss an approach to manage the consistency between MBSA models and system architectures. Our study is based on the experimentation of the co-design of an RPAS (Remotely Piloted Aircraft System) involving system design and safety teams during the early conception phases of an industrial development process. We simulate the process of exchange between the system design and the safety assessment with the constraint of creating safety models close to system architecture. We identify significant exchange points between these two activities. We also discuss the encountered problems and perspectives on the possibility to ensure the consistency between safety and system models.