Comparing Automatic Allocation of Safety Integrity Levels in the Aerospace and Automotive Domains

Safety standards guide the development of systems whose operation raises concerns about safety. We focus our attention on the automotive and aerospace standards, ISO 26262 and ARP4754-A respectively. Both standards advocate a process for controlled allocation of safety integrity requirements that starts early in the design and continues as the system architecture is being refined. This procedure may generate a plethora of feasible design variants, all satisfying system safety requirement, but each having different allocations of integrity to components and different costs. In this paper, we describe a model-based safety analysis method for automating this allocation process in a way that cost-optimal design variants are selected. We show that the proposed method is generic and can satisfy both the automotive and aerospace safety standards with application to both industries. We apply the method using both standards on a common case study and discuss the differences in the results obtained, reflecting on the commonalities and differences between the two standards.