SAE ARP4754B / ED-79B - Guidelines for Development of Civil Aircraft and Systems 5.1.2: 5.1.2 Preliminary aircraft safety assessment

The PASA systematically evaluates a proposed aircraft architecture to see how failures, errors or external events could lead to the AFHA's failure conditions and whether the safety objectives at aircraft level are achievable; it identifies how systems interact and depend on one another, considers common causes and shared resources, proposes safety requirements and assumptions for the aircraft and for its systems, and identifies independence requirements and FDAL assignments for aircraft functions. It is iterative throughout development and leads into the ASA as designs mature.