The Preliminary System Safety Assessment is a safety assessment technique defined in SAE ARP4761.
An iterative process, the PSSA assures that requirements identified in the Functional Hazard Assessment (FHA) are met.
The PSSA is used to complete the failure conditions list and the corresponding safety requirements. It is also used to demonstrate how the system will meet the qualitative (system Development Assurance Levels (DALs); item DALs, hardware DALs and software levels) and quantitative (safety-related reliability targets) safety requirements for the various hazards identified.
It identifies and captures all derived system safety requirements. The PSSA process identifies protective strategies, taking into account fail-safe concepts and architectural attributes which may be needed to meet the safety objectives.
PSSA outputs are used as inputs to the System Safety Assessment (SSA) and other documents, including, but not limited to, system requirements, hardware requirements and software requirements.
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