Safety Case

Section 06: System Safety & Functional Safety

Definition

A structured argument, supported by a body of evidence, that provides a compelling, comprehensible, and valid case that a system is acceptably safe for a given application in a given operating environment. The safety case integrates all safety-related evidence — including safety analyses (FHA, PSSA, SSA), design data, test results, process evidence (development assurance), and operational considerations — into a coherent narrative demonstrating that safety objectives are met. The safety case concept is used explicitly in some regulatory frameworks and implicitly in others where the certification evidence package serves the same function.

Where This Shows Up

While the FAA certification process does not explicitly use the term 'safety case' as a formal deliverable, the combination of the SSA, certification plan, and compliance documentation effectively constitutes a safety case. EASA and some military standards more explicitly reference the safety case concept. The Goal Structuring Notation (GSN) is sometimes used to formally structure safety case arguments. A well-constructed safety case makes the logic of the safety argument transparent and auditable.

Primary Sources

SAE ARP4761A — Safety Assessment Guidelines

The SSA and overall safety assessment form the basis of the safety case for civil aviation systems.

EASA Certification Specifications and related guidanceEASA

EASA references the safety case concept in the context of demonstrating compliance with safety requirements.

Related Terms

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