sikkerhedscase

Sikkerhedscase, in English often called a safety case, is a structured set of arguments supported by evidence that a system is acceptably safe for a defined use and operating environment. It is used to persuade regulators, customers, and operators that safety risks have been identified, analyzed, and mitigated to an appropriate level.

A safety case typically contains a top-level safety claim or goal, together with a chain of reasoning that links that claim to concrete evidence. The argument shows how hazards have been identified, how safety requirements address those hazards, and how design, implementation, verification, and validation activities demonstrate that safety goals are met. Evidence may include hazard analyses, risk assessments, design descriptions, test results, validation data, safety plans, and maintenance or operation procedures. Many safety cases use a graphical notation such as Goal Structuring Notation (GSN) or similar methods to present the justification clearly.

Lifecycle and domains: A safety case is usually created during system development and maintained as a living document throughout the lifecycle, evolving with design changes, component updates, field incidents, or new regulatory requirements. It is commonly required in high-assurance domains such as rail, aviation, automotive, medical devices, nuclear, and other safety-critical industries. It is often aligned with recognized standards and frameworks, including IEC 61508 and ISO 26262 for functional safety, EN 50126/50128/50129 for railway applications, and DO-178C/DO-254 in aerospace contexts.

Evaluation and limitations: A safety case supports risk-based decision making but is not a guaranteed guarantee of safety. Its credibility depends on the quality of the argument, the relevance and sufficiency of the supporting evidence, and independent assessment.