Safety-Critical

Adjective · Development

Definitions

  1. Describing a system whose failure could cause death, serious injury, or major damage to property or the environment, such as flight controls, medical devices, railway signalling, automotive braking, and industrial process control. Software in these systems is developed under domain standards that demand traceability from requirements to code to tests, independent verification, and documented hazard analysis: DO-178C for avionics, ISO 26262 for road vehicles, IEC 62304 for medical device software, and IEC 61508 as the general functional-safety standard. Many standards grade rigour by risk, for example Safety Integrity Levels or Design Assurance Levels. Common techniques include restricted language subsets such as MISRA C, static analysis, formal methods, redundancy, and fail-safe defaults. Safety-critical is distinct from mission-critical, where failure is costly but not dangerous, and from security, which defends against deliberate attack rather than accidental failure. The Therac-25 radiation overdoses remain the textbook case study.

    In plain English: Software or hardware where a bug could literally hurt or kill people, like in planes, medical devices, or nuclear plants.

    Example: "Avionics code is safety-critical — every line goes through DO-178C certification."

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