criticalsystems

Critical systems are information technology and operational systems whose failure or degraded performance could result in loss of life, serious injury, substantial property damage, or disruption of essential societal functions. They demand high levels of safety, reliability, availability, integrity, and maintainability. The term is used across sectors such as aerospace, aviation, energy, transportation, healthcare, industrial control, defense, finance, and telecommunications.

Design and operation of critical systems incorporate redundancy, fail-safe or fail-operational architectures, deterministic behavior, and strong change control. They usually undergo formal hazard and risk assessment, define safety requirements, and implement safety functions with specified performance targets. The safety integrity level (SIL) or equivalent metric is used to categorize critical functionality. In many domains, compliance with rigorous lifecycle processes and documentation is required to demonstrate safety and reliability.

Management follows a safety or reliability lifecycle: requirement specification, design, implementation, integration, testing, validation, deployment, operation, maintenance, and decommissioning. Standards and guidelines provide methodologies for hazard analysis, verification and validation, configuration management, and cybersecurity. Examples include the IEC 61508 family for functional safety, ISO 26262 for automotive, IEC 61511 for process industries, IEC 62443 for industrial cybersecurity, and ISO 14971 for medical devices, among sector-specific norms. In information-rich domains, resilience and continuity planning play a complementary role.

Risk and security considerations increasingly treat physical safety and cyber threats as intertwined, with defense-in-depth, network segmentation, access control, and incident response planning embedded in the lifecycle. Ensuring reliability of critical systems remains a balance among safety, security, cost, and maintainability.