This article provides an introduction to the topic of safety-critical control systems for those engineers and managers who are skilled in the disciplines of computer-based control, but have not had to face the additional engineering problems which arise when equipment is crucial to the protection and preservation of human life. Increasingly, control engineers are using computers and complex real-time software in circumstances in which serious malfunctions can result in accidents and loss of human life. Those involved professionally in such work need wide, general engineering experience, plus specialised knowledge of topics such as:• Hazard analysis, to identify the risks• Methods of writing engineering specifications• Rigorous approaches to computer programming• Testing, verification and validation• Training and education for specialist staff.