The field of safety-critical systems covers computer systems in hazardous applications. As traditional means of control such as relays are replaced by software, the field is rapidly expanding and increasing in importance. It is formed by the convergence of software engineering and safety engineering, and its criticality emphasises the importance of a number of other disciplines, such as human factors, management, psychology, sociology and quality. This volume contains the invited papers presented at the fifth annual Safety-critical Systems Symposium . They cover a broad spectrum of issues affecting safety, from a philosophical appraisal to technology transfer, intelligence and psychological aspects. They touch on a number of industry sectors, but are restricted to none, for the essence of the event is the transfer of lessons and technologies between sectors. All address practical issues and offer useful information and advice.