Each year there are improvements in safety-critical system technology. These arise both from developments in the contributing technologies, such as safety engineering, software engineering, human factors and risk assessment, and from the adoption or adaptation of appropriate techniques from other domains, such as security. For these improvements to be of real benefit, they need to be applied during the appropriate stage in the life cycle of the system, whether it be development, assessment, or operation. For this to occur, they must be communicated and explained. Each year the Safety-critical Systems Symposium offers a distinguished forum for the presentation of papers on such developments, and also for papers from industry on the lessons learned from the use of technologies and methods. The results of many collaborative research projects, with components from both industry and academia, are reported in a universally understandable form. In 1995 the Symposium was held in Brighton, a venue calculated to stimulate not just the presenters of papers, but all the delegates. Yet, this book of Proceedings is intended not only for the delegates but also for readers not able to attend the event itself. We welcome both categories of reader. Delegates have the benefit of attending the presentations and the opportunity to participate in the discussions; those who take up this book after the event can peruse it attheir leisure and, perhaps, on account of it will resolve to attend subsequent symposia.