Experience with the application of HAZOP to computer-based systems

This paper summarises the experience gained from application of Hazard and Operability Studies (HAZOP) and related techniques to four computer-based systems. Emphasis is placed on working practices and the integration of HAZOP-style analysis into a safety-oriented lifecycle. Two of the case studies are described in some detail. An industrial study is used to investigate working practices, highlighting a number of areas of concern with the traditional team approach. A second example is described using an alternative process known as Software Hazard Analysis and Resolution in Design (SHARD), showing its effectiveness on a technology demonstrator case study. This example also demonstrates the integration of our approach with other techniques such as our Failure Propagation and Transformation Notation (FPTN) and Software Fault Trees.