A Modified Hazop Methodology For Safety Critical System Assessment

Abstract

The concept of a Safety Lifecycle for Programmable Electronic System (PES) based systems has previously been suggested by the Working Group for an IEC draft standard dealing with safety-related software. The starting point in such a Lifecycle is Hazard Analysis which may be performed using a variety of accepted tools, including Fault Tree Analysis (FTA), Failure Modes, Effects and Criticality Analysis (FMECA) and Hazard and Operability studies (HAZOP). This paper describes work carried out to extend the standard FMECA and HAZOP approaches to suit the analysis of Programmable Electronic Systems, based on a number of case studies.