Analysing the safety of a software development process

Abstract

The UK Defence Standard for developing safety-related software, [16], requires that a safety analysis be performed on the process used to develop safety-related software. This paper describes the experience of performing such a safety analysis, and reflects upon the lessons learnt. It discusses the issues involved in defining the process at the appropriate level of abstraction, and it evaluates the difficulties and benefits of performing Function Failure Analysis and Fault-Tree Analysis on a development process. It concludes that the benefits of performing safety-analysis of a software development process are limited, but if such an analysis must be performed, it is best done to develop a qualitative understanding of the ways the process may fail, rather than to develop a quantitative understanding of the likelihood of the process failing.