Myths and Barriers to the Introduction of Safety Cases in Space-Based Systems

Safety cases provide high-level support for the development of critical systems. They present an overview of the arguments and evidence that demonstrate a complex application is acceptably safe within a particular context of use. This approach offers particular benefits as organisations seek to procure services rather systems, for instance in government projects. Contractors can present safety arguments to explain the steps that have been taken to mitigate potential risks without providing low level proprietary information. Government agencies can inspect graphical overviews of safety arguments to identify potential weaknesses in the evidence that supports particular applications. There are, however, a number of concerns about the use of safety cases. For instance, the UK Hadden-Cave review has shown that safety cases can become ‘tick-box exercises’ if they are not supported by an appropriate safety culture. Other concerns stem from misunderstandings. For example, recent discussions about possible space based applications revealed that many engineers view safety argumentation as a means of reducing expenditure on existing forms of risk assessment and testing. This paper identifies the myths and rumours that jeopardise the development of safety cases to support complex spacebased systems.