The purpose of a safety case report

The format is influenced by the purpose of a Safety Case Report, which needs to introduce and communicate the safety case to the reader, helping them to understand the system and services concerned. 

A Safety Case Report can be:

• an introduction to the safety case, assisting in its comprehension

• a management briefing to obtain release for the safety case

• a representation of the safety case that is sufficient to gain an approval or facilitate assessment leading to such an approval.

The broadest requirement for the content of the Safety Case Report comes from the last of these, and encompasses the content needed for the others. To satisfy this requirement, the Safety Case Report needs to fully present a safety case in a way that facilitates review and assessment, and provides a formal configuration-controlled statement that the safety case is complete. Such a report, along with any supporting documents, is intended to be sufficient to eliminate or at least minimise the need for direct access to the safety case.

The Safety Case Report represents the safety case by including an extract of the safety case argument. The extract shows a truncated version of the safety case argument, with selected supporting evidence, that is intended to be sufficient to support review and assessment. For some parts where the argument is truncated, a précis is substituted for the truncated parts.

Whilst the arguments in a safety case may use various other approvals and their associated materials, the Safety Case Report format in the book is not intended to support gaining these approvals. Pragmatically, the Safety Case Report format does make some concessions in this direction, especially where there is an indirect link to safety performance (e.g. showing the project has selected a good solution from a safety point of view), but it does not attempt to accommodate demonstration of meeting project or customer requirements. Whilst the principle of assuring any property or behaviour can be approached in a similar way to safety, usually a lower degree of confidence is required, at lower cost.