The influence of architecture in assurance of system safety is being increasingly recognised in mission-critical software applications. Nevertheless, most architectural strategies have not been developed to the extent necessary to ensure safety of these systems. Moreover, many software safety standards fail to discuss the rationale behind the adoption of alternative architectural mechanisms. Safety has not been explicitly considered by existing software architecture design methodologies. As a result, there is little practical guidance on how to address safety concerns in ?shaping? a ?safe? software architecture.

This paper presents a method for software architecture design within the context of safety. This method is centred upon extending the existing notion of architectural tactics to include safety as a consideration. The approach extends existing software architecture design methodologies and demonstrates the true value of deployment of specific protection mechanisms. The feasibility of this method is demonstrated by an example.