Urgent Operational Requirements: Impact on the Safety Case

Cant, T. and Mahony, B.

Modern Defence systems are complex and software-intensive. In response to the technical challenges posed by such systems Defence has developed a capability lifecycle with suitably rigorous quality control measures. Unfortunately, in today�s rapidly evolving Defence environment, unforeseen threats can lead to capability gaps that require rapidly fielded solutions. Such Urgent Operational Requirements (UOR) can accelerate (and perhaps curtail) the normal capability lifecycle. Defence systems are often safety-critical: they have the potential to cause death or injury as a result of accidents arising from unintended system behaviour. For such systems an effective safety engineering process (along with choice of the appropriate safety standards) must be established at an early stage of the capability lifecycle, and reflected in contract documents. This process culminates in a safety case, which is a structured argument, supported by a body of evidence, that provides a compelling, comprehensible valid case that a system is safe for a given application in a given environment. In this paper we discuss the impact of Urgent Operational Requirements and the above lifecycle issues on the Safety Case. We use the processes and terminology of the recently published standard DEF (AUST) 5679 Issue 2. In discussing the impact of UORs on the safety case, we find it useful to distinguish three cases: Greenfield Acquisition, In-Service Modification and Modified Operational Context.

Cite as: Cant, T. and Mahony, B. (2011). Urgent Operational Requirements: Impact on the Safety Case. In Proc. Australian System Safety Conference 2011 (ASSC 2011) Melbourne, Australia. CRPIT, 133. Cant, T. Eds., ACS. 37-48

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