Cause–consequence analysis of non-repairable phased missions

Many systems can be modelled as a mission made up of a sequence of discrete phases. Each phase has a different requirement for successful completion and mission failure will result if any phase is unsuccessful. Fault tree analysis and Markov techniques have been used previously to model this type of system for non-repairable and repairable systems, respectively. Cause–consequence analysis is an alternative assessment technique capable of modelling all system outcomes on one logic diagram. The structure of the diagram has been shown to have advantageous features in both its representation of the system failure logic and its subsequent quantification, which could be applied to phased mission analysis. This paper outlines the use of the cause–consequence diagram method for systems undergoing non-repairable phased missions. Methods for construction of the cause–consequence diagram are first considered. The disjoint nature of the resulting diagram structure can be utilised in the later quantification process. The similarity with the Binary Decision Diagram method enables the use of efficient and accurate solution routines.