The use of fault tree analysis to visualise the importance of human factors for safe diving with closed-circuit rebreathers (CCR)

Closed-circuit rebreathers (CCR) have been used for many years in military diving but have only recently been adopted by technical leisure divers, media and scientific divers. Rebreather divers appreciate the value of training, pre-dive checks and equipment maintenance but it is often difficult to visualise just how important these factors are and how they inter-relate for a rebreather. In this paper, the well-known technique of fault tree analysis (FTA) is used to identify risk in a rebreather. Due to space constraints, only the branch of the tree for unconsciousness as a result of hyperoxia is considered in detail but, in common with the whole tree, end events are shown to be humanfactor related. The importance of training to the emergency situation, the use of formal pre-dive checklists and the value of good design to prevent accident escalation are discussed further.