Accident investigation has long been recognised as a core element of effective safety programs. Few would argue with the premise that the fundamental purpose of an investigation is to determine the facts, conditions and circumstances relating to an incident so that the causes may be established and appropriate steps taken to prevent a recurrence. In 1931 H. W. Heinrich in his book "Industrial Accident Prevention" proposed a chain of multiple events model for understanding accident causation (Heinrich (1931)). He suggested that accidents were the result of a series of factors, each acting on the next over a period of time leading to the accident. In 1946, in the First Edition of its Accident Prevention Manual for Industrial Operations, the National Safety Council (NSC 1946)) suggested that "accident investigation and analysis is one of the means used to prevent accidents. As such, the investigation or analysis must produce information that leads to countermeasures which prevent or reduce the number of accidents." This base purpose has since remained unchanged, as the Australian Transport Safety Board (ATSB) suggested: “The objective of investigating accidents and incidents is to prevent the occurrence of future accidents” (ATSB (2010)).