Fatigue, watchkeeping and accidents : a content analysis of incidents at sea reports

The profession of seafaring involves rest and sleep in a 24-hour-a-day work environment; obtaining sufficient sleep under such conditions is often difficult, and sleep loss and the need for sleep is often related to fatigue and contributory to accidents. Maritime incident reports form a rich source of human performance data with high face validity, however fatigue as contributory to human error is elusive, and direct evidence of accident causation is hard to come by. In Australia, the Australian Transportation Safety Board has responsibility to investigate incidents at sea. The present study aimed to identify evidence of time of day and sleep deprivation as factors that appear contributory to fatigue in \Incidents at Sea\" reports. Both quantitative and qualitative analyses of the text of these reports were conducted using NUDIST¬¨vÜ categories were developed and patterns identified. The effect of time of day was identified from analysis of the conclusions of 100 consecutive reports to determine the nature and distribution of behaviours associated with fatigue. Collisions and groundings were more prevalent during the early morning watches. Behaviours consistent with fatigue were identified categorised and described for different times of the day with deficits in alertness predominating in the early morning watches and deficits in information processing predominating in the afternoon watches. The contribution of sleep deprivation and its relationship with fatigue and accidents was identified from analysis of the full text of 44 reports which incorporated three levels of association of sleep with accident causation. The highest level establishes either being asleep or being sleep deprived as causal to an accident. At an intermediate level reference to the conflicting pressures -' of work and sleep suggests a work environment that is not conducive to obtaining sufficient sleep and accident investigators were usually unable to link the watchkeeping environment with fatigue as a contributing factor. At the lowest level of association reference is made to the integrated nature of sleeping and work on board. Finally a model illustrating the relationships between sleep deprivation time of day and fatigue behaviours in the maritime setting was proposed providing accident investigators with a tool to assist with the identification of fatigue in their analyses of maritime incidents. In addition this model would be useful in the education of maritime administrators and policy developers shipping companies and seafarers."