Abstract
AbstractIt is a well-known fact that humans are subject to circadian alterations caused by the action of sunlight. This strongly affects their behaviour and skill, making them change their level of alertness from high at daytime to low at night-time. Taking into account this biological feature, and considering that commercial shipping is one of the oldest round-the-clock activities, raises the question whether bridge watchkeepers can carry out their tasks on night shifts with the same level of alertness as on day shifts. Furthermore, night bridge watchkeeping has to be performed in darkness or very dim light to improve the visual capacity of lookouts. A sample of vessel collisions was analysed and it was find out that this kind of accident tends to be more frequent and more serious during the darkness period of the solar day.
Highlights
Investigations have shown that humans maintain a roughly 24 h cycle of physiological and behavioural changes following the daily light–dark cycles
In order to analyse the influence of solar light on the behaviour of the crew engaged in bridge watchkeeping, the abovementioned hypothesis is assumed: that navigation watchkeepers on a four-on/eight-off fixed schedule can maintain a level of alertness during their night shifts similar to that of their day shifts, provided that they develop a good adaptation to the night shifts
Excessive working hours and fatigue on board have become widely recognised issues. This has been confirmed by many accident investigations which reflect that the low alertness of bridge watchkeepers and lookouts is the cause of fatal navigational errors
Summary
Investigations have shown that humans maintain a roughly 24 h cycle of physiological and behavioural changes following the daily light–dark cycles. The ineffectiveness of regulations and industrial practices in dealing with the psychophysical disorders of people on board becomes noticeable on the bridge navigation shift-working at night This is supported by research findings that the effect of circadian disorders on human alertness is more intense in the absence of light, the common situation on a ship’s bridge during the night (Cajochen et al, 2000). Taking into consideration the circumstances mentioned above, the aim of the present paper is to investigate if the average level of alertness of people engaged in bridge navigation tasks on board the world’s merchant fleet is lower at night For this purpose, the study analysed, first, if shipping accidents are more frequent during night shifts than during daylight shifts and, second, if the response to incidents that occur at night is slower than during daylight shifts, which would make accidents more serious at night. The novelty of this paper is that it deals with the world’s commercial fleet incidents
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