ABSTRACT
Fatigue, it has long been recognized, affects the mind and emotions as well as the body. The issue of fatigue is, therefore, an important one in any discussion of pilots' cognitive performance. This is perhaps most obvious where aircrew fatigue is implicated in aviation accidents, but it is relevant not only to considerations of public safety but to pilot efficiency and wellbeing. A review of the subject, however, shows a decided lack of consensus as to how fatigue should be measured or, indeed, defined. Since no widely accepted definition of fatigue currently exists, each investigator typically supplies his or her own,18 one result being that studies of pilot fatigue vary so much in both criteria and methodology that they are often difficult to compare with one another.
