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Medical aspects of airline operations. II: Aircrew schedules and emergency considerations.

The need to operate commercial airlines world wide for 24 hours each day inevitably leads to problems of aircrew management: to the stresses of flying an aircraft must be added those of unsocial and irregular hours, time zone (transmeridian), climatic and cultural changes, sleep disturbances, and alterations to circadian rhythms. Fatigue is the main danger, since a decline in performance is likely to accompany it. The economic and operational requirements of an airline must be balanced against these undesirable factors, but good aircrew scheduling is essential to the health, morale, and safety of aircrew: the narrow area wherein lies safe and economic management has concerned the civil aviation industry for many years.