Aviation medicine came into existence as a recognized entity when certain standards were established during and shortly after World War I.1 During this time, accident rates were high.2 In fact, a larger number of pilots were dying in accidents than in combat. Figures from Great Britain's casualty list at the close of the first year of World War I indicated that for every 100 aviators killed, 60 died as a result of some individual physical defect, 30 from some form of recklessness or careless behavior, 8 as a result of some mechanical defect in the airplane, and only 2 at the hands of the enemy.3 Aviators were found to be in poor physical condition. Because there were no established regulations with regard to workloads, aviators were frequently found to have been flying to a point beyond exhaustion. Because of workload, chronic fatigue, and emotional stress, aviators were constantly called upon to perform superhuman feats when not in peak physical condition. Errors in judgement were common. The majority of pilots lost weight as a somatic sign of stress. This was recognized by Theodore Lister who had recently been appointed as the Chief Surgeon, Aviation Section of the U.S. Army. Such problems were not diagnosed by medical officers because they were not trained to recognize them. Theodore Charles Lister was the son of Captain William J. and Martha Doughty Lister. He was an Army “brat” who entered the world on July 10, 1875. His childhood was spent in various posts around the country. At the age of 7, Lister contracted yellow fever while living in Fort Brown, TX. The boy was treated by William Gorgas, a young post surgeon. Gorgas was credited with the young boy's recovery. Later, Gorgas was to marry Lister's aunt making Lister his nephew by marriage. Having survived the yellow fever infection, young Lister had a lifelong immunity to the disease.