The flight surgeon, specialized out of the army medical officer, was one of the early developments of training for air warfare and soon also there appeared, first devised and used at an American field, the flying ambulance, which enabled him and his assistants to go at once to the help of an injured airman, give him first aid and bring him back in the fuselage of the ambulance plane to the hospital. The end of hostilities saw at least one flight surgeon at every aviation training field in this country and several at each of the large ones. And there had been established a division of flight surgeons for which medical officers could receive a special course under the direction of the Medical Research Board of the Surgeon General’s Office. The flight surgeon’s duty was to keep every aviator under observation, to examine each one physically before and after flying, to note the effects of flight, especially at high altitudes, to determine how frequently he should fly and to discover whether or not he had physical peculiarities which would unfit him for any special kind of air service. To aid in this work, which was producing remarkable results in the way of both efficiency and safety, there had been established at many of the flying fields research laboratories which worked out new tests and special and ingenious apparatus for using them and made examinations and observations of the airmen in training. Associated with the work of the flight surgeon was that of the athletic instructors who, toward the end of the war period, were appointed for service at the flying fields. They were former college athletes and athletic instructors who had received special training for the work of keeping the student aviators in the best possible physical condition. These phases of the system of training that was worked out at American fields aimed to lessen the chances of accident and to gain greater speed and efficiency in the progress of the cadets. Throughout the war period the United States made a much greater effort to lessen the casualties of training than did any other nation. A longer period of work under dual control and more knowledge and skill before the cadet began solo flying were demanded by our system of training than other nations thought necessary. This and other provisions for the safety of the cadets made our training casualties less than half those of any other nation among our war associates. The record of American flying field casualties showed 278 fliers killed in training, an average of one to each 236,800 miles flown by cadets.