Changes of Heart Rate in AIrcraft Pilots During Actual Flight.

The main factor that affects the heart rate of the modern aircraft pilots during the actual flight is considered to be a mental stress rather than a physical one with particular exception of the G stress. Electrocardiograms of the pilots, which were recorded during various patterns of the actual flight in a light aircraft (T-34, F-86 F, and F-104 J), were investigated and the relationships between chages of the heart rate and stresses, especially mental strain or G stress, were discussed. The results are summarized as follows. 1. Pulse rate showed a considerable increase during the actual flight corresponding with each flight pattern such as taking-off, level flight, or landing, in which the effects of G force were believed to be negligible. For example, during the level flight, in which the pilots were most relaxed, pulse rate was maintained at about 50% level above the normal resting value on the ground. Pulse rate during the taking-off landing showed an increase by about 80%. In super-sonic jet fighter, the pilots with pressure suits showed a much more increase in their heart rate during ordinary flight. These facts may indicate that pilots are in a considerably strained mental condition during the fight. 2. Pulse rate of pilots and G value during acrobatic flights such as loop, immelman turn, airlon roll, barrel roll, spin, and clover leaf were studied by T-34 trainer. Maximum Gz during these acrobatic maneuvers in this type of aircraft was about +3Gz, and the pulse rate of pilots showed a nearly positive correlation with +Gz. Increasing rate of pulses by the acrobatic G stress was about 10 to 15 beats per minute per +1Gz, while in the human centrifuge experiments it was about 8 beats per mintue per +1Gz. This difference between actual flight and human centrifuge experiment may be considered to be due to an additional mental strain in the actual flight.