Of all the aeromedical treats to flying safety, G-induced loss of consciousness (G-LOC) must be one of the most important. The present study is undertaken to acquire the physiological normative data (including lifestyle and physical fitness) of KAF pilots and to investigate the factors that will be related with G-LOC. From 15 May through 27 Nov 2000, 464 KAF pilots underwent high G training and flight performance tests at the Aeromedical Research and Training Center are checked CBC, total cholesterol, PFT, physical fitness battery tests-muscular strength, muscular endurance, power, and flexibility. High G training and 2 kinds (before and after the G-training) of questionnaire were tried. Pilot's attitude for health promotion was relatively passive and the proportions as of high and borderline risk for atherosclerosis in total cholesterol level were 4.98% and 22.1%, respectively. 17.6% of the pilots had G-LOC and three quarters of them fell into G-LOC within the first 5 seconds. Variables showing significant correlation (p<0.05) with G-LOC were as follows; height, age, total flying time, and high G-training times. Trunk extension had positive correlation and curls ups had negative correlation, but the reasons are needed more following study. Also, the judgments of pilots and a supervisor in skillfulness of L1 maneuver were significant with G-LOC.