BACKGROUND: While the factors affecting fighter pilots’ G level tolerance have been widely accepted, the factors affecting fighter pilots’ G duration tolerance have not been well understood.METHODS: Thirty-eight subjects wearing anti-G suits were exposed to sustained high G forces using a centrifuge. The subjects exerted AGSM and decelerated the centrifuge when they reached the point of loss of peripheral vision. The G profile consisted of a +2.3 G onset rate, +7.3 G single plateau, and −1.6 G offset rate. Each subject’s G tolerance time was recorded and the relationship between the tolerance time and the subject's anthropometric and physiological factors were analyzed.RESULTS: The mean tolerance time of the 38 subjects was 31.6 s, and the min and max tolerance times were 20 s and 58 s, respectively. The correlation analysis indicated that none of the factors had statistically significant correlations with the subjects’ G duration tolerance. Stepwise multiple regression analysis showed that G duration tolerance was not dependent on any personal factors of the subjects. After the values of personal factors were simplified into 0 or 1, the t-test analysis showed that subjects’ heights were inversely correlated with G duration tolerance at a statistically significant level. However, a logistic regression analysis suggested that the effect of the height factor to a pilot's G duration tolerance was too weak to be used as a predictor of a pilot's G tolerance.CONCLUSION: Fighter pilots' G duration tolerance could not be predicted by pilots' anthropometric and physiological factors.Park M, Yoo S, Seol H, Kim C, Hong Y. Unpredictability of fighter pilots' G duration tolerance by anthropometric and physiological characteristics. Aerosp Med Hum Perform. 2015; 86(4):397–401.