G-induced loss of consciousness: case-control study of 78 G-Locs in the F-15, F-16, and A-10.
BACKGROUND
This study determined the trends of reported G-induced loss of consciousness (G-LOC) mishaps from 1980--1999, and determined potential risk factors in pilot characteristics; specifically, 30/60/ 90-h and sortie history, total flight hours, total hours in the aircraft, age, height, weight, and BMI.


METHODS
Using aircraft malfunction mishaps to reflect a cross-section of USAF pilots, potential risk factors were determined using a case-control method; cases were all G-LOC mishaps and controls were aircraft malfunction mishaps. The data consisted of 2002 mishap pilots in the history of the F-16, F-15, F-15E, and A-10 from 1980-1999.


RESULTS
During this time, G-LOCs represented only 2.5% of all mishaps. The mean engagement number for G-LOC mishaps was three at an average of 8 Gs. A poor anti-G straining maneuver was cited in 72% of the mishaps, fatigue and G-suit malfunction in 19%, low G-tolerance at 14%, and 37% were student pilots. Within pilot characteristics, only two factors were found to be statistically significant: the time in the aircraft and pilot age. In the F-16, there was a 3.5 times greater chance of experiencing a G-LOC mishap if the pilot had less than 600 h in the aircraft [3.5 (1.7-7.2, 95%CI)], and a 9.5 times greater chance in the F-15 [9.5 (2.2-41.9, 95%CI)]. There was a 4.5 times greater chance of experiencing a G-LOC mishap if under the age of 30 in the F-16 [4.5 (2.3-8.5, 95% CI)] and a 3 times greater chance in the F-15 [2.8 (1.2-6.8, 95% CI)].


CONCLUSIONS
Though it is difficult to predict who will experience G-LOC, emphasis on prevention must be concentrated in training and in pilots new to the aircraft.
Sevilla
Nereyda L
NL
Department of Preventive Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, USA. Nereyda.Sevilla@osan.af.mil
Gardner
John W
JW
D000337:Aerospace Medicine; D000401:Aircraft; D001359:Aviation; D016022:Case-Control Studies; D006801:Humans; D018471:Hypergravity / Q000009:adverse effects*; D008889:Military Personnel / Q000706:statistics & numerical data*; D012307:Risk Factors; D012449:Safety; D014474:Unconsciousness / Q000453:epidemiology / Q000209:etiology*; D014481:United States / Q000453:epidemiology; D000078329:Workforce