Background: In many high-intensity wartime scenarios, pilots may be required to fly multiple, strenuous missions during the same day. Hypothesis: New anti-G protection allows fighter pilots to endure multiple high +Gz exposures during several sorties in a limited time interval. Methods: Nine well-trained centrifuge subjects were exposed to tactical aerial combat maneuvers using balanced pressure breathing during G (PBG) and an extended coverage anti-G suit. The centrifuge exposures consisted of five simulated sorties during a 4-h period, each consisting of four engagements with rapid onset cycles (6 G . s(-1)) varying between +4 Gz and +9 Gz. The subjects executed a tracking task before, during, and after each engagement and verbally indicated their effort level. Neck muscle strength was measured before and after the test. Results: Seven of the nine subjects could endure all five sorties during the 4-h period. On a scale from 0 (no effort) to 11 (maximum possible effort), highest effort level during runs varied from 5.5 to 11 units (mean 8.7). Maximal heart rate varied from 140-173 bpm (mean 159) and minimum finger oxygen saturation from 75-93% (mean 88). Maximal peripheral and central light-loss varied from 0 to 100% (mean 71 and 40, respectively). Three G-LOCs (two in the same subject) and four cases of near loss of consciousness occurred. The general fatigue recovery time varied from 9 to 48 h (mean 2 1). The tracking tests showed that performance deteriorated significantly during all G exposures; the neck muscle contraction was impaired by 12% (p = 0.035) after the G exposures. Conclusion: It is possible to train subjects to withstand five simulated flight sorties during a 4-h period with a total of up to 80 peaks to +9 Gz and 80 peaks to +8 Gz using PBG and an extended coverage anti-G suit.
