BACKGROUND: Current studies have focused mainly on the push-pull effect (PPE), the reduction of +Gz tolerance when hypergravity (>+1 Gz) preceded by hypogravity (<+1 Gz). However, the reduced G tolerance could be induced by any G-transition. The frequency and extent of maneuvers to cause G-transition effect (GTEM) have not been studied previously in fighter aircraft. METHODS: 26 HUD (head-up display) videotapes from F-16 aerial combat training missions were reviewed for the presence of GTEM. The frequency and magnitude of the +Gz profiles were analyzed. RESULTS: GTEMs were found in 34 (29.6%) of 115 engagements reviewed. PPEMs (maneuvers found to cause push-pull effect) and rPPEMs (maneuvers found to cause reversed PPE) were found in 7.8%, 11.3% respectively. Combined maneuver that rPPEM followed by PPEM consecutively was found in 10.4% of engagements. There was no difference the frequency of GTEMs between BFM and ACM engagements (28.8% vs. 30.9%). CONCLUSION: GTEMs including PPEMs and rPPEMs are present in aerial combat training missions of F-16 aircraft and represent a significant source for accidents. These findings support the necessity of continued research into the physiologic response to GTE.