FREQUENCY OF THE PUSH-PULL EFFECT IN US AIR-FORCE FIGHTER OPERATIONS

Background: Recent investigation into the push-pull effect (PPE), the reduction of +Gz tolerance when preceded by less than +1 Gz, has focus ed on centrifuge studies to demonstrate the presence of adverse cardio vascular responses. Maneuvers found to cause the Push-Pull Effect (PPE M) have not been studied previously in U.S. Air Force (USAF) fighter a ircraft. The frequency of and extent to which PPEMs are performed in f ighter aircraft are unknown. Methods: Head-up display (HUD) videotapes from F-15 and F-16 air combat training missions were reviewed for the presence of PPEMs. The frequency of engagements containing PPEMs and the magnitude of the Gz profiles were noted. Results: PPEMs were found in 11 to 67% of engagements reviewed, depending on the nature of the training mission, with an overall average of 32%. The PPEMs that were observed contained segments of less than +1 Ct, ranging on average fro m 0.0 to 0.5 Gz for an average of 3.5 to 5 s duration. Conclusions: PP EMs are present in air combat training missions performed by today's U SAF fighter aircraft and represent an operationally significant source of risk for accidents. These findings support continued research into the physiologic response to PPE and the development of countermeasure s.