G-LOC Due to the Push-Pull Effect in a Fatal F-16 Mishap

BACKGROUND: The risks associated with high positive G(z) (+G(z)) aerobatic flight, especially with respect to +G(z)-induced loss of consciousness (G-LOC), are well known. Less appreciated is the effect of negative G(z) (-G(z)) flight on subsequent +G(z) maneuvers, known as the push-pull effect. This is an example involving the loss of an F-16 and pilot that was caused by the push-pull effect. CASE REPORT: The mishap pilot (MP) was killed during a training flight when his F-16 crashed without an ejection attempt. The MP, while transitioning from prolonged -G(z) flight to sustained +G(z) flight, maneuvered the mishap aircraft (MA) from -2.06 G(z) to +8.56 G(z) in less than 5 s. At this point, there were only minimal control inputs for 5 s, indicating the MP experienced transient incapacitation, most likely due to G-LOC or almost loss of consciousness (A-LOC). The MP's subsequent recovery attempt was interrupted by ground impact. The Accident Investigation Board (AIB) concluded the MP experienced G-LOC due to the push-pull effect. DISCUSSION: Since this is not the first time the push-pull effect has resulted in G-LOC mishaps, the adverse effects of such maneuvers should continue to be emphasized during military physiological training, as well as during general aviation (GA) aerobatics training. Furthermore, A-LOC, instead of being considered a discrete phenomenon, may need to be included in a broader G-LOC definition that encompasses the entire continuum of G-LOC and A-LOC.