Visual field contraction during G stress at 13 degrees, 45 degrees, and 65 degrees seatback angles

In support of the High Acceleration Cockpit program, two groups of six experienced subjects, operating a high-resolution visual field limit tracker, were exposed to gradual-onset (0.067 G/s) G stress to a 7-G maximum on the USAFSAM human centrifuge. Data obtained from one group described the G-induced vertical visual field contraction, and that from the other described horizontal visual field contraction--as they occurred in relaxed subjects in seats with 13 degrees, 45 degrees, and 65 degrees seatback angles. Curves of peripheral vision remaining vs. G level indicated a statistically significant difference in tolerance provided by the 65 degrees seat over that provided by the 13 degrees and 45 degrees seats in the 5- to 7-G range, and a significant difference in tolerance provided by the 45 degrees and 65 degrees seats over that provided by the 13 degrees seat in the 4- to 5-G range. Two-dimensional reconstructions of the superior half of mean binocular vision remaining at the various levels of G stress showed complete visual loss near 5 G in the 13 degrees seat, complete loss near 6 G in the 45 degrees seat, and substantial peripheral vision remaining at 7 G in the 65 degrees seat.