Further Investigation of Contrast Sensitivity and Visual Acuity in Pilot Detection of Aircraft

Abstract

Contrast sensitivity (CS) has been reported (Ginsburg et al., 1983) to be strongly related to pilots' aircraft detection performance; however, examination of their results shows a lack of consistency for the CS at any particular spatial frequency to correlate with detection, even for days with similar visibility conditions. To further investigate this relationship, sixty-seven (67) USAF pilots were divided among 8 groups, individually isolated in a bus near the end of a runway on separate days, and detected a T-38 jet aircraft during about 8 landings. CS was measured using the criterion-free two-alternative, temporal forced-choice (2 AFC) technique on the Optronix and with the Vistech VCTS 6500 chart. Visual acuity was assessed at three contrast levels using 3%, 6%, & 85% contrast Regan charts. The mean detection distance of each group ranged from 4.77 to 6.73 miles, and intersubject difference within any group was 0.64 to 2.21 miles. For these partly-cloudy to cloudy weather conditions, neither contrast sensitivity nor visual acuity correlated well with pilot detection of actual aircraft. There was a lack of consistency for the CS at any particular spatial frequency to correlate with detection distance. The best indicator of the pilots with worse detection distances was the performance on the 6% contrast visual acuity chart; with all 5 pilots in the lower 10% of visual performance also being the worst or second worst at aircraft detection in their group.