Contrast sensitivity was found to be better than visual acuity for predicting a pilot's ability to detect a small, semi-isolated, air-to-ground target. Eleven instructor pilots had their acuity measured by both conventional and contrast sensitivity methods. Scotopic contract sensitivity showed the highest correlation with slant detection range (0.83). Conventionally determined visual acuity proved to be a poor predictor of a pilot's ability to detect a small low contrast target.