This study examined the time-course of alcohol impairment of general aviation pilot simulator performance. We tested 14 young (mean age 25.8 years) and 14 older (mean age 37.9 years) pilots in a Frasca 141 simulator during alcohol and placebo conditions. In the alcohol condition, pilots drank alcohol and were tested after reaching 0.10% BAL, and then 2, 4, 8, 24, and 48 h after they had stopped drinking. They were tested at the same times in the placebo condition. Alcohol impaired overall performance. Alcohol impairment also depended on the order in which subjects participated in the alcohol and placebo sessions, with larger decrements for the alcohol-placebo order than for the opposite order. To examine the influence of alcohol independent of session order effects, we compared performance in the first alcohol session with performance in the first placebo session. This analysis showed that alcohol significantly reduced mean performance in the alcohol condition at 0.10% BAL and at 2 h. In addition, alcohol increased variability in performance in the alcohol session from 0.10% BAL to 8 h, suggesting that some subjects were more susceptible to alcohol than others. Older pilots tended to perform some radio communication tasks less accurately than younger pilots.