A research program is proposed to investigate the effects blood alcohol level on pilot performance. Through use of a flight simulator, performance is to be analyzed in highly demanding instrument flight conditions as well as in those involving system malfunctions and other emergency situations where the task load is very high and the effects of alcohol are expected to be at a maximum. It is hypothesized that the effects of alcohol interact with the attentional and task complexity demands that characterize certain aspects of flying. The impairment due to alcohol is presumed to result in a compensatory increased effort being directed to the primary flight-control and instrument flight task resulting in a narrowing of the functional attentional field. A a consequence, attention to and the integration of other information necessary for safe flight is diminished leading to a failure of the pilot to become aware of or react properly to potentially dangerous situations. The following factors will be varied in order to examine the interaction of task difficulty and blood alcohol level: number of flying tasks to be performed simultaneously, communication load, instrument flight difficulty, and degrees of freedom in navigational tasks. Dependent measures to be obtained include various error indices of aircraft positioning, latency to detect and respond to emergency situations and the procedures used. In addition, measures of pilot control input and oculomotor behavior, including visual scanning patterns and the latency of saccadic eye movements, are to be obtained and analyzed under various alcohol blood level conditions. It is believed that the blood alcohol level at which dangerous flying situations can arise is lower than generally recognized, and that the information to be obtained under particularly demanding flying conditions is important both with respect to a better understanding of the situational factors involved in alcohol impairment and in increasing general awareness of the potential dangers of flying under the influence of alcohol.