Effects of alcohol on pilot performance in simulated flight

Ethyl alcohol's known ability to produce reliable decrements in pilot performance was used in a study designed to evaluate objective methods for assessing pilot performance. Four air carrier pilot volunteers were studied during eight simulated flights between San Francisco and Los Angeles in a Boeing 727-232 simulator. Two flights were conducted at each of four target blood alcohol levels, 0, 0.025, 0.050, and 0.075%. Each flight lasted about 1 h. Flights were conducted with full crews in a full simulated ATC environment. Data from direct observations and videotapes were used to examine discrete errors committed by the subjects. Total errors increased linearly and significantly with increasing blood alcohol. Planning and performance errors, procedural errors and failures of vigilance each increased significantly in one or more pilots and in the group as a whole. Failures of crew coordination were not associated with blood alcohol level. Serious errors increased significantly even at the lowest alcohol level studied, 0.025% (25 mg/dl), compared with control values.