Personal Fitness to Fly: Alcohol, Drugs, Fatigue and IMSAFE

The regulations set clear limits on alcohol and drugs: a pilot may not act as a crewmember within 8 hours of drinking ("8 hours bottle to throttle"), while under the influence, with a blood alcohol concentration of 0.04 percent or greater, or while using any drug that affects safety. Alcohol is doubly dangerous because it also causes histotoxic hypoxia, and its impairment worsens at altitude. Fatigue — whether acute from one long, stressful day or chronic from accumulated poor rest — dulls attention, judgment, and reaction time, and dehydration and heat stress add headache and impaired concentration on top. Rest, water, and food are the simple defenses. To pull all of this together, pilots run the IMSAFE checklist before flight — Illness, Medication, Stress, Alcohol, Fatigue, and Emotion — and decline to fly whenever any item makes the flight unsafe. IMSAFE complements the medical certificate by checking readiness on the specific day, not just once every few years.