Alcohol and Flying: Eight Hours Bottle to Throttle

Scenario & Physics Summary

14 CFR 91.17 sets three separate limits at once: not within 8 hours of drinking, not under the influence, and not with an alcohol concentration of 0.04 or greater. Meeting the clock does not clear the other two.

Interactive 3D Visual Plates & Scenario Media

Plate 1: Alcohol and Flying: Eight Hours Bottle to Throttle

Plate 2: Alcohol and Flying: Eight Hours Bottle to Throttle

Plate 3: Alcohol and Flying: Eight Hours Bottle to Throttle

Plate 4: Alcohol and Flying: Eight Hours Bottle to Throttle

Aerodynamic & Operational Physics

• 14 CFR 91.17(a): no person may act or attempt to act as a crewmember within 8 hours after consuming any alcoholic beverage, while under the influence of alcohol, or with an alcohol concentration of 0.04 or greater in blood or breath.
• Alcohol concentration is grams of alcohol per deciliter of blood, or per 210 liters of breath.
• The Pilot's Handbook of Aeronautical Knowledge notes that as little as one ounce of liquor, one bottle of beer or four ounces of wine can impair flying skills, and that alcohol makes a pilot more susceptible to disorientation and hypoxia.
• The IMSAFE checklist asks both questions: have I been drinking within 8 hours, and within 24 hours?

FAA Exam Gotcha Alert

Exam Trap: The 8-hour rule is a minimum, not a safe limit. A pilot can be outside 8 hours and still be over 0.04 or impaired, and any one of the three conditions in 91.17(a) is enough to make the flight illegal.

Frequently Asked Questions & Exam Explanations