Definition
An FAA regulation (14 CFR 91.17) prohibiting any person from acting or attempting to act as a crewmember of a civil aircraft within 8 hours after the consumption of any alcoholic beverage. The rule sets a minimum waiting period; other provisions of the same regulation also prohibit flying while under the influence, with a blood alcohol concentration of 0.04% or greater, or while using any drug that affects faculties contrary to safety.
Plain English
You cannot fly an aircraft within 8 hours of having an alcoholic drink. The 8 hours is the bare minimum -- if you still feel any effects after 8 hours, you still cannot fly.
Context Anchor
Used in preflight fitness decisions, alcohol discussions, and FAA rules about when a pilot may legally act as a crew member.
Why Pilots Care
Following the rule prevents alcohol-related impairment that reduces judgment, reaction time, and decision-making during flight.
Grounding Statement
The rule sets a minimum time barrier between drinking alcohol and acting as flight crew, not a guarantee that the alcohol is gone.
Intuition Check
Do not read the 8-hour rule as “safe after 8 hours.” Read it as “not before 8 hours, and only if fully sober and fit.”
Example Sentence 1
She declined the second glass of wine at dinner because she had an early flight and wanted to stay well clear of the 8-hour rule.
Example Sentence 2
Even after one beer the evening before, the pilot still observed the 8-hour rule before the morning flight.