FAA Instrument Rating Airplane (IRA)Aeromedical and ADMMedium
A pilot has two glasses of wine with dinner ending at 9:00 p.m. and plans to depart on an IFR flight at 4:00 a.m. the next day, roughly 7 hours later. A breathalyzer at the airport shows a blood alcohol level of 0.02. According to 14 CFR 91.17, may this pilot legally act as pilot in command?
- ANo, because any alcohol consumption within 24 hours prohibits flight
- BYes, because the blood alcohol level is below 0.04
- CYes, because 0.02 is below the legal limit for driving
- DNo, because less than 8 hours have elapsed since the last drink
Show answer & explanationAnswer & explanation
Correct answer: D. No, because less than 8 hours have elapsed since the last drink
14 CFR 91.17 prohibits acting as a crewmember within 8 hours after consuming alcohol, regardless of blood alcohol concentration, and also prohibits it if BAC is 0.04 or greater. Even though this pilot's BAC of 0.02 is under the 0.04 threshold, only 7 hours have passed since the last drink, violating the 8-hour rule.
Why the other options are wrong
- A. There is no blanket 24-hour prohibition; the regulation specifies 8 hours and a BAC limit.
- B. BAC being under 0.04 does not override the separate 8-hour requirement under 91.17.
- C. Highway driving limits are irrelevant; 14 CFR 91.17 sets its own, stricter standard.
14 CFR 91.17 — Alcohol and Drugs
Federal regulation prohibiting a person from acting as a crewmember within 8 hours after consuming alcohol, while under the influence, or with a blood alcohol concentration of 0.04 or greater.
- 8-hour rule: no alcohol consumption within 8 hours of flight
- BAC limit: must be below 0.04
- 'Under the influence' clause can apply even if both other conditions are met
Memory trick: 8 hours bottle to throttle, no matter the number