“Eight hours bottle to throttle” is the legal minimum, not the whole rule. Under 14 CFR 91.17, you may not act or attempt to act as a crewmember within 8 hours after drinking any alcoholic beverage, while under the influence of alcohol, while using a drug that affects your faculties in any way contrary to safety, or with an alcohol concentration of 0.04 or greater. Each limit applies on its own, so passing the 8-hour mark does not by itself make you legal, and the FAA recommends waiting longer: at least 12 to 24 hours in the AIM, and 24 hours in its alcohol brochure.
This guide explains the regulation and the FAA’s published guidance, not legal or medical advice. For a DUI, a medical question, or an enforcement matter, talk to an Aviation Medical Examiner or an aviation attorney.
What 14 CFR 91.17 says
Paragraph (a) of 14 CFR 91.17 says no person may act or attempt to act as a crewmember of a civil aircraft:
- Within 8 hours after the consumption of any alcoholic beverage;
- While under the influence of alcohol;
- While using any drug that affects the person’s faculties in any way contrary to safety; or
- While having an alcohol concentration of 0.04 or greater in a blood or breath specimen.
Alcohol concentration means grams of alcohol per deciliter of blood or per 210 liters of breath; the PHAK describes the limit as a blood alcohol level of .04 percent. A crewmember, under 14 CFR 1.1, is a person assigned to perform duty in an aircraft during flight time, and the rule covers attempting to act as one, not just flying.
Why 8 hours is a floor, not a target
The three alcohol limits work independently, and you must satisfy all of them every time:
| Situation | Legal under the alcohol rules? | Why |
|---|---|---|
| Last drink 7 hours ago, feeling completely sober | No | Inside the 8-hour window of 91.17(a)(1), however you feel |
| Last drink 10 hours ago, alcohol concentration 0.05 | No | At or above 0.04, which 91.17(a)(4) prohibits |
| Last drink 10 hours ago, below 0.04 but still impaired | No | Still under the influence, which 91.17(a)(2) prohibits |
| Last drink 26 hours ago, rested, no hangover symptoms | Yes | Clear of all three limits, and beyond the FAA’s 24-hour recommendation |
The PHAK puts it plainly: a pilot with a blood alcohol level of .04 percent or greater after 8 hours cannot fly until it falls below that amount, and even well below .04 percent, a pilot cannot fly sooner than 8 hours after drinking. It then adds that it is a good idea to be more conservative than the regulations.
What the FAA recommends instead
- AIM 8-1-1d: because the body breaks down alcohol slowly, a pilot may still be under the influence 8 hours after drinking a moderate amount, so “an excellent rule is to allow at least 12 to 24 hours between ‘bottle and throttle,’ depending on the amount of alcoholic beverage consumed.”
- The FAA brochure Alcohol and Flying: A Deadly Combination: follow 91.17 “as a minimum,” and “a more conservative approach is to wait 24 hours from the last use of alcohol before flying,” especially if intoxication occurred or you plan to fly IFR.
Nothing speeds the process up. The FAA brochure says cold showers, black coffee, or breathing 100% oxygen cannot speed the elimination of alcohol, which happens at a fairly constant rate no matter how much you drank, so more drinks simply mean more time. Small amounts matter too: the AIM says as little as one ounce of liquor, one bottle of beer, or four ounces of wine can impair flying skills.
Beer is not a safer choice
The FAA brochure calls the idea that low-concentration drinks are safer than hard liquor erroneous. Its table shows how similar typical servings are:
| Drink | Typical serving | Pure alcohol |
|---|---|---|
| Light beer | 12 oz | 0.48 oz |
| Table wine | 4 oz | 0.48 oz |
| Champagne | 4 oz | 0.48 oz |
| Vodka | 1 oz | 0.50 oz |
| Whiskey | 1.25 oz | 0.50 oz |
Hangovers: legal is not the same as fit
- The FAA brochure says hangover effects can last 48 to 72 hours after the last drink, even after all the alcohol is eliminated, and that a pilot with symptoms such as headache, dizziness, fatigue, or impaired judgment “would certainly not be fit to safely operate an aircraft.”
- The PHAK says that while experiencing a hangover, a pilot is still under the influence of alcohol, and that considerable amounts of alcohol can remain in the body for over 16 hours.
- The PHAK lists inner-ear disturbance and spatial disorientation, for up to 48 hours, among the possible side effects of alcohol.
- Altitude makes it worse: combined with altitude, the PHAK says, the alcohol from two drinks may have the same effect as three or four.
Studies cited in the FAA brochure found that serious pilot errors increase dramatically at or above 0.04 percent blood alcohol, and some showed performance decrements as low as 0.025 percent. The 0.04 limit is a legal line, not a safe one.
Drugs and medications under 91.17
Paragraph (a)(3) applies the same logic to drugs. The PHAK notes that the regulations include no specific references to medication use, so 91.17(a)(3) and 14 CFR 61.53, which bars flying as pilot in command while a medication leaves you unable to meet your medical standards, do the work. FAA guidance for pilots fills in the details:
- Wait at least 48 hours after the first dose of any new medication and confirm there are no side effects.
- After medications with side effects, wait 5 times the maximum half-life, or 5 times the maximum dosing interval: 30 hours for a medicine taken every 4 to 6 hours.
- Do not fly on any medication whose label warns of drowsiness or cautions about driving or operating machinery.
- Marijuana is prohibited for pilots even where state law allows it. The PHAK quotes the FAA: “Marijuana is an illicit drug per federal law and its use by airmen is prohibited.”
Our IMSAFE guide covers medication in more depth. For a specific drug, ask an Aviation Medical Examiner (AME) before you fly.
Carrying intoxicated passengers
Paragraph (b) puts a duty on the pilot: except in an emergency, no pilot may allow a person who appears to be intoxicated, or who shows signs of being under the influence of drugs, to be carried in the aircraft. A medical patient under proper care is the exception. As pilot in command you are the final authority as to the operation of the aircraft (14 CFR 91.3), so the decision to say no is yours.
Alcohol tests and refusing them
- Police tests, 91.17(c)(1): a crewmember must submit to a blood or breath alcohol test when a law enforcement officer authorized under state or local law requests it to investigate a suspected violation of a state or local law covering substantially similar conduct.
- FAA requests, 91.17(c)(2) and (d): when the FAA has a reasonable basis to believe you may have violated the alcohol or drug rules, you must furnish, or authorize release of, the results of each test taken within 4 hours after acting or attempting to act as a crewmember.
- Use of results, 91.17(e): the FAA may use that information to evaluate your qualifications for any airman certificate and as evidence in legal proceedings.
Under 14 CFR 61.16, refusing such a test, or refusing to furnish or release results the FAA requests, is grounds for denial of an application for any certificate, rating, or authorization for up to 1 year, or for suspension or revocation of what you hold.
Penalties for violating 91.17
Under 14 CFR 61.15(b), committing an act prohibited by 91.17(a) is grounds for denial of an application for up to 1 year after the act, or for suspension or revocation of any certificate, rating, or authorization issued under Part 61, which includes a student pilot certificate.
DUI and other motor vehicle actions: the 60-day report
14 CFR 61.15(e) requires each person holding a certificate issued under Part 61, student pilots included, to send the FAA a written report of each motor vehicle action no later than 60 days after it. A motor vehicle action is a conviction for driving while intoxicated by, impaired by, or under the influence of alcohol or a drug, or the cancellation, suspension, revocation, or denial of a driver’s license for that cause. The report must include your name, address, date of birth, and airman certificate number, the type of violation, its date, the state holding the record, and whether it relates to a previously reported action.
The FAA’s motor vehicle action page offers an online notification letter and adds these details:
- An administrative license suspension, including one for failing or refusing a chemical test, is reportable without a conviction, and a later conviction needs its own report within 60 days.
- A suspension of any length counts, even one day.
- Arrests are not reported under 61.15, but drug- and alcohol-related arrests must be reported on your next medical application (FAA Form 8500-8).
- The medical application authorizes the FAA to check the National Driver Register, and the FAA says it will find an unreported action.
Failing to report within 60 days is itself grounds for denial of an application for up to 1 year or for suspension or revocation, and so is a motor vehicle action within 3 years of a previous one, unless both arise from the same incident. Our FAA medical certificate guide explains the medical application.
How this comes up in training
The Private Pilot ACS Human Factors task includes the regulations regarding use of alcohol and drugs (PA.I.H.K2) and the effects of alcohol, drugs, and over-the-counter medications (PA.I.H.K3), so they are fair game on the knowledge test and the oral exam. A strong answer names all four prohibitions in 91.17(a), not just the 8 hours, and adds the FAA’s 24-hour recommendation. In preflight planning, alcohol falls under the pilot item of the PAVE checklist. The rule applies the same way with an FAA medical certificate or under BasicMed; see our BasicMed guide and the medical certificate classes.
References for the rule
What you'll need
The references that hold the rule and the FAA's aeromedical guidance, plus a logbook for your training record.
Frequently asked questions
Is it really 8 hours from bottle to throttle?
Eight hours is the legal minimum in 14 CFR 91.17(a)(1), but it is not enough on its own: you must also be below 0.04 and not under the influence. The AIM recommends at least 12 to 24 hours, and the FAA alcohol brochure suggests 24 hours.
What is the FAA blood alcohol limit for pilots?
Under 14 CFR 91.17(a)(4), no one may act as a crewmember with an alcohol concentration of 0.04 or greater in a blood or breath specimen.
Does the 8 hours start from the first drink or the last?
From the last. The rule prohibits acting as a crewmember within 8 hours after the consumption of any alcoholic beverage, so every drink restarts the clock.
Can I fly with a hangover?
The FAA says no. Its alcohol brochure says a pilot with hangover symptoms would certainly not be fit to safely operate an aircraft, and the PHAK says a pilot experiencing a hangover is still under the influence of alcohol.
Do I have to report a DUI to the FAA?
Yes. 14 CFR 61.15(e) requires a written report within 60 days of each alcohol- or drug-related driving conviction or driver’s license suspension, revocation, cancellation, or denial. Student pilots are included, and arrests go on your next medical application.