Regulation Text
(a) No person may act or attempt to act as a crewmember of a civil aircraft—
(1) Within 8 hours after the consumption of any alcoholic beverage;
(2) While under the influence of alcohol;
(3) While using any drug that affects the person's faculties in any way contrary to safety; or
(4) 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 grams of alcohol per 210 liters of breath.
(b) Except in an emergency, no pilot of a civil aircraft may allow a person who appears to be intoxicated or who demonstrates by manner or physical indications that the individual is under the influence of drugs (except a medical patient under proper care) to be carried in that aircraft.
(c) A crewmember shall do the following:
(1) On request of a law enforcement officer, submit to a test to indicate the alcohol concentration in the blood or breath, when—
(i) The law enforcement officer is authorized under State or local law to conduct the test or to have the test conducted; and
(ii) The law enforcement officer is requesting submission to the test to investigate a suspected violation of State or local law governing the same or substantially similar conduct prohibited by paragraph (a)(1), (a)(2), or (a)(4) of this section.
(2) Whenever the FAA has a reasonable basis to believe that a person may have violated paragraph (a)(1), (a)(2), or (a)(4) of this section, on request of the FAA, that person must furnish to the FAA the results, or authorize any clinic, hospital, or doctor, or other person to release to the FAA, the results of each test taken within 4 hours after acting or attempting to act as a crewmember that indicates an alcohol concentration in the blood or breath specimen.
(d) Whenever the Administrator has a reasonable basis to believe that a person may have violated paragraph (a)(3) of this section, that person shall, upon request by the Administrator, furnish the Administrator, or authorize any clinic, hospital, doctor, or other person to release to the Administrator, the results of each test taken within 4 hours after acting or attempting to act as a crewmember that indicates the presence of any drugs in the body.
(e) Any test information obtained by the Administrator under paragraph (c) or (d) of this section may be evaluated in determining a person's qualifications for any airman certificate or possible violations of this chapter and may be used as evidence in any legal proceeding under section 602, 609, or 901 of the Federal Aviation Act of 1958.
[Docket 18334, 54 FR 34292, Aug. 18, 1989, as amended by Amdt. 91-291, June 21, 2006]
Research Notes
Section 91.17 is the FAA's alcohol-and-drugs rule for Part 91 operations. It establishes the famous "8 hours from bottle to throttle" floor along with three other prohibitions that bind every pilot.
The four prohibitions (paragraph a): A person may not act, or attempt to act, as a crewmember of a civil aircraft: (1) within 8 hours after the consumption of any alcoholic beverage; (2) while under the influence of alcohol; (3) while using any drug that affects the person's faculties in any way contrary to safety; or (4) while having an alcohol concentration of 0.04 or greater. Each prong is independent — a pilot can violate the rule by waiting 8 hours but still being under the influence, or by having a BAC under 0.04 but being affected by medication, etc.
The 0.04 BAC threshold: This is half the typical driving limit. The FAA chose 0.04 to align with the DOT-wide aviation safety-sensitive transportation worker standard. At 0.04, reaction time, depth perception, and decision-making are measurably impaired even in well-tolerated drinkers.
The 8-hour rule is a floor, not a ceiling: Eight hours after the last drink is the MINIMUM. A pilot who is still under the influence of alcohol 9 hours later (large quantity consumption, slow metabolism, mixing factors) still violates the rule. The FAA has prosecuted cases where pilots passed the 8-hour test but were still impaired. "Bottle to throttle" 12 hours is the conservative industry standard for high-consumption nights.
Testing (paragraph c): Crewmembers must submit to BAC testing when requested by an LE officer or the Administrator. Refusal carries the same enforcement consequences as a confirmed violation — both certificate suspension/revocation actions and possible 49 USC § 44726 implications.
Carriage of intoxicated persons (paragraph b): The PIC may not allow a person who appears to be intoxicated or under the influence of drugs (except a patient under proper care) to be carried on the aircraft. This applies to crew, passengers, and any other person aboard.
Medications: The "drug that affects faculties" prong captures both illegal substances and prescription medications. The FAA maintains a list of medications generally incompatible with flight crew duties; AME guidance and the FAA's Pilot Safety Brochure on medications are the operational references. Self-grounding is the prudent path when starting any new medication.
Reference: FAA Pilot Safety Brochure — Alcohol and Flying; FAA Pilot Safety Brochure — Medications and Flying; FAA Order 8900.1 Volume 5, Chapter 7 for inspector guidance on § 91.17.
Amendment History
Amendment History Coming Soon
Every time this regulation changes, we'll record it here — the date, what was amended, and a plain-English summary of what shifted.