Alcohol, drugs & medications

This element is about what affects the pilot chemically — the regulations that define when alcohol, narcotics, or medications make flying illegal, and the physiological effects that make those regulations matter even at their legal floor. Two principles run through every paragraph: the rule and the reason behind it, paired so they reinforce each other. The aeromedical encyclopedia of conditions lives in the aeromedical-factors element (K1); the synthesis, personal-minimums, and decision tempo live in the human-factors risk element (R1).

For any specific medication you take, or any specific diagnosis you carry, your AME is the source of truth. This element teaches the categories every pilot should understand and the regulatory floor every pilot must respect. It does not replace the AME consultation — and the redirect is automatic, not optional. §61.53 makes self-grounding for any condition that affects safe operation a regulatory duty regardless of certificate status.

The regulations are not the safety floor — they are the legal floor. The physiology of these substances often makes you unsafe to fly hours or days before the regulations make it illegal. Treat the rules as a hard backstop, not a target.

alcohol and 14 CFR 91.17

The rule has four operative pieces, and each one binds independently.

• The 8-hour rule. No person may act or attempt to act as a required crewmember within 8 hours after consumption of any alcoholic beverage. "Bottle-to-throttle" is the cockpit shorthand.
• The under-the-influence clause. No person may act while under the influence of alcohol — an elastic clause that catches hangover and residual impairment past the 8-hour line.
• The 0.04 BAC limit. No person may act with a blood alcohol concentration of 0.04 or greater. That is half the typical state driving limit.
• The submit-on-request duty. No person may refuse to submit to a breath or blood test when a law enforcement officer requests one with reasonable cause; refusal itself is a violation §91.17.

Each of these binds independently. Eight hours plus 0.04 plus not under the influence — all three must be satisfied. The rule reads as a backstop because the physiology runs longer than the law. Alcohol degrades cognition, judgment, vision (especially night vision), and vestibular function for hours after BAC reads zero. Hangover is its own impairment, slowing reactions and clouding judgment well past the 8-hour line. The standard conservative personal minimum is 12 hours or more after any consumption and 24+ hours after heavy consumption — both well above the 91.17 floor.

The same principle applies to medications: the FAA's 5x dosing rule says wait at least five times the longest recommended dosing interval before flying, and longer for sedating drugs. An ibuprofen on a 6-hour interval implies a 30-hour wait. The rule is conservative on purpose — pilots are the worst judges of their own impairment.

narcotics, marijuana, and dangerous drugs (91.19) and the license-side consequences (61.15)

14 CFR 91.19 is a carriage rule, not a consumption rule. It prohibits operating any civil aircraft within the United States with narcotic drugs, marijuana, or other dangerous drugs aboard, except where the carriage is authorized by Federal or State statute or by an agency of the Federal or State government with jurisdiction §91.19. The act it covers is what is in the airplane, regardless of who in the cockpit consumed what. The act 91.17 covers is what is in the pilot. The two rules sit next to each other and overlap only in their seriousness.

Both have teeth on the license side through 14 CFR 61.15. A conviction for violating 91.17 or 91.19 is grounds for denial of an application for up to a year, or for suspension or revocation of any existing certificate §61.15. Separately, a conviction for a motor-vehicle action involving alcohol or drugs — most commonly a DUI — carries the same denial/suspension/revocation exposure, plus an affirmative duty to report the action in writing to the FAA Civil Aviation Security Division (AMC-700) within 60 days. The reporting duty exists independent of any certificate action, and missing the 60-day window is itself a violation.

The integration point is that the FAA treats driving-side alcohol or drug actions as aviation-relevant. A pilot's driving record is part of their aviation record, by deliberate regulatory design.

the 5x dosing rule and over-the-counter medications

There is no per-medication FAA rule for most OTC drugs. There is a principle — the 5x dosing rule above — and a redirect: for any specific medication, the AME is the source of truth. Below are the categories every pilot should recognize. None of them should be self-prescribed for flight.

• Antihistamines, first-generation — diphenhydramine, doxylamine, chlorpheniramine. Sedating. These cross the blood-brain barrier and impair cognition, reactions, and judgment well past the user's subjective sense of being awake. They are the OTC class most commonly identified in fatal-accident toxicology. Sleep aids are usually one of these in disguise. The 5x figure for an OTC sleep aid is on the order of 30 hours.
• Antihistamines, second-generation — loratadine, fexofenadine, cetirizine. Less sedating, but AME consultation is still the source of truth on flight clearance.
• Decongestants — pseudoephedrine (vasoconstrictor stimulant; elevates heart rate and blood pressure), phenylephrine (similar mechanism, weaker). Combination cold products often pair a decongestant with a sedating antihistamine — read the label.
• Sleep aids — diphenhydramine, doxylamine, melatonin variants. Residual impairment is the operational hazard; "I woke up feeling fine" is not a clearance.
• Anti-anxiety and antidepressants — most are categorically disqualifying. A small number of SSRIs have an AME-managed special-issuance pathway. Pilots managing depression or anxiety should work with the AME, not around them.
• Pain medications — NSAIDs (ibuprofen, naproxen, aspirin) at standard doses are usually the lowest-friction category, subject to AME consultation. Opioids are categorically grounding. Sedating muscle relaxants are grounding. Benzodiazepines for procedure anxiety are grounding for hours to days.

The honest summary: the cold or the pain itself is often the bigger flight-clearance issue, and the medication that would treat it is the one you cannot fly under. The right call is usually to reschedule. For the specific medication you are taking, ask the AME.

the bigger picture

These three regulations — 91.17, 91.19, 61.15 — sit on top of 14 CFR 61.53, which makes self-grounding for any condition that affects safe operation a regulatory duty regardless of certificate currency. They reinforce, not duplicate. The aeromedical encyclopedia of physiological effects lives in the aeromedical-factors element (K1). The ADM-frameworks element (K3) carries IMSAFE, whose "M" is for Medication — the per-flight self-check that pairs with the regulations here. The human-factors risk element (R1) carries personal minimums, which can and should set substance-related limits well above the legal floor.

The point is not that the rules are wrong. The point is that the rules describe the minimum legal behavior, and the safe behavior typically lives further inside the envelope. The professional pilot answers a substance-related question with both — the rule, and the personal margin above the rule.

worked examples

Scenario 1 — hangover at 9 a.m. after Friday night.

You drank heavily Friday night, scheduled as PIC at 9 a.m. Saturday. The 8-hour bottle-to-throttle window is technically satisfied. You feel hungover but not drunk. The legal question is closed; the safety question is wide open.

Walk the rule: 91.17 also prohibits acting while under the influence, and a hangover is a credible "under the influence" condition. Walk the physiology: cognition, vision, reaction time, and judgment are all measurably degraded by hangover for hours past zero BAC. Walk the AME redirect: not applicable here — this is judgment, not medication. Decision: do not fly. Reschedule or hand the airplane to a clean pilot. The 8-hour rule is a floor, not a green light, and the under-the-influence clause is the trip-wire 91.17 builds in for exactly this scenario.

Scenario 2 — sleep aid the night before a planned 9 a.m. departure.

You took an OTC sleep aid (diphenhydramine-based) at 10 p.m., woke at 7 a.m. feeling alert, planning a 9 a.m. departure as PIC. The legal question is whether 91.17 applies — and it does not directly (no alcohol consumed). The safety question, again, is wide open.

Walk the 5x principle: for a sleep aid with a 6-hour dosing interval, the figure is on the order of 30 hours. You are at 11. Walk the physiology: diphenhydramine impairs cognition and reactions for many hours past subjective wakefulness; toxicology routinely catches this. Walk the AME redirect: for a specific medication question, the AME — not the pharmacy aisle, not me — is the source of truth on flight clearance. Decision: do not fly today. Delay until you are well past the 5x window, and consult the AME about your specific medication for future planning. The subjective "I feel fine" is the failure mode this scenario is built to expose.