Definition
A controlled substance classified by the U.S. Drug Enforcement Administration as having a high potential for abuse, no currently accepted medical use in the United States, and a lack of accepted safety for use under medical supervision. Examples include heroin, LSD, and marijuana. Use of any Schedule I drug is disqualifying for FAA medical certification and incompatible with acting as a flight crewmember.
Plain English
A drug the federal government considers highly addictive and not legal for medical use. Pilots are not allowed to use these drugs at all, and doing so will cost them their medical certificate.
Context Anchor
Seen in FAA discussions of drugs, pilot medical qualification, and whether a pilot is safe and legal to fly.
Derivation
The U.S. Controlled Substances Act of 1970 grouped regulated drugs into five 'schedules,' numbered I through V. 'Schedule' here means a numbered list or classification. Schedule I is the most restrictive group, reserved for drugs judged to have the highest abuse potential and no approved medical use.
Why Pilots Care
Any use of a Schedule I drug can lead to denial or revocation of an FAA medical certificate and may affect a pilot's legal right to fly.
Intuition Check
“Schedule” does not mean a dosing timetable here. It means an official federal drug category, and Schedule I is the most restrictive category.
Example Sentence 1
Because marijuana is still classified as a Schedule I drug under federal law, the FAA will not issue a medical certificate to a pilot who tests positive, even if the pilot lives in a state where recreational use is legal.
Example Sentence 2
Aviation regulations prohibit operating an aircraft after any use of a Schedule I drug.