Every air carrier that operates under 14 CFR Parts 121 or 135 — and every company that provides safety-sensitive services to those carriers — is legally required to establish and maintain a drug and alcohol testing program that meets the standards set out in 14 CFR Part 120 and the Department of Transportation's (DOT) companion regulation at 49 CFR Part 40. These programs exist because the consequences of impairment in aviation are catastrophic and irreversible. Understanding how these programs work, who they cover, and what the testing categories require is essential knowledge for any ATP candidate and, more importantly, for any professional pilot who will live under these rules throughout their career.
Part 120 was specifically created to consolidate FAA drug and alcohol testing requirements into a single regulatory framework. It draws heavily on the broader DOT drug and alcohol testing standards found in 49 CFR Part 40, which governs the procedural and laboratory side of testing across all DOT-regulated transportation modes. The FAA's role under Part 120 is to define who is covered, what testing events trigger a test, and what the compliance obligations are for employers and employees alike.
Who Is Covered: Safety-Sensitive Functions
Part 120 does not apply to every airline employee — it applies to individuals who perform safety-sensitive functions. The regulation defines these functions explicitly. They include: flight crewmember duties, flight attendant duties, flight instruction duties, aircraft dispatcher duties, aircraft maintenance and preventive maintenance duties, ground security coordinator duties, aviation screener duties (where applicable), and air traffic control duties performed by a certificate holder. If an employee performs any of these functions, even part of the time, they are subject to both the drug and the alcohol testing programs whenever they are performing or available to perform those functions.
Employers subject to Part 120 include certificate holders under Parts 121 and 135, as well as companies that contract safety-sensitive work to a Part 121 or 135 operator. This means a contract maintenance organization providing line maintenance for an airline must also have a compliant testing program. A Designated Employer Representative (DER) is the individual at each company who is responsible for implementing and overseeing the program and serves as the contact point with the Medical Review Officer (MRO).
The Six Categories of Drug Testing
Part 120, cross-referenced with 49 CFR Part 40, establishes six distinct circumstances under which an employer must conduct drug testing using a DOT-approved, federally certified laboratory. All drug testing uses a urine specimen analyzed for a standard five-panel drug screen: marijuana (THC metabolites), cocaine, opioids (including semi-synthetic opioids), phencyclidine (PCP), and amphetamines/methamphetamines.
- Pre-employment testing: Required before any individual first performs a safety-sensitive function for an employer, or after a lapse in the employer's random testing pool of more than 30 days. A verified negative result must be received before the employee can begin safety-sensitive duties. Note that a prior employer's negative result generally does not satisfy this requirement.
- Random testing: Employers must conduct unannounced random drug testing at an annual rate set by the FAA Administrator — currently 25% of the average number of safety-sensitive employees. Selections must be made using a scientifically valid method, such as a random number table or a computer-based random number generator, and each employee must have an equal chance of being selected each time. Employees must proceed to testing immediately upon notification.
- Post-accident testing: Required when an accident involves a fatality, or when an employee's performance cannot be completely discounted as a contributing factor to an accident. Urine collection must occur as soon as possible, and the employee must remain available. If the employer cannot collect a specimen within 32 hours of the accident, the attempt must cease and the reason documented.
- Reasonable suspicion testing: Required when a trained supervisor or company official observes specific, contemporaneous, articulable observations about the employee's appearance, behavior, speech, or body odor consistent with drug use. A single trained supervisor must make and document this determination. For alcohol, two supervisors are recommended but only one is required if only one is available.
- Return-to-duty testing: Required before an employee who has violated a DOT drug or alcohol standard returns to safety-sensitive functions. The employee must receive a verified negative drug test result and/or an alcohol test showing a BAC below 0.02, as applicable, after evaluation and clearance by a Substance Abuse Professional (SAP).
- Follow-up testing: After returning to duty, the employee must be subject to unannounced follow-up testing for a minimum of 12 direct observation collections over a minimum of 12 months. The SAP determines the frequency and duration, which may extend up to 60 months.
Alcohol Testing: The Two Thresholds
Alcohol testing under Part 120 uses an Evidential Breath Testing (EBT) device. Unlike drug testing, alcohol testing can produce an immediate result. Part 120 establishes two critical Blood Alcohol Concentration (BAC) thresholds that every ATP candidate must know:
- 0.04 BAC or greater: The employee is considered to have a confirmed positive alcohol test. They are immediately removed from safety-sensitive functions and may not return until they have been evaluated by a SAP and completed return-to-duty requirements.
- 0.02 to 0.039 BAC: The employee does not have a confirmed violation but must be removed from safety-sensitive duties for a minimum of 8 hours or until a subsequent test shows a BAC below 0.02. This lower threshold acknowledges that even sub-violation levels of alcohol impair performance.
Alcohol testing may only be conducted just before (within 4 hours), during, or just after (within 8 hours) the performance of safety-sensitive functions. Pre-employment alcohol testing is authorized but not required. Random alcohol testing is required at a rate of 10% of the average number of safety-sensitive employees per year, a rate that may be adjusted by the FAA. Post-accident and reasonable suspicion alcohol tests must be conducted within 2 and 8 hours respectively; if not, the reason must be documented and the attempt discontinued.
Medical Review Officer and Substance Abuse Professional Roles
A Medical Review Officer (MRO) is a licensed physician with specific DOT training who receives and reviews all laboratory drug test results. The MRO's critical role is to determine whether there is a legitimate medical explanation for a laboratory-confirmed positive. For example, if an employee tests positive for opioids and has a valid prescription, the MRO may verify the result as negative. If no legitimate explanation exists, the MRO reports a verified positive to the employer's DER.
A Substance Abuse Professional (SAP) evaluates any employee who has violated a DOT drug or alcohol standard. The SAP recommends an appropriate course of education and/or treatment, conducts a follow-up evaluation to determine if the employee has complied, and then determines when the employee is ready for a return-to-duty test. The SAP also prescribes the follow-up testing plan. Neither the employer nor the employee may waive SAP evaluation requirements.
Why This Matters Operationally
Part 120 compliance is not optional, and violations carry serious consequences. An employee who refuses to submit to a required test is treated the same as a verified positive result — they are immediately removed from safety-sensitive duties and must complete the full SAP process before returning. Refusal includes: failure to appear, failure to provide a sufficient specimen without a medical explanation, leaving the collection site before the process is complete, and adulteration or substitution of a specimen as confirmed by the laboratory.
For pilots specifically, a drug or alcohol violation also triggers action against their airman certificate under 14 CFR Part 61. Section 61.15 provides that an airman's certificate may be suspended or revoked for drug convictions, and the FAA's Civil Aerospace Medical Institute (CAMI) is notified of violations through DOT reporting channels. Additionally, airmen are required under 14 CFR §61.15(e) to report any motor vehicle action related to alcohol or drugs to the FAA Civil Aviation Security Division within 60 days.
Key Numbers and Rules
- Random drug testing rate: 25% of safety-sensitive employees annually
- Random alcohol testing rate: 10% of safety-sensitive employees annually
- Confirmed alcohol violation threshold: BAC ≥ 0.04
- Removal from duty (no violation) threshold: BAC 0.02–0.039, removed for at least 8 hours
- Post-accident drug collection window: 32 hours to attempt; cease and document if not achieved
- Post-accident alcohol test window: conduct within 2 hours; document why if not done by 8 hours; stop attempting after 8 hours
- Reasonable suspicion alcohol test: must be conducted within 8 hours of the observation
- Follow-up testing minimum: 12 tests over 12 months, up to 60 months
- Five-panel drug screen: marijuana, cocaine, opioids, PCP, amphetamines
Common Test Traps
- Confusing the two alcohol thresholds: Many students remember 0.04 as the only number. Remember that 0.02 triggers removal from duty even though it is not a formal violation.
- Mixing up random testing rates: Drug is 25%; alcohol is 10%. These are different rates and are tested separately in exam questions.
- Assuming pre-employment alcohol testing is required: It is permitted but not mandated, unlike pre-employment drug testing which is always required.
- Forgetting the refusal-equals-positive rule: A refusal is treated as a verified positive for all administrative and certificate purposes — students sometimes think a refusal is a lesser offense.
- Overlooking the SAP follow-up testing duration: The minimum is 12 tests over 12 months, but the SAP can extend follow-up testing up to 60 months. The exam may try to make 12 months sound like the maximum.