More than a quarter of pilots killed in U.S. aviation accidents in recent years had potentially impairing drugs in their systems, according to a series of National Transportation Safety Board (NTSB) studies tracking toxicology trends.
In its latest safety research covering civil aviation accidents from 2018 to 2022, the NTSB reported that 52.8% of fatally injured pilots tested positive for at least one drug of any type, and 28.6% had at least one potentially impairing drug detected. That figure is consistent with earlier updates for 2013–2017, when 28% of 952 fatally injured pilots with available toxicology also tested positive for at least one potentially impairing substance, up from 23% in a 2014 baseline study.
Across the studies, sedating antihistamines, particularly diphenhydramine, remained the most commonly detected potentially impairing drugs. Other frequently identified medications included sedating pain relievers such as opioids, antidepressants like citalopram, and benzodiazepines such as diazepam, as well as cardiovascular drugs, cholesterol-lowering medications, and prostate or erectile dysfunction drugs. Illicit drug detection, driven largely by delta-9-THC, increased to 7.4% in the most recent period, with cannabinoids accounting for about 5% in earlier years.
The NTSB stresses that a positive toxicology result does not prove impairment at the time of the crash, only prior use. However, investigators conclude that the rising prevalence of potentially impairing drugs among fatally injured pilots represents an ongoing safety concern and underscores the need for better pilot education on medication risks and stricter adherence to federal prohibitions on substances such as marijuana.