NTSB: More than a quarter of fatally injured pilots test positive for potentially impairing drugs

The prevalence of prescription, over-the-counter, and illicit drugs found in the bodies of pilots killed in aviation accidents has continued to trend upwards in recent years, according to a new study from the National Transportation Safety Board (NTSB).

Pilots' use of drugs
The NTSB’s study showed a rise in prevalence of potentially impairing drugs across all classes, including illicit drugs, and controlled substances such as prescription opioids. NTSB Image
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The study is a follow-up to a similar one published in 2014, which examined toxicology results from pilots killed in aviation accidents between 1990 and 2012. For the new study, investigators analyzed results from pilots who died in aviation accidents — including helicopter crashes — between 2013 and 2017, mostly in general aviation operations.

Toxicology test results were available for 952 pilots who were fatally injured in the United States between 2013 and 2017. Of these, more than a quarter — 28 percent — tested positive for at least one potentially impairing drug, up from 23 percent in the 2014 study.

Fifteen percent were positive for at least one drug indicating a potentially impairing condition, i.e., an underlying medical condition that could affect their performance. That represented an increase of three percentage points from 2014.

Moreover, 10 percent showed evidence of use of at least one controlled substance, compared to about eight percent previously. About five percent tested positive for an illicit drug, a slight increase from the less than four percent in the 2014 study.

In a report published on March 10, the NTSB notes that a positive toxicology finding doesn’t necessarily indicate that the pilot was impaired at the time of the crash. However, the analysis included some cases where drug use was explicitly identified as a contributing factor to the accident, such as the June 2015 crash of a cropdusting helicopter whose pilot was found to have been chronically taking high doses of hydrocodone, an opioid pain reliever.

Hydrocodone was one of the three most common drugs in the study indicating a potentially impairing condition. The others were citalopram, an antidepressant; and diazepam, used to treat anxiety and muscle spasms.

Some drugs were classified as potentially impairing without necessarily indicating a chronic medical condition. Of these, sedating antihistamines were the most common category, found in 11.9 percent of pilots in the study — up from 9.9 percent in 2014.

Just as it had in the previous study, the NTSB found no reliable relationship between evidence of drug use and the circumstances of the fatal accidents.

“Further research may identify increased accident risk associated with some drugs or combinations of drugs, which would support improved guidance or limitations on use of those drugs while flying,” the NTSB’s report states. “Conversely, some drugs believed to be ‘potentially impairing’ may not be correlated with accident risk and concerns about their specific effects may be reduced.”

Consequently, the NTSB is recommending that the Federal Aviation Administration (FAA) conduct a study to assess the prevalence of over-the-counter, prescription, and illicit drug use among flying pilots not involved in accidents, and compare those results with findings from pilots who have died in crashes.

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Because the most recent study also revealed an increase in the percentage of fatally injured pilots who tested positive for tetrahydrocannabinol (THC) — the psychoactive compound in marijuana — the NTSB also wants the FAA to update its literature to explicitly inform pilots that they are prohibited from using marijuana.

In its previous study, the NTSB found that pilots lacked access to information about potentially impairing drugs and non-impairing alternatives. That led it to recommend that the FAA do more to educate pilots on the subject.

With the release of its latest study, the NTSB applauded the FAA’s recent efforts on this front, including the issuance of guidance for pilots on how to read and understand medication labels, as well as information on how long they should refrain from flying after using a potentially impairing drug.

“The plain language information on potentially impairing over-the-counter drugs that the FAA has made available to pilots can be an extremely valuable safety resource,” stated NTSB Chairman Robert Sumwalt. “Now all pilots can quickly and easily find information on potentially impairing drugs and even find possible alternatives that are safe to use while flying.”

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