AINsight: Impaired in the Air

 - September 24, 2019, 10:06 AM

Drug use in the U.S. is on the rise. In aviation, through post-accident toxicology testing there is growing evidence of an increase in the use of over-the-counter (OTC), prescription, and—to a lesser extent—illicit drugs by pilots involved in fatal accidents. Of concern, many drugs have impairing side effects that negatively affect the ability of an individual to perform complex operations, such as operating an aircraft or other vehicles.  

Evidence of headline-grabbing illicit drug use is low. In fact, illegal drugs are involved in only 2 to 3 percent of all aviation accidents. The main problem is the rise in the use of prescription and/or OTC drugs. A 2014 NTSB study on Drug Use Trends in Aviation showed nearly 40 percent of all general aviation pilots in fatal accidents had at least one positive drug finding in their system. Sedating antihistamines—such as diphenhydramine (common brands: Benadryl, Unisom, and Nytol)—are the most commonly found impairing substance in fatal crashes.

Surprisingly, pilots might be using OTC or prescription drugs without realizing they can cause impairment or fully understanding how long these substances remain in their system. As an example, since aviation is a complex 24/7 system, a well-intended pilot attempting to enhance a sleep opportunity may take an OTC sleep aid, not knowing that the side effects of that drug might last up to 30 hours.

The FAA provides some guidance for pilots on the use of OTC and prescription drugs. For medications that warn about the hazards of “operating vehicles” or “may cause drowsiness,” a good rule of thumb, according to the FAA, is to wait at least five times the longest recommended interval between doses before flying. For example, if the dosing interval states “take every four to six hours,” the recommendation is to wait 30 hours (five times the longest dosing interval of six hours).

According to the NTSB, pilots need to be better educated about the effects of both prescription and OTC drugs. Education is good, but asking the right questions is better. Discuss all medication that you take with your aviation medical examiner. Likewise, let other medical professionals know that you’re a pilot and ask if a prescription is safe to take before flying or if there are any dangerous interactions with other medications.

When taking a new medication, it is good practice to begin during a period when you are not scheduled to fly. Prescription and OTC drugs can be tricky; unlike alcohol, drugs can affect individuals differently, adding to the challenge.

Another recommendation is to become familiar or reacquainted with the “I’M SAFE” checklist located in the Aeronautical Information Manual (AIM). This checklist is great to help pilots assess and verify that they are fit for flight by evaluating various issues such as illness, medication, stress, alcohol, fatigue, and eating (nourishment).  

Obviously, illicit and “recreational” drug and alcohol use in any form of transportation is never acceptable. As more and more states legalize the use of marijuana, it’s important to recognize that it is still considered a Schedule 1 prohibited drug in the U.S. Marijuana impairs performance and the ability to safely operate an aircraft. Transport Canada in June 2019 amended its fitness-for-duty regulations to require safety-sensitive aviation personnel (pilots, cabin crew, and air traffic controllers) to be cannabis-free for 28 days before going on duty.  

Most safety issues affecting aviation are extremely complex and require multi-layered mitigation strategies to enhance safety. This one does not. According to the NTSB, alcohol and drug impairment in all modes of transportation is 100 percent preventable. It seems easy enough, but for many pilots the effects of OTC and prescription drugs might be insidious and may require a better understanding of the lasting side effects of each medication.  

Pilot, safety expert, consultant and aviation journalist Kipp Lau writes about flight safety and airmanship for AIN. He can be reached at