Study shows that pilots who drink and drive are at higher risk to crash planes

Jan 31 2005

General aviation pilots with a previous conviction for driving while intoxicated (DWI) are 43 percent more likely to crash their plane than pilots with no history of DWI, according to a new study of more than 300,000 pilot records by researchers at Johns Hopkins.

The Hopkins findings, published in the January issue of the journal Accident Analysis & Prevention, provide strong evidence for the link between DWI history and crash risk among pilots.

Since 1990, anyone who applies for a pilot license is required to undergo a background check of their DWI history. Federal regulations also require the reporting of DWI convictions by licensed pilots to the FAA within 60 days. Indeed, two or more DWI convictions within a three-year period can result in the FAA's suspending or revoking a license.

"While much progress has been made to date in improving aviation safety, little is known about the effectiveness of specific preventive policies, such as background checks for DWI histories," says lead study author and medical epidemiologist Guohua Li, M.D., Dr.P.H., a professor of emergency medicine at The Johns Hopkins University School of Medicine and a professor of health policy and management at the Bloomberg School of Public Health.

"This study supports background checks for DWI histories as a legitimate indicator for predicting which pilots are at greater risk of having a crash, and can be used effectively to prevent crashes," says study co-author Susan Baker, M.P.H., a professor of emergency medicine at Hopkins and a professor of health policy and management at the Bloomberg School of Public Health, who is also a certified pilot.

Alcohol involvement in fatal general aviation crashes has declined considerably in the last four decades, falling from 30 percent in the 1960s to 8 percent in the early 1990s.

To evaluate the effectiveness of background checking, the Hopkins team analyzed the medical records of more than 300,000 pilots who held a Class III medical certificate in the United States in 1994, and then tracked their flying records until 2000. During the seven-year period, these pilots were involved in a total of 2,665 aviation crashes. At the start, the researchers found that 3.4 percent of pilots had a DWI history, a figure comparable to that of the general population. These pilots were predominantly young males between the age of 30 and 34, with limited flying experience of less than nine hours in the preceding six months.

When the crash records for the group of pilots with a DWI history were compared to the group without one, the increased rate of crashes was observed. Adjusting for age, gender and flight experience, the researchers estimated that pilots with a DWI history had a 43 percent higher crash risk than their counterparts without a DWI history.

"If the crash risk for pilots with a DWI history could be reduced to the same level as their counterparts without a DWI history, then approximately 25 fewer aviation crashes would happen each year," says Li. According to the researchers, however, the vast majority of pilots with DWI histories (99 percent) flew safely, free of any crash involvement.

"There are several possible reasons why people who drink and drive have poorer flight safety records," adds Baker. "Drinking behaviors can be transmissible across activities as DWI is an indicator of chronic drinking problems, which can impair cognitive brain function and safety performance when flying. Pilots with DWI histories may simply be more prone to risk taking, in general, or be less concerned about safety, such as flying at night, under bad weather conditions and in violation of safety rules."

Current federal regulations do not allow any person to operate any aircraft - major airlines, commuter aircraft, air taxis, or private planes - within eight hours after having consumed alcohol, or with a blood alcohol concentration (BAC) above 40 milligrams per deciliter.

Major airlines are required to perform regular, random testing throughout the year, and on a minimum of 10 percent of employees with safety responsibilities, including pilots. While the number of alcohol-related infractions is low, statistics compiled by the Federal Aviation Administration indicate that about one person in 200 of the tested flight crew had BACs above the legal limit. In crashes of commuter aircraft or air taxis, measurable BACs were found in only three of 108 pilots who died between 1983 and 1988, and there are no cases where alcohol has been implicated as a probable cause in a fatal crash of a major U.S. airline. Currently, approximately 700,000 Americans are certified pilots.

Funding for the study was provided by the National Institute on Alcohol Abuse and Alcoholism, a part of the National Institutes of Health (NIH). Other researchers who took part in this study, conducted solely at Hopkins, were Yandong Qiang, M.D., M.P.H., M.H.S.; Jurek Grabowski, M.P.H.; and Melissa McCarthy, Sc.D.