Researchers at Johns Hopkins have found that nighttime
flying and worsening weather conditions are two key
characteristics of fatal plane crashes in general aviation
where alcohol consumption by the pilot was also a
The Johns Hopkins team found that most alcohol-related
plane crashes, 52 percent, occurred during nighttime hours,
between 7 p.m. and 6 a.m. In contrast, most
nonalcohol-related plane crashes, 72 percent, occurred
during the day, between 7 a.m. and 6 p.m. Statistics also
showed that 64 percent of alcohol-related crashes occurred
in worsening weather conditions, such as rain or fog, that
force the pilot to switch from visual flight rules to
The researchers hope their findings, published in the
January issue of the journal Accident Analysis &
Prevention, can be used to design programs similar to
those that combat drunk-driving to lower accident rates.
"Pilots should never mix alcohol consumption with
flying because it can impair their ability to think about
key functions in operating a plane, such as interpreting
flight instruments or coping with spatial disorientation,"
said lead study author and medical epidemiologist Guohua
Li, professor of
emergency medicine in the School of Medicine and
policy and management in the Bloomberg School of Public
Health. "While regulations currently ban drinking and
flying, only major airlines have programs in place for
regular testing of pilots, and no program exists for the
general aviation pilot."
To better understand the circumstances of and identify
specific risk factors involved in alcohol-related plane
crashes, the Johns Hopkins team studied medical records for
313 general aviation crashes fatal to the pilot from 1985
to 2000. Specifically, the researchers separated the files
using a cut-off blood alcohol concentration, or BAC, of 20
milligrams per deciliter (0.02 percent BAC), the minimum
reliably detectable level. A trained flight instructor then
coded each case based on nearly 20 characteristics and
circumstances, including age of pilot, type of flying
certificate, total flight time experience, type of
airplane, weather conditions, time of day, place and cause
The information came from a combination of databases
at the National Transportation Safety Board and autopsy
records from state medical examiners offices in three
states — Maryland, New Mexico and North Carolina
— whose coroners routinely perform toxicology tests
on people who are fatally injured. Some of the 313 cases
were excluded because of incomplete information.
Overall, the researchers found that 11 percent (25
cases) had positive BACs, and 6 percent (15 cases) had BACs
above the legal limit of 40 milligrams per deciliter (0.04
percent BAC). Alcohol was listed as a contributing factor
by the NTSB in eight of the 25 alcohol-related plane
crashes, with BACs for these pilots ranging from 70 to 239
milligrams per deciliter. A total of 194 other people,
mostly passengers, also died in these plane crashes.
While the two most significant risk factors were
nighttime flying and worsening weather conditions, pilot
error was recorded as a contributing factor in all the
alcohol-related crashes and in 96 percent of other crashes.
These included cases where the pilot was "showing off" to
friends by flying too low or lost control of the aircraft
in darkness or in bad weather.
"This study provides a better understanding of the
role played by alcohol in fatal plane crashes, including
identification of the risk factors, such as when and where
disaster is most likely to strike," said study co-author
Susan Baker, a professor of medicine in the School of
Medicine and of health policy and management in the School
of Public Health, who is also a certified pilot. "Our
results provide additional evidence that 'zero tolerance'
policies on alcohol are justified. Alcohol is a
contributing risk factor in fatal plane crashes."
The researchers will now focus on nighttime flying in
different weather conditions and develop test programs to
improve aviation safety, such as routine spot checks or
asking about drinking behavior during pilots' biannual
physical exams, that might help reduce alcohol-related
crashes in the future.
Current federal regulations do not allow any person to
operate any aircraft — planes of major airlines,
commuter aircraft, air taxis or private planes —
within eight hours after consuming alcohol, or with a BAC
above 40 milligrams per deciliter. Only 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 the
1960s, more than 30 percent of pilots who were killed in
plane crashes had elevated BACs.
Some studies have shown that this level dropped to 8
percent in the 1990s. 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 for general
aviation and can pilot a plane.
Funding for the study was provided by the National
Institute on Alcohol Abuse and Alcoholism, part of the
National Institutes of Health.
Other researchers who took part in this study were
Yandong Qiang and Melissa McCarthy, both from Johns
Hopkins; and Margaret Lamb, a flight instructor from
Sunshine Aviation Safety Studies, in Alamosa, Colo.