Darkness More Than Triples EMS Helicopter Crash Fatality Risk

Bad Weather Increases Risk Eight-Fold

Susan P. Baker, MPH

Post-crash fires, darkness or bad weather greatly decrease the likelihood of surviving an emergency medical service (EMS) helicopter crash, according to a study by researchers from the Johns Hopkins Bloomberg School of Public Health’s Center for Injury Research and Policy and Johns Hopkins School of Medicine. Improving crashworthiness of helicopters and reducing trips during hazardous conditions can decrease EMS helicopter fatality rates. The study was recently published online by Annals of Emergency Medicine.

“Crashes of EMS helicopters have increased in recent years, raising concern for patients, as well as pilots, paramedics and flight nurses,” said Susan P. Baker, MPH, a professor in the Bloomberg School of Public Health’s Department of Health Policy and Management and Center for Injury Research and Policy. “Our study found that darkness more than triples the risk of fatalities when EMS helicopters crash and that bad weather increases the risk eight-fold. Helicopter EMS programs should recognize these risky conditions and transport patients by air only when the benefit clearly exceeds the risk of the flight.”

The study authors examined National Transportation Safety Board records of EMS helicopter crashes between January 1, 1983, and April 30, 2005. During the 22-year study period, 184 occupants died in 182 EMS helicopter crashes. A majority (77 percent) of crashes occurred when weather conditions required pilots to fly primarily by referencing their instruments rather than using outside visual cues. In darkness, 56 percent of crashes were fatal, as compared with 24 percent of crashes not in darkness. One in four EMS helicopters is likely to crash during 15 years of service. The death rate for EMS flight crew members is 20 times the rate of all U.S. workers.

The researchers also found that 76 percent of the crashes with post-crash fires were fatal. A previous study by Baker and colleagues published in the August 2005 edition of Aviation, Space and Environmental Medicine, revealed that the potential for post-crash fires in survivable crashes was greater in civilian helicopters than in their military counterparts because the standards for civilian fuel systems are not as strict as those for military helicopters.

Additional studies should be conducted to determine which preventive measures—such as equipping pilots with night-vision goggles, reducing night flights by using a protocol to determine which cases absolutely require helicopter transport, using better restraints, energy-absorbing landing gear and seats and crash-resistant fuel systems—are most efficient and cost effective, according to the study authors.

Co-authors of the study are Susan P. Baker, Jurek G. Grabowski, Robert S. Dodd, Dennis F. Shanahan, Margaret W. Lamb and Guohua Li.

“EMS Helicopter Crashes: What Influences Fatal Outcome?” was supported by grants from the Johns Hopkins Center for Injury Research and Policy, Centers for Disease Control and Prevention and National Institutes of Health.