The pilot of a medical helicopter twice radioed for help in foggy weather before crashing, killing four of the five people on board in the latest of a growing number of air ambulance accidents, authorities said Sunday.
The helicopter was carrying victims of a traffic accident when it went down in a suburban Washington park about midnight Saturday.
It was the deadliest medevac helicopter accident in Maryland since the State Police began flying those missions nearly 40 years ago and the eighth fatal medical helicopter crash in the last 12 months nationwide.
About 30 people have died in such crashes during that period, National Transportation Safety Board member Debbie Hersman said.
A veteran pilot, a flight paramedic, a county emergency medical technician and one of the traffic accident victims died in the latest crash, authorities said.
An 18-year-old woman also injured in the traffic accident in Charles County, Md., survived the helicopter crash. She was in critical condition at a hospital.
The helicopter was on a roughly 25-mile trip from the traffic accident scene to the hospital when the aircraft radioed late Saturday that it would land at Andrews Air Force Base instead because conditions were "not favorable" at the hospital.
As it approached, the pilot radioed that he was having trouble assessing his surroundings. At 11:55 p.m., he again asked for assistance with the landing, and that was the last air traffic controllers heard from him, Hersman said.
The chopper crashed three miles from the Air Force base, Hersman said. The NTSB and the Federal Aviation Administration were investigating the cause.
A federal investigation in 2006 found that there were 55 air ambulance accidents from 2002 to 2005, prompting the safety board to issue four recommendations, including higher standards for medical aircraft and more stringent decision-making in determining whether to fly in bad weather, which resulted in stricter government regulation.
Crashes of medical aircraft have been increasing since the 1990s, in part because it is a booming business, fueled by the closing of emergency rooms in rural areas and an aging population, according to the National EMS Pilots Assn. The state-run program in Maryland, however, does not charge for its services and has been known for its safety record.