DISTRICT HEIGHTS, Md. (AP) -- The sole survivor of a weekend medical helicopter crash that killed four people in suburban Washington clung to life Monday, while federal air safety investigators combed through wreckage to determine what caused the accident.
About 20 investigators were on the scene of the crash, including members of the National Transportation Safety Board, the U.S. Park Police, the Federal Aviation Administration and the manufacturers of the helicopter. Several people were perched in trees looking for debris.
The main part of the aircraft was resting on its side and was badly crumpled. Among the debris was a bright-blue backboard that was in one piece, as well as pieces of the propeller.
The debris was contained to about a 200-yard area and the main pieces of the helicopter were accounted for, indicating that the aircraft didn't break apart in the air, National Transportation Safety Board member Debbie Hersman said. It appears the helicopter crashed on a 10-foot-wide paved path at the bottom of a small hill.
Gregory Livingston was in the back yard of his home about 11:45 p.m. Saturday when he heard the helicopter.
"I was smoking a cigarette, and I heard the chopper go past, and it was fluttering," Livingston, 57, said after he gave his account to National Transportation Safety Board authorities. "I worked at the Pentagon for eight years, so I always heard helicopters coming and going. The blade is always steady, but it was fluttering, and it didn't sound right to me. I heard it go silent, and that was it."
The crash, one of a growing number of air ambulance accidents that has prompted aviation officials to begin planning a public hearing, happened after the pilot twice radioed for help in foggy weather.
The medical helicopter was carrying victims of a Saturday night traffic accident when it went down around midnight in a suburban Washington park. It was the deadliest emergency 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.
The helicopter was on a roughly 25-mile trip from the traffic accident 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 they 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.
Killed in the crash were pilot Stephen Bunker, 59; flight paramedic Mickey Lippy, 34; emergency medical technician Tanya Mallard, 39; and 18-year-old Ashley Younger. Younger and Jordan Wells, who survived, were involved in the traffic accident in Charles County. Wells was in critical but stable condition at a hospital Monday.
Medical aircraft crashes 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 Association.
However, the state-run program in Maryland does not charge for its services and has been known for its safety record. It has had just three other fatal helicopter crashes in four decades.
"We are the only operation in the country that has the multiple mission of medevac, search and rescue, law enforcement, homeland security," State Police spokesman Greg Shipley said.
A federal investigation in 2006 found there were 55 air ambulance accidents nationally 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.
Crashes in Texas, Wisconsin and Arizona, where two medical helicopters were in a fiery collision in June, have underscored the dangers of the medical flights. Some have questioned whether it would be safer to transport patients by ground ambulance.
Dr. Bryan Bledsoe, an emergency medicine physician who teaches at the University of Nevada and has researched accident rates of medical helicopters, said the Maryland medevac system has a good safety record, but medical flights are overused nationwide.
There is a tendency to fly in questionable weather, he said. In many cases, the flights aren't justified because the distance to the nearest hospital is not that great or the injuries are not severe enough, he said.
"We've just gotten into a situation here in the United States where we think that the helicopters are a panacea," Bledsoe said. "And they are an important tool, but they are just a tool. We vastly overuse them, patients don't benefit and they are expensive."
A recent Maryland legislative audit faulted the police agency for failing to document maintenance needs and costs for its fleet of 12 twin-engine helicopters. The helicopter that crashed was bought in 1989 and was the second-oldest in the fleet. It had been inspected Wednesday, State Police Superintendent Terrence Sheridan said.
State Police have grounded all of their flights until the cause of the crash can be determined. Other states and private companies will cover Maryland in the meantime, Sheridan said.
An aunt of Mallard, the medical technician killed in the crash, said she was proud of her niece's work.
"I lost someone I truly, truly love, I'm sorry for everybody else's loss," Cheri Douglas said. "My family is truly, truly hurt."
Associated Press Writer Alex Dominguez in Baltimore contributed to this report.