Cowley could be dismissive of much of the medical establishment, and his staff sometimes described him as a bully, but he was able to charm politicians to win the funding to launch his system. It grew to nine trauma centers, in hospitals from Salisbury to Cumberland. Rural areas lobbied for - and got - their own medevac helicopter bases to complement those between Baltimore and Washington. The system now has 12 high-end aircraft at eight bases.
His system worked: A 1973 study published in The Journal of Trauma by Cowley found that the mortality rate for accident victims fell after the trauma center and medevac transport began, from a rate of 50 percent to less than 20 percent. By 1980, the rate was down to 8 percent.
"If you want to be a country singer, you go to Nashville. If you want to be on Broadway, you go to New York," Sgt. Walter A. Kerr said during a tour last week of the sprawling hangar at Martin State Airport in Middle River that houses the state police helicopter unit he supervises. "And if you want to be in air medical service, you come here."
Other states have less centralized systems. In most, helicopter transport is provided by private operators exclusively, or by a mix of public and private aircraft, as with ground ambulance service, said Thomas Judge, president of the Association of Air Medical Services, a trade group based in Alexandria, Va.
Privately operated systems emerged and took control in the 1980s before most states considered organizing a large public system like Maryland's, said Steven Sittig, a respiratory specialist at Mayo Clinic in Minnesota and chairman of the American Association for Respiratory Care's Transport Specialty Section.
The medical helicopter industry's development was largely influenced by hospitals in response to various factors, from technological advances to population sprawl.
As the most sophisticated hospitals, such as Johns Hopkins and University of Maryland, built a variety of high-tech services in specialties such as heart surgery and newborn intensive care, they began relying more on helicopters to bring patients to them from community hospitals. The helicopters were much better than ambulances for avoiding traffic congestion and in shuttling patients long distances from rural facilities.
Hospitals, or groups of them, financed air transport not as a moneymaker in itself, but to help deliver customers for expensive services.
"Most rotor-wing systems don't generate revenue," Sittig said. "If you can break even, you're doing OK. Once you get the patient here, it's a revenue generator."
The two private systems that operate in Maryland, each about 20 years old, were developed by hospital systems. MedStar Transport belongs to MedStar Health, a collection of six hospitals. STAT MedEvac, owned by a nonprofit consortium of Pittsburgh-area hospitals, came to Maryland in 2001 to transport patients to Hopkins for heart surgery and other services.
In response to a call to transport a 50-year-old woman awaiting heart treatment, the STAT MedEvac chopper lifted off recently from Martin State Airport, soon passing over the U.S. Naval Academy and the Bay Bridge. After 30 minutes in the air, it banked sharply over St. Mary's Hospital in Southern Maryland.
An area about the size of a minivan interior contained the equivalent of what medic Guy Barber dubbed a "mobile ICU": ventilator, pacemaker, obstetrics kit and a cooler with four pints of blood. Barber and a nurse, in black jumpsuits and carrying a large red gym bag of medications, wheeled a stretcher into the emergency room at St. Mary's.
"You guys take over," a doctor said. They confirmed medications and adjusted intravenous lines and monitors. In about 15 minutes, they wheeled the patient to the helicopter for a flight to George Washington University Hospital in the nation's capital.
When there was trouble starting the helicopter, the heart patient was quickly switched to a MedStar one that was just arriving. After a short delay, Barber's crew took a less urgent patient (the one MedStar would have transported) to Georgetown University Hospital for a neurological evaluation.
Experts say no research exists that compares public and private, or for-profit and nonprofit, air medical services on travel times, patient outcomes or safety records, partly because the different population densities and geographies of states offer so many variables.
One distinction is that the private companies have a nurse and a medic on board for every flight, while the state police have only a medic on about 80 percent of their flights.
"We have two highly skilled medical professionals," said Popham, the lobbyist for the Pennsylvania company that leases helicopters to private operators. "We provide a level of care that's at least equal to, if not better, than the care provided by the state."