HOUSTON -- Deadly crashes involving medical helicopters, like the one that killed four people last week near Huntsville, are becoming more common and are fueling a debate about whether the emergency flights are worth the risk.

Hospitals and the helicopter operators say flying ambulances can deliver patients to the emergency room faster than ground ambulances, raising the chances for survival.

But other trauma-care specialists say studies show that regular ambulances often get patients to the hospital just about as fast and that patients who go by ground have about the same chance of surviving as those ferried by helicopter, the Houston Chronicle reported in Sunday editions.

Last week, a medical helicopter crashed near Huntsville, killing the three-member crew and a patient.

It was the third fatal crash this year for the 1,000 or so medical helicopters used around the country, killing 10 people.  Three other crashes this year resulted in injuries.

The number of crashes has been rising since the early 1990s, partly due to the increase in air ambulances. But the rate of crashes has also been increasing this decade, more than tripling per 100,000 flight hours from 1993 to 2004, according to congressional researchers. They said the accident rate for medical helicopters was nearly twice that of helicopters used to transport businessmen and industrial workers.

If passenger jets crashed at the same rate as medical helicopters, more than 80 airliners would go down each year across the country, Bart Elias, the aviation safety specialist who wrote the report, told the newspaper.

“It’s about as dangerous as combat,” said Bryan Bledsoe, a Midlothian doctor who specializes in trauma care and teaches emergency medicine at the University of Nevada.

The National Transportation Safety Board said medical helicopters would crash less often if they had night-vision equipment and crash-avoidance warning systems.

On June 8, the crew of a PHI Air Medical helicopter agreed to pick up a patient in Huntsville in the early-morning darkness after a Life Flight crew abandoned the mission. Life Flight crew members said the cloud ceiling had dropped to 700 feet, or 300 feet below Federal Aviation Administration standards for night flying by helicopters.

The PHI pilot’s weather reports, reviewed by a PHI pilot at the company’s dispatch center in Phoenix, indicated the cloud ceiling was at least 1,000 feet, according to the NTSB lead investigator.

The PHI helicopter, which didn’t have the NTSB-recommended ground-warning systems, crashed in Sam Houston National Forest, killing the patient, David Disman, 58, who had a ruptured aortic aneurysm; pilot Charles Wayne Kirby, 63, of Bryan; paramedic Stephanie Waters, 27, of Cedar Park; and nurse Jana Bishop, 28, of Magnolia.

In February, a three-member crew died when their helicopter crashed off South Padre Island while attempting to pick up a patient. Last month in Wisconsin, a three-member crew were killed when their helicopter crashed into trees.