The National Transportation Safety Board (NTSB) is calling on regulators to require new lifesaving technologies on many air ambulances, including night-vision goggles, terrain avoidance computers and autopilot controls. The devices are costly, but the NTSB says they would save lives in a health care system increasingly reliant on choppers for transporting critically ill patients.

Industry groups such as the Air Medical Operators Association say their members should have the freedom to adopt some, but not all, of the technologies. The group, which represents companies operating more than 90% of medevac helicopters, has pushed its members to make voluntary safety improvements.

Amid the recent spate of deaths, the NTSB says the voluntary approach is not working. "While some operators have voluntarily adopted measures to address our safety recommendations, others have not," NTSB Chairwoman Debbie Hersman said.

At least two of the recent crashes happened amid conditions that the new technology devices are designed to address. Some smaller air ambulance companies and family members of crash victims say that the industry is opposed to the safety equipment the NTSB wants because of cost.

"If the economic bottom line gets in the way of protecting our workforce and protecting patients, we have a problem," said Tom Judge, director of Maine's medevac program.

After a record number of fatal accidents killed 35 people from December 2007 through October 2008, air ambulance industry groups adopted several safety improvements on their own. The Federal Aviation Administration (FAA), which regulates the industry, also pushed for voluntary improvements while it worked on drafting new requirements.

Those efforts coincided with an 11-month span through last September in which no one died on a medevac helicopter, according to the NTSB.

That period was shattered when a helicopter crashed in Georgetown, S.C., on Sept. 25 in severe weather, killing three people. Since then, 10 more medevac choppers have crashed, including three since June. An air ambulance plane crashed last month in Alpine, Texas, killing five people and bringing the death toll on emergency aircraft to 24.

On June 2, a CareFlite medevac chopper crashed near Midlothian, Texas, after breaking up in flight, killing a pilot and a mechanic, according to the NTSB. A pilot and flight nurse died July 22 in Kingfisher, Okla., when an EagleMed chopper went down. An Air Methods helicopter plunged to the ground in Tucson on July 28, killing three.

Chris Eastlee, managing director of the Air Medical Operators Association, said the group's members take "a very dramatic and extremely broad look at safety." The group asked members to increase pilot training and get night-vision goggles, Eastlee said.

The association balked at key NTSB recommendations to install multiple layers of safety to prevent crashes in bad weather and poor visibility.

Operators believe they should have the flexibility to adapt to their own circumstances, Eastlee said.