WASHINGTON -- A recent spate of nighttime crashes by medevac helicopters has renewed calls for widespread use of an industry-desired safety feature: goggles that allow pilots to see at night.

Nineteen people have died in medevac helicopter crashes since Dec. 30, putting this year on pace to be the deadliest in the industry's history. Four of the five fatal crashes -- which caused 13 of the 19 deaths -- happened when helicopters crashed in remote, nighttime conditions. None of the pilots was using night-vision goggles, according to federal accident data.

Any air-ambulance company that wants to use goggles on one of its helicopters must get approval from the Federal Aviation Administration. However, the agency has a shortage of trained inspectors, so the approval process can take months, according to industry officials, pilots and government inspectors. Some companies have dozens of helicopters and the FAA must grant approval for goggle use in each individual helicopter.

A survey of air-ambulance pilots found overwhelming support for night-vision equipment, which provides pilots with the equivalence of nearly 20/20 vision in the dark, said Gary Sizemore, president of the National EMS Pilots Association. "The guys that are flying are pretty frustrated that they can't get these," he said.

The FAA, which met last week with air-ambulance industry leaders, has said it supports night-vision technology and is aware of the industry's frustration. The agency is trying to streamline the process for approving goggles, said spokeswoman Alison Duquette.

"We're looking at ways we can help the industry get any technology that prevents accidents," Duquette said. The National Transportation Safety Board concluded in 2006 that goggles could have prevented 13 of the 55 accidents it had studied.

James Loftin, vice president of aviation at Air Evac Lifeteam, which operates 84 helicopter bases in 14 states, said five of his company's helicopters are night-vision equipped. But the firm has $500,000 in night-vision goggles, which cost about $10,000 apiece, "sitting on the shelf" while it awaits approval to use them.

The FAA conducts a wide-ranging review of equipment and training at individual companies before approving goggle use.

The Association of Air Medical Services is encouraged by the FAA's recent offers to help, but members remain frustrated, said Christopher Eastlee, the group's government relations manager.