Washington (CNN) -- The Federal Aviation Administration on Thursday proposed broad new rules for medical evacuation helicopters and more modest changes for other commercial choppers. The rules hope to turn a deadly tide that has marred the industry in recent years.
In the air ambulance world -- one devoted to saving lives by evacuating injured people or ferrying patients between hospitals -- 28 crashes have resulted in 57 deaths since January 2008.
In the most recent crash, a pilot and two medical personnel were killed when a helicopter went down August 31 near Walnut Grove, Arkansas.
The proposed rules for medevac helicopters would:
-- Require helicopters to have ground warning systems
-- Tighten crew rest and flight time requirements
-- Require large helicopter operations to have dispatchers monitor weather conditions and track the flights
-- Require pilots to conduct quick risk assessments before flights
The FAA also is seeking comment on whether air ambulances should have recording devices like the "black box" flight data recorders on commercial aircraft.
"No question about it, there will be fewer helicopter accidents as a result of what the FAA did this morning," assuming the rules are enacted, said Gary C. Robb, an aviation attorney and author of "Helicopter Crash Investigation."
The proposals track recommendations sought by the National Transportation Safety Board. The NTSB declined to comment on the proposals Thursday, saying it needs time to review them. The Air Medical Operators Association also said it needed time to review the proposed rule.
John Allen, director of flight standards for the FAA, told reporters Thursday the new rule contained both technical and administrative changes that will improve safety.
On the technical front, the proposal would require ground proximity warning systems that would alert pilots to the presence of trees, poles, buildings or terrain.
On the administrative front, operators would have to ensure that the pilots in command hold "instrument" ratings, so they are skilled at flying in low-visibility conditions. Pilots would have to conduct quick risk assessments before conducting flights, and supervisors would have to review those deemed risky.
Following the 2008 crash of a Maryland State Police helicopter which killed four, the police department designed a tool that classifies flights as risk level green (low), yellow (medium) or red (high), and requires a supervisor's approval before high-risk flights can be conducted.
Finally, governments and companies that operate 10 or more helicopter air ambulances would have to control centers that would be required to monitor helicopter flights and the weather.
FAA Administrator Randy Babbitt said the changes are designed to protect passengers, patients, medical personnel and pilots.
While lauding the changes, aviation attorney Robb said the FAA did not propose the one change that could have the biggest impact on safety -- requiring night vision goggles.
"About 40 percent of air ambulance operators in this country are equipped and have the potential to use night vision goggles. But that 60 leaves percent of these helicopters that are going out day in and day out without that critical technology. That's the most significant omission and that's the number one thing that would have had the most dramatic effect in decreasing helicopter crashes in this country," Robb said.
The FAA's Allen said the agency considered mandating goggles, but feared "unintended consequences," saying goggles can be dangerous in situations such as landing on dusty roads or some urban settings. He said technological improvements in goggles and market forces will eventually will prompt operators to adopt goggles.
In recent years, as the number of air ambulance services has soared, the FAA has proposed a number of voluntary measures to protect helicopter occupants. Thursday's proposal was a tacit statement from the FAA that voluntary measures alone wouldn't solve the problem.
According to the FAA, air ambulance accidents declined in 2005 and 2006 following an FAA safety initiative. But 2008 proved to be the deadliest year on record, with six accidents that claimed 24 lives.
"The FAA's initiatives have helped the helicopter industry make progress on many safety issues, but it's time to take steps towards mandating these major safety improvements," Transportation Secretary Ray LaHood said in a prepared statement.
A 90-day public comment period on the new rule closes on January 10. It is expected to take several more months before the first of the measures would be implemented.