U.S. aviation regulators proposed broad new safety rules on Oct. 7 for air ambulances and other commercial helicopters in response to crashes that have killed more than 200 people in a 16-year period.

The regulation, if finalized by the Federal Aviation Administration (FAA), would build on existing standards and guidelines.

Safety upgrades would rely on equipping aircraft with the latest anti-collision and communications technology. The FAA also wants to impose tougher crew training requirements and more comprehensive standards for operators who fly in bad weather or over water and rugged terrain.

The FAA sought public comment on a proposal to equip helicopters with flight recorders. Some of the changes would apply to small planes that also operate medical service flights.

"We can prevent accidents by preparing pilots and equipping helicopters for all of the unique flying conditions they encounter," FAA Administrator Randy Babbitt said in a press release.

The National Transportation Safety Board (NTSB) has made improving helicopter safety a priority, pressuring the FAA to take stronger action.

The FAA estimates the safety upgrade will cost the commercial helicopter industry US$225 million over 10 years with air ambulance, tourist and business helicopter services bearing more than half of the expense.

There were 210 commercial helicopter crashes between 1992 and 2008 that killed more than 214 people, according to the FAA.

More than half of the crashes and deaths cited by the FAA and the NTSB involved air ambulances, but the accident that received a considerable amount of attention was the collision of a tourist helicopter and a small plane over New York's Hudson River in August 2009 that killed nine people.

FAA and NTSB statistics show 74 air ambulance companies in the United States operating 850 helicopters. About 400,000 patients and transplant organs are transported by helicopter annually, safety officials said.

Most medical helicopters are operated by public safety groups, hospitals, and charitable and other non-profit organizations.

Eurocopter, a unit of EADS, is the world's largest civil helicopter manufacturer. Sikorsky, a unit of United Technologies, Japan's Kawasaki, Bell Helicopter, a unit of Textron, also make commercial helicopters.

The FAA did not recommend any mechanical or design changes to those aircraft.