LE BOURGET, France – U.S. aviation regulators have unveiled plans to ease noise restrictions for testing proposed supersonic commercial planes in American skies, part of a broader initiative to promote development of such technology.

The effort, described Monday during the international air show here, looks to eliminate regulatory hurdles that effectively have stymied a number of startups and established aerospace companies from testing new commercial supersonic designs in U.S. airspace.

“Supersonic aircraft are back on the horizon,” acting Federal Aviation Administration chief Daniel Elwell said during a panel discussion. He predicted that the development work is likely to prompt research and design efforts outside the U.S. As a result, he said, today’s projects warrant eventually drafting new noise limits for the supersonic segment of flights.

But for now, the FAA is poised to propose first-of-their-kind noise standards targeting takeoffs and landings of supersonic aircraft during test flights. Such maneuvers can exceed current standards for comparably sized conventional aircraft operating around airports.

Some of the proposed supersonic jetliners are projected to be about one-third longer than the roughly 120-foot length of an older Boeing Co. 737.

Based on size, the FAA wants to permit more takeoff noise for supersonic craft than would be allowed under existing standards, but in every case no more than is now permitted for the largest wide-body airliners.

The FAA’s primary goal, according to Elwell, is to make sure “we don’t become a hindrance to the movement of this technology” into commercial applications.

For the European-built Concorde, which stopped flying in 2003, the agency issued a blanket waiver covering noise limits during takeoffs and landings. Since the sleek jet was pulled out of service, the FAA hasn’t had to confront supersonic-related noise issues.

But today, FAA and Transportation Department officials say there are at least four separate commercial ventures seeking to certify supersonic planes in the U.S.

One of the ventures likely to benefit from the new noise rules is Arapahoe County-based startup Boom Technology, which aims to build an airliner able to slash the time for transcontinental trips by more than half.

Round trips between the U.S. West Coast and Asia could be completed within the same day for business travelers – the plush cabins would offer only premium seats – in a hurry.

The anticipated regulations won’t deal with noise constraints at higher altitudes and supersonic speeds, where controlling sonic boom remains a major design and operational challenge requiring a new generation of quieter, more fuel-efficient engines.

But for some time, supersonic proponents have lobbied Congress and tried to persuade the FAA to take preliminary steps to remove hurdles to development flights.

“Let’s hope we can get some sort of global consensus” on long-term noise standards to pave the way for widespread supersonic operations, David Short, the Transportation Department’s deputy assistant secretary for aviation and international affairs, said during the same panel.

An agency spokesman said a formal document, expected to be released later in the week, will be “the first of several regulatory actions planned by the FAA to help enable the reintroduction of civil supersonic flight.”

The spokesman also said the proposal won’t change the prohibition on flying faster than the speed of sound over land in domestic airspace, but the FAA will retain authority to grant special authorizations for supersonic flight testing, subject to environmental factors.