The Federal Aviation Administration has developed a surveillance plan to step up enforcement in Hawaii of flight regulations for powered hang gliders known as “trikes.”

The move toward stricter enforcement comes in response to five crashes involving such aircraft in the islands in a year and a half, including three that were fatal.

“That’s too many. That’s why we’re here today,” said Nick Reyes, FAA’s westernPacific flight standards manager.

In an FAA conference room at Honolulu Airport, Reyes acknowledged that some aircraft operators were ignoring federal rules that ban the use of trikes for air tours.

Qualified pilots of trikes, also known as weight-shift control aircraft, are allowed to carry passengers only if they are student pilots, according to federal flight standard rules.

“It appears some operators are trying to get around the air tour provision by offering scenic flights under the guise of introductory flying instructions,” Reyes said.

Reyes said he and other FAA officials met Thursday on Kauai with weight-shift control operators.

“We made sure everyone understood the regulations,” he said.

During the meeting, weight-shift control operators were told any advertisement that appears to offer air tours is basis for enforcement action that ranges from warnings to revocation of certification. Operators were also told that changes need to be made in ads on the Internet within a week or two.

Reyes said the FAA did not need new regulations, since the rules are clear.

“Rather, we need to insure that all operators follow existing regulations,” he said.

He said the best approach is voluntary compliance and working with weight-shift control aircraft operators. “We do not want to impede people’s ability to make a living,” he said.

“It is our hope and expectation that operators will embrace this approach.”

Five commercial trike businesses are operating in the state — one each on Oahu, Kauai, and Maui and two on Hawaii island.

Reyes said FAA officials plan to have more visits, meetings and conference with the operators to encourage compliance.

The flight surveillance plan includes unannounced visits, interviews with pilots and student pilots, and records examinations.

In at least two fatal accidents in Hawaii since 2009, operators of trikes were carrying people for commercial tours, according friends who were waiting for them on the ground.

The first, involving pilot Tedd Hecklin, 38, and Kailua-Kona resident Kathryn Moran, 37, occurred at Kealakekua Bay on Hawaii island on April 21, 2010.

A friend of Moran’s said she was celebrating her birthday and taking a tour.

The second took place in the ocean off Hanapepe on Kauai on Feb. 15 that killed the pilot, Jim Gaither, 55, and visitor Kim Buergel of Washington state.

Buergel, 49, just wanted an air tour that was entertaining, said her friend Patty Hanson, who had taken an earlier flight.

Pilot Steve Sprague, 49, and California resident Ray Foreman, 53, celebrating his 25th wedding anniversary, died when an ultralight crashed in north Kauai on May 17.

All three crashes remain under investigation by the FAA.