WASHINGTON — Hawai'i Volcanoes National Park is among the top five parks most at risk from growing noise pollution, according to a coalition of retired national park employees.

The problem at the park is uncontrolled orbiting time by tour aircraft over eruption sites, the Coalition of National Park Service Retirees said.

Bill Wade, executive council chairman of the coalition, said people think of national parks as places of "genuine peace, quiet and natural sounds."

"Some parks remain natural cathedrals to silence and natural sounds, while others now face an onslaught of airplane overflights, traffic sounds, snowmobiles, jet skis and other man-made noise pollution," Wade said.

Volcanoes National Park is most often visited to view the Kilauea and Mauna Loa active volcanoes, which can't always be viewed by foot or car, the 650-member group said. In these cases, over flights are the only way to see eruptions, the group said.

"But there are tens of thousands of air tour flights per year," the group said. "The routes in the park are subject to nominal Federal Aviation Administration regulation, but orbiting time over eruption sites is uncontrolled."

U.S. Sen. Daniel K. Akaka, D-Hawai'i, chairman of the Senate national parks subcommittee, said that Congress passed a bill in 2000 to established a framework to control National Park system air tour traffic and lessen its impacts.

"We must continue to balance tourism opportunities for all visitors while remaining sensitive to the environmental and noise concerns," he said.

Preston Myers, owner of Safari Helicopters, said his company has one helicopter on the Big Island, and limits its activity near the national park to the area where lava is erupting near Pu'u 'O'o. That area is closed to the public, Myers said. The ocean entry at Kalapana is outside the of the park.

From there, the flights trace the lava flows to the point near Kalapana where the lava is currently entering the ocean.

Fred Adlard, assistant chief pilot for Sunshine Helicopters, said his company also stays outside the park boundary.

"Where we fly, it's the live lava fields; there's nobody out there," he said. "There might be the volcanologists, but they're out there in a helicopter, too. There's no tourists."

Adlard said his company stays away from Halema'uma'u crater, and if they are forced by weather to fly to the south of the most populated park areas, they steer clear of the crater. "We make every effort to avoid that, and we definitely don't overfly it," he said.

The group said the other four parks at risk are: