The Hawaii County Civil Defense has requested that the Federal Aviation Administration establish a no-fly zone over a Kalapana subdivision threatened by molten lava.

Kalapana Gardens residents have complained about the constant buzzing of tour helicopters flying low over their homes.

Tourists swarm the area to get a closer glimpse, but the viewing site is far from any glowing lava. They sometimes trespass through private property to get a closer look. Their alternatives are to take a helicopter or boat tour.

"We’re preparing for the worst," said Civil Defense Administrator Quince Mento. "I’m not going to make a show out of someone’s home burning down. Hopefully, it never happens, but should it come to that …"

Lava from Kilauea already enveloped one Kalapana Gardens house Sunday and has come within 250 feet of a second house but has not moved any closer within the past few days, Mento said.

Most of the lava activity seen yesterday was southwest of Kalapana Gardens where two flows are entering the ocean, the western entry being more robust, the U.S. Geological Survey’s Hawaiian Volcano Observatory reported.

Mento said he expects the FAA to impose the restrictions sometime next week but added that those restrictions should not affect the tour operators who fly along the coastline.

FAA spokesman Ian Gregor said a temporary restriction has been in place since March 2008 over Kilauea summit with a 3-nautical-mile radius, up to an altitude of 4,000 feet due to hazards. That, however, does not include Kalapana.

Gregor, based on the West Coast, was unaware of any future restrictions in the area. But he emphasized the FAA does not impose flight restrictions for nuisance reasons.

"The only reason we implement flight restrictions is for safety or security," Gregor said.

FAA regulations require airplanes fly 1,000 feet or more above the nearest obstacle. Helicopters can fly lower provided that the altitude does not pose a hazard to people or objects, and should a helicopter lose power, its pilot must be able to safely guide it down.