Pilot Scott Bahan in a Piper Cherokee small plane as it taxis to the icy runway in Alton, New Hampshire on Lake Winnipesaukee

Pilots comfortable with an icy landing can now use a runway on a frozen lake in the northeastern US state of New Hampshire.

The 2,600-foot strip at Alton Bay on Lake Winnipesaukee opened to the public earlier this month when the ice became at least 12 inches thick.

On Saturday, almost 20 inches of solid ice was measured.

It is the only ice approved by the Federal Aviation Administration in the United States and is not for the faint-hearted.

"Ice is slippery. We get that a lot from the pilots," said airport supervisor Carol Niewola of New Hampshire's aeronautic transportation department.

"Turning, stopping, those are all really difficult moves that are very easy to do out on paved or grass runways, but here on the ice it can be very different.

"There is a little bit of snow cover on the ice that gives it just a little bit of grip, but it's not very good," she added.

The runway did not open for take-offs and landings last year because the ice was not thick enough.

Paul LaRochelle manages the airport and goes out every day to measure the ice's thickness.

"We won't drive our trucks out here without having at least 12 inches of ice. If we have 9 inches here, 12 over here, 10 down there, we don't open. Not until we're even everywhere," he said.

The New Hampshire Department of Transportation helps manage the runway and provides LaRochelle with a crew of workers.

They clear the runway of snow and ensuring planes take-off, land and park safely.