Sean Janssen, The Union Democrat

Aircraft were expected to continue searching today from the skies above Yosemite National Park for a single-engine airplane and its pilot missing since Monday.

A Mooney M20F four-seater plane piloted by Nicol Struan Wilson, 68, of Solvang, flying out of Santa Ynez Airport, disappeared from radar near North Dome after leaving shortly after noon on Monday.

Wilson, described as "an experienced pilot" by Yosemite National Park spokeswoman Kari Cobb, took off with Mammoth Lakes as his scheduled destination.

Searching began after Wilson's wife, Constance, reported him missing on Monday night, said Ian Gregor, a spokesman for the Federal Aviation Administration. Wilson was flying alone in the plane manufactured in 1966 and had flown in the area on a number of previous occasions, Cobb said.

She said the search has to be conducted by aircraft because the area in which the plane went missing cannot be accessed by foot or by ground vehicle. It is in the vicinity of Tioga Road, which is closed for the winter due to snow accumulation.

Weather conditions were not favorable due to low clouds Tuesday, Cobb said, but visibility improved to near-perfect conditions on Wednesday, allowing for the first full day of searching. California Highway Patrol and Civil Air Patrol craft were participating in the search, which she said continued until darkness.

"We don't know that it's gone down," Cobb said. "All we know is it went off the radar … and that he did not arrive at his scheduled destination."

Wilson is listed as the president of a Santa Ynez-based company called Horizon Concepts. Shawn Knight, president of the Santa Ynez Airport Authority, said he is known to be "a brilliant person who came up with some pretty unique patents" as an engineer.

Unlike some of the tiny airfield's recreational pilots, Wilson did not spend a lot of time hanging around the lounge and drinking coffee.

"When he needed to go some place, he usually got in his plane and went," Knight said.

It is not uncommon for a plane to go temporarily "missing" after leaving the airport, as the pilot can choose for various reasons to land at a different airport than originally intended, he said.

"It's a rarity that we ever hear about an airplane that's just disappeared," Knight said.

The fact that the plane's emergency locator beacon never triggered has frustrated search efforts, he said.

The North Dome area is substantially north of the flight path for Mammoth Lakes, indicating Wilson "deviated his course, and we're not quite sure why," Knight said.

"Who knows why he was into the park that far," Cobb added.