LAS VEGAS: A search was under way in the mountainous terrain of western Nevada on Tuesday for Steve Fossett, the millionaire aviator, who disappeared on Monday after taking off from a ranch for a brief recreational flight in a single-engine plane.

Mr. Fossett, 63, took off from a ranch owned by the hotel magnate William Barron Hilton at about 9 a.m. but was expected back by noon to leave the ranch with his wife on a private jet, said Major Cynthia S. Ryan, public information officer of the Civil Air Patrol Nevada Wing.

Mr. Fossett is a veteran aviator known for his quests to set world records. In 2002, on his sixth try, he became the first person to fly around the world uninterrupted in a hot-air balloon. He has an application pending with the federal Bureau of Land Management to allow him to try to break the land-speed record in a jet-powered race car in the northern Nevada desert sometime next year.

Nine aircraft have been searching several hundred square miles for signs of Mr. Fossett or the blue-and-white single-engine Citabria Super Decathlon he was last seen in, Major Ryan said. Mr. Fossett took off heading south from the Flying M Ranch, which is about 90 miles southeast of Reno.

A spokeswoman for the Federal Aviation Administration, Alison Duquette, said that Mr. Fossett's family had called when he did not return, and that her agency had issued a notice on Tuesday morning to all pilots in the area to look for wreckage.

Among the aircraft used in the search were six Civil Air Patrol Cessna 182 planes, each with three-person crews and helicopters from the Nevada National Guard, the California Highway Patrol and the Naval Air Station Fallon in Fallon, Nev.

"We're committing federal resources to this mission," Major Ryan said. "We'd do this for anyone."

At a news conference Tuesday afternoon, Major Ryan said the plane has a tracking device that can be detected by satellite, but she didn't know if searchers had gotten any information from it.

Major Ryan said that the weather was clear and wind was light on Monday when Mr. Fossett took off, and that the plane he was in was used the day before by other guests of the ranch. She said technicians at the ranch said it was in "excellent technical condition."

Major Ryan also noted that Mr. Fossett did not take along a satellite phone or other radio equipment "he would normally take because he only intended to be gone a short while."

The plane is owned by the Flying M Hunting Club, Inc. It is a fairly simple private plane, with two seats and fixed landing gear. F.A.A. records indicate it was built in 1980 or earlier.

More Fossett Pieces, all from NYT unless otherwise noted: