Rescue crews on Wednesday were to resume their search for the plane of aviation adventurer Steve Fossett, who disappeared after takeoff from a private airstrip in Nevada.
Fossett, 63, the first person to fly solo around the world in a hot-air balloon, last was seen on Monday in a single engine plane heading south of Smith Valley, Nev., Ian Gregor, a spokesman for the Western-Pacific region of the Federal Aviation Administration, told FOXNews.com.
Fossett departed at 8:45 a.m. Monday from the Flying M Ranch in Yerington, Nev., but did not file a flight plan so it is unknown where he was going.
A friend at the ranch reported Fossett missing Monday night when he didn't return, Gregor said.
• Click here for photos of Fossett.
Air Force’s Rescue Coordination Center in Langley, Va., is coordinating the search with Civil Air Patrol to find Fossett's blue and white plane.
Rescue crews have found no signs of Fossett’s plane yet, said Maj. Cynthia Ryan, a spokeswoman for the Civil Air Patrol.
Six single engine planes carrying crews of three launched Tuesday morning to search the air for Fossett. Fossett had a full tank of fuel that would provide four to five hours, Ryan said.
The search area includes hundreds of square miles of rugged terrain and area airports are on alert for the missing plane.
Richard Branson, friend of Fossett who financially backed some missions, called him a “tough old boot.”
“I suspect he is waiting by his plane right now for someone to pick him up,” Branson, Virgin Group founder, said in a statement. “Based on his track record, I feel confident we’ll get some good news soon.”
In 2005, Fossett made the first solo non-stop, non-refueled circumnavigation of the world in 67 hours.
He and a co-pilot also claim to have set a world glider altitude record of 50,671 feet during a flight in August over the Andes Mountains.
Fossett, a Stanford University graduate with a master's degree from Washington University in St. Louis, came to Chicago to work in the securities business and ultimately founded his own firm, Marathon Securities.
The 63-year-old has climbed some of the world's tallest peaks, including the Matterhorn in Switzerland and Mount Kilimanjaro in Tanzania. He also swam the English Channel in 1985, placed 47th in the Iditarod dog sled race in 1992 and participated in the 24 Hours of Le Mans car race in 1996.
In 1995, Fossett became the first person to fly solo across the Pacific Ocean in a balloon, landing in Leader, Saskatchewan, Canada.
Fossett, of Beaver Creek, Colo., was inducted into the National Aviation Hall of Fame in July. He told a crowd gathered at the Dayton Convention Center in Ohio that he would continue flying.
"I'm hoping you didn't give me this award because you think my career is complete, because I'm not done," Fossett said.
Fossett said he planned to go to Argentina in November in an effort to break a glider record.
FOXNews.com's Melissa Drosjack and The Associated Press contributed to this report.