Search teams continued their hunt for Steve Fossett (63) today after the world aviation record-holder disappeared while flying over Neveda four days ago.
Rescuers expanded their search area to cover 10,000 square miles of mountains and desert across western Nevada and California.
The Nevada National Guard has carried out night flights equipped with thermal imaging systems.
Mr Fossett was last seen taking off from the Hilton Ranch on Monday night in a single-engined aircraft.
Sir Richard Branson
There have been no signals from the emergency locator beacon aboard Mr Fossett's plane.
British tycoon Sir Richard Branson, who has funded many of Mr Fossett's record-breaking attempts, said that if anybody could glide the plane to safety it was Mr Fossett.
He added: "If the worse comes to the worse . . . Steve's lived his life to the full, and he hasn't wasted a minute of it."
Mr Fossett was searching for empty and dry lake beds which might be suitable for a world land speed record attempt in a car.
The American millionaire businessman was the first person to fly solo around the world in a balloon and the first to fly a plane solo around the world without refuelling.