The search continues for missing billionaire adventurer Steve Fossit. Fossett, 63, is the first person to solo around the world in a balloon, and has broken numerous other flight records; he was in a single-engine plane when he took off at 9 a.m. (noon ET) in good flying conditions from hotel magnate Barron Hilton’s Flying M Ranch, and had four to five hours of fuel for flight.

Rescue teams continue to search for the famed daredevil after a routine scouting mission for Steve’s next adventure took an eerie turn Monday, when his tiny plane seemed to have just vanished into thin air over the treacherous mountains of Nevada.

Fossett had planned to return to the ranch, which is about 30 miles south of Yerington, Nevada, at noon (3 p.m. ET). The search for him began about six hours later. Fossett did not file a flight plan, which is not required on flights using visual navigation. Rescue teams are scouring over 600 square miles in 12 search planes over treacherous territory aggravated by strong winds though they remain optimistic as Steve had been known to walk 30 miles to safety after doing an emergency landing in the past.