Steve Fossett survived a nearly 30,000-foot plunge in a crippled balloon, a dangerous swim through the frigid English Channel and hours stranded in shark-infested seas.
But 10 days after he took off on a routine flight and never returned,
doubts were growing Wednesday as to whether he was still alive.
Fossett was scouting sites to attempt to break a land-speed record when his small plane disappeared.
Searchers have taken to the air and conducted ground searches, but even with thousands of volunteers scanning satellite images of Nevada's high desert, they have yet to find any sign of him.
Wednesday morning, the pilots set out again for the rugged region.
"It's frustrating, but not tiring," said George Mixon, a crew member with the Colorado Civil Air Patrol who has been part of the search since Sunday.
Survival experts say a trained outdoorsman such as Fossett should have been able to signal rescuers with the emergency beacon from the plane or with his specially equipped wristwatch.
Even if those didn't work, he could have built a fire or an X made of rocks or sticks, they said.
"He's either so injured he can't signal or he's perished," said David McMullen of Berkeley, Calif., a leader of the hiking group Desert Survivors, whose members frequently venture into some of the country's harshest terrain.
Fossett took off on Sept. 3 in a single-engine plane from a private airstrip about 80 miles southeast of Reno. He didn't leave a flight plan.
Maj. Cynthia Ryan of the Nevada Civil Air Patrol said Tuesday she's still betting on Fossett's "sheer grit and determination" to keep him alive.
"We still find people against all odds," she said. "Maybe he's got a couple of broken arms and can't signal."
Such injuries would worsen Fossett's chances of finding water in the 17,000-square-mile search area - about twice the size of New Jersey.
Authorities believe he was carrying only one bottle of water.
"No food, that's not a problem. No water, that's a problem. That's a harsh desert out there," said Lee Bergthold, director of the Palmdale, Calif.-based Center for Wilderness Studies and a former Marine Corps survival instructor.
People can go only two or three days without water in the summer, experts say, and Fossett would be hard-pressed to find water in unfamiliar country, even if he was in good health.
Nevada, the driest state in the nation with less than 10 inches of
precipitation a year, had an unusually dry winter, and stream flows
usually diminish by the late summer even in wet years.
"At this point, you'd be lucky to find him alive," Bergthold said.
Temperatures in the search area have been in the 80s and 90s, with lows in the 50s and 60s. Shelter from the sun would be just as important as water, McMullen said.
McMullen knows what he's talking about.
Six years ago, he found himself stranded with a severely sprained ankle for three nights in Death Valley National Park.
He stayed in the shade of a tree until he was rescued by a military helicopter, with the help of a detailed itinerary he had left his wife.
"You'll lose water faster than you can absorb it in heat, and that's why a shelter is so important," he said.
McMullen and other survival experts faulted Fossett for not filing a flight plan, which might have allowed searchers to focus on a smaller area.
"The itinerary I filed for my 2001 hike saved my life," McMullen said.