MAMMOTH LAKES, Calif. (AP) - Steve Fossett chose a small single-engine airplane to scout a site for his next big adventure. But the crash that authorities say almost certainly claimed his life was as epic as the life the millionaire thrill-seeker tried to live.

Deep in the Sierra Nevada, searchers on Thursday identified the wreckage of the plane Fossett was piloting when he disappeared during what was supposed to be a quick trip. The debris, hidden from easy view for more than a year, littered an area longer than a football field and nearly as wide.

From the looks of it, the plane had slammed straight into a mountainside.

"It was a hard-impact crash, and he would've died instantly," said Jeff Page, emergency management coordinator for Lyon County, Nev., who assisted in the search.

Crews with cadaver dogs located a few personal effects amid the mangled metal and, late Thursday, a possible sign of a person.

According to the National Transportation Safety Board, searchers uncovered human remains - not much, but enough to perform DNA tests
to determine if they belonged to the missing aviator.

"We found human remains, but there's very little. Given the length of time the wreckage has been out there, it's not surprising there's not very much," said NTSB acting Chairman Mark Rosenker. "I'm not going to elaborate on what it is."

Later Thursday, Madera County Sheriff John Anderson described the promising finding by one of his lieutenants as an oblong piece of bone, measuring 2 by 1½ inches. Anderson also made a point of saying the bone fragment had not yet been confirmed as human.

"We don't know if it's human. It certainly could be," Anderson said during a news conference Thursday evening. "I refuse to speculate."

He said it would be sent to a California Department of Justice lab for testing.

Asked about the sheriff's assessment of the physical evidence, NTSB spokesman Terry Wiliams reaffirmed Rosenker's earlier statement.

"We stick by that. It's human remains," said Williams, who declined to say how the NTSB had arrived at that conclusion.

Fossett, 63, vanished on a solo flight 13 months ago. The mangled remnants of the Bellanca he had borrowed was spotted from the air late Wednesday near the town of Mammoth Lakes and was identified by its tail number.

NTSB investigators went into the mountains Thursday to figure out what caused the plane to go down. Most of the fuselage disintegrated on impact, and the engine was found several hundred feet away at an elevation of 9,700 feet, authorities said.

"It will take weeks, perhaps months, to get a better understanding of what happened," Rosenker said before investigators set off.

Search crews and cadaver dogs scoured the steep terrain around the crash site in hopes of finding at least some trace of Fossett's body and solving the mystery of his disappearance once and for all.

Rosenker said enough remains were found to provide coroners with
DNA.

Fossett was last seen on Sept. 3, 2007, when he took off from a Nevada ranch owned by hotel magnate Barron Hilton. The intrepid balloonist and pilot was scouting locations for an attempt to break the land speed record in a rocket-propelled car.

His disappearance spurred a huge search that covered 20,000 square miles, cost millions of dollars and included the use of infrared echnology. For a while, many of his friends held out hope he survived, given his many close scrapes with death over the years. Eventually, a judge declared Fossett legally dead in February.

The first solid clues of what may have happened to him surfaced only this week when a hiker stumbled across a pilot's license and other ID cards belonging to Fossett. The documents were a quarter-mile from where the plane was later spotted in the Inyo National Forest. Investigators said animals might have dragged the IDs from the wreckage while picking over Fossett's remains.

The rugged area, situated about 65 miles from the ranch, had been flown over 19 times by the California Civil Air Patrol during the initial search, Anderson said. But it had not been considered a likely place to find the plane.

Instead, searchers had concentrated on an area north of Mammoth Lakes, given what they knew about sightings of Fossett's plane, his travel plans and the amount of fuel he had.

"With it being an extremely mountainous area, it doesn't surprise me they had not found the aircraft there before," Lyon County Undersheriff Joe Sanford said.

Lt. Col. Ronald Butts, who coordinated search efforts for the Civil Air Patrol, said the dense, tree-covered terrain gave searchers a less than 10 percent chance of finding the wreckage by air.

"Everything we could have done was done," Lt. Col. Ronald Butts said.

As for what might have caused the wreck, Mono County, Calif., Undersheriff Ralph Obenberger said large storm clouds mustered
above Mammoth Lakes on the day of the crash.

Fossett made a fortune in the Chicago commodities market and gained worldwide fame for setting records in high-tech balloons, gliders, jets and boats. In 2002, he became the first person to circle the world solo in a balloon.

He also swam the English Channel, completed an Ironman triathlon, competed in the Iditarod dog sled race and climbed some of the world's best-known peaks, including the Matterhorn in Switzerland and Mount Kilimanjaro in Tanzania.

"I hope now to be able to bring to closure a very painful chapter in my life," Fossett's widow, Peggy, said in a statement. "I prefer to think about Steve's life rather than his death and celebrate his many extraordinary accomplishments."

Marcus Wohlsen reported from San Francisco. Associated Press
writers Malia Wollan in San Francisco and Scott Sonner in Reno, Nev., contributed to this report.

(Copyright 2008 by The Associated Press. All Rights Reserved.)

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