By DAMON SYSON

Last updated at 16:23 18 January 2008

A hugely experienced pilot, a hi-tech search by hundreds of volunteers over 10,000 square miles that has turned up six plane wreckages... and still no trace after four months. Damon Syson reports on a missing millionaire - and how a conspiracy theory is born

We're 8,000ft above sea level in a single-engined plane half an hour out of Reno, Nevada.

The pilot turns and says casually, "You'd better get strapped in. It's going to get damn-ass bumpy once we hit the mountains."

It's an unfortunate phrase, especially when you consider the mission.

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The six-seater Cessna T210N is already moving around enough to make my stomach lurch.

But Tom Grossman, the amateur pilot taking me on an aerial tour of the Nevada wilderness, insists conditions are exceptionally calm today.

"In the summer," he says with morbid relish, "a downdraught will slam-dunk you at 2,000ft a minute.

"Flying near the ground is a dangerous game in these parts."

Quite.

This is where multimillionaire adventurer Steve Fossett went missing on September 3 last year.

His disappearance led to one of the largest manhunts in US history using the most up-to-date search-and-rescue technology.

Yet no trace of the 63-year-old has ever been found.

After three months of fading hope, Fossett's wife Peggy, asked the courts to declare him legally dead.

Like most people in the UK, my immediate reaction was one of incredulity.

Central Nevada is one of the most remote wildernesses in America, but if satellite wizardry means we can photograph a beer can from space, surely we can locate a plane crash?

Actually, the further we get from the suburban sprawl of Reno, the more I understand the problem the rescue teams faced.

The area they were searching is bigger than Wales.

They did find, however, six previously unaccounted for aircraft, including a wreck dating back to 1965.

Apart from the bizarre sight of a distant geo-thermal power plant emitting a plume of steam from the side of a mountain, there is no sign of habitation as far as the eye can see.

Just desolate mountains creased with canyons and crevasses.

Our ground speed is 200mph, and it's been almost half an hour since we last saw a road.

"If you keep flying in this direction you'll eventually hit Las Vegas," says Tom.

"But there's not much in between; just sage brush, scorpions, rattlesnakes and coyotes. The real Wild West."

There's no doubting the savagery of the landscape, but if Fossett was to die, everyone assumed it would be in a blaze of glory, not doing something so banal as taking a plane for a spin on a clear day.

It's the equivalent of Sir Ranulph Fiennes passing out from exhaustion on his way to Tesco.

Fossett, who accompanied Sir Richard Branson on numerous jaunts, ran across Death Valley and swam the English Channel (in a record-breakingly slow time, 22hrs 15mins – which merely attests to his dogged endurance).

He broke more than 100 records in aviation, sailing and ballooning, and was constantly seeking new challenges.

While studying for an economics degree at Stanford, his friends persuaded him to swim the 1.5 miles to Alcatraz island off San Francisco.

After college, he set about climbing the highest peaks on each continent.

At work, he made a multimillion-dollar fortune as a commodities trader, earning enough to retire in 1990, when he focused on setting records full-time.

The land-speed record was to be the jewel in his crown.

Borrowing Tom's state-of-the-art binoculars, I scan the ground for any sign of glinting metal.

Even though they're £2,500 gyro-stabilised Canons, it's exhausting work.

After a few miles of seeing nothing but 20ft conifers, my eyes begin to swim.

Tom throws the plane into a steep banking turn and we circle above a ranch owned by hotel magnate Barron Hilton.

It's made up of a central building, a scattering of guest houses, a small lake, a tennis court and a mile-long runway.

It was from here that Steve Fossett took off that fateful morning, flying one of Hilton's planes, a blue-and-white Bellanca Citabria Super Decathlon – a super-light, single-engined aerobatic plane used for practising rolls and spins.

Tom then points the Cessna towards the Wassuk Range, a jagged row of mountain peaks, the highest of which, Mount Grant, rises to 11,000ft.

As promised, things start to get bumpy.

This area has a reputation for some of the continent's worst turbulence – even commercial flights are prone to doing a bucking-bronco act when passing through.

At this year's Reno Air Show there were three fatal crashes in four days.

Passing over the peak, we're suddenly greeted with an awesome sight – Walker Lake, a wide, blank expanse of deep blue.

There are no buildings along its shore and no boats on the surface.

Some believe that Fossett's body lies here.

The engine whines and my stomach jumps. "Whoa – sorry," says Tom.

"We just hit a downdraught."

Off to our right is Hawthorne, Nevada, a US Army depot plonked down in a windswept valley ringed by Tolkien-esque mountains.

Beside the lake there's a square mile of military storage bunkers – weird man-made mounds connected by railway tracks, which Tom tells me contain "decommissioned bombs, old munitions and who knows what".

In fact, Hawthorne is America's biggest ammunition storage depot.

To the northeast of Walker Lake is one of the most extensive clusters of Military Operations Areas (MOAs) in the US.

Bearing this in mind, it's hardly a surprise that conspiracy theories abound among local people.

Perhaps Fossett strayed in and was shot down, or even had a heart attack, lost control and careered into the MOA unwittingly.

Aeronautical charts clearly mark the MOAs, alongside printed warnings that incoming aircraft face the danger of interception, while the Nevada Bureau of Land Management warns of "unusual, often invisible hazards to aircraft such as artillery firing, aerial gunnery, missiles or ground target attacks. Penetration of restricted areas," it continues, "may be extremely hazardous for non-authorised aircraft and is legally prohibited."

Since Fossett disappeared, the bars of Reno have been abuzz: "he must have seen

something he wasn't meant to"; "he's in Panama – like that English canoe dude"; "he's been abducted by aliens" (this is, after all, not far north of Area 51, one of the most secretive places in the world and the subject of UFO speculation).

Aviation internet forums are also humming: "Maybe he flew into a place in Nevada where he shouldn't have?" says one.

Another suggests he strayed into "a secretive military controlled area that's off limits to civilians or to all but a tiny number of military".

No one knows of course, but Fossett was healthy and an experienced and sensible flier, and the thorough search of the area – at least that permitted to be searched – found nothing. The theories will continue.

One thing everyone agrees on, however, is that if Fossett had survived the crash he would have found some way to signal – he would have known how to make a fire with petrol from the plane, using the battery to make a spark.

I ask if we need permission to land at Hawthorne.

"Not really," Tom says.

"There are airstrips like this all over the country – you can hop from one to the other. I'll see if there's anyone manning the radio.

"Good morning, Hawthorne, how are things looking down there?"

After a pause, a female voice crackles back through our Bose headsets: "Hi there. I'm just out in the back yard feeding my dogs but y'all are

welcome to land."

Tom eases the Cessna down onto the dusty airstrip, brings it to a standstill and we climb out.

The icy wind hits us immediately.

It's a beautiful clear day but the temperature up here at 4,375ft is about minus five.

In the summer, however, it can get so hot in the high desert that it's almost uninhabitable. It's eerily beautiful; and, of course, deadly.

On an unassuming doorway in a light-industrial park in Sparks, Nevada, a sign reads Marathon Racing.

You'd never guess it, but behind a small office is a cavernous 60ft garage containing a piece of history in the making – the Fossett LSR (land-speed racer).

It's a sleek and delicate-looking machine, like Concorde without the wings.

The plan of those working here is to use it to push past the 800mph barrier and keep going.

"I first met Steve Fossett on the Bonneville Salt Flats in the autumn of 2006," says my guide Louise Ann Noeth, author of land-speed racing's bible, Bonneville Salt Flats, and part of the Fossett team.

"He climbed into a streamliner [the common name for long, slim, land-speed racing vehicles] for the first time and I'll be damned if he didn't get up to 300mph in two or three runs.

"I was seriously impressed – this guy looked like an accountant, but he managed in two runs what it takes some people years to achieve. It was exquisite driving."

Fossett's experience that day convinced him that he had what it took to go for the record – to drive a jet-powered vehicle across a dry lake bed, eating up a mile every four seconds.

Designing and building a car from scratch is a Herculean task, not to mention prohibitively expensive, but as luck would have it there was one already half there in the shape of Craig Breedlove's mothballed Spirit Of America.

Breedlove, the land-speed-racing pioneer and five-time record holder, had designed the vehicle with claims he could take it in excess of 800mph.

But on his first time out, in October 1996, it flipped onto its side and performed a dramatic 180-degree turn at 675mph.

A year later he tried again, reaching 676mph and again sustaining major damage.

Meanwhile, a British team led by Richard Noble had arrived at Nevada's Black Rock desert and in October 1997 RAF fighter pilot Andy Green drove the Rolls-Royce jet engine-powered Thrust SSC at 763mph, becoming the first person to officially break the sound barrier and gaining the land-speed record, which he still holds today.

Breedlove's car gathered dust in a Californian garage for nearly a decade.

Fossett heard that he was looking to sell and, after months of negotiations, he finally bought it from him and set about putting together a team of technicians, led by rocket scientist Eric Ahlstrom.

The tall and intense Ahlstrom has a touch of the mad scientist about him.

The son of a former senior executive and chief scientist at Boeing, he's been steeped in aeronautics since he was a child.

Fossett was in daily contact with Ahlstrom via email and phone and visited the workshop every few weeks to see how things were progressing.

His last visit was in August, a fortnight before his final flight.

"There's a perception of Steve being this rich guy who bought thrills," says Ahlstrom.

"He wasn't like that at all.

"He was the nicest guy – an extremely honest and open individual.

"But the second he stepped into the car or started planning something, there was an intensity about him that's very rare, and very inspiring."

On the morning of Tuesday September 4, 2007, Eric Ahlstrom received a call from one of Fossett's aides telling him their boss was missing.

Fossett had taken off the previous morning at 08:45 on what was expected to be a two-hour pleasure flight, planning to return in time to leave for home in his own aircraft at midday.

He was not wearing the Breitling Emergency watch with a built-in transponder that he often wore.

Initially, it was suggested that Fossett was looking for potential sites on which to run the jet car.

"Absolutely not," says Ahlstrom, shaking his head.

"We had already come up with our test plan – we knew where we were going.

"He did a lot of surveying for dry lake beds earlier in the year but always took very specific mapping equipment with him to mark it on his GPS.

"He didn't take any of that equipment with him that day. He was just taking the Citabria for a spin."

Some suggest he might have got into difficulties.

The Citabria is the aircraft equivalent of a dune buggy; Fossett had never flown one before, but he was still regarded as one of the world's most talented airmen.

"He was a great pilot because he had good judgment," says Ahlstrom.

"At test-pilot school you're given a nickname to describe you.

"His was “Cucumber”, as in “cool as”. Nothing ever panicked Steve. Under stress, he just focused."

No one who knew Fossett believes he would have taken risks by flying too near the ground.

"He was well aware of the risks and had flown in this region many times," says Ahlstrom.

"Fossett was a friend of Barron Hilton's and had been visiting his ranch for nearly a decade. If I defined him as a pilot," adds Ahlstrom, "it would be this: extremely conservative."

Ahlstrom and the team's crew chief, Leigh Golden, joined the search, flying two sorties and then co-ordinating a public satellite image search from the Marathon Racing office.

They received more than 200 messages each day from concerned well-wishers who were scanning up-to-date Google Earth satellite images of Nevada for signs of Fossett's plane.

The Air National Guard continued running sorties throughout the night using infrared detection equipment, while the Nevada Civil Air Patrol expanded their total search territory to more than 10,000 square miles.

Every bit of technology available was thrown at the effort, including High Altitude Mapping Missions (HAMM) photography.

Flying at approximately 20,000ft over the mountainous terrain, the HAMM aircraft photographed 800 square miles per hour, generating images with a pixel size of six inches (far more detailed than standard satellite images), which the team then analysed.

Volunteers arrived from all over the region, joining a systematic grid search focused on a 600-square-mile area south of the ranch.

The mountain ridge along Walker Lake that I flew over with Tom Grossman was scoured with a fine tooth comb by 20 aircraft, including helicopters and planes able to fly at less than 30ft above treetop level.

One of the search aircraft was fitted with hyperspectral imaging equipment, capable of recognising disturbed earth and impact sites not visible to the human eye.

And still nothing.

So is it possible they were looking in the wrong place?

Eric Ahlstrom thinks not.

"This was not a fast aircraft.

"It had a top speed of 160mph and at high altitude the performance falls off – so it was probably closer to 90mph.

"A ground witness report correlated with a radar track we had.

"That put him south of Hawthorne at about 10.20am, and a second radar track put him over the pass south of the mountain range next to Walker Lake, coming back towards the ranch at just shy of 11am.

"He's got to be heading back, right?

"Or at the very least he's not going far.

"People say, “Oh, he had enough fuel to get another 100 miles,” but you don't fly that way.

"A conservative pilot is never going to land with less than a quarter of a tank."

Even after a week with no clues, many believed Fossett would come walking out of the desert with yet another tale of superhuman endurance to tell.

"If anyone's going to end up walking back up to the ranch and apologising for pranging the Hiltons' plane, it's likely to be Steve Fossett," said Richard Branson.

The idea that Fossett committed suicide has been universally dismissed. He was excited about the record attempt and, although this fact has never been made public before, Branson had also asked him to be one of the pilots on his inaugural Virgin Galactic space flight.

Locally, some believe he crashed into the 60ft deep Walker Lake.

Ahlstrom is sceptical: "A sheriff's department boat with sonar and six professional divers was dispatched to check not only Walker Lake but a couple of other lakes in the area. They came up empty."

Eric Ahlstrom believes there are only two credible theories.

"The wreckage may have impacted on a slope and rolled into a hole between boulders.

"If there's enough scrub, someone would have to be literally walking over the ground to find it.

"There are also a lot of exploratory mines out there. If the wreckage somehow fell down a mineshaft… It would be extraordinary, but not beyond the realm of possibility."

The second theory is that Fossett suffered a medical emergency in mid-air, such as a heart attack. "Perhaps very late into his flight," says Ahlstrom, "after the last radar ping, something happened to incapacitate him.

"If the aircraft was in trim it could have gone off in a random direction to the exhaustion of its fuel.

"It could have gone 100 miles. That's 30,000 square miles of search area – 30,000 square miles of rough uninhabited terrain."

But it's all just speculation.

The only thing we know for certain is that Steve Fossett strolled out of Barron Hilton's ranch one morning last September wearing shorts and a T-shirt, carrying nothing but a bottle of water – and vanished into thin air.