A jet plane piloted by US adventurer Steve Fossett, aiming to make the first solo non-stop flight around the world without refuelling, has taken off.
Virgin GlobalFlyer took to the skies from Salina in Kansas, US, at 0047 GMT on Tuesday morning.
The single jet engine aircraft is loaded with more than four times its own weight in fuel for the challenge, which is expected to last 80 hours.
The flight's departure date had been delayed for weeks due to bad weather.
"I suppose I am a little bit of a nervous person - perhaps it is justified in this case"
The route for the circumnavigation bid was changed at the last minute. The jet will now fly over North Africa instead of Europe because winds have shifted south.
Before setting out on the journey, millionaire Mr Fossett, 60, admitted he had little margin for error, with the most dangerous part of the attempt being take-off.
GlobalFlyer had never been tested with a full load of fuel and any unexpected turbulence or technical glitches could have potentially been disastrous.
"Turbulence is worse at the lower altitudes, so I've got to make my climb to the cruising altitude without encountering any significant turbulence," Mr Fossett told the BBC News website before the flight.
Watching as the plane disappeared into the night, British entrepreneur Sir Richard Branson, chairman of the sponsoring Virgin Group, said it was "an emotional moment".
"It was an enormous relief when it actually came off the ground," he said.
It took GlobalFlyer about two hours to get to an initial altitude of 11.8km (39,000ft) before climbing at just 2.4m (eight feet) per minute to reach its cruising altitude of 15km (49,000ft).
Issue of trust
Mr Fossett said he had to place his complete trust in the makers of GlobalFlyer, the Californian company Scaled Composites, run by aviation legend Burt Rutan, which was also behind Ansari-X-prize winner SpaceShipOne.
"I suppose I am a little bit of a nervous person - perhaps it is justified in this case," Mr Fossett told a news conference in Salina before take-off.
"It is a major endeavour and I am willing to take that risk," Mr Fossett said.
Mr Branson promised the adventurer free flights on Virgin for life if he completed the challenge and lent him his watch, adding: "I want you and it back in one piece."
Mr Fossett has set dozens of world records and world firsts with jet airplanes and gliders, hot air balloons and sailing boats.
The former stock options trader became famous in the mid 1990s when he made an attempt with Mr Branson to circumnavigate the globe in a hot air balloon. He managed the trip solo on his sixth attempt in the summer of 2002.
The 1,522-kg (3,350lbs) single-engine aircraft is carrying nearly 8,636kg (19,000lbs) of fuel in 13 tanks for the approximately 37,000km (23,000-mile) journey at altitudes as high as 15,800m (52,000ft).
Its progress around the world is being tracked live on the GlobalFlyer website.
Jeana Yeager and Dick Rutan made the first non-stop, non-refuelled global flight in 1986 in the propeller-driven Voyager.
Their nine-day circumnavigation covered 42,420km (26,366 miles).
VIRGIN ATLANTIC GLOBAL FLYER - LONG-DISTANCE JET PLANE
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