Honolulu: Solar Impulse 2 (Si2), the solar-powered plane on a round-the world trip bid, is closing in on Hawaii after a record-breaking flight which has tested its exhausted pilot to the limit in “difficult” conditions.
If all goes well, Veteran Swiss aviator Andre Borschberg, who has spent more than four days flying from Japan in the Solar Impulse 2, is expected to land on the Pacific US island state early Friday.
The organizers` latest estimate for arrival is 1600 GMT, although that could change depending on conditions.
The current flight from Japan to Hawaii is the eight leg of Solar Impulse 2's round-the-world trip. The whole trip from Japan to Hawaii was expected to take 120 hours.
By 0200 GMT the plane had traveled 91 percent of the way to the tropical US state, having flown 7,471 kilometers (4,642 miles), with just 700 kilometers to go -- barely 12 hours of flying time, in theory.
More importantly, it had crossed a last cold weather front before Hawaii, which organizers described as "jumping over the wall" before the final stretch towards the Pacific archipelago.
Before that hurdle organizers had tweeted "@andreborschberg is tired. W/ turbulence at 8`000 feet & a cold front close, SITUATION IS DIFFICULT."
But later came the celebratory tweet, saying the plane had "successfully crossed the second & last front separating him from Hawaii! Everybody clap your hands!"
The pioneering plane is due to land Friday morning local time at Kalaeloa Airport on the main Hawaiian island of Oahu.
So far Borschberg has flown more than 104 hours -- easily beating the previous longest solo endurance flight by Steve Fossett, who flew for 76 hours and 45 minutes in 2006.
Only napping periods of 20 minutes at a time over the past four days, Borschberg is equipped with a parachute and life raft, in case he needs to ditch in the Pacific.
The experimental solar-powered aircraft left Japan around 1800 GMT Sunday -- the early hours of Monday local time – for Hawaii after spending a month in the central city of Nagoya.
Traveling at altitudes of more than 9,000 meters (29,500 feet), he has to use oxygen tanks to breathe and experiences huge swings in temperature throughout the day.
Meanwhile, Borschberg has been tweeting and taking selfies at intervals, including the live streaming video of the cockpit.
As he approached Hawaii overnight Thursday into Friday, Borschberg flashed a thumbs up for the camera, in clearly optimistic mood.
"At the moment the airplane`s critical components are working well! It`s important to continue this way until the end."
Solar Impulse 2 set off from Abu Dhabi earlier this year in a multi-leg attempt to fly around the world without a single drop of fuel. Since then, it has stopped in Oman, India, Myanmar and Nanjing, China, en route to an unscheduled stop in Japan.
After landing in Hawaii, the plane will fly to Phoenix, Arizona, and then pilots Borschberg and Piccard will fly together across the Atlantic on a return path to Abu Dhabi, where it began.
(With AFP inputs)