Solar Impulse 2 (Si2), the sun-powered plane, is entering the critical phase of its flight, the Pacific Ocean crossing from Japan to Hawaii.
The solar plane has approximately one day and a half left from landing, its organisers Solar Impulse twitted on its official Twitter page early Thursday.
— SOLAR IMPULSE (@solarimpulse) July 2, 2015
The upcoming night will be the most critical and Andre Borschberg will have to cut systems to maximise energy savings, added Solar Impulse.
This current flight is the eight leg of Solar Impulse 2's round-the-world trip.
The solar-powered plane had traveled 67 percent of the way to the tropical US state by 2100 GMT Wednesday, having flown 5,199 kilometers (3,230 miles) with 2,536 km more to go, according to the project.
By that time the plane and its veteran Swiss pilot Andre Borschberg had logged nearly 75 hours of continuous flight, having already bettered the previous record of 44 hours they had set between China and Japan.
The Japan-Hawaii flight has been billed as the most dangerous part of the adventure.
The experimental solar-powered aircraft took off from Japan around 1800 GMT Sunday--the early hours of Monday local time—for Hawaii after spending a month in the central city of Nagoya.
Originally, the plane was scheduled to fly directly from Nanjing in China to Hawaii, but bad weather along the way forced a diversion to Japan forcing it to spend a month there.
Travelling alone and at an altitudes of more than 9,000 metres, Borschberg has to use oxygen tanks to breathe and experiences huge swings in temperature throughout the day.
He rests for only 20 minutes at a time and cannot move from his seat, which has a built-in toilet, as well as a parachute and a life raft attached.
Solar Impulse 2 set off from Abu Dhabi in March 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.
If all goes well, the Solar Impulse 2 will arrive in Hawaii in less than 40 hours.
After Hawaii, the propeller-driven plane will take-off for Phoenix and is slated to stop in New York before flying over the Atlantic Ocean.
(With AFP inputs)