According to sources, the solar plane took off from Nagoya Airfield in Japan at dawn and is scheduled to land in Hawaii in approximately 120 hours.
Roughly eight hours into the flight, project spokeswoman Elke Neumann said it was still unknown whether the plane would continue its bid for Hawaii, a flight that would last at least five days and nights and would need clear, calm conditions throughout, Japan Times reported.
“We are not sure if we can continue,” she said, adding that a decision would be taken in the early afternoon.
Co-piloted by Swiss businessman Andre Borschberg and Swiss psychiatrist and aeronaut Bertrand Piccard, the Solar Impulse 2 is a lightweight aircraft driven by four electric propellers and banks of solar panels atop its wings and fuselage.
It took shelter at the Nagoya city airport, also known as Komaki Airport, on June 1, part way through a flight from Nanjing, China, to Hawaii.
A previous effort to resume the flight on June 24 was cancelled at the last minute. This time, the project team announced plans to take off only about an hour before departure.
“We just wanted to make sure that we are really safely on the way to Hawaii,” explained Neumann. “It created a lot of disappointment.”
In the statement, the team thanked its Japanese hosts for helping accommodate the aircraft and its support staff during the unplanned visit.
“Solar Impulse extends its gratitude to all those in Japan who have worked very hard to accommodate us,” the statement said.
From Hawaii, the plane aims to reach the US mainland and to cross the Atlantic while calm summer conditions still persist. It would end its round-the-world voyage at its starting point, Abu Dhabi.
Capable of flying over oceans for several days and nights in a row, the single-seater Si2, started its journey from Abu Dhabi in the United Arab Emirates (UAE) on March 9.
The plane has set two world records for manned solar-powered flight.
The first was for the longest distance covered on a single journey — that of 1,468 km between Muscat in Oman and Ahmedabad in India.
The second was for a groundspeed of 117 knots (216 kmph), which was achieved during the flight from Varanasi in India to Mandalay.