Solar-powered plane finally leaves Japan for Hawaii

Doyle Rice | USA TODAY

Show Caption Hide Caption Solar impulse leaves Japan on delayed Pacific flight The revolutionary Solar Impulse 2 aircraft takes off from Japan bound for Hawaii, passing "the point of no return" on its most ambitious leg of its quest to circumnavigate the globe powered only by the sun. Video provided by AFP

After weeks of waiting, the sun-powered Solar Impulse 2 plane finally lifted off on early Monday from Japan, bound for Hawaii.

Bad weather had postponed the planned 4,000-mile leg of the around-the-world flight, the world's longest solar-powered flight both by time and by distance. It would also be the longest solo flight by time in world history.

The plane had been grounded in Japan for three weeks due to bad weather over the Pacific, but early Monday morning Japan time, officials with the project emailed supporters to tell them the plane was preparing for takeoff.

The BBC reported that it took off from Nagoya Airfield at 6:03 p.m. GMT, or 2:03 p.m. ET Sunday (which was 3:03 a.m. Monday in Japan).

The eighth leg of the mission, piloted by Swiss pilot and adventurer Andre Borschberg, is expected to last five days. He plans to take short naps, do yoga and meditate to endure the lack of extensive sleep.

The mission began March 9 with a flight from Abu Dhabi, United Arab Emirates, to Muscat, Oman. Pilots Borschberg and Bertrand Piccard have alternated the legs of the journey.

To date, the pilots, both from Switzerland, have completed seven legs of the mission. The most recent leg, from Nanjing, China, to Honolulu, had to be shortened because of bad weather, necessitating a landing in Japan on June 1. The plane was also slightly damaged upon landing in Japan, but necessary repairs were made.

One of the weather obstacles plaguing the flight has been a meteorological phenomenon common over eastern Asia and the western Pacific Ocean this time of year. The "baiu" (BUY-Yu) or "mei-yu" (MAY-Yu) front pulls in humid, tropical air from Asia and brings wet weather to much of Japan in June and July.

It was just the latest string of bad weather to bedevil the mission to power a plane around the world using only the sun.

The Solar Impulse — which needs an abundance of clear skies — had been waiting for a weather window to make the non-stop trek to Hawaii. A takeoff last Wednesday was aborted at the last moment due to a prediction of clouds near Hawaii.

Once the plane reaches Hawaii, the next flight will be over the Pacific to Phoenix. From there, Solar Impulse will land at a location in the Midwest, then in New York City. It will undertake two final flights over the Atlantic Ocean and the Mediterranean Sea before landing back at Abu Dhabi.

In addition to aviation records, the pilots, who are the mission's founders, want to raise awareness about climate change, showcasing what can be done using nothing but renewable energy.

"The most important thing isn't to make world records," Piccard said. "It's to show what we can do with clean technologies," which can simultaneously reduce carbon dioxide emissions and stimulate economic growth.

"An airplane flying day and night without fuel is more than a spectacular milestone in aviation, it's the living proof that clean technologies and renewable energies can achieve incredible feats; and that all these energy-efficient technologies should now be used globally in order to have a cleaner world," Piccard added.

Contributing: Greg Toppo, USA TODAY