Photograph by Anna Pizzolante, Solar Impulse/
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Solar Impulse 2, powered entirely by sunlight, is midway through a planned circumnavigation of the globe, but stormy Pacific weather has proven to be a major challenge in recent weeks.

Photograph by Anna Pizzolante, Solar Impulse/

Solar Plane Makes Second Attempt to Reach Hawaii

Swiss pilot to fly solo over the same desloate stretch of the Pacific Ocean where Amelia Earhart disappeared.

The sunlight-powered plane known as Solar Impulse 2 took off Sunday around 2:00 p.m. ET from Nagoya, Japan, making a second attempt to fly from Asia to Hawaii as part of its of its historic attempt to circumnavigate the world.

On June 1, Swiss pilot Andre Borschberg made the first attempt, departing from Nanjing, China, but shifting weather patterns forced him to abort the planned six-day trip. Thirty-six hours into the flight, his ground control team became concerned about shifting weather fronts and high winds and directed him to make an unplanned stop in Nagoya. Since then the Solar Impulse team has nervously waited for another window of good weather to align over the Pacific to continue the journey.

This leg of the journey is considered the most dangerous because of the vast stretches of remote Pacific Ocean it covers and the volatility of the region’s weather this time of year. The flight is expected to take five days and five nights, crossing a total of more than 4,000 miles (6,400 kilometers) and traversing the same desolate region where Amelia Earhart disappeared 77 years ago.

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The flight is expected to take five days and five nights, crossing the same desolate region where Amelia Earhart disappeared.

If all goes smoothly, Borschberg would land in Honolulu around July 3.

Because Solar Impulse is powered entirely by 17,000 photovoltaic cells attached to the top of its wings and fuselage, the plane relies on clear, sunny days to collect enough solar power to run its engines. Though it can fly through cloudy weather for up to 10 hours, it must soak up enough sunlight during the day to charge the batteries that keep the aircraft aloft during nighttime flying. Too much head wind drains its power, and high winds could pose a threat to its lightweight carbon-fiber construction. One of the plane’s ailerons was slightly damaged by high winds after it landed in Nagoya, but the Solar Impulse team was able to repair it.

WATCH: Bad weather on June 1, 2015, forces Swiss pilot André Borschberg to make a U-turn on what was supposed to be a solar-powered flight from China to Hawaii. Video courtesy Solar Impulse SA


Waiting for optimal weather windows has proven the most difficult part of the journey. So far, the plane has been grounded for weeks at a time at several stops. Meteorologists on the Solar Impulse team, which is co-led by Borschberg’s fellow pilot, Bertrand Piccard, have been tracking the weather patterns along the route for years, but accurately forecasting beyond three days out has proved difficult, especially over the Pacific where—with no place to land—there is little room for error. That challenge is only increasing with the arrival of summer rainy seasons in much of the Pacific.

Piccard has said that many of Solar Impulse’s corporate sponsors have remained steadfast in their support, but he has acknowledged that keeping the project’s team of 150 employees intact will be a challenge if the delays were to continue.

But for now, Borschberg is aloft with his course set for the record books.