Solar Impulse 2 to Resume Round-the-World Flight in April

"The first possible departure from Hawaii to reach the US West coast is on April 15th," she said, adding that location of the first stop on the US mainland has yet to be determined.

The experimental aircraft was grounded in July, when its solar-powered batteries suffered problems halfway through its 21,700-mile (35,000-kilometer) trip.

The French crew took several months to repair the damage from high tropical temperatures during the flight's final Pacific stage, a record journey of 5 days and 5 nights between Nagoya, Japan and Hawaii.

The plane conducted its first successful test flight following repairs in late February.

The next leg, estimated to take four days, may end in Los Angeles, San Francisco or Phoenix, Arizona, the spokeswoman said.

"The destinations in US mainland have not been confirmed yet and will be dependent on weather conditions," she said. "We know from experience that crossing the United States is challenging in terms of weather."

The goal is to reach New York's JFK Airport before crossing the Atlantic, she added.

Solar Impulse 2 left Abu Dhabi in the United Arab Emirates in March last year and has since traveled nearly 11,200 miles (18,000 kilometers).

Its wings are covered with more than 17,000 photovoltaic cells that charge the batteries when the sun is shining during the day.

Pilots Bertrand Piccard and Andre Borschberg are taking alternating turns flying each stage because the aircraft can fit only one at a time.

Dubbed the "paper plane," Solar Impulse 2 has a wingspan of 79 yards (72 meters), larger than a Boeing 747's, and a weight of 2.3 tonnes, approximately that of a van.

It flies at a maximum altitude of 28,327 feet (8,634 meters) and must withstand high temperature fluctuations, with the pilots using oxygen tanks to breathe inside the tiny cockpit.

The project aims to demonstrate the possibilities of renewable solar energy.