The Swiss-made solar airplane Solar Impulse 2 is continuing its around-the-world journey with the latest leg in the United States.
The aircraft took off from Tulsa, Oklahoma, on Saturday morning local time and is headed for Dayton in Ohio, according to organisers.
The flight, with André Borschberg at the controls, is expected to take about 18 hours.
The globe-circling voyage began in March 2015 from Abu Dhabi, the capital of the United Arab Emirates, and made stops in Oman, Myanmar, India, China and Japan. Then the plane hibernated in Hawaii for the winter before resuming its tour in April 2016.
The plane, Si2, was expected to make at least one more stop in the United States before crossing the Atlantic Ocean to Europe or northern Africa, according to the website documenting the journey.
Si2's wings, which stretch wider than those of a Boeing 747, are equipped with 17,000 solar cells that power propellers and charge batteries. The plane runs on stored energy at night.
The solar project, with pilots Bertrand Piccard and Borschberg taking turns, began in 2002 to highlight the importance of renewable energy and the spirit of innovation. It is estimated to cost more than $100 million (CHF99 million).
swissinfo.ch and agencies