The Solar Impulse HB-SIA single-seater prototype took off from Payerne airfield in Switzerland at 8:40 a.m. after a three-hour delay due to strong winds. It is expected to reach Brussels by nightfall.
The plane with the wingspan of a Boeing 777 made its 2009 maiden flight in Switzerland and further tests have all taken place there. Last year it completed a 26-hour non-stop flight that proved the plane can stay aloft at night from the solar energy its 12,000 solar cells soaked up during the day.
The team, led by pilot Andre Borschberg and adventurer Bertrand Piccard, said Friday's flight across France, Luxembourg and Belgium poses a fresh challenge as it requires navigation across international air traffic networks.
They hope to fly an improved version of the plane around the world in 2012.
The flight can be followed on the team's website, where visitors can track the plane's progress live on a map and see key parameters such as altitude, ground speed, battery levels and how much energy its solar cells are generating.
