Payerne, Switzerland: Today,Solar Impulse 2, the second single-seater solar aircraft of Bertrand Piccard and André Borschberg designed to take up the challenge of the first round-the-world solar flight, without any fuel in 2015, carried out its eighteenth test flight out of the Payerne aerodrome in Switzerland. The plane flew at a high altitude. There will be several other test flights taking place in the coming months in order for this experimental machine to attain certification. They will be followed by training flights of Bertrand Piccard and André Borschberg later in the season still from Payerne airfield. The attempt to make the first round-the-world solar-powered flight is scheduled to start in March 2015 from Gulf area. Solar Impulse will fly, in order, over the Arabian Sea, India, Myanmar, China, the Pacific Ocean, the United States, the Atlantic Ocean and Southern Europe or North Africa before closing the loop by returning to the departure point. Landings will be made every few days to change pilots and organize public events for governments, schools and universities.