Finding the perfect route for Solar Impulse

The zero-fuel Solar Impulse plane depends on perfect weather for its journey around the world. All forecasts are made by a team of specialists in Monaco, who also work out the best flight route. (RTS/swissinfo.ch)
Swiss aviation pioneers Bertrand Piccard and André Borschberg are currently on the China leg of their first solar plane journey around the world. The pilots are constantly assisted by their team of meteorologists and engineers at headquarters in Monaco. At the Solar Impulse control base, the specialists work out the perfect flight route hour by hour.
For every change of route, Solar Impulse must get the green light from the air traffic control of the country it’s flying through. Because the plane is so light, even a bit of rain or wind can cause problems. But it also needs a lot of sun to recharge the batteries.
Weather was a key factor in the planning phase. The plane’s journey through India and Southern China was scheduled for certain months to avoid monsoon season. With so little sun in winter, Switzerland had to be ruled out as the starting point. One big hurdle for Solar Impulse will be crossing the Pacific and the Atlantic. Both require five days of non-stop cloudless weather.