It is expected to take six full days and nights to make the journey from China to Hawaii. Swiss pilot Andre Borschberg has begun his bid to cross the Pacific, from China to Hawaii, in the zero-fuel Solar Impulse aeroplane. The experimental aircraft, which has a wingspan bigger than a jumbo but weighs little more than a large car, left Nanjing at 02:39 (18:39 GMT).
It is likely to take Mr Borschberg five to six days of continuous flight to reach his central Pacific destination.
He will try to stay awake for much of that time, taking only short catnaps. His progress will be monitored the entire way from a control room in Monaco. Meteorologists and flight strategists will constantly update him on the best route to follow.