Weather has forced a major change to the Solar Impulse round-the-world flight plan, with a five-day leg from Nanjing to Hawaii ending with an unscheduled stop in Nagoya, Japan.

With a looming Pacific weather front deemed impassable, flight controllers in Monaco instructed pilot André Borschberg to head for Nagoya.

At that point, Borschberg had been aloft for 36h. The single-seater, which derives all of its power from solar panels on its wings, tailplane and fuselage, had flown through the night on power stored before take-off and during the day before beginning its recharge cycle with morning sunlight.

Borschberg and his partner in the venture, Bertrand Piccard, have trained to endure several days solo in the cockpit; diet, yoga and “micro-napping” all feature in their physical regime.

But the aircraft, with the wingspan of a jumbo jet but the weight of a family car and capable of flying on the power output of a motor scooter from its four electric motors, is a fragile machine and highly sensitive to weather.

The departure from Nanjing had already been delayed by the search for a suitable weather window. The flight to Hawaii was to have been the seventh of 12 legs in the original flightplan, which started from Abu Dhabi on 10 March.

Solar Impulse in Nanjing c Solar Impulse

Preparing for take-off in Nanjing

Solar Impulse