Solar Impulse, the Swiss-based initiative to demonstrate the power of advanced technologies to tackle global energy challenges, has finally begun its bid to fly around the world on solar power alone, taking off from Abu Dhabi at 07:12 local time this morning for a 12h, 220nm (400km) first leg to Muscat, Oman.

The single-seat aircraft has a wingspan of 72m (236ft) – a Boeing 747-8I comes in at 68.5m – but weighs just 2,300kg (5,070lb), about the mass of a car and including its 2,077kg load of lithium batteries.

The five-month, 12-stage journey will cover 18,900nm to take the aircraft around the world, via India and China – then across the Pacific via Hawaii, to New York and then transatlantic, ultimately returning to Abu Dhabi.

For pilots and programme founders Bertrand Piccard and André Borschberg, the multiple-leg itinerary is a test of their physiological limits, with cross-Pacific stages to require up to six days aloft. Their aircraft, Solar Impulse 2, is a second iteration of the original Solar Impulse, which proved critical capabilities such as flying through the night on energy harvested during the day from its wing-top solar cells.

From Abu Dhabi to Muscat, Borschberg is flying. At approximately 10:00 local time he will enter Omani aerial space in the region of Al Ain at an altitude of around 12,000ft. He will then continue towards Muscat, ascending to about 19,000ft, and loiter on a waiting pattern until traffic and weather conditions are suitable for landing at Muscat International airport around 19:00 local time.

Solar Impulse 2 takes off Abu Dhabi

Solar Impulse 2 airborne from Abu Dhabi

Solar Impulse