A plane powered purely by solar power has taken off from Egypt for the final leg of the first-ever fuel-free flight around the world.
Solar Impulse 2 took flight from Cairo in the early hours of Sunday morning, heading for Abu Dhabi - completing its loop around the globe.
It is the final leg of a bid to fly around the world without using any fossil fuel, with the aim of the mission being to "demonstrate that clean technologies can achieve impossible goals".
The plane first set off from Abu Dhabi in March last year, and has involved two different pilots - Mr Piccard and André Borschberg - completing different legs.
The small, spindle-winged vessel landed in Egypt for its penultimate stop last week, but had to delay its final journey due to a heatwave in Saudi Arabia.
The plane had previously been grounded for eight months for repairs after suffering battery damage during a record-setting five-day flight from Japan to Hawaii.
"The round the world flight ends in Abu Dhabi, but not the project," Piccard said, speaking before takeoff.
"The project is a big promotion of clean technologies around the world and the legacy of Solar Impulse is the created international community."
Solar Impulse 2 has the wingspan of a Boeing 747 Jumbo Jet, carrying some 17,000 photovoltaic cells which power the plane's propellers and recharge its batteries.
It weighs just 2.3 tonnes - not much more than a large family car - and can climb to around 28,000ft (8,500 metres), with a cruising speed of 34 to 62mph.