The Saudi General Authority of Civil Aviation (GACA) on Thursday issued a special permit for Solar Impulse 2 to use the kingdom's skies in the last leg of the first fuel-free flight around the globe.
The solar-powered aircraft will fly from Cairo, Egypt on Friday to Abu Dhabi, United Arab Emirates, where it started its odyssey in March 2015. The flight is expected to last for two days.
Solar Impulse 2 landed at Cairo airport on July 13, ending a flight leg that lasted 48 hours and 50 minutes from Seville, Spain.
The plane has been piloted in turns by Swiss aviators Andre Borschberg and Bertrand Piccard in a campaign to build support for clean energy technologies.
“Thanks to clean technologies, today you can reconcile economy and ecology ... this was my goal when I started the project,” Piccard told Reuters.
Solar Impulse flies without a drop of fuel, its four engines powered solely by energy collected from more than 17,000 solar cells in its wings. Surplus power is stored in batteries during the day to keep the plane aloft on long-distance flights.
The carbon fiber plane, with a wingspan exceeding that of a Boeing 747 and the weight of a family car, is unlikely to set speed records. It can climb to about 8,500 meters (28,000 feet) and cruise at 55-100 kph (34-62 mph).
The Solar Impulse team will now prepare for the final leg of the journey to United Arab Emirates, they said.
“Explorers have gone everywhere, even to the Moon. Now, we need to explore a better quality of life here on Earth,” Piccard said. 
The aircraft landed in Spain last month, after completing the first solo transatlantic flight powered only by sunlight.
After setting off from Seville on Monday morning, the plane passed through Algerian, Tunisian, Italian and Greek airspace, and flew over the Giza Pyramids before touching down at Cairo airport at around 7:10 a.m. (0510 GMT).

Source: Arab News