Solar Impulse 2’s flight back to Abu Dhabi in the United Arab Emirates is on hold as the crew waits for a break in the weather that will allow the solar-powered aircraft to fly over the Saudi desert.
Ground teams at Cairo International Airport, where the sun-powered plane landed last week, were prepared for take-off in the early hours on Sunday.
But in the end, mission control said the final wind reading was too high to take off safely.
Since leaving Abu Dhabi last year, the experimental aircraft has made 16 different stops and crossed both the Pacific and Atlantic Oceans.
But the final leg of the journey, a 48-hour flight from Cairo to Abu Dhabi is expected to be particularly challenging because of the desert heat. Even at night, temperatures in the cockpit with range between 77 and 86 degrees Fahrenheit (25 to 30 degrees Celsius).
In addition to simple discomfort and heat-related fatigue, pilot Bertrand Piccard will have to be more hands-on than on other legs of the flight because with excessive heat, also comes turbulence. On prior legs of the journey, Piccard and co-pilot Andre Borschberg have been able to switch on the auto-pilot from time to time to get some much-needed rest.
If there's a silver lining to the weather-related grounding of Solar Impulse 2, it's that the delay with give Piccard time to get over a stomach bug.
The delay came after a spectacular flight from Seville airport in Spain to Cairo International Airport, during which Solar Impulse 2 flew through a thick haze to pass over the pyramids of Giza.
Photo caption: Solar Impulse 2 flies over Egypt’s iconic pyramids of Giza. (Credit: Solar Impulse)