Solar Impulse: Zero-fuel plane leaves Seville for Cairo
Solar Impulse has begun what should be its penultimate flight, leaving Seville in Spain bound for Cairo in Egypt.
It should take the zero-fuel aircraft somewhere between 48 and 72 hours, depending on the weather conditions encountered en route.
Solar Impulse is now in the home straight of its bid to circumnavigate the globe.
After this leg, there is just the final hop to Abu Dhabi where the challenge began in March 2015.
The two pilots who have shared the flying duties around the world are each taking one more turn at the controls.
Andre Borschberg is running the Seville-Cairo stage; Bertrand Piccard will complete the challenge by taking Solar Impulse back into the UAE.
Mission managers want to land in Egypt in the morning when the winds and temperatures will be most favourable.
And they will have to be particularly careful not to expose the solar cells on the plane to too much heat when it is stationary on the ground in Cairo.
If Solar Impulse is not in Egypt ready to touch down on Wednesday AM, it will wait in the sky until Thursday AM.
"The winds for landing are good from about 2AM until 8AM," explained flight director Raymond Clerc.
"Then, if we were to land afterwards, the temperatures on the ground would be too high, and it would be a problem for the structure [as we move Solar Impulse to the hanger]. If we're flying, it's not a problem because we're ventilated by the air speed."