Hot weather proves a problem for pilots

If aircraft are not certified to fly in high temperatures, they will remain grounded, which is what happened to some Bombardier jets

Much of Arizona rarely sees a cloud, and it usually offers great weather for flying. Phoenix is one of the top four US locations for number of flying days per year. But last week more than 50 flights were cancelled, not because the weather was bad but because it was too hot.

Hot air is less dense that cold. The wings of an aircraft generate lift by effectively pushing down on the air, and less dense air provides less lift. An aircraft needs a certain amount of lift to take off and gain altitude. The hotter the weather, the less dense the air and the less lift the wings produce.