Why Phoenix's Airplanes Can't Take Off in Extreme Heat

Phoenix just provided another reason to hate flying: the heat. With temperatures there expected to hit 119 degrees Fahrenheit, airlines canceled more than 40 flights today. Wait. What? Airplanes can't fly because it's too hot? That's crazy. No, not really. According to news reports, the heat poses a particular problem for the Bombardier CRJ airliners, which have a maximum operating temperature of 118 degrees. Bigger planes from Airbus and Boeing can handle 126 degrees or so. OK.