Because of extreme heat in Phoenix, American Airlines has cancelled all four flights between Flagstaff and Sky Harbor Airport for today between two and six p.m. Airline officials say the jet that serves Flagstaff has a maximum operating temperature of 118 degrees. The forecast high in Phoenix is expected to be 120 degrees and possibly higher. Due to safety concerns, the airline cancelled the flights. If you were booked on a flight that was set to leave Flagstaff between two and six p.m., contact the airline to try to get on an earlier flight or make other arrangements.