By its sixth hour sitting on a deserted tarmac, Continental Express Flight 2816 had taken on the smell of diapers and an overwhelmed lone toilet. What should have been a 2 1/2-hour trip from Houston to Minneapolis had moved into its ninth hour, and the 47 passengers on board had burned through the free pretzels and drinks handed out early in their Friday night flight from Houston. It took 12 hours and a new flight crew for Flight 2816 to complete its journey. Passengers on another flight that had been diverted to the airport in Rochester, Minn., because of storms...