Colgan Air will take Shuttle America’s place at Washington Dulles Airport as the Saab 340 turboprop provider for United Airlines (UAL) under an agreement-in-principle reached between Colgan and UAL last month. Already flying 10 Saab 340Bs for Continental Airlines from Houston, Colgan will add six more of the 34-seat propjets for United starting October 4. Destinations include Allentown, Pa.; Binghamton, N.Y.; Charleston, W.Va.; Charlottesville, Va.; State College, Pa.; and White Plains, N.Y. Shuttle America continues to fly Embraer 170s for United.