PASCO, Wash. - Travelers in the Tri-Cities will have a new flight option starting in August. Alaska Airlines announced today that it will begin flying from Tri-Cities Airport in Pasco (PSC) to Portland International Airport (PDX) in Oregon. The once-daily Portland-Pasco roundtrip flights will begin on August 27, using Horizon Air Q-400 turboprops, sometimes known as the Dash-8.