ウェブDulles International Airport. Coordinates: 077°27′21″W. Dulles International Airport [a] ( IATA: IAD, ICAO: KIAD, FAA LID: IAD) is an international airport in Loudoun County and Fairfax County in Northern Virginia, United States, [4] 26 miles (42 km) west of downtown Washington, D.C. [5]