Turkish Airlines at IAD operates out of Terminal 1, serving its regular flights between Washington DC and Istanbul. For passengers flying Turkish, the Turkish Airlines IAD Terminal offers standard check-in and departure facilities.Once through security, many travelers use the airline’s dedicated lounge in Concourse B — the Turkish Airlines Lounge — where you’ll find Turkish-style food and drinks, Wi-Fi, charging stations, showers, and work areas.The setup makes IAD a convenient departure point for international travelers flying with Turkish Airlines.