Wondering What Terminal is Avianca Airlines at IAD?, Avianca Airlines operates out of Terminal B of Washington Dulles International Airport. Terminal B provides tourists with well-organized check-in desks, fast luggage processing, and polite staff to ensure a seamless start to their journey. Passengers have access to a variety of amenities, including comfortable seats, dining options, shops, and lounges, which make the airport experience more convenient and enjoyable. Clear signs and a well-organized layout assist tourists in quickly navigating from arrival to boarding.