Wondering What Terminal is Avianca Airlines at IAD?, Avianca Airlines operates from Terminal B at Washington Dulles International Airport. Terminal B offers a smooth, traveler-friendly experience with organized check-in areas, clear guidance, and supportive staff ready to assist with pre-flight needs. Passengers can enjoy convenient amenities, including seating spaces, shops, dining options, and essential travel services that help create a relaxed start to the trip. With efficient processes and easy navigation, Terminal B ensures a comfortable and dependable airport experience for anyone flying with Avianca.