- With a variety of inexpensive flights, Spirit Airlines is based out of Concourse A of the Baltimore/Washington International Airport. Travelers will find the Spirit Airlines BWI Terminal fully furnished with check-in desks, ticket kiosks, and plenty of seats. Before you board, you can find places to eat and shops for last-minute necessities. The check-in process on Spirit is usually swift, but it's best to arrive early because they frequently charge extra for items like baggage or seat preference. Overall, Spirit travelers find BWI to be a simple and convenient trip.