Spirit Airlines offers inexpensive flights to a number of locations, operating out of Concourse D of Baltimore/Washington International Thurgood Marshall Airport (BWI) Spirit Airlines BWI Terminal  passengers should check in at Zone D, where self-service kiosks are conveniently located. It is advised to arrive three hours prior to international flights and at least two hours prior to domestic flights to give sufficient time for security checks, boarding, and check-in. Learn about Spirit’s baggage policies in order to prevent paying extra, particularly for checked and carry-on luggage. Travelers can choose from a variety of eating options in Concourse D at BWI before their trip. Furthermore, BWI offers complimentary Wi-Fi for connectivity throughout the terminal.