What Terminal is Delta Airlines at SEA? Concourses A and B at Seattle-Tacoma International Airport (SEA) are the main operating locations for Delta Air Lines. Concourse A, which is situated in the southeast portion of the airport and contains multiple Delta gates, offers passengers a cozy lounge experience with facilities like the Delta Sky Club close to Gate A1. Concourse B facilitates Delta operations by offering more gate alternatives and practical passenger services. The airport's subterranean train system provides good connections between the two concourses, guaranteeing seamless gate changes. At SEA, passengers flying with Delta can anticipate prompt service as well as access to a variety of dining and shopping options throughout these concourses.