what terminal is southwest at san diego? Southwest Airlines only uses San Diego International Airport's Terminal 1 for operations (SAN). With expedited check-in, security, and boarding procedures, this terminal manages Southwest flight arrivals and departures. Terminal 1 is still operational and effective, offering passengers the necessary facilities and services even with continuous modifications. This is best to confirm with the airline directly or go to the official airport website for most current details on flight times and terminal updates. ​