Which Terminal is Southwest Airlines at SFO At San Francisco International Airport (SFO), specifically the Harvey Milk Terminal 1, is where Southwest Airlines is based. Travelers can enjoy a variety of amenities at this recently renovated airport, such as cozy seating areas, a wide selection of restaurants and shopping options, and quick security checks. With the AirTrain system connecting Terminal 1 to other terminals, parking lots, and BART (Bay Area Rapid Transit), passengers may easily navigate the airport, making it handy for people going to and from the city and neighboring areas.