What Terminal is Southwest Airlines at PHX (https://airterminalinfo.com/terminals/southwest-airlines-phx-terminal-phoenix-sky-harbor-airport/)? Southwest Airlines operates exclusively out of Terminal 4 at Phoenix Sky Harbor International Airport. Terminal 4 is the airport's largest and most active terminal, designed to handle high passenger volumes with ease and efficiency. Travelers flying with Southwest Airlines can access numerous check-in counters, expedited security lanes, and a wide selection of retail stores, restaurants, and lounges. Terminal 4 also offers convenient ground transportation, free Wi-Fi, and accessible facilities for all passengers. Known for its customer-friendly services, Southwest Airlines ensures a smooth travel experience from this terminal.