Southwest Airlines LAS Terminal +1-888-839-0502 Passengers can select their seats when they board Southwest Airlines LAS Terminal. Groups A, B, and C are assigned upon check-in and are used for boarding. Early Bird Business and Check-In First, a select group of passengers board. Passengers must arrive at the gate promptly, and boarding usually starts 30 minutes prior to departure. For More : https://www.terminalfind.com/southwest-airlines/southwest-airlines-las-terminal-harry-reid-international-airport/