Frontier Airlines primarily operates from the South Terminal at Hartsfield-Jackson Atlanta International Airport (ATL), even for international flights. However, depending on the specific route, some international flights may depart from the International Terminal (Terminal F). The International Terminal is equipped with customs and immigration facilities to handle international travel. Passengers flying internationally with Frontier Airlines International Terminal Atlanta should check their boarding pass for the correct terminal and gate information, as these may vary. It’s recommended to arrive at least three hours before departure to allow ample time for check-in, security, and customs procedures.