At Hartsfield-Jackson Atlanta International Airport (ATL), a significant hub for both domestic and international travel, Frontier Airlines is based in Terminal N (North). For your convenience, Frontier airlines atlanta terminal provides several alternatives for check-in. Up to 24 hours prior to your trip, you can check in online to select your seat, pay for your luggage, and print your boarding ticket. If you would rather check in at the airport, Terminal N has both manned counters and self-service kiosks. In order to guarantee enough time for security and check-in, arrive at least two hours before to departure.