What Terminal is Frontier Airlines at ATL , Frontier Airlines is located in Terminal S. Frontier's self-service kiosks and passenger check-in counters are located in this terminal. It is advised that you arrive early to give yourself ample time for check-in and security clearance. To improve your travel experience, Terminal S provides a range of services, including shops, lounges, and food & beverage options. Keep an eye on the digital monitors at the airport for the most recent information on flights and gates. Finding your terminal is the first step to a trouble-free Frontier Airlines trip!