Passengers flying with Frontier Airlines can check in at self-service kiosks or staffed counters in Terminal 1. The airline also allows online check-in starting 24 hours before departure, making it easier to select seats and handle baggage fees in advance. Due to potential wait times at security, it’s best to arrive at least 2 hours before domestic flights and 3 hours before international flights to complete check-in and TSA screening on time.