The check-in process for What Terminal is spirit Airlines at ORD is designed to be straightforward and efficient, reflecting the airline’s focus on low-cost, no-frills service. Upon arriving at Terminal 3, passengers can find the Spirit Airlines check-in counters located conveniently near the entrance of the terminal. For those who prefer to check in before arriving at the airport, Spirit offers an online check-in option that opens 24 hours before departure, allowing passengers to print their boarding passes at home or use mobile boarding passes.