If you missed your Frontier flight, then you should reach Frontier Airlines' customer service immediately. You could rebook depending on fees and fare differences. The "Flat Tire" policy of Frontier has been cited by some passengers as allowing them to fly standby on the next available flight if they get in two hours before their original flight. Any rebooking option will depend on av... https://airlinesmissedflight.blogspot.com/2024/10/what-if-i-missed-my-frontier-flight.html