If you miss your flight by not checking in or boarding on time, your ticket will be marked as a No-Show Cancellation. This means:
- Check-in must be completed at least 60 minutes before departure
- Boarding must be completed at least 20 minutes before departure
If you miss either of these cutoffs, your reservation — including any return or connecting flights — will be canceled and no longer valid.
For full details, please refer to the Contract of Carriage | Frontier Airlines.