Allegiant Airlines Cancellation Policy: Everything You Need to Know Allegiant Airlines offers a straightforward cancellation policy designed to accommodate various needs of travelers 1-866-463-2404. Here?s a comprehensive guide to understanding their cancellation policy and answering common queries. 1. Can I cancel my Allegiant flight without a penalty? Yes, Allegiant Airlines allows passengers to cancel their flights within 24 hours of booking without incurring any penalty fees. This policy applies as long as the booking was made at least one week (168 hours) prior to the scheduled departure time.