Book Flight with Sun Country Thru April of 2022 Minneapolis based Sun Country airlines is taking advantage of some cancelled and postponed Spring Break travel. Normally you can't book a flight that far in advance. But when almost everything has been cancelled and/or postponed in recent times because of the pandemic, Sun Country is allowing people to book travel more than a year in advance. Sun Country Airlines If something happens, and let's hope nothing does, but if something happens and you are needing to postpone your trip, you will need to do so within 60 days of travel. This is to avoid any fees.