If passengers are looking for changes in flight destination, date and time, they must do it when 24 hours or more are left in the flight departure.
However, the airlines have set different guidelines if you still want to make changes in flight when less than 24 hours are left.
Passengers will be glad to know that Frontier Airlines have removed the flight change fee, be it a ticket or fare purchase. But this is only applicable if the flight is originating from North America. And Basic Economic Fare does not come under this.