A non-guaranteed fare means that the selected time of departure is not guaranteed. This applies to single-passenger bookings only. We offer the lowest single-passenger fare, but the tradeoff is that you will not be guaranteed the departure time you selected. If you absolutely need to depart at a particular time, we recommend selecting the guaranteed fare. On rare occasions, we may need to cancel your non-guaranteed booking if there is no availability on any schedule for your selected date. 90% of the time there will be no change in the date and time you select.