Delta does not require passengers who need a seatbelt extender or are unable to lower the armrest to purchase additional seats. However, for the safety and comfort of our other passengers, you may be asked to move to another location that provides additional space. In the event of a full flight you will be asked to take a later flight with available seating. To avoid this situation, we recommend that you purchase an additional seat. For assistance please call Delta Reservations at 1-800-221-1212 and they will be glad to assist.