Gate card: Delta Air Lines (DL)

The airline's policy: “Extra Seat - Personal Comfort (Delta's term on its agency policy page; consumer pages say 'Requesting additional seat space')”

Delta says customers should arrange an extra seat if, based on the aircraft's seat dimensions, they will encroach into the seat next to them while seated, or if the seat armrests cannot stay down while seated. Options Delta lists for customers needing more space than the standard Economy seat: purchase an additional seat for each flight (sold at the same fare when purchased at the same time), upgrade to First Class, or ask to be reseated next to an empty seat once onboard. Customers who do not purchase an extra seat in advance risk being moved to another location on the aircraft with more space, and on a full flight may be rebooked onto a later flight with available seating. The extra seat is booked under 'EXST' with adjacent seat assignments; exit row and bulkhead seats cannot be used; Basic Economy fares cannot be used to buy an extra seat.

Refunds: For wholly unused, nonrefundable tickets, the value of the extra seat ticket may only be used toward a new ticket in the passenger's name; the extra seat ticket is not transferable. No proactive refund of the extra seat is published (Delta does not publish a Southwest-style automatic refund).