Gate card: United Airlines (UA)

The airline's policy: “Extra seats (United's Accessible Seating page; United does not use the term 'customer of size')”

United requires that every passenger fit in their seat: you must make additional arrangements if you cannot buckle the seatbelt even with an extender, the armrests will not stay down, or you encroach into the neighboring seat. In economy your options are buying an extra seat (same fare as your original seat if bought at the same time, possibly more if bought day-of), buying a premium-cabin seat or upgrade instead, or — if no extra seat is available — changing to a flight that has one (with meal/hotel vouchers if you are stranded overnight away from home). You may raise the armrest in flight but can be asked to show it goes down; a willing seatmate does not waive the extra-seat requirement.

Refunds: Not stated on United's extra-seat policy page. United publishes no specific promise to refund an extra seat if the flight departs with open seats; its general refund form is at united.com/refunds. Recorded as a gap rather than guessed.