Gate card: JetBlue (B6)

The airline's policy: “None (no customer-of-size policy; JetBlue offers optional 'Booking Extra Seats')”

JetBlue does not publish a customer-of-size policy and does not state that larger passengers must buy a second seat. Its 'Booking Extra Seats' page frames extra seats as a voluntary option for anyone who 'wants more physical distance from other travelers' or is carrying a large musical instrument: you book the extra seat yourself by adding an additional traveler to the booking. The Contract of Carriage separately allows JetBlue to refuse or remove, for comfort or safety, 'persons who are unable to sit in the seat in the full upright position with the seat belt fastened.'

Refunds: Standard fare rules apply -- no special size-related refund. Per the extra-seats FAQ: a non-refundable fare may be cancelled before scheduled departure for a Travel Bank credit toward future travel; cancelling after scheduled departure forfeits all credits. There is no provision for refunding an extra seat after travel (unlike Alaska/Southwest-style policies).