We used choice air for our Trans-Atlantic (just for the return flight) & flew back 2 days after the cruise ended. I'm pretty sure that you don't pay the fees until you book your flight. We did not choose Choice Air at the time of booking, but added it later. The air fares for our cruise were much cheaper through choice air than if we would have booked on our own. Our non stop American flight from Barcelona was $2600.00 each for a one way flight, & Choice Air was $507.00 each!