Whether you found alternative transportation home or simply decided to stay longer at your destination, you might find yourself in possession of a round trip airline ticket that has suddenly become a one way pass. Depending upon your situation, you can either try to change the return date on the ticket or simply elect not to use it. By doing a bit of online research and paying careful attention to your ticket details, you can determine the best way to cancel the flight.
Decide whether you will need a return flight following the same itinerary within a 12 month period. If so, contact the airlines and ask to change the date of your return flight. Expect to pay certain fees for this service per your fare agreement with the airline.
Check the booking class of your ticket and the cost of a one way fare in the same class that follows an identical itinerary. You need to do this because, once you notify the airlines of your wish to cancel the return flight, they will consider your ticket a one way pass, which might make you liable for any additional fees associated with this change.
Contact the airline to ask for a refund if you do not need the ticket at all and if you determine that a one way fare costs less than a round trip ticket. Depending upon your airline's rules and regulations--and whether you purchased a refundable or non-refundable ticket, you may be eligible for a refund of the airfare minus any cancellation fees.
Consider simply failing to show up for the return flight if you determine that a one way ticket to your destination costs considerably more than a round trip one. According to travel columnist and frequent flyer Ed Perkins of the website smarterTRAVEL.com, this can be an effective solution if you really do not need the return portion of the ticket since it allows you to skip cancellation or change fees.
Even if you purchased a non-refundable ticket, it might still be reusable. This means you might not get your money back after cancellation, but you can use the value of the ticket towards a future reservation. Check with your airline for specific details.
Never fail to show up for the first part of a flight without calling to cancel or change the reservation; if you do not appear, the airline will automatically cancel your entire reservation. Do not make a habit of not showing up for flights or cancelling the return part of round trip tickets since airlines might suspect habitual offenders of using an airline loophole known as a "throwaway ticket" in which they book a round trip ticket with the intention of only using a portion of it. Airlines can punish people who engage in this practice by taking away frequent flyer miles or refusing to allow them on flights.