• If your flight is canceled for whatever reason or the airline is responsible for you missing your flight, the conditions of carriage require the airlines give you a full refund.
• If you miss your flight because of an illness or death in your immediate family, and you present written proof from a doctor or funeral director, most airlines allow you to use the ticket for a later flight going to the same destination. In many cases, if you decide not to reschedule your flight at all, you can get a full refund for your ticket with the proper certification.
• If you are called for jury duty or are subpoenaed, some airlines will allow you to cancel your flight (though they prefer you to reschedule at a later time) and will give you a refund.
• If you miss your flight completely because of an unexpected, unavoidable delay (i.e., extremely heavy airport traffic due to construction, an accident, etc.), some airlines will let you use your nonrefundable ticket for a standby flight on their airline to the same place as the original ticket.

If you buy a discount airline ticket that carries a cancellation penalty, you can obtain a partial refund (minus the cancellation fee) plus 8 percent airline ticket tax due the IRS on each domestic ticket used. If the ticket is not used, then the tax is not due. However, in the past, airlines included the tax in the calculation of the cancellation penalty and therefore refunded less to the customer than was due. The IRS should have received its portion of the refund (the whole tax) but instead, some airlines kept the entire amount including the 8 percent windfall. Due to rulings on several class action suits going back to 1985, any part of the 8 percent tax must be turned over to the IRS. However, class action suits have not been brought against all of the airlines, and some continue to base the cancellation penalty on the full price of the ticket (including the tax), cheating the customer out of part of his refund. On a nonrefundable ticket, it is up to the ticket holder to demand a refund of the 8 percent.

• If you possess a nonrefundable, restricted ticket, many airlines will allow you to use your ticket for an earlier flight to the same destination on a standby basis (although this bends their rules). By checking the available seats on the earlier flights, you can usually tell what your chances are for getting on.
• If a ticket is not totally refundable, some airlines will endorse the ticket, allowing you to take a flight on another airline after you have paid the cancellation penalties. If missing your flight was the airline's fault, they should endorse your restricted ticket for use on another airline (with no penalties) if they cannot provide an adequate alternate flight.

If you are bumped from a flight because it is overbooked and are holding a nonrefundable ticket, you can sue the airline for damages if you are not satisfied with the refund or free ticket they offer you.

If you don't want to gamble on something going wrong, you can purchase "trip cancellation insurance," which protects you in case your flight is canceled.

In the case of a national emergency, most airlines loosened their restrictions on flights, giving credit to fliers afraid to fly because of terrorist threats. Vouchers were valid for travel up to a year after being issued.

If you need to cancel a nonrefundable ticket on Wednesday through Monday, your "friendly" travel agent could void the ticket without a penalty since most agencies pay for tickets only once a week-on Tuesdays.

Finally, for a fee, most airlines will allow you to change the return flight on a nonrefundable ticket. You still cannot get a refund or change destinations or routes, but what you get is a bit of flexibility in your plan should you need to make a change.