Frequent Flyer? Book with the Right Airline to Guarantee a Seat

Last Updated Aug 16, 2010 1:07 AM EDT

Frequent Flier programs aren't all scams. Per se. But if you've ever noticed that it's sometimes quite difficult to actually book a trip using your reward miles, well, it's not your imagination. Not only have we got the data to prove it, but we can point you to the airlines that perform the best (and worst) when you try to cash in.

Recently, the Atlantic documented the availability of reward miles by airline. It's a bit eye-opening.

Southwest, for example, ranks best, with 99.3% of its seats available for booking with frequent flyer miles. A handful of other airlines, including Air Berlin, Air Canada, and Virgin Blue, all placed in the 90 percents.

Delta and US Airways pulled up the rear with a paltry 12.9% and 10.7%, respectively.

Granted, airlines don't make money by giving seats away for free, but Delta performed three times worse in this category than the next closest carrier, Turkish Airlines.

I should also point out that US Airways recently finished rather dismally in another comparison chart -- on-time arrival performance.