Add-On Airline Fees Rise, Get Even More Confusing: Survey

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Add-on airline fees for extra services that used to be included in fares are increasing in price and changing frequently, making fare comparison shopping more difficult, according to a new TravelNerd study.

Roughly 69 percent of the 52 fee changes at major U.S. carriers during the past year were direct fee increases, according to the survey. TravelNerd, a developer of online and mobile app travel tools, compared add-on fees at 14 major American airlines in January 2013 to those charged by carriers in 2012, tracking each fee change. Add-on fees are for services such as checked baggage, priority boarding and preferred seating.

And hold onto your pocketbooks and mental energy.

Airlines are creating complex new ways to charge for ancillary services — in some cases bundling or packaging those amenities together and offering fliers combined services at a discount to what they would cost on a one-off basis. (Read more: Add-On Airlines Fees: Good or Bad?)

The growing practice of fee bundling was among the fee-change trends cited in the survey.

Fee bundling to a certain extent is a marketing tool. Carriers can offer grouped services at a discount — always a welcome word to fliers — compared to charging more for singular add-on services.

"A new trend that we're currently seeing is carriers bundling and tiering services," said Alicia Jao, TravelNerd's vice president of travel media, in a release. "This practice is not only more confusing for travelers, but it also complicates price comparison." (Read more: Fees Undermine Fliers' Ability to Compare Airfares)

American Airlines is one of the carriers bundling new add-on fees. (Read more: American Fare Revamp Includes Options to Waive Fees)

So how do you figure out how much each airline charges for services beyond the ticket price? TravelNerd has a nifty online tool that compares the fees across all major U.S. airlines. And if you'd prefer a printable PDF listing, on Thursday released its updated table of comprehensive airline fees.