In perhaps not-so-shocking news, airlines are squeezing their customers.

The fees that airlines add to tickets ostensibly to cover fuel costs rose twice as fast as the costs themselves last year, according to a study from Carson Wagonlit Travel cited by the Los Angeles Times. And even though the cost of fuel has dropped since 2009, most airlines haven’t lowered their fuel surcharges in response.

The study’s findings may be fodder for critics who argue that airlines use the fuel surcharges as a way to be less transparent about ticket pricing. Many foreign airlines use the fuel surcharges as a way to add an expensive fee on to tickets purchased using frequent flier or other loyalty programs, according to Ed Perkins of SmarterTravel.com. In addition, non-U.S. based airlines sometimes post their ticket prices without the surcharge in an aim to make their fares appear lower.

In the U.S., airlines can’t post fares that exclude the fuel surcharges, according to Perkins.

Airlines worldwide are feeling the heat over fuel surcharges. Qantas and Virgin Australia are facing pressure from Australian travel agencies to lower their fuel surcharges after the cost of jet fuel fell 25 percent over the past three months, according to the Sydney Morning Herald. The travel agencies argue that the airlines responded quickly to a surge in fuel prices by hiking their surcharges, but they’ve been slow to react to the drop.

Though airlines may be squeezing customers on fuel surcharges, airline fees overall have been falling. Airlines took home more than $3 billion in fees in 2011, according to a June report from the Bureau of Travel Statistics, that’s a drop from 2010.

Check out some notorious airline fees below:

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  • Blanket Fee

    Back in 2010, American Airlines <a href="http://www.huffingtonpost.com/2010/02/08/american-airlines-to-char_n_454109.html" target="_hplink">started charging $8 for blankets</a>.

  • Ryanair Boarding Pass Fees

    Songstress Lily Allen took to twitter to express anger over<a href="http://news.travel.aol.com/2011/06/06/lily-allen-twitter-ryanair-boarding-pass/" target="_hplink"> Ryanair's policy of charging passengers to print out their boarding passes</a>.

  • Spirit's Online Booking Fee

    In November 2011, Spirit Airlines <a href="http://www.huffingtonpost.com/2011/11/14/spirit-airlines-raises-on_0_n_1093430.html" target="_hplink">raised its domestic "passenger usage fee" (aka online booking fee) from $8.99 to $16.99</a> each way.

  • Fuel Fees

    Southwest Airlines <a href="http://www.huffingtonpost.com/2012/03/26/southwest-airlines-fees-fuel-costs_n_1381008.html" target="_hplink">raised its ticket prices by $4 to $10 to offset the high cost of jet fuel</a> in March 2012. Its subsidiary AirTran, plus United Airlines, Delta Air Lines, American Airlines, US Airways, Frontier Airlines and Virgin America followed suit.

  • Ryanair Emergency Row Fee

    Ryanair found itself under investigation after <a href="http://www.huffingtonpost.com/2012/03/20/ryanair-in-hot-water-over_n_1366497.html" target="_hplink">instituting a 10 pound fee to sit in the emergency row</a>.

  • Allegiant Air's Carry-On Fee

    In April 2012 the budget carrier announced a <a href="http://www.huffingtonpost.com/2012/04/02/allegiant-air-carry-on-fe_n_1397911.html" target="_hplink">$35 carry-on fee</a>.

  • Spirit's New Carry-On Fee

    A month later, low-cost Spirit Airlines <a href="http://www.huffingtonpost.com/2012/05/02/spirit-airlines-carry-on-fee_n_1472508.html" target="_hplink">upped carry-on fees to as much as $100</a>.

  • Airlines Could Charge Extra For Seats Together

    Late May 2012 saw airlines start to <a href="http://www.huffingtonpost.com/2012/05/21/airline-charges-seats_n_1533866.html" target="_hplink">reserve more window and aisle seats for passengers willing to pay extra</a>. This would make it it harder for friends and family members to sit next to each other.<br /> <br /> Sen. Charles Schumer urged airlines to <a href="http://www.huffingtonpost.com/2012/05/27/chuck-schumer-airlines_n_1548794.html" target="_hplink">allow families with young children to sit together without paying extra</a>.

  • United's $100 Bag Fee

    In June 2012, United <a href="http://www.huffingtonpost.com/2012/06/12/united-airlines-raises-international-bag-fee_n_1589223.html" target="_hplink">raised its fee for a second checked bag on trans-Atlantic flights to $100</a>. Delta had done the same a few months earlier.

  • Wizz Air's Carry-On Fee

    Carry-on fees have finally hopped the pond. <a href="http://skift.com/2012/07/09/carry-on-bag-fee-spreading-wizz-air-charge-europe/" target="_hplink">European regional carrier Wizz Air instituted a 10 Euro (about $12) fee to use the overhead bins</a>. Bags that fit under the seats still fly free.

  • Credit Card Booking Fee

    In August 2012, Airefarewatchdog called out <a href="http://www.huffingtonpost.com/george-hobica/the-latest-airline-fee-credit-card_b_1829396.html">Allegiant Airlines for charging more to book flights via credit card</a>.

  • Southwest Airlines' Early Boarding Fee

    <a href="http://www.huffingtonpost.com/2013/01/22/southwest-airlines-fees_n_2525443.html?utm_hp_ref=travel#slide=more232494">Southwest passengers can pay $40 to be one of the first 15 people on the plane</a>, as of January 2013.

Earlier on HuffPost: