US Airways Group Inc., the smallest of the U.S. full-fare airlines, will charge a $5 fee to passengers who don't prepay online when they check luggage.

The new fee is an effort to speed up passenger check-in at airports, Chief Executive Officer Doug Parker said today. The Tempe, Ariz.-based carrier began charging $15 to check one bag and $25 for a second last year. Payments through US Airways' Web site can be made today for flights starting July 9, Morgan Durrant, a spokesman, said in an interview.

“;It clearly drives some additional time to charge $15 for the first checked bag,”; Parker said on a call with analysts and investors. “;It's more about having less go on at the airport in terms of processing passengers.”;

U.S. airlines are adding fees for luggage handling and other services and selling pillows and blankets to boost revenue from sources other than tickets. US Airways' charge for paying the bag-check fee at airports is part of an effort to produce as much as $500 million in so-called ancillary revenue this year.

“;We felt there was room for an increase but wanted to find a balance and also roll out an increase where there was a way around it,”; Durrant said. The airline didn't say how much revenue it expects from the service charge.

Delta Air Lines Inc. and UAL Corp.'s United Airlines lets customers pay checked-bag fees online and doesn't add the extra charge if they pay at the airport. Continental Airlines Inc. passengers can specify the number of bags they plan to check and pay at the airport.

US Airways dropped a $2 charge for sodas and juices and $1 for coffee on March 1, saying the fees had become a competitive disadvantage. It was the only U.S. airline to adopt such charges.

The carrier posted today a first-quarter net loss of $103 million, or 90 cents a share.

Excluding costs for advance-purchase fuel contracts, the loss was $260 million, or $2.28 a share, less than analysts expected.