Low-cost carrier Frontier Airlines, which charges passengers for advanced seat assignments and carry-on luggage, is trying a new tack to attract travelers: lowering and in some cases eliminating date-change fees altogether.

The 10th largest U.S. airline by travelers carried, used to charge customers $99 to change their dates. Effective immediately, date changes on Frontier will be free if they're made before 90 days of departure, and $49 if the customer makes the change between 89 and 14 days before the flight, the airline said Thursday. Travelers who need to make last-minute changes will still have to pay the $99 fee if the change is within 13 days of a flight. All passengers will still be responsible for any change in fare.

The move by privately held Frontier makes it an outlier among U.S. carriers, which are increasing fees as they struggle with a surge in fuel costs, generally their second-largest expense after labor.

American Airlines, the world's largest airline, on Thursday said it will start charging passengers $30, up from $25, to check a first bag on flights in North America, starting with tickets purchased on Friday. American's move follows similar fee increases by United Airlines, Delta Air Lines and JetBlue Airways. JetBlue also increased date-change fees, a step Alaska Airlines took earlier this year.

Ancillary revenue from seat selection, baggage and other fees are a cash cow for airlines. These fees are not subject to the same 7.5 percent tax as airfare is and have provided an additional revenue stream to carriers, particularly after fuel prices climbed.

Several lawmakers are seeking that a bill to reauthorize the Federal Aviation Administration includes a provision that would require federal officials to determine whether fees are reasonable. Earlier this month, several lawmakers asked airlines to explain the costs behind some of the fees they charge passengers, including those for checked baggage and seat assignments.

The cheaper change-fee policy is an attempt to get more travelers on board. Frontier carried just under 2 percent of the 965 million passengers carried by U.S. airlines last year, according to the U.S. Department of Transportation. Southwest Airlines, which does not charge customers a fee to change tickets but requires them to pay any difference in fare, flew 157.7 million passengers, more than any U.S. carrier.

Frontier collected $36.5 million in reservation change and cancellation fees last year, just over 1 percent of the $2.9 billion U.S. carriers brought in for those fees, according to the Department of Transportation.