DALLAS – American Airlines says its new $15 fee for a first checked bag will affect fewer than one in four customers and won’t lengthen lines at boarding gates.

The carrier said Thursday that it’s taking steps, which it didn’t specify, to avoid such disruptions caused by the new policy.

American last month was the first airline to announce it would charge customers to check a single piece of luggage. The fee takes effect on tickets bought on or after June 15. American said three-quarters of summer travelers had already bought their tickets and wouldn’t pay the fee.

The airline defended the fee, saying it was a bargain compared with the cost of shipping a 45-pound bag overnight on a package-delivery company. A spokesman for the airline said the cost of sending a bag from Dallas to New York would range from $150 to $230 or more.

Members of the elite levels of American’s frequent flyer program won’t have to pay the fee, and neither will those who bought full-fare tickets or are traveling overseas.

American and other carriers charge $25 for checking a second bag. The airlines are raising fares and fees to cover the soaring cost of jet fuel, which has nearly doubled in the past year.

American said it has raised fares 15 times since April, but it pointed to an Air Transport Association study that said airlines are recovering only 40 percent of their higher fuel bills.