FORT WORTH, Texas (AP) -- American Airlines will require passengers to check their oversized carry-on bags at 10 airports next month.

The Fort Worth-based carrier said Tuesday it would install templates at security X-ray machines at selected airports on Dec. 1. Bags must fit through the opening in the template to be carried on board aircraft, airline officials said.The openings will be 15-by-9 inches for standard bags and 24-by-5 inches for folded hanging bags.

American and its commuter affiliate, American Eagle, will use the devices at Dallas-Fort Worth International Airport; Kennedy and LaGuardia airports in New York; Boston; Newark, N.J.; Miami; Kansas City, Mo.; Chicago O'Hare; Los Angeles; and San Francisco. Devices will be installed at other airports thereafter, American officials said.

Daniel P. Garton, American's senior vice president of customer services, said keeping large baggage out of the passenger cabin would free more bin space for smaller carry-ons, speed the boarding process, and improve the airline's on-time performance.

Other airlines, including the largest carrier, Chicago-based United Airlines, and Dallas-based Southwest Airlines, have installed similar devices in recent months at several airports.

But some airlines are resisting. Houston-based Continental sued Atlanta-based Delta for installing a barrier at a security gate the two airlines share in San Diego.

Federal regulators have considered setting rules for carry-ons but so far have only printed brochures asking travelers to "think small."

About 4,000 passengers and crew members are hurt each year by bags and objects falling from overhead bins, according to the Association of Flight Attendants and the luggage manufacturers' group.

The FAA requires airlines to develop carry-on policies but leaves the details to them. That has resulted in a hodgepodge of policies from one airline to another.