Just in time for the holidays, American Airlines has started attaching templates to airport X-ray machines to screen carry-on bags that are too large to fit in the overhead compartment or under the seat in front of you.
A year ago United and Delta adopted the technique, which has met with complaints from some passengers but has succeeded in limiting oversized bags.
Most airlines say enforcing bag limits speeds boarding and ensures enough storage room for all passengers.
American started using the templates, also known as baggage sizers, Dec. 1 at 10 major airports, and would initially post employees nearby to help check luggage if it exceeded the template dimensions.
American's templates are 15 by 9 inches for standard bags, with a little extra room at the top for outside pockets, and 24 by 5 inches for fold-over hanging bags.
Passengers feed their bags through the template onto the X-ray conveyor.