As American, United and US Airways prepare to start collecting fees on every piece of checked luggage, including $30 round trip to check one bag and an additional $50 round trip to check a second, they are also getting ready to strictly enforce limits on carry-on baggage — which are commonly flouted — in hopes of minimizing delays and disruption as flights board. Battles with customers likely will ensue, and fliers will be peppered with baggage-rule announcements, adding more aggravation to the already trying travel experience.

All three airlines say it's possible that metal templates — which prevent larger bags from making it through X-ray machines — will be reintroduced. That's a tactic that angered many customers in the past and was eliminated when the Transportation Security Administration took control of screening after the 2001 terrorist attacks.

"It's something we've looked at in the past and may look at again," says Mark Dupont, American's senior vice president of airport services planning.

United is in favor of bringing back templates, says Senior Vice President Scott Dolan, and US Airways Group Inc. President Scott Kirby says a return of baggage templates is "likely" at some airports. While security checkpoints are controlled by the TSA, airlines can pressure the federal agency to allow templates if a checkpoint serves a single airline, or several airlines with the same policy on templates.