ATLANTA - Gun rights groups are appealing a federal judge's decision to dismiss a lawsuit that sought to allow licensed gun owners to pack heat in parts of the world's busiest airport.

U.S. District Judge Marvin Shoob tossed the lawsuit on Friday, ruling that GeorgiaCarry.org failed to prove that a new Georgia law would allow weapons into unsecured areas of Hartsfield-Jackson Atlanta International Airport.

State Rep. Tim Bearden, a Republican who co-sponsored the law, said Monday the ruling came as "no surprise" and that the advocacy group is preparing an appeal.

City of Atlanta officials, meanwhile, celebrated the judge's ruling with a statement that said the airport "will continue to remain a safe, secure, gun-free environment, for its almost 90 million passengers a year."

The legal showdown erupted when a new state law that allows people with a gun permit to carry guns into restaurants, state parks and on public transportation took effect on July 1.

Atlanta officials quickly declared the airport a "gun-free zone" and warned that anyone carrying a gun there would be arrested. GeorgiaCarry.org then sued the city and the airport, claiming that the airport qualifies as public transportation under the new state law.

City attorneys argued in court that allowing some residents to carry guns at the airport could pose a threat to passengers. Even an accidental firearm discharge, they warned, could cause mayhem.

Gun rights advocates argued that the Legislature intended the law to allow residents with permits to take their guns into airport terminals, parking lots and other unsecured areas.

In a 14-page ruling, Shoob sharply rejected the gun rights group's claims. The ordinary definition of "public transportation" does not include airports, he wrote, and there's no clear evidence that Georgia legislators intended the law to apply to airports.

It was a stinging defeat for GeorgiaCarry.org, a two-year-old advocacy group which bills itself as a "no-compromise voice for gun owners."

But Bearden, a former police officer, said he is hopeful the argument will fare better in the 11th Circuit Court of Appeals.

"We're doing everything we can to protect the rights of law-abiding citizens from criminals," he said.