Washington - At airports across the United States, passengers are trying to walk through security with loaded guns in their carry-on bags, purses or pockets, even in a boot. And, nearly a dozen years after the 9/11 attacks, it's happening a lot more often.
In the first six months of this year, transportation security administration (TSA) screeners found 894 guns on passengers or in their carry-on bags, a 30% increase over the same period last year.
The TSA set a record in May for the most guns seized in one week - 65 in all, 45 of them loaded and 15 with bullets in the chamber and ready to be fired. That was 30% more than the previous record of 50 guns, set just two weeks earlier.
Last year, TSA found 1 549 firearms on passengers attempting to go through screening, up 17% from the year before.
In response to a request from The Associated Press, the agency provided figures on the number of firearm incidents in 2011 and 2012 for all US airports, as well as the number of passengers screened at each airport. The AP analysed the data, as well as weekly blog reports from the agency on intercepted guns from this year and last year.
Eighty-five percent of the guns intercepted last year were loaded. The most common type of gun was a .38.
Airports in the south and the west, where the American gun culture is strongest, had the greatest number of guns intercepted, according to TSA data.
TSA didn't keep statistics on guns intercepted before 2011, but officials have noticed an upward trend in recent years, said spokesperson David Castelveter.
'I forgot it was there'
TSA doesn't believe these gun-toting passengers are terrorists, but the agency can't explain why so many passengers try to board planes with guns either, Castelveter said. The most common excuse offered by passengers is "I forgot it was there".
"We don't analyse the behavioural traits of people who carry weapons. We're looking for terrorists," he said. "But sometimes you have to scratch your head and say, 'Why?'"
As one passenger took off his jacket to go through screening in Sacramento, California, last year, TSA officers noticed he was wearing a shoulder holster, and in it was a loaded 9mm pistol.
The same passenger was found to have three more loaded pistols, 192 rounds of ammunition, two magazines and three knives.
Screeners elsewhere found a .45 and magazine hidden inside a cassette deck. Another .45 pistol loaded with seven rounds, including a round in the chamber, was hidden under the lining of a carry-on bag in Charlotte, North Carolina.
A passenger in Allentown, Pennsylvania, was carrying a pistol designed to look like a writing pen. At first the passenger said it was just a pen, but later acknowledged it was a gun, according to TSA.
A passenger in March at Bradley Hartford International Airport in Connecticut had a loaded .38 pistol containing eight rounds strapped to his lower left leg. At Salt Lake City International Airport, a gun was found inside a passenger's boot strapped to a prosthetic leg.
Many passengers found to have guns by screeners are arrested, but not all. It depends on the gun laws where the airport is located.
If the state or jurisdiction where the airport is located has tolerant gun laws, TSA screeners will frequently hand the gun back to the passenger and recommend locking it in a car or finding some other safe place for it. The government doesn't track what happens to the people who are arrested.
Is it plausible that some people are so used to carrying guns that they simply forget that they have them, even when they're at an airport about to walk through a scanner? Or do some people try to bring their guns with them when they fly because they think they won't get caught?
Jimmy Taylor, a sociology professor at Ohio University and the author of several books on the nation's gun culture, said some gun owners are so used to carrying concealed weapons that it's no different to them than carrying keys or a wallet.
Carrying guns for protection
The most common reason people say they carry guns is for protection, so it also makes sense that most of the guns intercepted by TSA are loaded, Taylor said. Many gun owners keep their weapons loaded so they're ready if needed, he said.
Even so, Taylor said he finds it hard to believe airline passengers forget they're carrying guns.
"My wife and I check on things like eye drops and Chapstick to see if we're allowed to take them on a plane, so it's a little difficult to imagine that you aren't checking the policies about your loaded firearm before you get to the airport," he said.
Occasionally passengers stopped by TSA are people who are used to carrying guns because they work in law enforcement, security or the military, but that doesn't appear to be the case most of the time.
Robert Spitzer, an expert on gun policy and a professor at the State University of New York, theorises that for some, the "I forgot" answer is an excuse.
"There are some Americans who believe that there are no limits," he said, "that they not only have a constitutional but a God-given right to have a gun and 'By gosh, if I want to bring a gun on a plane I'm going to do it'."