India, Aug. 17 -- In Die Hard, John McClane steps off a red-eye to Los Angeles with his service Beretta tucked into his waistband. Nobody at the gate blinks. He then goes on, in his vest, to take down a skyscraper full of terrorists - and for nearly four decades, viewers have watched all of it without lingering on the airport paperwork. Neither in 1988 nor today would that walk off the jet bridge have been legal, on either side of the Pacific.

The legality of carrying guns on commercial flights is back in the news after a passenger's licensed pistol went off during a mandatory security check at Varanasi's Lal Bahadur Shastri International Airport on Sunday, injuring two screeners when the round ricocheted. The passenger, Kamlesh Kedarnat...