A pilot was arrested this morning at St. Louis Lambert International Airport after security discovered a loaded 9mm pistol in his carry-on bag, airport officials say.The 51-year-old pilot, a first officer for Southwest Airlines, was headed for Las Vegas when he was stopped at a Terminal 2 checkpoint. Transportation Security Administration officers detained him shortly before 5 a.m., according to a statement from Lambert.
It was not clear if the pilot was on duty or planned to fly as a passenger.…