This is embarrassing for the TSA. A soldier accused of taking C4 explosives on a plane apparently carried them on a flight from North Carolina to Texas. Airport screeners found a military smoke grenade in his carry-on, confiscated it, and let him fly to Texas. But when he tried to fly back, screeners found C4 explosives in his bag as well. The soldier, Trey Scott Atwater, a demolitions expert returning from Afghanistan, says he didn’t realize the explosives were in his bag when he packed.