Source: The TSA BlogWhat’s the biggest threat to an airplane? A knife? A pistol? While these items can be dangerous, with hardened cockpit doors installed after 9/11, an improvised explosive device poses the biggest threat to aviation security today.I’ve talked about using Advanced Imaging Technologies to detect non-metallic and metallic threats, including IEDs already, but today I wanted to talk about another technology we have to detect explosives hidden on people and in bags.While going through checkpoints, you might have seen officers using little white swabs at TSA checkpoints at one point or another. In case you had no idea what our officers were doing, they were conducting state of the art Explosives Trace Detection (ETD) tests.