Originally Posted by Bart

Checkpoint x-rays do not detect explosives. The screener has to study the image and look for certain things that are consistent with improvised explosive device configurations. No matter what type of IED you have, they all have one common trait. To explain it another way, without violating SSI, every firearm has to have a trigger mechanism, a device that acts as a firing pin mechanism, a chamber to house the bullet itself and a barrel to launch the bullet through. Doesn't matter whether you're looking at a zip gun or Smith & Wesson pistol or M-16 rifle; all firearms have to have certain components in order to work. A similar principle applies to explosives.

The procedure is that you either submit your shoes for x-ray examination OR we will swab it for explosive residue.

Having said that, I believe TSA can scale back on its shoe examination policy and go to a random procedure (one out of every five, one out of every seven, one out of every ten, for instance) rather than inspecting each and every shoe. The reason I say this is because there has only been one incident of an attempt to use shoes as improvised explosive devices in the past four years. We can accept the risk of mitigating that threat with a random check as opposed to a mandatory check. Should there be any indication of an increased threat to aviation based on intelligence information (and not just a response to political rhetoric), then perhaps we can go to a mandatory check of all shoes until the "threat window" is closed, then go back to the random checks.

This is the difference between risk management and risk avoidance.