I don't know much about the specifics of airport security. Can I just ask what x-ray screeners are hoping to see in checked bags? Afterall, the explosive of choice for the terrorist is C4. As I understand it, C4 won't show up on the x-ray machine and can be molded to almost any shape. Detonators are tiny, and almost every bag must have a battery or two and integrated circuits packed somewhere. The US is getting explosive detection installed at their airports. X-ray machines just don't sound too effective to me.