I have not posted in a long time but I still read them,every now and then. I read that people say my shoes did not alarm and are mad when asked to take them off and run them thru the x-ray. I may be wrong in this but I would think that about 90% of the airports have metal detectors, guess what they won't detect C4, or any other type of explosive materials. They only detect metal, I think that is why them call them metal detectors. There are only a few ways to find explosive materials. 1. view it on x-ray. 2. ETD the shoes. 3. Have the current method, of dogs sniff them. 4. Install the puffer machines there may be more. You can put enough C4 in the sole of a shoe to easily bring down a aircraft and mold it to fit your shoe. There are numerous item available that could be used to complete the process that won't be detected by a metal detector or you could have numerous people carry one item each. I think in a perfect world for security on aircraft they should only have 1 carry on item the size of a laptop bag, do full bag searches, and do full body pat downs, but that won't happen and this is not a perfect world. Passenger needs to demand that congress makes airports upgrade checkpoint to handle passenger flow and install better equipment.