I walk through these security-checkpoints every day, and it strikes me...
These things are metal-detectors... Nowadays, with all the fine composites and plastics we have, a knifeblade made of kevlar or carbon would easily pass through the detector unnoticed, and it would certainly do just as good a job as one of metal would...
....and some people still say that the the aircrafts, terminals, and airside is sterile?
You must be even dumber than anyone ever gave you credit for...
Fact is, nothing is perfectly sterile, and anyone working at an airport (exept those dealing with security of course) will know of many loopholes around the security-system. They may not use it, but they know of it...
If anyone working airside at an airport would feel the urge to commit to wrong-doings, they would know how to..
...and a pilot with the same urge wouldn't even have to bring anything with him/her... Simply pushing the yoke on short final would do the trick...