I did notice a hole in security recently at one airport. I saw that all passengers and cabin crew were made to remove their shoes and pass them through the x-ray equipment. (I don't know why a pilot would need to blow up a plane in order to crash it!) However, airport staff, those with ID cards (e,g, those who were wearing restaurant uniforms) did not have to remove their shoes. The security hole is this. A terrorist could get on board a plane with explosives in their shoes by simply get an accomplice to get a job as a worker for a gate area company, (waiter, cleaner) and wear the shoes through security. Once through the security check the terrorist passenger would swap shoes with his/her accomplice in the toilets.
I can't be the only one to see the flaw in security and that spot checks are made on airport staff.
3rd