The paranoia was there long before 9/11. I remember being in Washington Dulles waiting on my flight to Heathrow to board. (Quick note: at Dulles the planes did not pull up to the terminal. Instead you boarded something like a mobile lounge on a scissor-jack that could raise or lower to line up with any airplane. So the gates in the terminal were very close together.) A couple of gates away some airline was using metal detectors on the passengers as they came through the gate. There was a group of three pax that had run into trouble.

A father and mother and their teen son. The son had apparently shattered his leg in a skiing accident and it had to be reassembled using a steel rod and many steel screws. Needless to say the metal detectors screamed loudly when they were anywhere near his leg. The parents took the precaution of calling the airline in advance and were told "Fine, no problem" but that apparently was not passed down the line. The parents had the x-rays and the doctors' reports but the hired security was adamant, they would not let him board. One even insisted that it would be possible to pull out the steel rod during the flight and use it to threaten the other pax.

My plane departed before the end and last I saw there was a crowd standing around the poor kid - cops, security, airline reps and such. The kid hadn't been able (or wasn't being allowed) to sit down in over an hour and the pain on his face was obvious. I have aways wondered what happened.

Add: This was in 1975.