Originally Posted by
Often1
Pretty random. Most gate secondaries are ID checks and random carry-on. My buddies in the security business tell me that the random gate checks are probably the most effective device out there, but only if there's a way of assuring that everbody who sees the secondary TSO's arrive on-scene and wants to not board, has to go through the secondary.
Okay, I am a dumb redneck so write slowly.
If their ID and boarding pass got them past the checkpoint, why will it suddenly not be good enough to get them on the plane? The bag checks I have seen are simple glance and go with no possibility of detecting anything that someone really wants to hide.