I know that it is a little hard to believe but back in the sixties before hijackers changed the rules flying was a whole lot more relaxed. No security, just walk out on the tarmack, climb the steps and you're on the plane.

It was like a ship, friends could accompany you and then leave when they asked for all guests without a ticket to depart. I was just a kid but I do seem to remember them checking tickets. But I suppose you could wander aboard and find a good hiding place, unlikely but not impossible.