The time to see Pan Am charters was whenever the US President was in town. They seemed first choice for the "press charter" by the news media that followed the circus around. I recall one description by a journalist of life on board these during such a trip, on a Pan Am 747. They had apparently decided that, because it was a charter, aviation rules did not apply, so seatbelts were not mandatory and you could stand up during takeoff. And apparently quite a number did. What childish idiots.