When I was on an RAF transport squadron in Germany, it was not unusual for our wives to get the odd trip back to UK on one of the squadron aircraft. We had a good social life, so the loadmaster and captain would always see them them in the passenger lounge on their way through and recognise them. On one occasion, my wife was asked if she'd like to come up to the jump seat. They put her in there and gave her a head-set.
The trouble with the Andover was that the jump seat was just behind the line of vision of the pilots and it was very easy, once you were busy, to forget that you'd got someone in there. It was even easier to forget that they were on intercom.
They talked to her quite nicely en route, explaining things, until they were nearly back at Wildenrath. Then the ATC situation got a bit hectic, lot of Phantoms short of fuel, all trying to recover at once, just as they arrived. Delays and hold-offs, and lots of buggaring about. Suddenly there was a change of voice from ATC which they recognised. It was SATCO, taking personal charge. Unfortunately, everyone knew that he wasn't very good. He might have been good at getting promoted, but he wasn't as good an ATCO as his minions.
Completely forgetting about my wife on intercom, the captain remarked to the co, "Oh, God, it's SATCO! We'll never get in now. Brief the passengers for a delay. And keep a bloody good look-out!"