Back when I was in high school in the late 70s, television stations actually ended broadcast for the day. What often directly preceded the impending
TV “snow” was the poem heard in the video below, High Flight, by aviator John Gillespie. The short film depicted an airplane doing all kinds of tricky maneuvers as the poem’s words were intoned. Yeah. If you were going to “Slip the Surly Bonds of Earth,” this was how you did it, in a shiny, American, cold-war airplane. It’s still unclear to me what any of it had to do with signing off, but what it actually meant was, “Look — the broadcast day is over. This station has done all it can for you today. No more Petticoat Junction reruns. Nothing more to see here until 6 am. Get some sleep. Goodnight.”