Random memory: giant escalator

A long time ago when I was young, I was watching tv, presumably with another one of my family members.  On the television was this strange program; it was in black and white and there was what appeared to be an escalator out of nowhere.  But it was absolutely enormous, and was able to carry maybe a hundred or so people.  The quality of the film itself wasn’t very good, as if taken a long time ago.  The escalator was heading up — to what, I don’t know.  Then suddenly, without warning, it stopped.  People began falling down the escalator, slowly and silently.  For some reason, this still haunts me to this day.