It's "Nightmare at 20,000 Feet". There was a TZ episode and it was in the movie.
"Portrait of a frightened man: Mr. Robert Wilson, thirty-seven, husband, father, and salesman on sick leave. Mr. Wilson has just been discharged from a sanitarium where he spent the last six months recovering from a nervous breakdown, the onset of which took place on an evening not dissimilar to this one, on an airliner very much like the one in which Mr. Wilson is about to be flown home--the difference being that, on that evening half a year ago, Mr. Wilson's flight was terminated by the onslaught of his mental breakdown. Tonight, he's travelling all the way to his appointed destination which, contrary to Mr. Wilson's plan, happens to be in the darkest corner of
The Twilight Zone."
