Upon its original broadcast, "Trapped in the Sky" was praised by L Marsland Gander of "The Daily Telegraph", who called it "a show that has to be seen to be disbelieved." Writing for the same newspaper in 2011, Simon Heffer recalled watching the episode as a boy: "I felt as though the whole landscape of what passes for my imagination had been changed ... It caused an excitement of the sort that is possible only for the very young, and it lasted for days. Indeed, every Saturday night was a renewal of the miracle." Sylvia Anderson noted that as the first episode of the series, "Trapped in the Sky" includes a large amount of exposition. She considered the roles of Penelope and Parker "brief but effective".