Brewster McCloud (1970)
Brewster McCloud is a 1970 movie, directed by Robert Altman, about a young recluse (Bud Cort, as the titular character) who lives in a fallout shelter of the Houston Astrodome, where he is building a pair of wings so he can fly. He is helped by his comely and enigmatic "fairy godmother", played by Sally Kellerman.
More at Wikipedia.