Typically suspenseful movie of the period, with chair gripping aerial sequences and plot twists aplenty.
Concludes happily (despite sad losses) on a humorous note.
First-rate acting.
This looks back to Hawks' The Dawn Patrol (1930), a WWI film about flyers and their response to the seeming inevitability of death, living under unusual pressures that form a bond and an unshakeable code of ethics. And it looks forward to the romance of Casablanca whose narrative is very similar to Only Angels Have Wings.
These men deliver the mail in the fog over the Andes. But they will transit anything, including nitroglycerine! The boss is Cary Grant who hires a pilot who happens to be now married to the only woman he ever cared about... And the husband is reckoned to have once bailed out of a crash which killed his co-pilot and thus breaking the code...
This was Cary Grant's first significant dramatic role. And Rita Hayworth broke through from B films here. Both are excellent. Two out of three ain't bad; Jean Arthur was badly cast as the showgirl interloper who stumbles on this exotic other world.
There's shadows and fog, and life threatening heroics with plenty of action and a lot of fast, tough crosstalk. There's a gallery of mavericks who wash up on a mountain in South America determined to get the mail out, no matter what. These are the types of thread that Hawks would continually weave over his career, creating a kind of genre of his own.