List of aviators who became ace in a day

The term "ace in a day" is used to designate a pilot who has shot down five or more aircraft in a single day, based on the usual definition of an "ace" as one with five or more aerial victories. == World War I == === Ace in a day on two occasions === A Bristol F2B crew – Canadian pilot Captain Alfred Atkey and English observer Lieutenant Charles Gass – became "ace in a day" twice in the same week.