Crack pilots, also known as ACES, are highly skilled military aviators who have achieved a high level of success in aerial combat. They are usually credited with shooting down a large number of enemy aircraft during wartime. The term 'crack pilot' is derived from the phrase 'crack shot, ' which means an expert marksman. ACES are often celebrated for their bravery and skill in the air, and their exploits are often recounted in books and films.