If it has to do with flying or operating a plane, it has to do with aviation. If someone tells you that he's in aviation school, that means he is learning how to fly a plane.
Aviation comes from the Latin avis meaning "bird," an appropriate translation given that aviation deals with travel by air, specifically in a plane. The aviation industry is the business sector dedicated to manufacturing and operating all types of aircraft. Air traffic controllers, when they are awake, are concerned with aviation safety.