idiosphere
A portion of the troposphere where idiot pilots are known to fly.
This is not limited to below FL180. This region of space includes altitudes where most student pilots and cowboy pilots fly. Stratosphere pilots (e.g. SR-71 and U-2 pilots) and Exosphere pilots (e.g. Apollo, Soyuz, and Space Shuttle) experience only brief passages through the idiosphere before continuing to spheres of higher existence.