Aero Center / Map Practice Test

In ATC sector labeling, the letters and suffix identify a specific control area and the altitude band it covers. GLH LO is the low-altitude sector for the Greenville area. That name, Greenville Low, is exactly what GLH LO designates.

The other options point to different sectors—Jackson Low, Helena Low, Greenville High—so they don’t match the GLH LO label, which is specifically tied to Greenville’s low-altitude sector. The LO suffix indicates the lower altitude block, separate from the high-altitude counterpart in the same general region.