What distinguishes Class D airspace in terms of size?

Class D airspace is characterized by its relatively small size, typically extending from the surface up to 2,500 feet above ground level, surrounding airports that have an operational control tower. This airspace is designed to handle the traffic in and out of the associated airport while allowing for efficient management of aircraft operations. Unlike larger airspaces such as Class A or Class B, which can cover significant geographical areas and accommodate high-density traffic involving commercial flights, Class D airspace is confined around specific airports to provide a buffer for local flight operations.

In addition, Class D airspace is not solely designated for military use; it is primarily composed of civilian airspace around airports. While larger airspace classifications can extend for miles and accommodate broader operational capabilities, Class D serves a focused purpose, enhancing safety and orderliness around smaller, controlled airports.