Generally, that airspace from the surface to 4000 feet above the airport elevation (charted in MSL) surrounding airports that have an operational control tower, are serviced by a radar approach control, and that have a certain number of IFR operations or passenger enplanements. Although the configuration of each class C airspace area is individually tailored, the airspace usually consists of a five NM radius core surface area that extends from the surface up to 4000 feet above the airport elevation, and a 10 NM radius shelf area that extends from 1200 feet to 4000 feet above the airport elevation.