Generally, if the airspace is not Class A, Class B, Class C, or Class D, and it is controlled airspace, it is Class E airspace. Class E airspace extends upward from either the surface or a designated altitude to the overlying controlled airspace. When designated as a surface area, the airspace will be configured to contain all instrument procedures. Also in this class are federal airways, airspace beginning at either 700 or 1200 feet AGL used to transition to or from the terminal or enroute environment, enroute domestic, and offshore airspace areas designated below 18,000 feet MSL. Unless designated at a lower altitude, Class E airspace begins at 14,500 feet MSL over the United States, including that airspace overlying the waters within 12 nautical miles of the coast of the 48 contiguous states and Alaska, up to, but not including 18,000 feet MSL, and the airspace above FL 600.

When designated in conjunction with an airport with an approved IAP, the floor of Class E airspace is 700 feet AGL. When designated in conjunction with a federal airway the floor is 1200 feet AGL.

Except for 18,000 feet MSL, Class E airspace has no defined vertical limit; rather, it extends upward from either the surface or a designated altitude to the overlying or adjacent controlled airspace. Unless designated at a lower altitude, Class E airspace begins at 14,500 feet MSL and extends up to, but not including 18,000 feet MSL, overlying the 48 contiguous states including the waters within 12 miles from the coast of the contiguous states.