Class E is controlled airspace. However, there is no requirement to call air traffic control or obtain a clearance to enter Class E under visual flight rules. For VFR flight, the main difference between Class E and Class G airspace, uncontrolled airspace, are higher visibility and cloud clearance requirements for VFR flight into Class E. For this reason, Class E airspace is often referred to by VFR pilots as weather-controlled airspace.
Class E airspace exists in a number of places. The airspace from 14,500 MSL up to 18,000 MSL across the continental United States and coastal waters out to the Pacific. to 12 nautical miles is all Class E. This lower limit of 14,500 MSL is extended downward to 1,200 AGL across widespread areas of the United States, based on radar coverage.
In order to protect instrument traffic conducting approaches in marginal weather conditions, Class E airspace is often further extended down. to 700 feet AGL, or even all the way to the surface. These 700 feet AGL, or surface areas, are usually customized to encompass portions of specific instrument approaches at an airport, and are depicted on aeronautical charts. Class E airspace is also designated along federal airways, called Victor Airways.
Victor Airways are normally 8 miles wide, 4 miles to either side of the airway's centerline, and extend from 1,200 feet AGL up to, but not including, 18,000 feet MSL. There are no specific airplane equipment requirements to enter Class E airspace. and pilots are not required to establish communications with any air traffic control facilities. Class G airspace is uncontrolled airspace. It is all airspace that is not designated as Class A, B, C, D, or E.
Although Class G airspace is uncontrolled, federal aviation regulations still apply. Similar to Class E, there are no specific airplane equipment requirements to operate in Class G airspace, and pilots are not required to establish communications with any air traffic control facilities. While the vast majority of towered airports are designated Class D, C, or B airspace, it is possible for an airport in Class E or G airspace to be towered.
As you can see, in 1991, 126D and 91127C below. If a control tower is present and operational, you must establish radio communications prior to 4 nautical miles from the airport, up to and including 2,500 feet AGL. Notice this area is identical to the typical size of a Class D airspace area.