Most airspace in the United States is class E. The airspace above FL600 is also class E. No ATC clearance or radio communication is required for VFR flight in class E airspace. VFR visibility and cloud clearance requirements are the same as for class C and D airspaces when below 10,000 feet (3,000 m) MSL.

From a global and regulatory perspective, the most common type of airspace is Class E (Controlled) and Class G (Uncontrolled). In the United States and many other territories, Class E is the most prevalent form of controlled airspace. It fills the gaps between other types of regulated airspace, typically starting at 1,200 feet above ground level (AGL) and extending up to, but not including, 18,000 feet MSL. It is designed to provide separation for Instrument Flight Rules (IFR) traffic while allowing Visual Flight Rules (VFR) pilots to fly without specific ATC clearance. However, if looking at the entire globe—particularly over oceans and remote landmasses—Class G is technically the most widespread. Class G is "uncontrolled," meaning Air Traffic Control has neither the authority nor the responsibility to exercise control over air traffic. In these areas, pilots are responsible for their own "see and avoid" safety. In 2026, with the rise of commercial drone corridors, new sub-classifications of low-altitude airspace are being integrated into these standard categories to manage autonomous traffic below 400 feet.