AIM Text
Class G airspace (uncontrolled) is that portion of airspace that has not been designated as Class A, Class B, Class C, Class D, or Class E airspace.
Source: FAA Aeronautical Information Manual · current edition · paragraph 3-3-1.
The short answer
This AIM section gives the FAA's advisory definition of Class G (uncontrolled) airspace as that portion of airspace not designated as Class A, B, C, D, or E. It frames Class G as everything left over once controlled airspace is designated, supporting the airspace structure in 14 CFR part 71.
Research Notes
Common Questions
What is Class G airspace?
Per this AIM section, Class G airspace is uncontrolled airspace — the portion of airspace that has not been designated as Class A, Class B, Class C, Class D, or Class E airspace.
Is Class G the same as uncontrolled airspace?
Yes. The AIM explicitly labels Class G as "uncontrolled" airspace. It is defined by exclusion: any airspace that is not one of the controlled classes (A through E) is Class G.