What type of airspace does NOT require ATC contact if flying under it?

Class G airspace is designated as uncontrolled airspace, which means that pilots flying in this airspace are not required to communicate with Air Traffic Control (ATC). This category of airspace usually exists from the surface up to a certain altitude, typically where controlled airspace begins, and it allows pilots to operate freely without ATC involvement, provided they adhere to basic visibility and cloud clearance rules.

In Class G airspace, pilots are responsible for their own navigation and communications, although they are encouraged to maintain situational awareness and avoid conflicts with other aircraft. This autonomy stands in contrast to controlled airspaces like Class A, B, and C, where ATC management and communication are integral to ensuring the safe separation of flights and efficient use of airspace.