Northern California TRACON's (NCT) Class Charlie Outer Area is defined as the entire approach control airspace excluding the charted airspace designated as Class Bravo or Class Charlie where additional services are provided and excluding the Class Delta and Class Echo Surface Areas where radar services are normally terminated. 

Participating VFR aircraft within NCT airspace in Northern California and Nevada are provided Class C services and separation in accordance with FAA JO 7110.65 and FAA JO 7110.659.

Pilots should be aware that control instructions may be issued to aircraft receiving traffic advisories.  14 CFR 91.123 states in part: "Except in an emergency, no person may operate an aircraft contrary to an ATC instruction in an area in which air traffic control is exercised".    

This CFR is further clarified in the Karas Letter issued in 2013 by the Office of Chief Counsel, requiring pilots comply with all ATC instructions, regardless of whether the pilot is flying VFR or IFR, in accordance with § 91.123(b). 

NCT's airspace is non-contiguous between Northern CA and Nevada. Oakland Center provides Air Traffic Control Service in the airspace between the two depicted airspace polygons.