Airspace Description
Class C airspace is controlled airspace. It is designated for airports having a significant amount of air traffic, but not enough to require the creation of a Class B airspace area. It is comprised of a surface area, an outer circle, and an outer area.
The surface area extends from the primary airport to a distance of five nautical miles from the primary airport. It includes altitudes between the surface and 4,000 feet above the primary airport's elevation. This area is also referred to as the inner circle.
The outer circle extends from five to 10 nautical miles from the primary airport and includes the altitudes between 1,200 AGL and 4,000 feet above the primary airport's elevation.
The outer area, which extends 10 nautical miles beyond the outer circle, is not part of the Class C airspace. It is actually Class E airspace most of the time. However, pilots are strongly encouraged to participate in the air traffic control services available in the outer area. Since the outer area is not actually part of the Class C airspace, this pilot participation is not mandatory.
Communications Requirement
Two way radio communications are required to enter a Class C airspace area. Two way radio communications are established as soon as the air traffic controller responds to you by stating your aircraft call sign.
Equipment Requirements
A two way radio is required to enter.
A transponder with operable mode C is required to operate within the Class C airspace.
A transponder with operable mode C is also required if operating above the Class C airspace at or below 10,000 feet MSL.
ยง 91.130 Operations in Class C airspace.