§ 91.117 Aircraft speed. (b) Unless otherwise authorized or required by ATC, no person may operate an aircraft at or below 2,500 feet above the surface within 4 nautical miles of the primary airport of a Class C or Class D airspace area at an indicated airspeed of more than 200 knots (230 mph.).

In Class C airspace, the primary speed limit is regulated by the Federal Aviation Administration (FAA) under 14 CFR 91.117. Generally, the speed limit for any aircraft operating at or below 2,500 feet above the surface within 4 nautical miles of the primary airport is 200 knots (approximately 230 mph). Outside this specific core area, but still within the Class C boundaries below 10,000 feet Mean Sea Level (MSL), the standard speed limit is 250 knots. These regulations are designed to ensure safety and allow for adequate separation by Air Traffic Control (ATC) in high-traffic environments. Pilots must adhere to these limits unless specifically authorized otherwise by ATC or if the aircraft's minimum safe airspeed exceeds these parameters.