Mode C Veil

A regulatory area extending 30 nautical miles from the primary airport of Class B airspace, within which all aircraft must be equipped with an operating Mode C (altitude-reporting) transponder from the surface up to 10,000 feet MSL, as required by 14 CFR 91.215. This helps ATC see both the position and altitude of traffic near busy airports. A pilot may request a deviation from ATC if the aircraft is not transponder-equipped.