Final answer:
Yes, a transponder with Mode C is required to fly in or above Class C airspace to provide air traffic control with the ability to identify and track the aircraft for safety and efficient airspace management.
Step-by-step explanation:
The correct answer is Yes, a transponder is required to fly in or above Class C airspace. In the United States, according to Federal Aviation Regulations, all aircraft must be equipped with an altitude-reporting Mode C transponder when flying at and above 10,000 feet MSL over the 48 contiguous states or the District of Columbia, excluding airspace at and below 2,500 feet above the surface.
More specifically, when operating within a Class C airspace, which generally extends from the surface to 4,000 feet above the airport elevation surrounding those airports that have an operational control tower, is serviced by radar approach control, and has a certain level of aircraft movements or passenger enplanements.
This requirement also extends to the airspace above Class C up to 10,000 feet MSL. The purpose of the transponder, particularly with Mode C, is to allow air traffic control to easily identify and track aircraft on radar, which enhances safety and efficiency in airspace management.
Without a working transponder, a pilot may need to obtain special permission to enter or transit the airspace, and this can considerably limit the aircraft's access to certain areas.