A coded transponder equipped with altitude reporting equipment is required in which airspace?

A coded transponder equipped with altitude reporting equipment is essential in Class A, B, and C airspace areas due to the need for traffic separation and situational awareness. In these controlled airspace classifications, the use of transponders enhances radar tracking of aircraft, which is crucial for air traffic control to manage the higher density of traffic safely, especially in busy terminal areas and along major air routes.

In Class A airspace, which starts at 18,000 feet MSL and extends to flight level 600, it is mandatory for all aircraft to maintain a transponder with altitude reporting. Similarly, Class B airspace, which typically surrounds busy airports, requires aircraft to operate with a transponder to ensure safe distances are maintained from heavily trafficked areas. Class C airspace, while somewhat less congested, still necessitates the use of transponders to aid in the identification of aircraft for air traffic management.

The requirement is based on safety regulations that support the overall integrity of the air traffic control system in these areas where the complexity of operations demands close monitoring of aircraft.