FAA Ground School Practice Test

An operable 4096-code transponder and mode C encoding altimeter are required in which airspace?

1. Class B airspace only

2. Class A only

3. Class B airspace and within 30 miles of the Class B primary airport

4. All controlled airspace

The correct answer is: Class B airspace and within 30 miles of the Class B primary airport

The requirement for an operable 4096-code transponder and mode C encoding altimeter is specifically relevant in Class B airspace and within a 30-mile radius from the Class B primary airport. This is designed to enhance the safety and efficiency of operations in busy airspaces where higher traffic levels and complex flight patterns are present. Class B airspace is typically airspace surrounding major airports where the volume of air traffic is significant, requiring added measures for situational awareness among pilots and air traffic controllers. Additionally, the requirement extends to the 30-mile veil to help maintain communication and monitoring of aircraft entering or exiting this busy airspace, thus ensuring a smooth flow and efficient separation of traffic. While Class A airspace requires a transponder, the inclusion of a mode C encoding altimeter is specific to areas where there's a need for altitude reporting to assist in maintaining the integrity of flight operations in conjunction with ground control. The requirement is not applicable to all controlled airspace, as certain classes like Class D may not have the same altitude and positional reporting necessities. Therefore, the specified airspace requirements are limited to ensure optimal safety in highly trafficked zones.