FAA Ground School Practice Test

In which airspace is an operable 4096-code transponder with an encoding altimeter required?

1. Class C only

2. Class A and B, and within 30 miles of Class B primary airport

3. Class D only

4. Class B and G airspace

The correct answer is: Class A and B, and within 30 miles of Class B primary airport

An operable 4096-code transponder with an encoding altimeter is essential for maintaining safety and effective air traffic management in specific airspaces, particularly because it allows for accurate altitude reporting and tracking of aircraft. The requirement for this type of transponder is prominent in Class A and Class B airspace. In Class A airspace, which exists from 18,000 feet MSL (Mean Sea Level) up to and including FL 600, all aircraft must be equipped with a transponder. This is because air traffic control maintains positive control over all aircraft in this area, which is critical due to the high volume of traffic typically present. Class B airspace, which encompasses the airspace around major airports, requires aircraft to have a transponder as it aids in managing the busy traffic environment that surrounds these airports. Moreover, there is an added requirement for aircraft operating within 30 nautical miles of a Class B primary airport, ensuring that even those transitioning near these areas maintain visibility and tracking capabilities. This necessity for a transponder with altitude encoding in these airspace classes helps prevent mid-air collisions and ensures adherence to air traffic control protocols, illustrating how safety is prioritized in busy flight environments.