Which equipment is required in Class B airspace and within 30 miles of the Class B primary airport?

In Class B airspace and within 30 nautical miles of the primary Class B airport, an operable transponder that has a 4096 code capability along with a Mode C encoding altimeter is required for aircraft. This equipment is crucial for ensuring proper communication and surveillance within these busy airspace environments.

The 4096 code transponder provides a unique transponder code for air traffic control, allowing them to monitor aircraft location and identify them on radar. The Mode C encoding altimeter capability is essential because it transmits the aircraft's altitude information, enabling air traffic controllers to maintain safe vertical separation between aircraft as well as manage airspace effectively. This requirement is particularly important in Class B airspace, which typically experiences higher traffic volumes and more complex operations.

Other options do not meet the requirements set by regulations for operations in Class B airspace, where safety and effective traffic management are paramount. Using equipment that does not comply, such as a transponder without Mode C or not having a transponder at all, would not provide the necessary altitude reporting and could lead to safety risks in this congested environment.