An RF congestion monitoring system and method is provided. In one or more examples, the RF congestion monitoring system can include a modified aircraft transponder capable of receiving signals associated with Air Traffic Control and Traffic Collision Avoidance Systems, analyzing the received signals to determine the presence on one or more events occurring in the received signals, and generating an event count that identifies the types of signals associated with the events being received. A processor can receive the generated event count and based on the received count can calculate a transponder occupancy percentage metric indicative of the amount of RF congestion in a given air space. In one or more examples, the modified transponder can be configured to receive various radar signals in the 1030 and 1090 MHz frequency signal bands and process those signals to determine the amount of RF congestion in the airspace.