How does secondary surveillance radar identify aircraft?

Secondary surveillance radar identifies aircraft primarily through the use of transponders embedded in the aircraft. When an aircraft is within the radar system's coverage, its transponder receives an interrogation signal from the ground radar. In response, the transponder sends back a signal that contains information such as the aircraft's unique identification code, altitude, and various other data.

This method is beneficial as it significantly reduces the interference caused by ground objects and precipitation, which can clutter primary radar returns. By relying on the transponder's response, the radar system can provide clearer and more accurate information about the aircraft’s identity and position. This function allows air traffic controllers to track multiple aircraft on their screens effectively, enhancing safety and efficiency in air traffic management.

Other methods of identifying aircraft, such as monitoring atmospheric pressure changes, visual contact from a control tower, or tracking GPS locations, do not contribute to the primary function of secondary surveillance radar and may not offer the same level of accuracy or reliability in busy airspace.