Which component of the IFF system is responsible for determining the reply code?

The transponder control box is the component of the Identification Friend or Foe (IFF) system that is responsible for determining the reply code. It is a critical part of the IFF system because it interprets the signals received from the interrogator and generates a response based on preset codes. These codes convey important information about the identity of an aircraft, such as whether it’s friendly, hostile, or neutral.

The transponder control box receives a query from the interrogator, processes that query, and then sends back the appropriate reply code. This functionality is essential in military and air traffic control operations to ensure clear identification and to prevent friendly fire incidents. In contrast, other components like the radar system and communication devices do not generate reply codes; they function in other capacities, such as detecting objects or facilitating communication, but rely on the transponder to provide the identification information necessary for effective operations.