Which function does the IDT button serve in relation to the transponder?

The IDT button serves the function of sending an identification signal from the transponder. When activated, this feature sends a specific code that allows air traffic control and other aircraft to positively identify the aircraft’s unique transponder code. This capability is crucial for maintaining situational awareness, especially in busy airspace where multiple aircraft are operating simultaneously.

Sending an identification signal enhances safety and allows air traffic controllers to track and manage aircraft more effectively, especially during critical phases of flight such as takeoffs and landings. By broadcasting this unique identifier, it ensures that air traffic is separated and managed safely.

The other options, while relating to the transponder's functionality, do not accurately represent the specific purpose of the IDT button. For instance, changing frequencies, initiating navigation data, or broadcasting proximity alerts involve different systems and controls that are not linked to the primary function of the IDT button in the context of the transponder.