What is a unique feature of Secondary Radar Mode A?

In Secondary Radar Mode A, a distinctive feature is that it allocates a four-digit code that the pilot must enter into the aircraft's transponder. This code, commonly known as a squawk code, is essential for identification. When the pilot inputs this code, it allows air traffic controllers to distinguish that specific aircraft from others in the vicinity. This identification capability enhances situational awareness for controllers, as they can easily correlate the transponder signal with their radar displays.

The additional options can be misleading as they pertain to features found in different radar modes or systems. For instance, height information is typically associated with Mode C, while more precise tracking and alerts for conformance monitoring relate to different operational functionalities within radar systems. Each option highlights aspects of radar technology but only the allocation of the four-digit code directly pertains to Secondary Radar Mode A.