What does an unpaired primary target indicate?

A primary target that is unpaired signifies a single aircraft that does not have a corresponding secondary contact, typically indicating that the aircraft is not equipped with a transponder. In radar systems, primary targets are displayed based on the radar return from the aircraft itself, capturing reflections from the physical structure. This absence of a secondary contact implies that the system can detect the aircraft, but the lack of a transponder signal means there is no additional data available, such as altitude, identification, or flight information, that would normally be displayed alongside a secondary target.

In the context of air traffic control, recognizing an unpaired primary target is crucial for understanding the type of aircraft being tracked and potentially the level of information available for safe management of that flight. The other choices represent scenarios that do not accurately describe the status of an unpaired primary target.