Identification

Unlike tower controllers, radar controllers cannot look outside to provide ATC services. They have to rely on data collected by radar systems. We distinguish between two different radar systems.

Primary radar

When radar was first invented it only existed as a primary radar. A primary radar sends out electromagnetic waves in all directions and displays a dot on the screen for each reflection it detects. However, there is no way to know which dot on the screen belongs to which aircraft - this is where identification comes into the picture.