Definition
The use of radar by an air traffic controller to keep aircraft apart by specified minimum distances, both horizontally and vertically, so that no two aircraft come closer to each other than the standards permit.
Plain English
When a controller is watching aircraft on radar, they keep each aircraft a set distance away from every other aircraft. Radar separation is the act of using the radar picture to maintain that safe gap.
Context Anchor
You will encounter this term in air traffic control, instrument flying, and discussions of how controllers keep aircraft apart when they can see their positions on a radar display.
Derivation
Radar comes from RAdio Detection And Ranging, coined in the 1940s. Separation comes from Latin separare, meaning to set apart. Together the term simply means using radar to set aircraft apart by safe distances.
Why Pilots Care
Prevents mid-air collisions when pilots cannot see other traffic and must rely on controllers for spacing.
Grounding Statement
Picture a controller looking at several aircraft targets on a screen and making sure none of them get closer than the allowed distance.
Intuition Check
Do not read “radar separation” as meaning the airplane’s own radar automatically keeps traffic away. Here it means air traffic control uses radar or approved surveillance information to keep aircraft at required distances from each other.
Example Sentence 1
Once we checked in with approach, the controller began providing radar separation from the arriving traffic ahead of us.
Example Sentence 2
Radar separation was reduced to three miles inside the terminal radar service area.