Definition
The minimum distance, vertically and horizontally, that air traffic control (ATC) maintains between aircraft to prevent collisions and wake turbulence encounters. Specific separation values depend on airspace class, aircraft type, phase of flight, and surveillance method (radar or non-radar).
Plain English
The job of keeping aircraft a safe distance apart in the air and on the ground so they don't get too close to each other.
Context Anchor
Seen in discussions of air traffic control automation, where computer systems help controllers track aircraft and notice when two aircraft may be getting too close.
Derivation
Separation comes from a Latin word meaning “to set apart.” That fits the aviation meaning: aircraft are intentionally kept apart by enough space to stay safe.
Why Pilots Care
Maintaining correct separation prevents mid-air collisions and is a core part of safe flight operations in controlled airspace.
Intuition Check
Do not read separation as just “not touching.” In aviation, aircraft separation means keeping aircraft apart by a required safety spacing, not merely avoiding a collision at the last moment.
Example Sentence 1
ATC turned us 20 degrees right to maintain separation from inbound traffic.
Example Sentence 2
Automation tools help ensure aircraft separation even when traffic volume increases.