All aircraft are managed by ATC to ensure that the distances between them never fall below certain prescribed minima (– AIRPROX).Vertical separation between two aircraft must be at least 1000 ft (– RVSM). Horizontal separation in Switzerland is normally 3 NM (nautical miles) in the vicinity of airports, and 5 NM in other airspace.

Spacing of aircraft while landing and taking off at airports to achieve safe and orderly movement in flight. The horizontal and vertical spacing of aircraft working over or near a wildfire or other incident. Spacing of personnel while performing line construction activities.

The spacing between aircraft, altitudes, or tracks. Fr: espacemen

The spacing of aircraft to achieve safe and orderly movement in flight and while landing and taking off.

In air traffic control, separation is the name for the concept of keeping an aircraft a minimum distance from another aircraft to reduce the risk of those aircraft colliding. Air traffic controllers apply rules, known as separation minima to do this. Pairs of aircraft to which these rules have been successfully applied are said to be separated: the risk of these aircraft colliding is therefore remote.