Separation

Separation is the spacing between aircraft maintained by ATC to prevent collision. Different types of separation apply in different situations: vertical separation (altitude difference), horizontal separation (lateral or longitudinal distance), and radar separation (distance on radar).

Standard Separation Minima

• Vertical: 1,000 ft below FL290; 1,000 ft in RVSM airspace (FL290–FL410); 2,000 ft above FL410
• Radar (en route): 5 NM (3 NM in some terminal environments)
• Non-radar (longitudinal): Time or distance-based, depending on the navigation system
• Wake turbulence: 3–6 NM depending on weight category

Pilot Responsibility

In IFR flight, ATC provides separation from other IFR aircraft. In VMC, pilots must see-and-avoid other aircraft as required. In Class G uncontrolled airspace, there is no ATC separation — pilots are entirely responsible for their own separation from all other traffic.

Related Terms

See also: RADAR, IFR, Wake Turbulence.