Own Separation

Description

The use of own separation means that for some flights, while in controlled airspace, separation is not provided by ATC. For the duration of the clearance, the responsibility for maintaining safe distance from the other aircraft lies with the pilots involved.

Conditions for Application

The use of own separation is described in ICAO Doc 4444 (PANS-ATM), Chapter 5, para 5.9, the key points being:

  • Own separation is applied:
    • upon crew request;
    • in airspace classes D and E only;
    • at or below 10,000 ft;
    • during climb or descent;
  • All flights must be in VMC (they may fly under IFR though);
  • All pilots must agree to the use of own separation;
  • Alternative instructions should be given to IFR flights if it is considered that VMC may not be maintained for the whole duration of the clearance.

Note: The conditions stated above are not exhaustive. Further restriction to the use of own separation may apply if so prescribed in regional air navigation agreements.

Controller Responsibilities

Before issuing a clearance for the use of own separation, the contoller should:

  • Ensure that all conditions are met;
  • Provide the pilots with essential traffic information (since the required separation is likely not to be maintained).

Pilot Responsibilities

If cleared to maintain own separation, the pilots concerned:

  • are responsible for flying at a safe distance from the other aircraft;
  • must inform the controller if they are about to enter IMC.

Safety Issues

There are two major safety issues with the use of own separation:

  • Sometimes the relevant ICAO SARPs are not correctly applied, e.g. because they have not been clearly understood or some circumstances have been misinterpreted.
  • Sometimes own separation is not compatible with ACAS logic.

Own separation is NOT to be used:

  • On controller's initiative;
  • In airspace classes A, B and C;
  • At night;
  • In IMC;
  • Above 10,000 ft;
  • If all aircraft are maintaining their level;
  • If the use of own separation is not agreed by all pilots concerned.

Relevant A&I Events

Related Articles

Further Reading

  • ICAO Doc 4444
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