Separation, spacing and segregation all affect one another. Separation minima define the limit for spacing while separation (and therefore spacing) may be applied with due regard to any segregation of airspace. Segregation can be applied without regards to separation and spacing or may be used directly to affect separation and spacing application levels via route or airspace design/eligibility criteria.
It is possible to view separation, spacing and segregation as having strategic and tactical applications. Strategic generally refers to the design and promulgation process while tactical refers to application by ATC of such promulgated procedures.
IFATCA Policy is:
Separation be defined as:
The action within defined airspace of keeping aircraft at such displacements from defined hazards that the risk of collision is limited to an acceptable safe level.
Spacing is defined as:
The application of a displacement equal to or greater than a specific separation minimum between an aircraft and a hazard.
Segregation is defined as:
The application of procedures and design with the purpose of setting apart an exclusive subset of users of the ATM system, based on a defined operational characteristic.
|See: WP 96 – Arusha 2008|
Last Update: September 29, 2020