Understand ATS Routes Designators and Airways Naming

Appendix 1 of ICAO Annex 11 outlines the guidelines for naming ATS routes, also known as Airways. This article delineates the structure for formulating designators for these vital air navigation routes.

ATS route designator can be subdivided in to 3 parts:

  1. Basic Designator
  2. Prefix (if required)
  3. Suffix (if required)

– Number of characters required to compose the designator should be kept to a maximum of five characters (as far as possible) and shall not exceed six characters.

– The same basic designator shall be assigned to a main trunk route throughout its entire length, irrespective of terminal control areas, States or regions traversed (In this context, “trunk” refers to main or primary air routes that connect significant destinations or regions).

– When two or more trunk air routes share a part of their path, that shared part will be given the names of all the routes involved. However, if this causes problems for air traffic control, then everyone involved will agree to only use one name for that part of the route.


Basic designators shall consist of one letter of the alphabet followed by a number from 1 to 999. Selection of letter shall be made from those listed here under:

  • A, B, G, R for routes which form part of the regional networks of ATS routes and are not area navigation routes;
  • L, M, N, P for area navigation routes which form part of the regional networks of ATS routes;
  • H, J, V, W for routes which do not form part of the regional networks of ATS rotes and are not area navigation routes;
  • Q, T, Y, Z for area navigation routes which do not form part of the regional networks of ATS routes.

Here non-regional means ‘domestic’ and regional means ‘international’. So H, J, V, W, Q, T, Y, Z are used for domestic routes.

PREFIX of ATS route designator

Prefix K, U and S is added to ATS route designator as per following conditions:

  • K to indicate a low-level route established for use primarily by helicopters;
  • U to indicate that the route or portion thereof is established in upper airspace;
  • S to indicate a route established exclusively for use by supersonic aircraft during acceleration, deceleration and while in supersonic flight

SUFFIX of ATS route designator (F and G)

Suffix is added only when prescribed by appropriate ATS authority or on the basis of regional air navigation agreements. Letter F is added to indicate that on the route or portion thereof advisory service only is provided and the letter G is added to indicate that on the route or portion thereof flight information service only is provided.

Due to limitations in the display equipment on board aircraft, the supplementary letter “F” or “G” may not be displayed to pilots.

ATS Route Designators (Airway Names) in Aviation Communications

The basic letter of designator should be pronounced using the ICAO spelling alphabet. Additionally, the prefixes K, U, and S are to be spoken as “KOPTER,” “UPPER,” and “SUPERSONIC,” respectively. Suffix F or G as specified, are not required to be used in voice communications.

Coloured Airways

Colored Airways are a subset of airways in the United States aviation system. These airways are distinctively designated by their color names such as Amber, Blue, Green, or Red, followed by a one or two-digit number, for example, “A 7.” These airways primarily operate in the Low Frequency (LF) and Medium Frequency (MF) bands and are predominantly found in Alaska.

The use of colored airways dates back to the early days of aviation, where visual aids were crucial for navigation, especially in remote or rugged terrain like Alaska. Despite advancements in navigation technology, these colored airways remain in existence, particularly in Alaska, where they continue to serve as important navigation aids for pilots navigating through the state’s diverse and often challenging terrain.

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