PUBLISHED RNAV ROUTES

Although RNAV systems allow you to select any number of routes that may or may not be published on a chart, en route charts are still crucial and required for RNAV flight. They assist you with both flight planning and inflight navigation. NACO en route charts are very helpful in the context of your RNAV flights. Published RNAV routes are fixed, permanent routes that can be flight planned and flown by aircraft with RNAV capability. These are being expanded worldwide as new RNAV routes are developed, and existing charted, conventional routes are being designated for RNAV use. It is important to be alert to the rapidly changing application of RNAV techniques being applied to conventional en route airways. Published RNAV routes may potentially be found on any NACO en route chart. The published RNAV route designation may be obvious, or, on the other hand, RNAV route designations may be less obvious, as in the case where a published route shares a common flight track with a conventional airway. Note: Since the use of RNAV is dynamic and rapidly changing, NACO en route charts are continuously being updated for information changes and you may find some differences between charts.

According to the International Civil Aviation Organization (ICAO), who develops standard principles and techniques for international air navigation, basic designators for air traffic service (ATS) routes and their use in voice communications have been established in Annex 11. ATS is a generic ICAO term for flight information service, alerting service, air traffic advisory service, and air traffic control service. One of the main purposes of a system of route designators is to allow both pilots and ATC to make unambiguous reference to RNAV airways and routes. Many countries have adopted ICAO recommendations with regard to ATS route designations. Basic designators for ATS routes consist of a maximum of five, and in no case exceed six, alpha/numeric characters in order to be usable by both ground and airborne automation systems. The designator indicates the type of the route such as high/low altitude, specific airborne navigation equipment requirements such as RNAV, and the aircraft type using the route primarily and exclusively. The basic route designator consists of one or two letter(s) followed by a number from 1 to 999.

COMPOSITION OF DESIGNATORS

1. The basic designator consists of one letter of the alphabet followed by a number from 1 to 999. The letters may be:
   a) A, B, G, R — for routes that form part of the regional networks of ATS routes and are not RNAV routes;
   b) L, M, N, P — for RNAV routes that form part of the regional networks of ATS routes;
   c) H, J, V, W — for routes that do not form part of the regional networks of ATS routes and are not RNAV routes;
   d) Q, T, Y, Z — for RNAV routes that do not form part of the regional networks of ATS routes.
   
   
2. Where applicable, one supplementary letter must be added as a prefix to the basic designator as follows:
   a) K — to indicate a low level route established for use primarily by helicopters.
   b) U — to indicate that the route or portion thereof is established in the upper airspace;
   c) S — to indicate a route established exclusively for use by supersonic airplanes during acceleration/deceleration and while in supersonic flight.
   
   
3. Where applicable, a supplementary letter may be added after the basic designator of the ATS route as a suffix as follows:
   a) F — to indicate that on the route or portion thereof advisory service only is provided;
   b) G — to indicate that on the route or portion thereof flight information service only is provided;
   c) Y — for RNP 1 routes at and above FL 200 to indicate that all turns on the route between 30° and 90° must be made within the tolerance of a tangential arc between the straight leg segments defined with a radius of 22.5 NM.
   d) Z — for RNP 1 routes at and below FL 190 to indicate that all turns on the route between 30° and 90° shall be made within the tolerance of a tangential arc between the straight leg segments defined with a radius of 15 NM.