Basic Data for Navaid

Introduction & Background

For Radio navigation aid, PANS-AIM requires some basic properties as part of the minimum AIP data set. These are

type, identification, name, aerodrome served...

The diagram below shows the AIXM classes, including the relevant data types, needed to encode that information:

Navaid Type

AIXM 5 defines the Navaid class as follows:

A service providing guidance information or position data for the efficient and safe operation of aircraft supported by one or more radio navigation aids.

In PANS-AIM this is the definition for "Radio navigation service".

However, in AIXM 5 a Navaid is composed of one or more NavaidEquipment.

The navaid.type attribute is used to code the type of the navaid (actually the service provided by one or more radio navigation aids).

Some examples:

A Navaid.type equal-to 'VOR' is composed of one NavaidEquipment which is a VOR.

A Navaid.type equal-to 'VOR_DME' is composed of two NavaidEquipment one which is the VOR and another one which is the DME.

A Navaid.type equal-to 'ILS' may be composed of  e.g. four NavaidEquipment, a Localizer, a Glidepath and two MarkerBeacon (one middle and one outer marker).

Navaid Purpose

This information is also not required by PANS-AIM to be provided as minimum data item but is considered conditional.

The Navaid.purpose attribute is used to indicate the intended usage of the navaid, i.e. 'ENROUTE' (E) or 'TERMINAL' (A) or 'ALL' (AE i.e. dual purpose).

In addition, navaids published in ENR 4.1 Radio navigation aids — en-route will be used 'ENROUTE' per definition. On the other hand navaids published in AD 2.19/AD 3.18 Radio navigation and landing aids are per definition of 'TERMINAL' usage.

PANS AIM requires in AD 2.19 / AD 3.18

When the same aid is used for both en-route and aerodrome purposes, a description shall also be given in section ENR 4.

ARINC 424 makes a distinction only for NDB. The Enroute NDB NAVAID file (DB) contains all enroute on-airway and off-airway NDBs. The Terminal NDB NAVAID file (PN) contains NDBs associated with the Airports and Heliport (see also section Aerodrome Served below). If a NDB is used in both the terminal and enroute environments, it appears in the Enroute NDB NAVAID (DB) file.

Navaid Designator & Name

A Navaid.designator is used to provide the coded identifier given to the navaid system.

It is limited to 4 characters, which may be upper case alpha and/or digit characters.

Depending on the specialised NavaidEquipment, different concepts and rules for the navaid designator may be applied (see also specialised navaid equipment topics).

The Navaid.name is used for the long name given to the composite navaid. For the name of the navaid, maximum 60 upper case alpha and/or numerical characters and also some special characters may be used. Some navaids will have no name.

Aerodrome Served

Navaids of type VOR, DME, NDB, TACAN and Marker with purpose Aerodrome (A or AE) or used for terminal procedures including e.g. ILS (generally published in AIP section AD 2.19/3.18) will be assigned to one (or more) AirportHeliport.

For instance, a VOR serving two different approaches for two different airports will be assigned to both airports.

This association is established via the Navaid.servedAirport property, i.e. not the individual navaid equipment is related to the airport/heliport but the whole navaid system (e.g. the VOR/DME and not the VOR and the DME).

Runway Direction Served

This information is not required by PANS-AIM as minimum/conditional data of the AIP data set (but it is listed in PANS-AIM Appendix 1). Landing aids, such as an ILS, which in AIXM 5 is coded as an instance of the Navaid class will be related to a RunwayDirection via the Navaid.runwayDirection property.

In an AIP, navaids that are situated at a runway direction are published in section AD 2.19 / AD 3.18 Radio navigation and landing aids.

Significant Point

In AIXM 5, the instance of a Navaid class is related to the SignificantPoint class (see also topic SignificantPoint (Overview)). The Significant point may be used as start or end point of a route or terminal procedure, or the centre point of a TAA/MSA, to describe the horizontal border of an airspace, etc.

Hence, navaids that are used as significant point have to be encoded using the Navaid class, whereas other navaids may be just encoded as NavigationEquipment (e.g. a marker beacon that is part of an ILS installation or a DME that is part of a VOR/DME).

Coding Examples

See topic Navaid [NAV] and sub-pages of topic Navaid Equipment.

References