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Introduction & Background

This topic contains only PANS-AIM requirements relevant for a marker. For general PANS-AIM requirements valid for all kind of Radio navigation aids see topic Navaid [NAV] and subordinated pages.

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• en-route or
• forming part of an ILS system.

In AIXM en-route marker will be coded as Navaid feature. In general, marker forming part of an ILS facility (e.g. outer marker, middle marker) will not be coded as own Navaid feature but as navaidEquipment for the Navaid with type equal-to 'ILS ', 'ILS_DME' or 'LOC', 'LOC_DME' (see also topic Navaid Equipment).

For a marker, PANS-AIM requires some specific properties as part of the minimum AIP data set. These are

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The diagram below shows the AIXM classes, including the relevant data types, needed to encode that information. The main class is the MarkerBeacon which is a specialisation of the NavaidEquipment.

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Marker Beacon Designator & Name

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According to ICAO Annex 10

  Chapter 3, the identification of markers part of an ILS should be as follows:

1. Inner marker (IM): dots only,
2. Middle marker (MM): Alternate dot and dash,
3. Outer marker (OM): 2 dashes,
4. Backcourse marker (BCM): shall be clearly distinguishable from the inner, middle and outer marker beacon identification.

In En-route Markers and in some States also ILS markers may also have alphanumeric designators.

In AIXM 5 the data type for Navaid.designator and also MarkerBeacon.designator viz. CodeNavaidDesignatorBaseType only allows the following pattern ([A-Z]|\d)* and is limited to 4 characters. Hence it can only be used for the designator of en-route markers.

For markers forming part of an ILS facility the MarkerBeacon.auralMorseCode attribute has to be used to code the identifier.

The long name given to the marker is coded using the MarkerBeacon.name attribute.

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See topic Basic Data for Navaid.

Hours of Operation

See topic Hours of Operation for Navaid.

Marker Frequency

In AIXM 5, the value of the radio emission frequency of the marker is coded by using the MarkerBeacon.frequency attribute.

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In general, marker beacons operate at 75 MHz.

Minor Axis Bearing

This information is not required by PANS-AIM. ARINC 424

defines a" Minor Axis Bearing (MINOR AXIS TRUE BRG)" data field for the "Airport Localizer Marker" records.

in AIXM 5 the MarkerBeacon.axisBearing attribute may be used to indicate the true bearing of the minor axis of marker beacons.

The figure below illustrates how the minor axis is defined for a marker.

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Also in some AIPs this information is published.

Tip
title AIP context
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Position

In case a marker beacon collocated with an NDB (Locator) is physically located at the same position as the Locator, the geographic position (latitude and longitude) of the Locator is also the geographic position of the Marker.

In case a Marker is collocated with an NDB (Locator) and the geographic position of the Marker is different from the geographic position of the locator, some restrictions have to be taken into account (see coding rules below).

For more details see topic Navaid Position & Elevation.

Operating Authority

See topic Operating Authority for Navaid.

Facility Coverage

See topic Facility coverage.

Navaid Collocation

In case the marker is used as part of a ILS or Localizer system, the position of it within that system has to be coded.

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Coding

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The geographical distance between the MarkerBeacon.location and the NDB.location used as NavaidEquipment for the same Navaid instance must be less than 100 metres.

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Coding Examples

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Examples

Coding examples can also be found in the AIP Data Set - Specimen (DONLON):

References