This topic contains only those 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.
A marker beacon serves to identify a particular certain location in space by means of a 75MHz transmitter, which transmits a directional signal to be received by aircraft flying overhead.
There are basically two application applications of marker beacons:
- en-route or
- forming part of an ILS system.
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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.
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:
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Marker Frequency
In AIXM 5, the value of the radio emission frequency of the marker is coded by using the MarkerBeacon.frequency attribute.
The corresponding data type contains a uom attribute. For a marker, only the value equal-to 'MHZ' shall be used.
In general, marker beacons operate at 75 MHz.
Position
In case a marker marker beacon collocated with a 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 a 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 trules rules below).
For more details see topic Navaid Position & Elevation.
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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.
One or more MarkerBeacon instances may be used as component (NavaidEquipment) for a single Navaid of type 'ILS' or 'ILS_DME' or 'LOC' or 'LOC_DME' . instance. However, each MarkerBeacon instance must be related to a maximum of one ILS, i.e. an ILS may have more than one related marker but a marker can only be related to one ILS.
As each marker related to the ILS has to have a different marker position, a maximum of four markers can be part of an ILS/Localizer system, i.e. a an Outer, a Middle, a an Inner and a Backcourse Marker.
Altough Although not required by PANS-AIM, this information is published in the AIP for ILS/Localizer systems. Also, the ARINC 424 record type "Airport and Heliport Localizer Marker" contains a data field "Marker Type" (MKR TYPE) for the corresponding information.
In an ILS/Localizer sytstem system, a marker may be located basically at 3 different positions: outer, middel middle and inner. An installation may have a marker at just one, two or all three positions.
Some ILS/Localizer sytstem systems provide the possibility to use them backcourse. In such cases, a dedicated marker may be provide provided to support that kind of operation.
Correspondingly, the data type class for NavaidComponent.markerPosition attribute allows the following values to be coded: 'OUTER', 'MIDDLE,' 'INNER' and 'BACKCOURSE'.
A MarkerBeacon may be collocated with a an NDB (Locator).
Usually, the NBD collocated with a Marker is a Locator (see also topic NDB), whereas the Locator in conjunction with the collocated Marker is used for ILS approaches.
In the AIP, collocated NDB and marker navaids are sometimes referred to as LOM, LMM or LIM, depending on marker position within the ILS.
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| Identifier | Data Encoding Rule | Justification | Data Verification Rule (UID) | Remarks |
|---|---|---|---|---|
| MKR-101 | The MarkerBeacon.designator attribute is mandatory. | Minimum AIP data set | TBD | |
| MKR-102 | The MarkerBeacon.name attribute is mandatory. | Minimum AIP data set | TBD | |
| MKR-103 | The MarkerBeacon.frequency attribute is mandatory. | Minimum AIP data set | TBD | |
| MKR-104 | The MarkerBeacon.location attribute is mandatory. | Minimum AIP data set | TBD | |
| MKR-105 | The NDB.designator shall not be duplicated within 600 NM of the location of the NDB. | EAD / ICAO Annex 11 | TBD | |
| MKR-106 | The value of the MarkerBeacon.frequency must be '75' 'MHz'. | EAD | TBD | |
| MKR-107 | The value of the NavaidComponent.markerPosition must be different for each MarkerBeacon that is used as NavaidComponent of the same Navaid instance wich which type is equal-to 'ILS' or 'ILS_DME' or 'LOC' or 'LOC_DME' . | EAD | TBD | |
| NDB-108 | 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. | EAD | TBD | |
| MKR-109 | No more than one MarkerBeacon may be co-located with same NDB. | EAD | TBD |
Coding Examples
TBD in the scope of the DONLON AIXM AIP data set.
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