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This topic contains only those PANS-AIM requirements relevant for a Microwave Landing System (MLS). For general PANS-AIM requirements valid for all kind of Radio navigation aids see topic Navaid [NAV] and subordinated pages.

ICAO Annex 10, Volume I:

MLS is a precision approach and landing guidance system which provides position information and various ground to air data. The position information is provided in a wide coverage sector and is determined by an azimuth anglemeasurement, an elevation angle measurement and a range (distance) measurement.

A MLS consits of two main components

  • Azimuth equipment: A SHF transmitter and associated equipment, radiating signals in a volume of airspace served by the MLS, thereby furnishing azimuth indications to aircraft approaching the runway or back azimuth indications to aircraft departing from the runway or performing a missed approach procedure.
  • Elevation equipment: SHF transmitter, and associated equipment radiating signals within a volume of airspace served by the MLS, thereby furnishing elevation information as an angular value to aircraft approaching the runway.

The range measurement is provided by a related DME.

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

... identification, name, ... hours of operation, ..., channel..., position, ..., magnetic bearing, true bearing, ...

In addtion PANS-AIM AD2.19/AD 3.18 require

...type of supported operation for ILS/MLS, ... and for VOR/ILS/MLS also station declination ...used for technical line-up of the aid;

...If the operating authority of the facility is other than the designated governmental agency, the name of the operating authority shall be indicated in the remarks column. Facility coverage shall be indicated in the remarks column.

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

Designator & Name

The Azimuth will be have designator coded.

In general, the Elevation will not have a value for the designator attribute. If yes, it shall be identical to the designator of the localizer.

In general, neither the Azimuth nor the Elevation will have a name.


Hours of Operation


See topic Hours of Operation for Navaid.

Azimuth Channel

The Azimuth.channel attribute is used to  code indicating the channel on which the Microwave Landing System is operating.

The corresponding data type class CodeMLSChannelType provides a list of values in a range from '500' to '699'.

Position

For mor edetails see topic Navaid Position & Elevation.

Glide Path Angle

For the minimum/conditional AIP data set the normal glide path angle of an MLS is actually not required by PANS-AIM (it is only listed in the PANS-AIM Appendix 1).

The angle of the glide path is coded using the Elevation.angleNominal and the Elevation.angleAccuracy attributes.

Station Declination

PANS AIM Appendix 1 requires a station declination for a MLS.

AIXM 5.1(.1) issue

 In contrary to the VOR  and ILS class for the Azimuth no declination and Zero Bearing Direction attribute is provided. In AIXM 5 this information can only be coded with a Note.

Type of Supported Operation

In AIXM 5 the type of supported operation (e.g. CAT IIIA) is coded using the Navaid.signalPerformance attribute. Hence, the signal performance level indicating the precision of an MLS is not encoded for a particular component but the whole MLS system.

Note

In AIXM 5 the degree to which navigation aids provide accurate approach guidance for a runway direction will be encoded using the precisionApproachGuidance attribue of the RunwayDirection class. In case data is provided for both attributes it has to be ensured that it is not contradictory, i.e. the ILS category defined for the runway direction can not be higher that the one of the ILS sytsem serving the runway firection.

In addition, the Azimuth.type attribute may be used to code if the MSL is a 'normal' ('FWD') or 'back' ('BWD') azimuth equipment.

For more information about the coding of an MLSsystem, see topic Navaid Component & Navaid Colocation.

Operating Authority

See topic Operating Authority for Navaid.

Facility Coverage

See topic Facility coverage.

Served Runway Direction

In AIXM 5 the runway direction the MLS is provided for has to be coded using the Navaid.runwayDirection property. The corresponding relationship isInstalledAt indicates that the navaid (i.e. the MLS system) is installed at a particular landing area. Hence, not a component of the MLS but the whole MLS system will be related to a particular runway direction. For more information about the coding of an MLS system, see topic Navaid Component & Navaid Colocation.

Coding Rules for MLS

IdentifierData Encoding RuleJustificationData Verification Rule (UID)Remarks
MLS-101The Azimuth.designator attribute is mandatory.Minimum AIP data setTBD
ILZ-105The Azimuth.channel attribute is mandatory.Minimum AIP data setTBD
ILZ-106The Azimuth.location property is mandatory.Minimum AIP data setTBD
IGP-102The Elevation.location property is mandatory.Minimum AIP data setTBD
IGP-103The Glidepath.angleNominal atribute is mandatory.PANS-AIMTBD
IGP-104The Glidepath.angleAccuracy property should be provided.PANS-AIMTBD
IGP-105The Glidepath.rdh property sis mandatory.PANS-AIMTBD
IGP-106The Glidepath.rdhAccuracy property should be provided.PANS-AIMTBD
ILZ-107Either the Localizer.magneticBearing or the Localizer.magneticBearing attribute shall be provided.Minimum AIP data setTBD
ILZ-108If the Localizer.magneticBearing is provided than the Localizer.magneticBearingAccuray should be provided.PANS-AIMTBD
ILZ-109If the Localizer.trueBearing is provided than also the Localizer.trueBearingAccuray should be provided.PANS-AIMTBD
ILZ-110The Localizer.declination attribute should be provided.PANS-AIMTBD
NAV-901If Navaid.type equal-to 'ILS' or 'ILS_DME' or 'LOC' or 'LOC_DME'  the Navaid.signalPerformance shall be provided.PANS-AIMTBD
NAV-902The Navaid.signalPerformance and the related RunwayDirection.precisionAppraochGuidance shall be consistent.Data consistancyTBDFor example if signalPerformance is CAT IIIA also the precisionAppraochGuidance shall be CAT IIIA.
ILZ-111The Localizer.backCourseUsable attribute should be provided.PANS-AIMTBD
ILZ-112If Navaid.type equal-to 'ILS' or 'ILS_DME' or 'LOC' or 'LOC_DME'  it must have exactly one NavaidEquipment which is a Localizer.EAD / Data consistancyTBD
NAV-903If Navaid.type equal-to 'ILS' or 'ILS_DME' it must have exactly one NavaidEquipment which is a Glidepath.Data consistancyTBD
NAV-904If Navaid.type equal-to 'ILS_DME'  or 'LOC_DME' it must have exactly one NavaidEquipment which is a DME.Data consistancyTBD
ILZ-113The Localizer.location must be plausibly close (less than 1 KM) to that of the end of the related (through Navaid.runwayDirection) RunwayDirection.EAD / Data consistancyTBD
ILZ-114The difference between Localizer.magneticBearing  and the related RunwayDirection.magneticBearing (through Navaid.runwayDirection)  cannot exceed 10 degrees.EAD / ICAO Doc 8168, PANS OPSTBD
ILZ-115The difference between Localizer.trueBearing and Localizer.magneticBearing has to be consistent with the value VAL_MAG_VAR in the referred AD_HP, taking in consideration the current date and the annual rate of change (VAL_MAG_VAR_CHG in the referred AD_HP).EADTBD
ILZ-116The value of the Localizer.frequency has to lie between '108' 'MHz' and '111.975' 'MHz'EAD/ ICAO Annex 10, Vol. 1TBD
IGP-107The Glidepath.location must be plausibly close (less than 1 KM) to that of the threshold of the related (through Navaid.runwayDirection) RunwayDirection.EADTBD
IGP-108The value of the Glidepath.frequency has to lie between '328.6' 'MHz' and '335.4' 'MHz'.EAD/ ICAO Annex 10, Vol. 1TBD
IGP-109The value of the Glidepath.slope has to lie between '1' and '5' degrees.EAD/ ICAO Annex 10, Vol. 1TBD
IGP-110The value of the Glidepath.rdh has to lie between '10' and '25'  'M' (metres).EAD/ ICAO Annex 10, Vol. 1TBD

Coding Examples

The figure below shows an outdated publication of an MLS in an AIP.

As there is hardly any MLS installation in the world remaining, it is not considered necessary to provide an example of a MLS in the scope of the DONLON AIXM AIP data set.

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