Model overview

It is important to note that "marking" refers to the visual marking of an obstacle, other than lighting. Marking specifications for obstacles are provided, for example, in the ICAO Annex 14, Chapter 6 - Visual aids for denoting obstacles. The figure below show the basic marking patterns as defined in ICAO Annex 14:

The AIXM 5.1(.1) model allows to code:

an overall indication whether the VerticalStructure marking is "ICAO standard" or not;
details of the marking elements, for each VerticalStructurePart - pattern ('MONOCOLOUR, CHEQUERED, HBANDS, VBANDS, FLAG, MARKERS, OTHER') and, if applicable, first colour and second colour;
any other marking details may be coded as annotation.Note.

Simple "marked" or "unmarked" indication

Contrary to lighting, in AIXM 5.1(.1) there is no dedicated element that can be used in order to code if an obstacle is simply "marked" or not. This information is important for VFR flying, as obstacles that are not marked might be more difficult to spot visually.

AIXM 5.1(.1) issue

The issue has been raised in the AIXM CCB and a change proposal (AIXM-322) will align the obstacle marking model with the obstacle lighting model, by introducing a new simple "marked" attribute in the next AIXM model version.

For AIXM 5.1(.1), the workaround for this model limitation consists in creating an annotation with the following elements:

purpose = 'REMARK'
translatedNote.LinguisticNote.note = ”marked=YES” (or "NO", as appropriate)

Example - Marked Obstacle

The example blow shows the encoding of an marked obstacle.

Marked obstacle

		<aixm:VerticalStructure gml:id="uuid.d22653bd-826d-411c-b8d3-838eba2a8325">
			<gml:identifier codeSpace="urn:uuid:">d22653bd-826d-411c-b8d3-838eba2a8325</gml:identifier>
			...
					<aixm:name>OBS-0001</aixm:name>
					<aixm:type>ANTENNA</aixm:type>
					<aixm:lighted>YES</aixm:lighted>
					<aixm:markingICAOStandard xsi:nil="true" nilReason="unknown"/>
					...
					<aixm:annotation>
						<aixm:Note gml:id="n0000">
							<aixm:purpose>REMARK</aixm:purpose>
							<aixm:translatedNote>
								<aixm:LinguisticNote gml:id="ln0000">
									<aixm:note>marked=YES</aixm:note>
								</aixm:LinguisticNote>
							</aixm:translatedNote>
						</aixm:Note>
					</aixm:annotation>
					...

Example - Unmarked Obstacle

The example blow shows the encoding of an unmarked obstacle.

Unmarked obstacle

		<aixm:VerticalStructure gml:id="uuid.6c7fac45-c24f-4e36-b196-687458d99070 ">
			<gml:identifier codeSpace="urn:uuid:">6c7fac45-c24f-4e36-b196-687458d99070</gml:identifier>
			...
					<aixm:name>WINDPARK DONLON IV</aixm:name>
					<aixm:type>WINDMILL_FARMS</aixm:type>
					<aixm:lighted>NO</aixm:lighted>
					...
					<aixm:markingICAOStandard xsi:nil="true" nilReason="inapplicable"/>
					...
					<aixm:annotation>
						<aixm:Note gml:id="n04000">
							<aixm:purpose>REMARK</aixm:purpose>
							<aixm:translatedNote>
								<aixm:LinguisticNote gml:id="ln04000">
									<aixm:note>marked=NO</aixm:note>
								</aixm:LinguisticNote>
							</aixm:translatedNote>
						</aixm:Note>
					</aixm:annotation>

Example - Unknown if marked

The example blow shows the encoding when it is not known if the obstacle is marked.

Unkown if marked

		<aixm:VerticalStructure gml:id="uuid.359c8b02-8be7-4e2c-aa6d-d990dbb6b057">
			<gml:identifier codeSpace="urn:uuid:">359c8b02-8be7-4e2c-aa6d-d990dbb6b057</gml:identifier>
					...
					<aixm:type>OTHER:CHIMNEY</aixm:type>
					<aixm:lighted>NO</aixm:lighted>
					<aixm:markingICAOStandard xsi:nil="true" nilReason="unknown"/>
					...
					<aixm:annotation>
						<aixm:Note gml:id="n05000">
							<aixm:purpose>REMARK</aixm:purpose>
							<aixm:translatedNote>
								<aixm:LinguisticNote gml:id="ln05000">
									<aixm:note>marked=Unknown</aixm:note>
								</aixm:LinguisticNote>
							</aixm:translatedNote>
						</aixm:Note>
					</aixm:annotation>

Detailed marking indication

A set of more specific elements can be used addition to code marking information in AIXM for each individual part:

VerticalStructurePart.markingPattern
VerticalStructurePart.markingFirstColour
VerticalStructurePart.markingSecondColour

These details about markings are not required by PANS-AIM (but are described in ICAO Annex 14).

Example - Marked Obstacle With Details

The example blow shows the encoding of an marked obstacle more with details.

Marked obstacle with details

		<aixm:VerticalStructure gml:id="uuid.66e649c8-aaba-4fac-9432-7ee33f90e2d5">
			<gml:identifier codeSpace="urn:uuid:">66e649c8-aaba-4fac-9432-7ee33f90e2d5</gml:identifier>
			...
					<aixm:type>OTHER:WINDSOCK</aixm:type>
					...
					<aixm:markingICAOStandard>YES</aixm:markingICAOStandard>
					...
					<aixm:part>
						<aixm:VerticalStructurePart gml:id="V-af4ee6d6">
							...
							<!-- PANS-AIM table A6-2 only requires information if an obstacle is marked.
								Marking pattern and colour is not explicitly required by PANS-AIM. -->
							<aixm:markingPattern>HBANDS</aixm:markingPattern>
							<aixm:markingFirstColour>RED</aixm:markingFirstColour>
							<aixm:markingSecondColour>WHITE</aixm:markingSecondColour>
							...
					</aixm:part>
				...

Marking property in PANS-AIM

NOTE

The attribute "Marking" was erroneously omitted in ICAO PANS-AIM Table A6-2 when transferring the table from the previous edition of ICAO Annex 15 Appendix 8.

(ICAO) Obstacle Data Sets