Basic Data for Runway Direction (FATO Direction)

Introduction

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

designator, true bearing, threshold, ...

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

The RunwayDirection class is used for coding the data of one of the two landing and take-off directions of a runway for which attributes like Take-off Run Available (TORA), Take-off Distance Available (TODA), Landing Distance Available (LDA), etc. may be defined.

A Runway can have one or more related runway directions. In general, it will have two runway directions. A runway direction will be associated with maximum one runway.

For each runway direction, at least a designator and its true bearing has to be specified. Also, a magnetic bearing may be specified.

Furthermore, also the related threshold (i.e. reference to RunwayCentrelinePoint) has to be encoded.

The RunwayDeclaredDistance class is used to code TODA, TORA, ASDA, LDA, rejected TODA, etc. and also a displaced threshold.

Runway Direction Designator

The RunwayDirection.designator is the full textual designator of the landing and take-off direction. 

Examples: '09', '09L', '09R', '09C', '09T', etc.

It may carry up to 16 characters. However, the naming convention of the RWY direction designator shall comply with that of the RWY designator (see also Basic Data for Runway (and FATO)).

Example: RWY designator is specified as '08L/26R', thus the RWY direction designators shall be '08L' and '26R' respectively.

See also coding rules below.

Runway Bearing

For each RunwayDirection, a trueBearing shall be defined. The true bearing is the measured angle between the runway direction and True North at a given position. For the true bearing, also the trueBearingAccuray shall be provided.

In addition, a magneticBearing may also be coded. The magnetic bearing is the measured angle between the runway direction and Magnetic North at a given position.

The figure below shows an example for a runway bearing for runway direction 08L and 26R.

Threshold

In AIXM 5, the RunwayCentrelinePoint class is used to encode operationally significant positions on the centre line of a runway direction. A typical example is the runway threshold.

ICAO, Annex 14, Volume 1 defines the threshold:

The beginning of that portion of the runway usable for landing.

The threshold centre line point for a runway direction is not necessarily the physical start of the runway and may be displaced for operational reasons.

In case of runway threshold, the RunwayCentrelinePoint.role is assigned the value 'THR' (threshold) or 'DISTHR' (displaced threshold, see coding guidelines further down on this page).

Consequently, the geographical location for the threshold or displaced threshold is coded using the ElevatedPoint class. In general, a threshold will have an assigned elevation value.

If appropriate, the geoidUndulation at a threshold position will be coded.

For the elevation and the geoidUndulation, a verticalAcurracy shall be provided.

A threshold is related with at maximum one RunwayDirection.

A RunwayCentrelinePoint may have a designator, used to uniquely identify it at an aerodrome/heliport.

The figure below shows an example for a threshold for runway direction 08L and a displaced threshold for 26R. The coded role for 08L will be 'THR' and for 26R 'DISTHR'.

To encode terminal procedures (SID, STAR, IAP) it may be necessary to reference the runway centre line point (especially the THR) as procedure fix. Therefore, the RunwayCentrelinePoint can be encoded as DesignatedPoint.

Displaced Threshold

A threshold displacement is declared from the physical start of the runway direction. The position of the displaced threshold is encoded as a RunwayCentrelinePoint with the role equal-to 'DISTHR'. A runway direction cannot have both a THR and a DTHR, as it would be unclear which one is used for landings.

The actual displacement distance can be coded as DeclaredDistance.type equal-to 'DTHR'.

		...		
				<aixm:RunwayCentrelinePointTimeSlice gml:id="RCP_EADD_27R_DISTHR">
					...
					<aixm:role>DISTHR</aixm:role>
					<aixm:location>
						<aixm:ElevatedPoint srsName="urn:ogc:def:crs:EPSG::4326" gml:id="RCPP1">
							<gml:pos>52.377736 -31.930628</gml:pos>
							<!-- ICAO AIP specimen data of DONLON have altered, a displaced THR (of 300m) has been calculated-->
							<aixm:horizontalAccuracy uom="M">1</aixm:horizontalAccuracy>
							<aixm:elevation uom="M">16.5</aixm:elevation>
							<aixm:geoidUndulation uom="M">11.5</aixm:geoidUndulation>
							<aixm:verticalAccuracy uom="M">0.25</aixm:verticalAccuracy>
						</aixm:ElevatedPoint>
					</aixm:location>
					<aixm:onRunway xlink:href="urn:uuid:b802d439-e9f3-49f9-96e1-0153b837e113"
						xlink:title="RDN_EADD_27R"/>
					...
					<aixm:associatedDeclaredDistance>
						<aixm:RunwayDeclaredDistance gml:id="rdd015">
							<aixm:type>DTHR</aixm:type>
							<aixm:declaredValue>
								<aixm:RunwayDeclaredDistanceValue gml:id="rddv015">
									<aixm:distance uom="M">300</aixm:distance>
									<aixm:distanceAccuracy xsi:nil="true" nilReason="unknown"/>
								</aixm:RunwayDeclaredDistanceValue>
							</aixm:declaredValue>
						</aixm:RunwayDeclaredDistance>
					</aixm:associatedDeclaredDistance>
					<aixm:associatedDeclaredDistance>
						<aixm:RunwayDeclaredDistance gml:id="rdd0141">
							<aixm:type>LDA</aixm:type>
							<aixm:declaredValue>
								<aixm:RunwayDeclaredDistanceValue gml:id="rddv0141">
									<aixm:distance uom="M">2500</aixm:distance>
								</aixm:RunwayDeclaredDistanceValue>
							</aixm:declaredValue>
						</aixm:RunwayDeclaredDistance>
					</aixm:associatedDeclaredDistance>
					...
				</aixm:RunwayCentrelinePointTimeSlice>
	...

Other runway centre line points

Apart from the threshold position, the ICAO Annex 15 also requires the publication of the runway end, in each of landing and take-off direction.These can be encoded as RunwayCentrelinePoint with role='END'.

The following table provides a complete list of values the RunwayCentrelinePoint.role attribute can take:

Start of take-off run positions designation

Many AIP (as in the example shown above) provide a designator for the start of take-off run positions along the runway centerline. In addition, when developing the Digital NOTAM scenarios for declared distance changes, it became clear that such designators would greatly simplify the coding/decoding scenarios.  They would allow to identify the point concerned by in the situation where such distances are changes, both when the data is provided by the originator and in the Event/NOTAM text. 

Therefore, the RunwayCentrelinePoint.designator is required in for any RunwayCentrelinePoint that has a role different from 'THR' or 'DISTHR' and that has associated DeclaredDistance. For the 'THR'/'DISTHR' it is not important to also have a designator as their role is sufficient to identify them. However, for uniformity sake, they could also be allocated a designator in the form "THR 25R", for example.

Coding Examples

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

References