[2.0] [SFC.CON] Surface condition report (SNOWTAM)

Text SNOWTAM production rules

This section provides rules for the automated production of the text NOTAM message items, based on the AIXM 5.1 data encoding of the Event. Therefore, AIXM specific terms are used, such as names of features and properties, types of TimeSlices, etc:

• the abbreviation RWY.BL. indicates that the corresponding data item must be taken from from the valid BASELINE of the Runway on which the Event occurs;
• the abbreviation RDN.BL. indicates that the corresponding data item must be taken from from the valid BASELINE of the RunwayDirection with the lower designator number associated with the Runway on which the Event occurs;
• the abbreviation TWY.BL. indicates that the corresponding data item must be taken from the valid BASELINE of the Taxiway on which the Event occurs;
• the abbreviation APN.BL. indicates that the corresponding data item must be taken from the valid BASELINE of the Apron on which the Event occurs;
• the abbreviation AHP.BL. indicates that the corresponding data item must be taken from the valid BASELINE of the AirportHeliport associated with a Runway on which the Event occurs;
• the abbreviation AHP.TD. indicates that the corresponding data item must be taken from the AirportHeliport TEMPDELTA that was created for the Event;
• the abbreviation RWY.TD. indicates that the corresponding data item must be taken from the Runway TEMPDELTA that was created for the Event;
• the abbreviation TWY.TD. indicates that the corresponding data item must be taken from the Taxiway TEMPDELTA that was created for the Event;
• the abbreviation APN.TD. indicates that the corresponding data item must be taken from the Apron TEMPDELTA that was created for the Event;

In general, the ICAO DOC 8126, OPADD rules and ICAO Doc 10066 shall be followed. These have not been copied in this document in order to avoid duplication with those documents. Only instructions that are specific to the AIXM encoding of this event are stated here. 

The item identifying letter (A, B, etc.) used below correspond to the SNOWTAM format table contained in the ICAO DOC 10066, PANS-AIM, Appendix 4. The item identifiers themselves are not included in the SNOWTAM message, but are provided for convenience and easy mapping with the description of the SNOWTAM format in PANS-AIM.

template =  "Item A" \n
"(1)" "\n" "Item B" "Item C" "Item D" ["Item E"] ["Item F"] "Item G" ["Item H"]  {"(1)" "\n" "Item B" "Item C" "Item D" ["Item E"] ["Item F"] "Item G" ["Item H"]} \n
"(2)" {"Item I" "."} {"Item J" "."} {"Item K" "."} {"Item L" "."} {"Item M" "."} {"Item N" "."} {"Item O" "."} {"Item P" "."} \n
{"Item R" "."} {"Item S" "."} {"Item T" "."} .

Item A 

The item A shall be generated according to the general production rules for item A using the Event.concernedAirportHeliport, 

(1) Aeroplane performance calculation section

If more than one RWY.TD is associated with the Event, then repeat this branch for each Runway (RWY.BL and RWY.TD)

Item B 

Item B shall contain the RWY.TD.overallContaminant.observationTime formatted according to the following syntax: mmddhhmm (month-day-hour-minutes).

Item C

Item C shall contain the RDN.BL.designator with the lower number. associated with the RWY.BL that is being processed. For example, "09L" shall be inserted, not "27R".

Item D 

The following syntax shall be used for item D:

RWY.TD.RunwaySectionContamination.frictionEstimation for section='1_THIRD'/RWY.TD.RunwaySectionContamination.frictionEstimation for section='2_THIRD'/RWY.TD.RunwaySectionContamination.frictionEstimation for section='3_THIRD' (e.g. 5/5/5).

The RWY.TD.RunwaySectionContamination.frictionEstimation for each runway third shall be decoded as follows:

Item E

Insert here the RWY.TD.RunwaySectionContamination.proportion values for each runway third. The following syntax shall be used:  

RWY.TD.RunwaySectionContamination.proportion for section='1_THIRD' / RWY.TD.RunwaySectionContamination.proportion for section='2_THIRD' / RWY.TD.RunwaySectionContamination.proportion for section='3_THIRD' (e.g. 100/100/100).

If RWY.TD.RunwaySectionContamination.proportion is not reported for a runway third (xsi:nil='True', nilReason='inapplicable'), then "NR" shall be inserted as value for the appropriate runway third. (e.g. 50/50/NR).

Item F

Insert here the RWY.TD.RunwaySectionContamination.depth for each runway third, in millimeters, formatted with two digits (e.g. "03" for 3 mm). The following syntax shall be used: 

RWY.TD.RunwaySectionContamination.depth for section='1_THIRD' / RWY.TD.RunwaySectionContamination.depth for section='2_THIRD' / RWY.TD.RunwaySectionContamination.depth for section='3_THIRD' (e.g. 03/04/03)

If RWY.TD.RunwaySectionContamination.depth is not reported for a runway third (xsi:nil='True', nilReason='inapplicable'), then "NR" shall be inserted as value for the appropriate runway third. (e.g. 03/03/NR).

Item G

Insert here the RWY.TD.RunwaySectionContamination/SurfaceContaminationLayer.type for each runway third. The following syntax shall be used: 

RWY.TD.RunwaySectionContamination/SurfaceContaminationLayer.type for section='1_THIRD' / RWY.TD.RunwaySectionContamination/SurfaceContaminationLayer.type for section='2_THIRD' / RWY.TD.RunwaySectionContamination/SurfaceContaminationLayer.type for section='3_THIRD'

If no RWY.TD.RunwaySectionContamination/SurfaceContaminationLayer.layerOrder is provided, the RWY.TD.RunwaySectionContamination/SurfaceContaminationLayer.type for each runway third shall be decoded as follows:

If RWY.TD.RunwaySectionContamination/SurfaceContaminationLayer.layerOrder is provided, insert the condition description for the appropriate runway third decoded as follows: 

If RWY.TD.RunwaySectionContamination/SurfaceContaminationLayer.type is not reported for a runway third (xsi:nil='True', nilReason='inapplicable'), "NR" shall be inserted as value for the appropriate runway third. 

Item H 

If provided, insert here the numerical value (in meters) from RWY.TD.overallContaminant/RunwayContamination.clearedWidth (e.g. "35").

(2) Situational awareness section

Item I 

If RWY.TD.overallContaminant/RunwayContamination.clearedLength is provided, Item I shall contain:

"RWY" followed by the applicable runway designator numbers (if multiple, they should be inserted from the lowest to the highest) of the RWY.BL.designator for which the assessment is concerned followed by "reduced to" and the RWY.TD.overallContaminant/RunwayContamination.clearedLength (without units of measurement)

Note: PANS-AIM indicates that item I does not need to be provided if this information is published through a separate NOTAM for declared distance changes (RDD.CHG scenario).

Item J 

Note:  Drifting Snow in SNOWTAM refers to the whole airport, however for large airports with several runways where drifting snow could exist in one or some runways (not all), item J) might be reported with relevant runway designator, e.g. RWY 08 DRIFTING SNOW

1. If there exist AHP.TD.contaminant/AirportHeliportContamination.layer/SurfaceContaminationLayer.type equal to 'OTHER:DRIFTING_SNOW' then in Item J the text to be inserted is "Drifting snow";
2. Irrespective of the check of condition 1, if there is any RWY.TD.overallContaminant/RunwayContamination.layer/SurfaceContaminationLayer.type equal to 'OTHER:DRIFTING_SNOW', Item J may contain: "RWY" followed by the applicable lower runway designator number of the RWY.BL.designator for which the assessment is concerned followed by "drifting snow". If multiple RWY.TD are concerned, each text shall be listed and separated by "."

Item K 

If there is any RWY.TD.overallContaminant/RunwayContamination.layer/SurfaceContaminationLayer.type equal to 'OTHER:LOOSE_SAND' then Item K shall contain:

"RWY" followed by the RDN.BL.designator (lower runway designator number) followed by "loose sand". If multiple RWY.TD are concerned, then each one shall be listed and separated by "."

Item L 

If there is any RWY.TD.overallContaminant/RunwayContamination.layer/SurfaceContaminationLayer.type equal to 'OTHER:CHEMICAL_TREATMENT' then Item L shall contain:

"RWY" followed by the RDN.BL.designator (lower runway designator number) followed by "chemically treated". If multiple RWY.TD are concerned, each one shall be listed and separated by  "."

Item M 

If RWY.TD.overallContaminant.criticalRidge is provided and Ridge.annotation with propertyName='distance', purpose='DESCRIPTION' and note='distance measured from runway centerline' is present, item M shall be decoded as follows:

item_M = "RWY" "RDN.BL.designator" "snowbank" "RWY.TD.overallContaminant.criticalRidge.side(4)" "RWY.TD.overallContaminant.criticalRidge.distance(5)" "FM CL".

Item N 

If any TWY.TD.contaminant/TaxiwayContamination.annotation.Note with purpose='REMARK' , propertyName='criticalRidge' and note="Snowbanks present on the taxiway" is provided, item N shall contain:

"TWY" followed by the TWY.BL.designator followed by "Snowbank". If multiple TWY.TD exist, each shall be listed separately and followed by "/".

Item O 

If there exists any RWY.TD.overallContaminant/RunwayContamination.annotation.Note with purpose='REMARK', propertyName='criticalRidge' and note="Snowbanks present adjacent to the runway" insert here:

"RWY" followed by RDN.BL.designator (lower runway designator number) followed by "ADJ snowbanks". If multiple RWY.TD are concerned, each each shall be listed separately and followed by "."

Item P 

If there exists any TWY.TD.TaxiwayContamination.frictionEstimation='POOR' insert here:

"TWY" followed by TWY.BL.designator followed by "Poor".

If there exists any AirportHeliportContamination.annotation with purpose='REMARK' and note="ALL TWYs poor" insert here "All TWYs poor".

Item R 

If there exists APN.TD.ApronContamination.frictionEstimation='POOR' insert here:

"Apron" followed by APN.BL.name followed by "Poor".

Note: For the potential applications/implementations - the word "APRON" may appear twice depending on the coded APN.BL.name (e.g. APRON MILITARY APRON or APRON APRON A1). Caution shall be exercised for NOTAM production to avoid possible duplications.

If there exists any AHP.TD.AirportHeliportContamination.annotation with purpose='REMARK' and note="All aprons poor" insert here "All aprons poor".

Item S 

If provided, insert here the RWY.TD.areaContaminant.RunwaySectionContamination.frictionCoefficient for each runway third. The following syntax shall be used:  
"RWY" RDN.BL.designator followed by
RWY.TD.areaContaminant.RunwaySectionContamination.frictionCoefficient for section='1_THIRD' / RWY.TD.areaContaminant.RunwaySectionContamination.frictionCoefficient for section='2_THIRD' / RWY.TD.areaContaminant.RunwaySectionContamination.frictionCoefficient for section='3_THIRD' followed by RWY.TD.overallContaminant.RunwayContamination.frictionDevice.  (e.g. "RWY 09L 0.23/0.25/0.30 Skiddometer (high-pressure tire)")

The frictionDevice shall be decoded as follows:

If RWY.TD.areaContamination.RunwaySectionContamination.frictionCoefficient is not reported for one of the runway thirds (xsi:nil='True', nilReason='inapplicable'), "NR" shall be inserted. 

Item T

AHP.TD.contaminant.AirportHeliportContamination.annotation.Note, other than the Note specified in item R above. shall be translated into free text according to the rule for decoding annotations.

Event Update

The validity of a SNOWTAM is 8h. If a new Event with scenario=SFC.CON is to be released for the same AirportHeliport before the expiry of the valid one, the first Event validity shall be updated according to the Data encoding rules described in Event update or cancellation. The gml:validTime.TimePeriod.endPosition and gml:featureLifetime.TimePeriod.endPosition of the first Event shall be given the value of the gml:validTime.TimePeriod.beginPosition of the new Event. 

No "SNOWTAM R/C" message is defined by ICAO. The new SNOWTAM is considered as valid and de-facto replaces the previous SNOWTAM message for the same airport.