[WIP][TWY.CLS] Taxiway - closure

Definition

The temporary closure of movement areas established for the taxiing of aircraft or parts thereof. The closure can be total (any traffic is forbidden) or partial (with the exception of particular flights or aircraft categories).

Notes:

this scenario includes the closure of one or more full taxiways (could be all the taxiways at the airport);
this scenario includes closure of taxiway portions, provided the taxiway elements exist in the baseline data (see the specific assumptions for baseline data);
this scenario requires a graphical view of the taxiways and taxiways portions;
this scenario includes closure of a taxiway except for flight and/or aircraft categories;
more than one taxiway can be included only if the closure conditions (closed, exceptions, parts) applies equally to all taxiways. Otherwise, separate NOTAM shall be issued;
this scenario does not cover the temporary addition of a supplementary restriction to the taxiway availability, such as "closed for aircraft heavier than...". This will be dealt with in a separate scenario;
this scenario does not cover the temporary change of the operational hours of a taxiway;
this scenario does not cover the situation when the taxiway is operating normally, but subject to a reason for caution (such as "grass cutting in progress", etc.). Such situations will be covered in a different scenario.

Event data

The following diagram identifies the information items that are usually provided by a data originator for this kind of event. Note that the flight and/or aircraft categories branch is optional, but can be more than once.

EBNF Code

input = "airport designator" ["airport name"] ("taxiway designator" ["closed_taxiway_portion_input"]) {("taxiway designator" ["closed_taxiway_portion_input"])}\n
["closure reason"] {"excepted operation" ["PPR time" ["PPR details"]] [["aircraft"] ["flight"] {"other combination" ["aircraft"] ["flight"]}]} \n
"start time" "end time" [schedule] \n
{note}.

closed_taxiway_portion_input= "between" ("taxiway designator" | "runway designator" | "apron designator" | "stand designator") "and" ("taxiway designator" | "runway designator" | "apron designator" | "stand designator").

The table below provides more details about each information item contained in the diagram. It also provides the mapping of each information item within the AIXM 5.1.1 structure. The name of the variable (first column) is recommended for use as label of the data field in human-machine interfaces (HMI).

Data item	Description	AIXM mapping
airport designator	The published designator of the airport where the taxiway is located, used in combination with other elements in order to identify the taxiway(s) and/or taxiway portion(s) concerned.	AirportHeliport.designator
airport name	The published name of the airport where the taxiway is located, used in order to identify the taxiway(s) and/or taxiway portion(s) concerned.	AirportHeliport.name
taxiway designator	The published designator of the taxiway concerned. This information is used in combination with the airport designator/name in order to identify the affected taxiway(s) and/or taxiway portion(s)	Taxiway.designator
closed taxiway portion input	The portion of a published taxiway, specified using intersection elements between that taxiway and other taxiways, runways, aprons or stands. Note on closed taxiway portion input: The application shall allow graphical display and selection of taxiway(s) and/or taxiway portion(s) to be closed; The HMI application should support the operator in identifying all relevant taxiways, taxiways portions and other elements that are affected by the closure and have an impact on operations. As a general rule, if an intersection has to be closed, the Taxiways and/or TaxiwayElements linked to this intersection shall also be closed up to the intersection. The application shall support the operator in avoiding cul-de-sac/dead-end situations and warn on situations when other Taxiways and/or TaxiwayElements are leading to nowhere. The application shall suggest to either include them in the NOTAM or generate a new NOTAM, as appropriate. The operator shall be the one manually selecting all the portions to be closed.	TaxiwayElement(s) identified as explained in the Data Encoding Rule ER-01.
closure reason	The reason for the taxiway(s) and/or taxiway portion(s) closure.	Taxiway/ or TaxiwayElement/ManoeuvringAreaAvailability.annotation with propertyName="operationalStatus" and purpose="REMARK". Note that the property "warning" of the ManoeuvringAreaAvailability class is not used here because it represents a reason for caution when allowed to operate on the taxiway, not a reason for a closure.
flight	The description of one or more type of flight categories (such as "emergency") that are exceptionally permitted on the taxiway(s) and/or taxiway portion(s) during closure.	Taxiway/ or TaxiwayElement/ManoeuvringAreaAvailability/..Usage/../FlightCharacteristics
aircraft	The description of one or more aircraft (such as "helicopter") types that are exceptionally permitted on the taxiway(s) and/or taxiway portion(s) during its closure.	Taxiway/ or TaxiwayElement/ManoeuvringAreaAvailability/..Usage/../AircraftCharacteristicsNote that only certain properties can be used in this scenario. See data validation rules for details.
other combination	Another combination of aircraft/flight characteristics that are excepted from the closure.	Taxiway/ or TaxiwayElement/ManoeuvringAreaAvailability/..Usage/ConditionCombination.logicalOperator with its value set to "OR".
PPR time	The value (minutes, hours, days) of the advanced permission request associated with the permitted operation.	Taxiway/ or TaxiwayElement/ManoeuvringAreaAvailability/..Usage.priorPermission with uom attribute
PPR details	Additional information concerning the prior permission requirement.	Taxiway/ or TaxiwayElement/ManoeuvringAreaAvailability/..Usage.annotation with propertyName="priorPermission" and purpose="REMARK"
start time	The effective date & time when the taxiway closure starts. This might be further detailed in a "schedule".	Taxiway/ or TaxiwayElement/TaxiwayTimeSlice/TimePeriod.beginPosition, Event/EventTimeSlice.validTime/beginPosition and Event/EventTimeSlice.featureLifetime/beginPosition
end time	The end date & time when the taxiway closure ends.	Taxiway/ or TaxiwayElement/TaxiwayTimeSlice/TimePeriod.endPosition, Event/EventTimeSlice.validTime/endPosition and Event/EventTimeSlice.featureLifetime/endPosition also applying the rules for {{Events with estimated end time}}
schedule	A schedule might be provided, in case the taxiway is effectively closed according to a regular timetable, within the overall closure period.	Taxiway/ or TaxiwayElement/ManoeuvringAreaAvailability/Timesheet/...according to the rules for {{Schedules}}
note	A free text note that provides further details concerning the taxiway closure.	Taxiway/ or TaxiwayElement/ManoeuvringAreaAvailability.annotation according to the rules for encoding annotations

Assumptions for baseline data

It is assumed that Airport/Heliport BASELINE Timeslice covering the entire duration of the event exist and have been coded as specified in the Coding Guidelines for the (ICAO) AIP Data Set. In addition:

the information about the Taxiway already exists in the form of a Taxiway BASELINE TimeSlice, which contains as a minimum:
1. a designator,
2. a type (ex: EXIT, FASTEXT, etc), and
3. an association with the AirportHeliport;
If taxiway portions are concerned, it is assumed that they are encoded in BASELINE TaxiwayElements as suggested in the following diagram:

Fig.1 - Encoding of TaxiwayElements
It is assumed that each TaxiwayElements BASELINE have an annotation with purpose="OTHER:NOTAM_DESCRIPTION" and note describing their location as depicted below:

Fig. 2 - Encoding of TaxiwayElement description

E.g.
* a TaxiwayElement of type INTERSECTION would have a description such as “intersection TWY A and TWY B”,
* a TaxiwayElement of type NORMAL would have a description such as "between RWY 08L/26R and TWY J".
It is assumed that the following principles have been followed for the encoding of BASELINE Taxiway.availability and TaxiwayElement.availability data (as available in the BASELINE data):
1. the operationalStatus has the value "NORMAL" (meaning that the facility operates with nominal parameters) for all Taxiway.availability and/or TaxiwayElement.availability that are part of the BASELINE data;
2. operations that are explicitly permitted have been encoded as availability.ManoeuvringAreaAvailability.usage.ManoeuvringAreaUsage with type=PERMIT or type=CONDITIONAL (in case a PPR is necessary);
3. operations that are explicitly forbidden have been encoded as availability.ManoeuvringAreaAvailability.usage.ManoeuvringAreaUsage with type=FORBID;
4. if the taxiway is exclusively reserved for certain operations, then the ManoeuvringAreaAvailability that describes this condition contains only ManoeuvringAreaUsage elements with type=RESERV;
5. in case of conflicts:
  1. the usages of type FORBID take precedence over usages of type PERMIT or RESERVE;
  2. the usages of type PERMIT take precedence over the usages of type RESERVE;

Data encoding rules

The data encoding rules provided in this section shall be followed in order to ensure the harmonisation of the digital encodings provided by different sources. The compliance with some of these encoding rules can be checked with automatic data validation rules. When this is the case, the number of the encoding rule is mentioned in the data validation rule.

Identifier	Data encoding rule
ER-01	The temporary closure of a taxiway or portion thereof shall be encoded as: a new Event with a BASELINE TimeSlice (encoding=DIGITAL, scenario=TWY.CLS, version=2.0), for which a PERMDELTA TimeSlice may also be provided; and in case of complete taxiway closure: a TEMPDELTA TimeSlice for each affected Taxiway feature, for which the "event:theEvent" property points to the Event instance created above; in case of partial taxiway closure: a TEMPDELTA TimeSlice for each affected TaxiwayElement feature, for which the "event:theEvent" property points to the Event instance created above; Identification of the TaxiwayElements to be closed shall be done as follows: The application shall support the operator in order to automatically select the TaxiwayElements that are concerned with a graphical view. With reference to Fig. 1 included in the “Assumptions for baseline data” further up in the document, if the operator specifies that the portion concerned is between intersections A/B and A/D, then the application shall automatically select the portions highlighted. By default, intersections are supposed to remain open, unless explicitly specified as closed.
ER-02	In case of complete taxiway closure, one ManoeuvringAreaAvailability element having operationalStatus=CLOSED shall be included in each Taxiway TEMPDELTA.
ER-03	In case of taxiway portion closure, one ManoeuvringAreaAvailability element having operationalStatus=CLOSED shall be included in each TaxiwayElement TEMPDELTA selected to be closed.
ER-04	If the closure is "except for" flight and/or aircraft categories, all specified exceptions shall be encoded as ManoeuvringAreaUsage child elements with: either type=PERMIT, if there is no prior permission requirement; or type=CONDITIONAL, if a prior permission requirement was specified. Note that this implies that a "closed" taxiway can still allow certain particular operations.
ER-05	If a unique flight or aircraft are specified as being excepted, they shall be encoded as one ConditionCombination with logicalOperator="NONE".
ER-06	Each pair of flight and aircraft conditions specified as being excepted shall be encoded as one ConditionCombination with logicalOperator="AND".
ER-07	If the "other combination" branch is used, then a root ConditionCombinations element shall be encoded having logicalOperator="OR" and each pair of flight/aircraft included as a sub-condition (with logicalOperator="AND", see ER-07).
ER-08	If the closure is limited to a discrete schedule within the overall time period between the "start time" and the "end time", then this shall be encoded using as many as necessary timeInterval/Timesheet properties for the ManoeuvringAreaAvailability of all affected Taxiway or TaxiwayElement TEMPDELTA Timeslice(s). See the rules for Event Schedules.
ER-09	In accordance with the AIXM Temporality Concept, the ManoeuvringAreaAvailability elements included in the TEMPDELTA completely replace all the BASELINE ManoeuvringAreaAvailability information, during the TEMPDELTA time of applicability. Therefore, if the closure only concerns certain times, then the other times, when the Taxiway and/or TaxiwayElement eventually remains subject to the availability conditions of the Baseline data, shall be explicitly included in the TEMPDELTA. The calculation of the necessary additional ManoeuvringAreaAvailability elements to be included in the TEMPDELTA shall be automatically done by the applications implementing this specification. All ManoeuvringAreaAvailability elements that are copied from the BASELINE data for completeness sake shall get an associated Note with purpose=REMARK and the text="Baseline data copy. Not included in the NOTAM text generation". This is based on the current NOTAM practice which consists of including in the NOTAM only the changed information and not explicitly including the static data that remains valid during the NOTAM applicability.It is recommended that the input interface provides a "calendar" view of each taxiway element closure, enabling the operator to graphically check the availability at different times, such as in the example below: In the calendar view, the Baseline information that remains valid during the Event validity time shall be visibly identified from the information that is specific to the Event, for example by using a different colour fill pattern.
ER-11	If there exists a single Taxiway leading to an Apron and/or ApronElement and if the Taxiway closure makes the Apron unavailable, then a consequence APN.CLS scenario shall also be encoded for the relevant Apron feature and shall include a reference to the current event with role 'causeEvent'.

Examples

Following coding examples can be found on GitHub (links attached):