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The temporary closure of area(s) intended to accommodate aircraft for purposes of loading or unloading passengers, mail or cargo, fuelling, parking or maintenance. The closure can be total (any traffic is forbidden) or partial (with the exception of particular operations, flights or aircraft categories).


  • this scenario includes the closure of one or more aprons (could be all the aprons at the airport);
  • more than one apron can be included only if the closure conditions (closed, exceptions, parts) applies equally to all. Otherwise, separate NOTAM shall be issued;
  • this scenario also includes closure of an apron except for flight and/or aircraft categories;
  • this scenario does not include closure of apron portions, defined by reference to intersection with other airport surfaces. For this refer to APE.CLS scenario.
  • this scenario does not cover the temporary addition of a supplementary restriction to the apron 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 an apron or apron element;
  • this scenario does not cover the situation when the apron and/or apron element 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.

input = "airport designator" ["airport name"] ("apron name") {("apron name")}\n
["closure reason"] {"except" ["PPR time" ["PPR details"]] [["aircraft"] ["flight"] {"other combination" ["aircraft"] ["flight"]}]} \n
"start time" "end time" [schedule] \n

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


AIXM mapping

airport designator

The published designator of the airport where the apron is located, used in combination with other elements in order to identify the apron(s) concerned.


airport name

The published name of the airport where the apron is located, used in order to identify the apron(s) concerned.

apron name

The published name of the apron concerned. This information is used in combination with the airport designator/name in order to identify the affected apron.

closure reason

The reason for the apron(s) closure.

Apron/ApronAreaAvailability.annotation with propertyName="operationalStatus" and purpose="REMARK". Note that the property "warning" of the ApronAreaAvailability class is not used here because it represents a reason for caution when allowed to operate on the apron, not a reason for a closure.


The description of one or more type of flight categories (such as "emergency") that are exceptionally permitted on the apron(s) during closure.



The description of one or more aircraft (such as "helicopter") types that are exceptionally permitted on the apron(s) during its closure.

Apron/ApronAreaAvailability/..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.

Apron/ApronAreaAvailability/..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.

Apron/ApronAreaAvailability/..Usage.priorPermission with uom attribute

PPR details

Additional information concerning the prior permission requirement.

Apron/ApronAreaAvailability/..Usage.annotation with propertyName="priorPermission" and purpose="REMARK"

start time

The effective date & time when the apron closure starts. This might be further detailed in a "schedule".

Apron/ApronTimeSlice/TimePeriod.beginPosition, Event/EventTimeSlice.validTime/beginPosition and Event/EventTimeSlice.featureLifetime/beginPosition

end time

The end date & time when the apron closure ends.

Apron/ApronTimeSlice/TimePeriod.endPosition, Event/EventTimeSlice.validTime/endPosition and Event/EventTimeSlice.featureLifetime/endPosition also applying the rules for {{Events with estimated end time}}


A schedule might be provided, in case the apron is effectively closed according to a regular timetable, within the overall closure period.

Apron/ApronAreaAvailability/Timesheet/...according to the rules for {{Schedules}}


A free text note that provides further details concerning the apron closure.

Apron/ManoeuvringAreaAvailability.annotation according to the rules for encoding annotations

Assumptions for baseline data

It is assumed that AirportHeliport 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:

  1. the information about the Apron already exists in the form of a Apron BASELINE TimeSlice, which contains as a minimum:
    1. a nameand
    2. an association with the AirportHeliport;

  2. It is assumed that the following principles have been followed for the encoding of BASELINE Apron.availability (as available in the BASELINE data):
    1. the operationalStatus has the value "NORMAL" (meaning that the facility operates with nominal parameters) for all Apron.availability that are part of the BASELINE data;
    2. operations that are explicitly permitted have been encoded as availability.ApronAreaAvailability.usage.ApronAreaUsage with type=PERMIT or type=CONDITIONAL (in case a PPR is necessary);
    3. operations that are explicitly forbidden have been encoded as availability.ApronAreaAvailability.usage.ApronAreaUsage with type=FORBID;
    4. if the taxiway is exclusively reserved for certain operations, then the ApronAreaAvailability that describes this condition contains only ApronAreaUsage 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.


Data encoding rule


The temporary closure of an apron shall be encoded as:

  • a new Event with a BASELINE TimeSlice (encoding=DIGITAL, scenario=APN.CLS, version=2.0), for which a PERMDELTA TimeSlice may also be provided; and
  • a TEMPDELTA TimeSlice for each affected Apron feature, for which the "event:theEvent" property points to the Event instance created above;
ER-02one ApronAreaAvailability element having operationalStatus=CLOSED shall be included in each Apron TEMPDELTA.


If the closure is "except for" flight and/or aircraft categories, all specified exceptions shall be encoded as ApronAreaUsage 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" apron can still allow certain particular operations.


If a unique flight or aircraft are specified as being excepted, they shall be encoded as one ConditionCombination with logicalOperator="NONE".


Each pair of flight and aircraft conditions specified as being excepted shall be encoded as one ConditionCombination with logicalOperator="AND".


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).


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 ApronAreaAvailability of all affected Apron TEMPDELTA Timeslice(s). See the rules for Event Schedules. 


In accordance with the AIXM Temporality Concept, the ApronAreaAvailability elements included in the TEMPDELTA completely replace all the BASELINE ApronAreaAvailability information, during the TEMPDELTA time of applicability. Therefore, if the closure only concerns certain times, then the other times, when the Apron and/or ApronElement eventually remains subject to the availability conditions of the Baseline data, shall be explicitly included in the TEMPDELTA. The calculation of the necessary additional ApronAreaAvailability elements to be included in the TEMPDELTA shall be automatically done by the applications implementing this specification.

All ApronAreaAvailability 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 apron 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.


If there exists aircraft stands on the closed Apron and if the apron closure makes the aircraft stand unavailable, then a consequence STAND.CLS scenario shall also be encoded for the relevant AircraftStand feature and shall include a reference to the current event with role 'causeEvent'. 


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

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