The Event class has two associations that enable coding an operational location of the event in relation with Airspace and/or AirportHeliport as shown in the diagram to the right,
Such Events might required several NOTAM to be published. The reason is primarily related to how NOTAM are currently selected for inclusion in Pre-flight Information Bulletins (PIB), based on the item A (airport code or FIR code). It has to be assured that the NOTAM appear correctly in the relevant en-route and airport PIB and that duplication in PIB (e.g. in the FIR) are avoided. Typical events are:
- airspace activities in the vicinity of airports;
- airspace activities affecting more than one FIR;
- outages of navigation aids affecting serving several airports and/or FIR;
- establishment of ATS airspace serving more than one airport;
- obstacles in the vicinity of several airports
For most Digital NOTAM scenarios the location of the Event is limited to a single airport or a single FIR and it can be deduced with simple queries, either based on the feature instance associations on or geographical queries. Therefore, the two associations with AirportHeliport and Airspace are used only for exceptional situations, when the event might have an operational impact beyond the direct location of the features affected and the associations Event - Airspace ('FIR') and Event - AirportHeliport cannot be derived fully automatically from the feature data.
- in the RWY.CLS scenario the FIR and the item A can be fully automatically be derived from the geographical location of the airport. There is no need to code the association between Event and the AirportHeliport concerned;
- in the SAA.NEW scenario, if the airspace reservation/restriction has an operational impact on some specific airports or on neighboring FIR, then all Event - Airspace/AirportHeliport associations should be coded explicitly. The NOTAM generation would use directly these associations,
For each scenario, an explicit statement is inserted in the coding rules indicating if necessary to consider explicitly coding the associations between Event and Airspace or AirportHeliport.