Updates synchronisation across data sets

According to the Feature types allocation to data set, instances of the same AIXM features might appear in more than one digital AIS data set. For example, the AirportHeliport instance may appear in the AIP data set, in the Airport Mapping Data Set and, for convenience, even in Obstacle data sets for that airport/heliport.

ICAO Annex 15 explicitly requires in paragraph 5.1.2 that "when aeronautical data and aeronautical information are provided in multiple formats, processes shall be implemented to ensure data and information consistency between formats". This is complemented by a PANS-AIM provision (6.1.1) which indicates that "The same update cycle shall be applied to the Aeronautical Information Publication (AIP) and the digital data sets in order to ensure the consistency of the data items that appear in multiple aeronautical information products."

In order to comply with the above ICAO requirements, whenever there is a change in the properties of an AIXM feature, all data sets that include a copy of that feature shall be re-issued or updated. There is no "master version" of an AIXM feature and all data sets in which an AIXM feature appears are of equal relevance. It is not allowed to mention the change in just one of these data set updates and to assume that the same is applicable to all other data sets. 

Note: As most of the data contained in the AIP, Airport Mapping and Instrument Flight Procedures data sets is subject to the AIRAC cycle rules, this practically means that these digital data sets are expected to be re-issued/updated for the AIRAC cycle dates. The Obstacle data sets are not bound to the AIRAC cycle. However, an Obstacle data set that includes copies of "Conditional" AIXM features (such as AirportHeliport, RunwayDirection) might also need to be re-issued/updated on the AIRAC cycle dates if there is a change in the properties of these features.