At what frequency should terrain and obstacle databases be updated?
Terrain and obstacles databases are not subject to major/planned changes, therefore, the principles and criteria applied in the maintenance of terrain and obstacle database should be specified in the DQR, including the frequency with which data products are updated. Depending on the intended use, the data/databases may be derived from the States published data (e.g. AIP) or from other sources (e.g. data services (DAT) providers). The data/databases may be updated based on the availability thereof, new sources that allow to improve their quality (e.g. accuracy or resolution), correction of detected errors, etc.
Please note that DAT providers are subject to Regulation (EU) 2017/373 (refer DAT.OR.100 and associated AMC/GM). In this context, when the databases (including terrain and obstacles) are used on certified aircraft application/equipment, (that support the flight operation where incorrect data leads to failures having at least minor or higher failure effect, excluding those databases approved as part of the type design of the aircraft) they should be produced and released by certified DAT providers.
In conclusion, the EU law does not address the frequency of terrain and obstacle database updates.