Any XML format is potentially useful for data ingestion for aeronautical purposes. The key here is the questions:
Is the vertical datum supplied useful for extracting height information or elevation information that I need? (if not can I convert it safely to what I need).
Are there features in the landxml that is useful for me?
Is the horizontal datum suitable for transformation to match up with my other aeronautical datasets for facilities, obstacles and or terrain?
I would need to look further into the specifics to see what might usefully be transformed.
I honestly need to say I will investigate further and if any links to Land XML is provided the better. Now for sure out of the box it will not be a one to one match with AIXM feature attributes so some sort of ETL will need to be done if information is to be stored in the AIXM DB or to produce Terrain and Obstacle datasets.
There is a filter for import data in the New Zealand LandXML format, also there are general filters for MAP (AutoCAD and Microstation) and other GIS vendors.