AIXM (Aeronautical Information Exchange Model) and FME
Aeronautical Information Exchange Model (AIXM) format was developed by EUROCONTROL, the European Organisation for the Safety of Air Navigation, to allow aeronautical data standardization and exchange. The role of AIXM is to enable systems to exchange aeronautical information in the form of XML-encoded data. AIXM is the XML representation of the Aeronautical Information Conceptual Model (AICM) data model.
Below are some excellent reference sites for additional AIXM/AICM information:
US Federal Aviation Authority
www.faa.gov/aixm 
Euro Control
www.eurocontrol.int/aim/public/standard_page/interop_aicm.html
The AICM 4.5 Entity Relationship Report can be downloaded from the FAA site.
AIXM is a format much like GDF or VPF, in that it is quite a complex format to both read and write, and almost certainly fairly sophisticated processing is necessary before the output can be created that is suitable for conventional GIS. AIXM is an extra cost premium level plug-in for FME. Safe Software Inc. would recommend that some of our professional services time be purchased as part of any purchase of the AIXM reader or writer.
When reading AIXM, FME will interpret the XML document and, wherever possible, create an appropriate geometry for features. However, relationships between AIXM entities are complex. In most cases a workspace has to be configured to join several features together to form complete AICM features. For example, to create airspace features, several airspace border vertices may have to be joined together. A single airspace border vertex may also refer to several geo-border vertices. So a single airspace may be a combination of airspace border vertices & geo-border vertices. In addition, the straight line vectors between the airspace border vertices have to be converted into great circles, rhumblines, arcs, etc. depending on the vertex type code.
The first issue is to know what version of AIXM you need. FME currently supports AIXM 4.5. Support for version 5.0 is under development. AIXM 5.0 is quite different as it is a GML representation of the AIXM documents - AIXM 3.3 and 4.0 and 4.5 are XML documents.
How complex the FME Workspace configuration will be depends largely on how closely the source data schema reflects the AIXM schema. Conversely, when writing AIXM to a GIS, the complexity of the workspace will be dictated by the differences between the AIXM & destination data models.
Please contact us to find out how Safe Software can help customize a solution to meet your needs.