Introduction

There is no singular and specific method that leads to successful creation of AMD. To create AMD, generally speaking two types of data are needed:

• Geographical data
• Aeronautical data 

Geographical data in essence is geospatial data (i.e. describing geographic features using geometries that can be referenced to earth locations) however not all aeronautical data is geospatial (e.g. a time schedule). Typically geographical data such as image maps are used to digitize AMD. Such geographical data, possibly following coordinate transformation, serve as geospatial reference. Using the geographical data the geospatial characteristics of AMD features within the aerodrome can then be captured in a geometry element of the resulting feature. Typical types of geometry are point, line and polygon. These notions are standardized in ISO 19107: Geographic Information - Spatial Schema. In the aeronautical information context all geospatial data shall be published in the WGS84 (EPSG 4326) Horizontal Reference System and the EGM-96 Vertical Reference System. 

Digitizing new AMD

When no geospatial aerodrome data exists, it is necessary to digitize the aerodrome features as AMD. Whilst not updated to the latest version of the AMDB industry standards, the EUROCAE ER-009 "Guidance Material for the Generation of Aerodrome Mapping Databases" contains relevant information on how to capture AMD features. In addition the EUROCONTROL Specification for the Origination of Aeronautical Data Edition 2.0 contains guidance on some of the AMD features (e.g. Runway Thresholds) and associated data capture requirements.

At a high level digitizing new AMD possibly includes the following steps:

• Data collection to capture necessary source material such as remote sensing images or aerial photographs used as the basis for data capturing
• Capturing of AMD features as vector data
• Transformation of AMD feature into target format

The capturing of AMD features requires making decisions on how to structure the data and which data coding rules to follow.

The structuring of data is in accordance with the AIXM 5.1 and the related AIXM 5.1 XML Schema based on the GML 3.2 format. When the EUROCAE ED-99D / RTCA DO-272D industry requirements need to be satisfied additional data format transformations apply based on the AMXM using GML3.2 or other GIS formats.

This supporting material does not cover the data coding rules that may apply. It is however worth mentioning the OGC discussion paper on “Use of Geography Markup Language (GML) for Aviation Data”, and the industry standards EUROCAE ED-99D / RTCA DO-272D for aerodrome mapping data. The data coding rules cover topics such as:

• Choice of geometry type used for each AMD feature coding
• Counter clockwise direction of encoding of vertices for outer boundaries of polygons
• Density of points for curved features
• Digitizing of features in one or more more geometries (e.g. splitting of Apron in several ApronElements)

Transforming existing geospatial data into AMD

When an aerodrome has geospatial data it may be transformed into a target AMD format. A typical use case is when the airport has layout drawings available in CAD files (e.g. DWG and DGN formats). It is then worth considering exploiting these files and transform their content into AMD features.

In this context it is important to note that such geospatial aerodrome data are frequently based on a local coordinate reference system. Therefore, transformation of the data into the WGS 84 coordination system is necessary.

Transformation of CAD files into AMD includes the following steps:

• CAD file CRS inspection
• CAD file geocoding in reference to earth location using control points and tools available in either CAD software or GIS software
• Transformation of coordinates into WGS84 (i.e. EPSG 4326)

More information on coordinate reference systems can be found here:

https://ext.eurocontrol.int/aixm_confluence/display/public/ACG/Coordinate+Reference+System