This information is historic and only relevant to X-Plane 10 and earlier
28 April 2009 Spec converted to this new format to support new web site (//data.x-plane.com). 12 July 2009 Minor typos fixed 14 July 2009 Minor errors in helipad spec fixed 6 Sept 2009 Added clearer examples of taxiway signs (submitted by Donald Good – thanks!) 1 Feb 2011 Clarified definitions of runway ends and thresholds
This specification (APT.DAT 850) is supported in X-Plane 8.50 until X-Plane 10.52. However, the significant new feature set in this file version was not fully supported until the release of X-Plane 8.61.
The prior specification for airport data was APT.DAT 810, which is recommended for X-Plane 8.10 – 8.60.
Support for Deprecated File Formats
The deprecated file specification (APT.DAT 810) is still supported. A large quantity of custom airport data exists only in this format. So airports defined according to this specification (APT.DAT 810) can be included in a file otherwise complying with the APT.DAT 850 specification.
Full 850 apt.dat File Spec
The full 850 apt.dat file specification can be found in this pdf document.