Airport data (apt.dat) update
FlightGear uses the same airport data as X-Plane, in the apt.dat format. This data has been updated a lot the last years. FlightGear however uses a deprecated data format (810 format) and needs to switch to the newer 850 format in order to enjoy all the updates.
Problems and questions
- We cannot just update the scenery as FlightGear contains a "hard-wired" apt.dat in fgdata. Simply updating this file does not change the airport visuals, but internally, runway positions and frequencies will. This will result in a mismatch when using old scenery.
- The xml files that can be put into every scenery folder (icao.threshold.xml and alike) are a small start to adress this issue, but they quickly come to a limit in cases where there are new runways/new airports or just a rename of a single runway, compared to the apt.dat file in fgdata.
- In contrast to X-Plane we do not create our airports on-the fly on startup of FlightGear. So distributing a huge apt.dat 850 file with approx. 90% of the lines being bezier curves definitions might just be a waste of ressources. (We should also consider that the curves can be useful for drawing airport maps, eg. like the currently existing groundradar or other types of maps)
- Apt 850 comes with an integrated signs definition for each airport, while FlightGear is currently shipping them via STG files.
- Some airports were enhanced for FlightGear use but never committed to Robin Peel DB.
- Some airports were created in FlightGear but just still don't exist in X-Plane.
- Workflow has to be clarified: a user wanting to update its airport layouts should download the latest data at this place (to be defined), update the data (in WorldEditor), send it to this address. Changes will be updated in FlightGear scenery release every x months.
Proposals and solutions
- Enhance the FlightGear scenery xml code to become independent from any apt.dat file, enhance the xml parameters to make a big apt.dat file in fgdata obsolete and thus distribute scenery data where it belongs: into the scenery folder.
- There has been an attempt to expand the xml per airport into a data file with almost all available data from apt.dat. The taxiways have been kept out, but it covers all the rest of the data plus some additional data like threshold coords etc. This data is produced with recent X-Plane apt.dat and can be updated with every new X-Plane data cycle, goes along the current X-Plane data specs. Example: http://code.google.com/p/flightgear-world-scenery/source/browse/data/xplane-single/C/CA69.xml
- Sign definitions from FlightGear can be written out to an apt.dat 850 format file (they are all tagged with the appropriate airport) to a 850 format text file (multiple, per airport?). Then should be submitted to Robin. TerraGear creates stg files with SIGN entries when creating the terrain.
- The enhanced Flightgear 810 airports are currently subject to review by papillon81. Layouts that are still not available in the X-Plane apt.dat release will be submitted, double layouts (available in both FlightGear 810 and X-Plane 850) will be compared and a decision will be made.
- Users reporting wrong/missing/obsolete/whatever airports should be pointed to the latest apt.dat X-Plane release. This is always the reference from now on. They can search the file for the ICAO code and use WED to load a layout and take a look at it (no need to build TerraGear for this). An aid for such cases would be a web frontend that builds apt.dat layouts submitted in text form and outputs them either as download (btg.gz) or for online viewing (WebGL).
Airports layout tobedone
Some of us have updated 8.10 layouts in FlightGear. We have to make sure their work is not lost. Either the 8.50 format layout is better, and then it will automatically be used. Either the 8.10 updated layout is better. Then, it has to be converted to the 8.50 format with WorldEditor and sent to Robin Peel database. Hereunder is a list of those airports which got updated. Please check whether the 8.50 data is better than the 8.10, and update the list below. Thanks.
| FlightGear data
better than Robin's?
|ICAO||8.10||8.50||Converted to 8.50||Sent to Robin Peel||Official apt.dat was updated|