Why Are Airports Sometimes Missing in Output Files?

Actually, they aren't really missing -- they have just had the airport attribute removed (in .DAT or .STX output files) or converted to style "Unknown" (in .CUP) output files.  Note that, depending on user settings, SeeYou or SeeYou Mobile may not display points that are set to the Unknown style.


The system checks each point that is listed as an airport in input turnpoint files to make sure it is listed in the FAA's airport database.  In cases where the FAA airport ID is not explicitly given in the file, the system tries to find one at the same or nearby location with a similar name.  If this check fails, the airport attribute is removed, and/or the point is set to style "Unknown" as described above.

The purpose of this check is to filter closed airports from output files so that pilots won't rely on them anymore. It is a safety feature. Unfortunately, airport closures are very common events.

Note:  the system will log these changes in the log file.  It is a great idea to always check the log file to look for unexpected changes.


Assuming you don't really want the airport attribute to change, there are several possible workarounds:

  1. If you just want to do a file conversion without the system updating any of your data, select the "Do not add or update airports in the output files" option from the drop-down list, right under the box where you entered the turnpoint file name. The system will leave your airports alone.  This is the option you would select if you were, for example, converting a file for an area outside the US.
  2. If the problem is that the airport has stale name or position information that is causing a problem in the database lookup, edit your turnpoint file manually and correct the name or position.
  3. If your input file is a .CUP file, you can change the style to "Outlanding Place".  In .STX or .DAT input files, you can remove the "A" attribute and replace it with the "L" attribute.
  4. Finally, if you really wish to retain the airport attribute on a point that does not exist in the FAA database, there is a way to force that.  For an input file in CUP format, edit the comment for the point such that it begins with "PRI-A:" (for a private airport) or "PUB-A" for a public airport.  This amounts to telling the system that the point is an airport, but does not have an FAA identifier code.  See the explanation of comment formats in Comments in .CUP Output Files for more information.  In STX files, you can set the value in the "ICAO" comment to an asterisk for the same effect.

One other hint:  if you are updating an old turnpoint file, remember to set bounding information for airport addition.  You can either set a bounding circle by choosing a center airport and a radius, or you can have the system automatically compute a bounding polygon that includes all the input file turnpoints.  Choose the appropriate option from the drop-down list right underneath the box where you entered the turnpoint name.

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