Route drawing prefers isec over airway data

[Jonas Kuster]

Hello Gergely

I've had reported a number of cases where the route drawing was not following according the flight plan. I was able to identify the issue related to specific waypoints in these routes, that exist multiple times (same navaid name at different locations around the world). The relevant files here are obviously the isec and the airway data file. Using the search function, I can observe that from waypoints used multiple times, only the first one will be known to ES. Now for the route drawing, it seems that not only the airway data file is used (which has both airway and waypoint information in it). I need to assume that the airway file is actually only used to decode the airway information and extract a waypoint list. For the drawing, or more precisely the determination of the waypoint coordinates, it seems only the isec file is used again.

As for waypoints used multiple times, only one entry from the isec file is considered by ES, it will always take the first from the isec file, which can be the wrong one. This then leads to incorrect route drawings. I suggest to use the coordinate information from the airway file instead. This will avoid such issues.

Two examples for routes that are not displayed correctly:

• SITET UN859 BCN (from UK to LEBC FIR)
• DELOG UN864 MONTY (https://stats.vatsim.net/connection/fp-details/79216750)

This isec and airway files used are the ones from the EURW sector file package: http://files.aero-nav.com/EURO.