Originally Posted by
Luc Lion
What is particularly strange is that there IS a database with unique 5 characters waypoint designators. This is the 5LNCs ICARD database promoted by ICAO and eurocontrol.
The purpose of this database and initiative is to progressively eliminate all duplicate 5LNCs, as all countries are invited to register their en-route designator documented in their AIP. Of course, no duplicate is allowed in the database. I understand that all countries participating in eurocontrol have already completed the process.
As the message format ADEXP originates from eurocontrol, it is strange that the paragraph RTEPTS does not contain an indicator stating for each 5LNC if it is a unique ICARD identifier or not. The non-unique identifiers could then simply be ignored by the NATS software.
https://www.icao.int/MID/Documents/2...520SG8/IP6.pdf
https://www.icao.int/EURNAT/Document...l%25202017.pdf
ICARD contains duplications that previously existed. It won't let you introduce new ones but not all states used it the last time I saw anything official on this matter. Eurocontrol tried very hard to make ICARD a complete list but accepted it wasn't although it should be complete for those states with an effective and up to date AIP.
It might get rather more difficult to take out duplications in the 3 letter designators for Navaids. I'm not aware that anybody considered those a problem before. In the UK at least the name is chosen to avoid confusion with similar sounding beacons but once you've chosen a name the available letter combinations are usually quite limited.
Why is everybody so determined to change systems other than FPRSA and any from the same family with the same flaw? There are good reasons to try and eliminate duplicates but this was a bug in a system used by NATS so lets fix that rather than change something else. It is perfectly possible to resolve this issue with the information already in the flight plan, every waypoint in the plan exists in the context of other waypoints which would allow you to do that.