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Waypoint names are not unique. Why ?

  • This is unnecessary (it would be possible to use unique names only).
  • It introduces potential for confusion.

So why are duplicate waypoint names permissible and used ?
I don't see a good reason for that.

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  • $\begingroup$ They sometimes get creative to avoid this problem. There are several examples around the US, at least. Check the COMIX TWO ARRIVAL into San Diego (KSAN.) They try their best to separate identical names as far as feasible. $\endgroup$
    – Mike Brass
    Jan 6, 2019 at 5:27

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ICAO does actually recommend that names for significant points are unique:

3.4 The unique five-letter pronounceable name-code designator assigned to a significant point shall not be assigned to any other significant point.

However, as you already know, not all names are in fact unique. So why is that?

This is unnecessary (it would be possible to use unique names only).

No, it probably wouldn't. There are millions of named significant points around the world. Assuming points could be named completely randomly (any combination of 5 letters), just about 12 million unique names would be available (26 to the power of 5). However, points are not just named randomly, they have to follow some rules:

3.2 The name-code designator shall be selected so as to avoid any difficulties in pronunciation by pilots or ATS personnel when speaking in the language used in ATS communications.

3.3 The name-code designator shall be easily recognizable in voice communications and shall be free of ambiguity with those used for other significant points in the same general area.

You can't just put together 5 letters in a unique way, you have to create a pronounceable, recognizable word, and it can't sound similar to other points in the same area. This significantly limits the number of options.

It introduces potential for confusion.

In theory, yes. In practice, this is not a problem. The risk of pilots navigating to a point with a duplicate name is next to none. Points with duplicate names are never located in close proximity, and most flight management systems will automatically select the nearest point, when inputting a route where duplicates exist. I'm not saying a mishap related to this issue has never happened in the history of aviation, but personally I have never heard of one, and I doubt I ever will.

All references from ICAO Annex 11, Appendix 2

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Waypoints do not have to have unique names as long as they are separated by enough distance so that confusion over names would be highly unlikely.

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