[spuz]

Thanks. One thing that I don't quite understand is how do new waypoints get added as part of the conversion of a flight plan from ICAO4444 to ADEXP format? Does it do some kind of interpolation?

Also, it appears the error was caused by the algorithm selecting two waypoints with the same identifier as the entry and exit points into UK airspace for this particular flight plan. But it also says non-unique waypoints should be at least 4000nm apart from each other so they can be disambiguated. Since UK airspace isn't that big, shouldn't the algorithm have chosen entry and exit waypoints closer to the borders?

Edit: actually it looks like UK airspace extends a few thousands km to the west of the coastline which makes it more plausible that it covers duplicate waypoints.

[macguillicuddy]

I'm just speculating as to what points are actually added but typically the flight plan includes 'airways' in addition to waypoints. Here's an example of a plan for London Gatwick (EGKK) to Edinburgh (EGPH):

``` EGKK/08R LAM1Z LAM L10 BPK UN601 INPIP INPI1E EGPH/24 ```

And to take a section out:

``` BPK UN601 INPIP ```

In this case, BPK and INPIP are two waypoints (one in the south of England and one in the north). UN601 is an airway that connects these two waypoints. The airway represents a ton of other waypoints between BPK and INPIP but that you don't need to specify manually in the flight plan. I suspect the additional waypoints added are the splitting of the airway into the underlying waypoints - but as I say it's speculation :-)