FlightSim Development Group

Hi, I recently bought the XP11 Mauritius. Nice scenery, good SAM integration, I´m satisfied.
What worry me, is whole FIMP misalignment. That something is wrong, I realized after my first ILS14 approach.
Exactly same issue as "Nekulturny" described in his topic here: viewtopic.php?f=3&t=3186&p=12654&hilit= ... ees#p12687

So I open the airport in WED to check what is wrong.
Basically whole airport is misaligned.

On first picture is FIMP in WED with Toggle Navaids "ON" and Slippy MAP "ESRI" - you can see that ILS is aligned with centre of RWY14.
Now I Imported ..X-Plane 11\Custom Scenery\FSDG-Mauritius_XP_1\Earth nav data\apt.dat

On second picture is clearly visible rotational misalignment of whole airport - so it perfectly confirming "Nekulturny" screen, which I can confirm also by my own experience. ILS14 of FIMP on FSDG scenery brings you to the right section of runway and lead you to the grass.

Any hope for correction of this issue?

Unfortunately, Navdata is a tricky thing in XP. Everytime XP updates (its database), custom changes are overridden.
Do you have the same issue with the default version of the scenery?

No Gateway scenery have ILS perfectly aligned with RWY (2nd picture) and RWY fits perfectly on ESRI slippy map (3rd picture).
I noticed that not only FIMP is misaligned, but also on road network one can notice a rotational misplacement.
See roundabouts on first picture in top left corner, where this is clearly visible even from 10.000ft which B767F just passing.

By the way XP nav data update is out of option in my case, as Mauritius was a last install and there was no XP update after it.
I see basically two solutions:
Correct alignment of whole scenery with slippy map (Best solution, but as XPL developer I know this is biggest pain in the a..), or correction of ILS in earth_nav.dat where IPL ILS data are already a present:

4 -20.438194444 57.700111111 232 10990 18 49077.194 IPL FIMP FI 14 ILS-cat-I
6 -20.424972222 57.675222222 232 10990 18 350117.194 IPL FIMP FI 14 GS
12 -20.424972222 57.675222222 232 10990 125 0.200 IPL FIMP FI SIR SEEWOOSAGUR RAMGOOLAM DME-ILS

My earth_nav.dat file is dated 17.3.2021 so FSDG installer of Mauritius which I installed 14.4.2021 did not changed it.

This is comparison of RWY data of Gateway scenery and FSDG scenery:
Parameter // Gateway // FSDG
Length // 3369,5 // 3374,5
Heading // 117,2 // 116,85
Latitude 1 // -20,423299 // -20,423172
Longtitude 1 // 57,669205 // 57,669184
Latitude CTR // -20,430231 // -20,430030
Longtitude CTR // 57,683595 // 57683639
Latitude 2 // -20,43 7162 // -20,436888
Longtitude 2 // 57,697984 // 57,698095

Solution:
ILS NAV DATA adjustment to FSDG misaligned scenery (RWY angle 0,35 deviation + ILS position correction to RWY centre)

Edit file user_nav.dat in your ..X-Plane 11\Custom Data\ directory by adding following three lines before 99 which is on the on the last line:
99

Properly aligned scenery would be better, but with this solution, ILS at least brings you to the centre of runway.
user_nav.dat remain intacted after navdata updates, so it is somehow "clean nondestructive" solution.
If you going to stop using FSDG Mauritius and uninstal it, you have to delete these three lines for gateway and other sceneries, which respecting proper NAV position, to work correctly.