After a lot of flights to this airport, I finally decided to take a look into this issue. Whenever I fly the ILS approach into runway 10, the localizer always bring me to the left side of the runway, which can be seen in the screenshot below.
I have compared the coordinate of the runway threshold on both sides and can confirm that it’s a match, so I now take a look at the antenna coordinate info on the earth_nav.dat and compare it to the current AIP for the aerodrome. This is the data that I extracted from the earth_nav.dat:
4 -3.444222222 114.774055556 54 11070 18 36460.476 IBDM WAOO WA 10 ILS-cat-I
6 -3.441694444 114.754194444 54 11070 18 300100.476 IBDM WAOO WA 10 GS
8 -3.438305556 114.740555556 0 0 0 100.476 IBDM WAOO WA 10 MM
7 -3.428361111 114.687250000 0 0 0 100.476 IBDM WAOO WA 10 OM
This is the screen capture from the AIP of the aerodrome:
After converting the coordinates from the AIP into DD format and then comparing it to the data from current earth_nav.dat, I found these coordinates to be consistent so it looks like the coordinate on the AIP is indeed wrong. Now i use the Google Maps to find the exact location of the antenna using the satellite imagery overlay and got this result:
ILS/LLZ: -3.444785781535938, 114.77594051766886
ILS/GP: -3.441798147916084, 114.75416623649822
As for the OM and MM, I can’t really pinpoint the exact location on the Maps since the imagery resolution is not that good. Is there something that can be done about this situation since it seems the error comes from the regulator body that publish the AIP?
Christo