Unfortunately I'm on the road at the moment, so unfortunately I can't check the scenery in X-Plane, but I have a faint recall that VTSP ILS is a slightly offset CAT-I localiser (in real life). Could this be the source of the "difference"? (If it is, neither is necessarily wrong; offset localisers are a thing
Well I don't think so. The localiser is off by 2 degrees lateral (267 degrees vs. 265 runway) in RL but it ends on the runway, says Jeppesen and Navigraph. On X-plane it is really way off, it's easily visible even on the map. (This time I can't check coz I'm not by my PC, but I had to slew my AC about 30 meters off the runway end to the right to be on the localizer.)
I also looked at the airport, but it is hard to tell what is right and what is wrong.
Looking at google earth I think we can all agree that the LOC antenna is indeed off the runway on the north side of it, about 120m laterally.
The official charts call the bearing offset 1.4 degrees (between runway and centerline). Doing some trigonometry, this should make the LOC cross the runway centerline about 4911m uprange.
This is roughly 2700m in front of the threshhold. This coincides well with the (relatively high for a CAT I approach) DH of 458´ (ca. 1.5NM = 2980m).
Thanks for looking into this Jan,
it took me a while to follow your explanation, but I think I'm getting it.
In theory, the localizer should cut the runway heading at decision height, am I right? Well, even so, that offset is missing in X-Plane, the ILS is in exact runway heading and the localizer never crosses the runway (runs parallel), so what you are saying here is a brilliant explanation of how it should be, but the X-Plane world is not properly simulating this.
I've checked the scenery using Wedomaker and it looks as if the runway is only very slightly off (like 5 feet) and the heading is spot-on so that's is not causing the problem. The hard-coded navdata seem to be at fault.
The red-white light poles for the flood lights are hanging in the air. They don't stand on the ground but start some 5-10m above ground only. Could this be corrected?
Runway/ILS+VOR mismatch by some 20 Meters. Don't know which is wrong, but airport does not fit in with the navaids for sure.
Markku Post-Uttula November 26, 2017 6:40 PM
Unfortunately I'm on the road at the moment, so unfortunately I can't check the scenery in X-Plane, but I have a faint recall that VTSP ILS is a slightly offset CAT-I localiser (in real life). Could this be the source of the "difference"? (If it is, neither is necessarily wrong; offset localisers are a thing
steffets November 26, 2017 7:11 PM
Well I don't think so. The localiser is off by 2 degrees lateral (267 degrees vs. 265 runway) in RL but it ends on the runway, says Jeppesen and Navigraph. On X-plane it is really way off, it's easily visible even on the map. (This time I can't check coz I'm not by my PC, but I had to slew my AC about 30 meters off the runway end to the right to be on the localizer.)
Jan Vogel November 27, 2017 1:44 AM
I also looked at the airport, but it is hard to tell what is right and what is wrong.
Looking at google earth I think we can all agree that the LOC antenna is indeed off the runway on the north side of it, about 120m laterally.
The official charts call the bearing offset 1.4 degrees (between runway and centerline). Doing some trigonometry, this should make the LOC cross the runway centerline about 4911m uprange.
This is roughly 2700m in front of the threshhold. This coincides well with the (relatively high for a CAT I approach) DH of 458´ (ca. 1.5NM = 2980m).
Jan
steffets November 27, 2017 8:33 AM
Thanks for looking into this Jan,
it took me a while to follow your explanation, but I think I'm getting it.
In theory, the localizer should cut the runway heading at decision height, am I right? Well, even so, that offset is missing in X-Plane, the ILS is in exact runway heading and the localizer never crosses the runway (runs parallel), so what you are saying here is a brilliant explanation of how it should be, but the X-Plane world is not properly simulating this.
I've checked the scenery using Wedomaker and it looks as if the runway is only very slightly off (like 5 feet) and the heading is spot-on so that's is not causing the problem. The hard-coded navdata seem to be at fault.
steffets November 27, 2017 8:56 AM
Uploaded screenshot, VTSP on localizer 27, 12 miles out, still visibly right of the runway
Jan Vogel November 27, 2017 7:01 PM
I invite you to update the localizer data (adjust the inbound course) and file it under the correct tab in the Gateway bug report site (A NAVAID):
https://gateway.x-plane.com/bugs
Robin peel will then add your new data for a future update.
Cheers, Jan
Julian Lockwood November 29, 2017 12:18 AM
Needs to be filed as a navigation aid bug report.
The red-white light poles for the flood lights are hanging in the air. They don't stand on the ground but start some 5-10m above ground only. Could this be corrected?
Jan Vogel June 22, 2025 2:44 PM
Fixed in recent submission.