I appreciate the feedback. I ran a lot of tests tonight and have concluded it's not an AFCAD. I checked for duplicates and found none. I deleted all of my WofAI, and reinstalled the scenery and addon manager - ORD is #1.
conflicting AFCAD are just the most common cause of such problems, but not the only one, which is why we always ask to check for these first.
I have concluded this is some kind of mesh issue.
If it's not the AFCAD, a 3rd party mesh is the most likely cause.
I did install FTX Global and Vector a while ago, but it didn't effect any of the other FSDT airports that I own - not sure if this is part of the issue.
You should have said that sooner, those products are causing a LOT of issue, see the forum. The first obvious thing to do, would have been disabling or removing them, so you would *know* for sure the are the cause.
The issue is, what causes terrain spikes at high resolution, is "noise" in the original mesh data, because the sensor picked things that are sticking out, but aren't part of terrain, like buildings, towers, trees, etc. A proper mesh product should be reprocessed to flat these anomalies at least inside the airports boundaries, but apparently they don't do that.
You might not see this problem elsewhere, perhaps because the original data is not made in the same way everywhere, usually mesh products are made using a combination of different data sources, and even the original data is not the same everywhere.
Nothing we can do from our side, of course, it must be fixed by the mesh developer, the airport of course comes with a proper flatten command and the its AFCAD will flattening the terrain too, but unfortunately, FSX display terrain spikes if the underlying mesh is of too high resolution and not cleaned up.
