Yet another FSX tweak.
Note, it is possible to tweak the shadow quality somewhat. Try adding this to the [DISPLAY] section of the FSX.cfg file:
where n can be 0,1,2,3.
The 1st 2 values affect the size of the shadow map. The 2nd 2 values affect the filtering algorithm.
In the D3D9 code path, this affects the external model shadow maps.
In the D3D10 code path, this affects the external model as the interior model ( VC ) shadow maps are hardcoded to the highest quality level.
You may be able to make the ground shadows look a bit better by tweaking this.