It's not possible to "define distance", since LOD is not a function of real world linear distance, but it's a function of how big the object is on your screen in *pixels* so, it's affected by your screen resolution, the width * height of your view window in relationship to the cockpit, and your zoom level.
Does it improve if you go near and/or if you put the zoom level to a less wide level ? If yes, then it's a matter of LOD, if no, then it might be a problem with that model.