From FSDeveloper Wiki
 Effects spawn problem
This is a common question, and one that is easily answered. This is the same method employed in the FS aircraft beacons that are included with Flight Simulator 9. The problem is that the further away from the effect, the effect size decreases and because of the alpha, you loose pixel resolution fast.
 The resolution
Create a set of effects, each getting brighter and brighter. Then, create a bunch of LOD models (with these different effects) and make them grow as the LODs get smaller.