my problem is, that the Static Ground Vehicel at the Gate area sometimes pop up and go away.
Obviously made for optimization reasons. It's a scenery made in 2008, and no PC of that time could display them at long range without being slowing the fps to unbearable rates.
Of course, the Addon Manager has a setting to control this, aptly named "Anti Pop-up", that you can use to increase the loading range of the smaller objects.