I guess the LOD of the helicopter is overlapping the LOD of the pickup truck. To avoid you will need to create custom LODs.
It's not that difficult to make them – just google for "custom LOD".
Unfortunately it has nothing to do with it. 
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Superbeautifull vessels!

Please
RELEASE them! And – if possible – in different angles, like cars 22,5 and 45 degrees? These would be perfect for my
R.D.E****
Or the LOD of the pick up itself doesn't match the model. Maybe to delete and rebuild the LOD of the pickup?