For all having problems with holes in the sky try the following, for those with ATI cards try updating RealFlight to version 2.00.637 which is the last version, once you have the update start RF and go to options and select "Graphics Optimization" and click on "Use Alternate Fog" ATI cards don't render fog or properly render it under Direct X in RF. For those Nvidia based chipset you should have no problems if you're running the latest drivers for the card, please don't make the mistake of downloading the drivers meant for the 5800-5900 cards, these drivers won't work on the earlier version of the chipsets.