..that is when your not looking directly at the sun.
For example, the first UN campaign mission, you fly west into the sunset. I thought it'd be a good idea to land with the sun behind me but when I turned 180 and was facing east everything went pitch black, couldn't see a thing!
In the second UN campaign mission, while flying up the valley, I found I was having to look 45 degrees to the right, so that I was looking at the sun enough to illuminate the terrain, see these screenshots:
Looking ahead - dark
Looking slightly to the right - can see the terrain!
HDR was set to normal, ATi 6970 with 13.4 drivers.
Is this how the missions were designed? or am I looking at a bug with DCS World?