First thing I would do is try turning the ground detail off, including the bump mapping. All of it in the details tab on the left side of the clipboard.
Then see if picking up the silhoette of the target planes is any easier. If it isn't, it has to be a color/shade/brightness/contrast/etc issue, and not a clutter one, or one caused by darkness created by the clutter and ground detail graphics.
I play around a lot with monitor settings, and my home theater PC I check in on AH now and then throughout the day was really, really dark as you describe. I just cranked up the contrast, gamma, and brightness, and played with various combinations, until I found one I liked. It would display TV shows and films so darkly at first, that many parts were just unseeable throughout playback, if it was dark, it was just a murky black hole. Jacking those 3 settings up in nVidia control panel fixed it. Now I don't know if that relates to your specific problem seeing planes/targets, but it's as good a comparison I can relate to you with.
Like I said, try turning off all the ground graphics, and see what happens. Also, do you notice any difference on maps where the terrain/ground is a different shade, or is it just universal all the time while in game, regardless of map?