Being quite annoyed by this myself, I took a look at what could be causing it and hopefully made a fix for it as well.
It seems the FOV calculation of the game is simply broken; When using a wide display, what is "meant" to be rendered and what actually is are entirely different. The wider the screen, the worse the problem. I'm using 5760x1200, which means aspect of 4.8 and the problem is very bad an unfixable by just using a wider FOV.
What I think is happening is that the game uses the correct FOV for clipping, preloading, etc. but the aspect ratio is applied wrong for Direct3D and the scene is just rendered as too narrow. If you try to go too wide, then the clipping and preloading goes wrong (over 180 degrees) and problems being to appear. A fix is to use aspect of 1.0 in game and override the rendered vertical aspect ratio with a Direct3D hook.
Some screenshots illustrating the issue and fix:
No fix, aspect of 4.8 and FOV of 175
in view.lua (default maximum is 120):
Very badly zoomed in, and this is not anywhere near 175 degrees in any direction. Pretty much unplayable. Even at this FOV, contrails in the sky seem to occasionally be invisible.
Going wider, problems begin to appear. Around 180 degrees the game beings to suck up memory until it freezes. If you go above this it works, but things being to get clipped out, for example FOV 330
The land from the sides is not visible at all, unplayable again.
Now, aspect of 1.0 in game + my fovfix + FOV of 155
Now everything is as it should. The horizontal FOV actually seems to be 155 degrees, nothing is clipped away and no performance problems.
The FOV fix is available here: http://junk.kegetys.net/lomac_fovfix.zip
Edit: See new version below!
It is a D3D9.DLL hook (like SoftTH), see readme for install instructions. (Basically, put the files to 'bin\x86\stable' and change game aspect ratio to 1.0). It is a quick "hack", I haven't tested it much so there could be some problems as the game does not know the aspect is forced in this way, but on some quick tests it seems to be working fine for me. Hopefully useful for someone else as well