Lima-Oscar-Lima; I don't think this feature request will be implemented. The 24-hour clock notation is a standard used by the military (and among many other institutions and the majority of world for that matter) to avoid any confusion and/or error. It's really not that hard; e.g. the start of the day is midnight is 00:00, 6 a.m. is 06:00, noon is 12:00, 6 p.m. is 18:00 and the end of the day is 24:00.

"0002510: Feature Request: 3D Optics using Picture-In-Picture engine capability. (Red Orchestra Style)"
Really? I'm shocked and offended. That suggestion would totally ruin the concept of the game as a military simulator. I'll vote this down and suggest everyone who loves every ArmA game ever made to do so too.

@ ViiK
Yes, I have used scope in RL several times; and I'll refer to what "Verox" said: "You don't really focus on the outside of the scope though, even with eye relief, you might be able to see something moving but you'd have to look away from the scope to see what it is."; or in other words when your focus is in the scope everyting outside the scope is a blur and for that reason your situation awareness outside the scope is extremely limited (and next to useless).