The IMC or Militia "Elite Pilot" achievements are to beat each campaign mission for the respective side. I've completed both campaigns, but didn't win at each mission. When looking at the mission list, there are symbols showing that I've completed the missions for each side, but is there any indication of whether I won that particular mission?
Unfortunately, the game doesn't keep track of this. According to the XboxAchievements.com Achievement Guide:
The game does not keep track of which maps you've won on, so make sure you copy this list and mark them off as you go or use the Excel file linked in the Road Map.
The first post in that thread links to a spreadsheet that you can download to keep track of which campaign missions you have won, as well as which maps and modes you have played on for the "I've Seen It All" achievement.