99.9% online.
Only offline for testing, mission building, and reviewing tracks for screenshots.
Every once in a while I go to the QMB when I forget that the AI will just spiral climb away from you no matter what matchup I choose. What nonsense.
I have tried to get into offline campaigns, but it's so hopeless. And just how immersive is watching your whole flight fly blindly into a hill side while ignoring your calls for help?