Yes that's right, lots of airbrushing on this one. The chipping is pretty much the last step, added (even after decals) by sponging on Charadon Granite and Dark Flesh (50/50).
So awesome. Ok so I'm quite sure you did this with an airbrush right? ...now did you start with the dark (chip) color then add mask, then paint the base coat? ...or did you just add the weathering afterward?