So say you are under the effects of the air walk spell 50 feet up and someone trips you and you fall prone. Do you fall prone in place or plummet to the ground 50ft below?
You're treated as if on solid ground. You just trip. It's kinda like on Bleach. They don't fly, just use their spiritual energy to stand and walk on air
We treated it in our home games that you fall as if on solid ground since Air Walk is walking on the air as on ground. Combat maneuvers like trip would also stop creatures movement etc.