If it has a fan to circulate air it's a forced air incubator. If it doesn't have a fan it's still air.I'm not sure? What is the difference, or how do I find out? My husband knows more than I do about the incubator, I have researched on the whole growth and progress part. But that's why I'm so worried, I really am pretty ignorant to this, but I want to hatch them so badly that I'm winging it. I'm only hopeful because of the one hatching, it leads me to believe that I'm doing something kind of right?