Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
Third Person (Limited Omniscient)
Most of the book is focused on Yossarian. We know what he knows, which is a lot. There are some exceptions, because Yossarian seems to have access to some of the other characters' knowledge – like the chaplain's. Since each of the chapters introduces a new character, we sometimes see through that character's eyes. For example, we learn the background stories of the chaplain, Milo, and Major Major. So it's not quite a cut-and-dry third person limited. Like much of Catch-22, traditional categories are questioned here.