Mortality and the inevitability of death pervade Catch-22. Yossarian's friends die in unnecessary and brutal ways. This instills a terror in Yossarian that some might consider irrational. In fact, his fear of death is justified given the situation. But horrifying as it is, the spectacle of death is strangely fascinating and people are drawn to it. When describing a death scene, Heller often slows down time to make it more dramatic.
Yossarian's paranoia that everyone is trying to kill him is unfounded and psychologically unhealthy.
Yossarian's fear of death is justified since there are people out to kill him. It is this fear that keeps him alive.