In Lord of the Flies, what started out as a "Beastie" existing largely in the boys' imaginations is now becoming a reality as Sameneric are convinced that they have seen the beast. In chapter five, what the boys thought might be the beast turns out to have been Simon walking around at night. However, the talk of the beast persists and when Simon tries to explain to the boys that it may be their own fear that is driving their vivid imaginations and that the beast is "only us," the boys worry that this means there are ghosts. They cannot understand Simon's philosophical approach and talking about it in the dark does not help the situation. The situation escalates when Piggy tries to make himself understood, denying the existence of ghosts but Jack is beginning to make his presence felt and Ralph's authority is diminishing as Jack suggests that they will "hunt it down."
After Jack leaves, Simon, Piggy and Ralph hold on to the remnants of civilization and wish for rescue, with no resolution of their difficulties. However, in chapter six, the beast takes on far more sinister and real proportions because, during the night, the "sign" that Ralph wished for but could not have anticipated changes everything on the island.
There is apparently fighting far overhead, part of the war being waged. The boys have no knowledge of it since it is "fought at ten miles height." It seems that an airman has attempted to parachute out of his plane after being hit. The reader hears how "There was a sudden bright explosion and a corkscrew trail..." Unfortunately, the parachutist is dead as he "hung with dangling limbs." The wind drags the parachute in all directions and when it stops, the position is such that "the figure seemed to peer across the brow of the mountains...and bowed and sank and bowed again." Although they are supposed to have been keeping watch, the twins have been sleeping and are therefore startled by what they think they see and hear and the beast takes on a whole new identity.
One night a plane that was fighting a battle over the island explodes and the dead pilot's body parachutes, landing on a mountainside of the island. Because it was nighttime, the boys are unaware of this incident and will later mistake the body of the pilot for the beast. This enhances the theme of the novel that the beast is human and is a part of everyone. Only Simon will actually get near enough to the body to see the truth and the consequences for him are dire.
The "Beast from Air" referred to in the title of Chapter 6 is actually a dead parachutist. He was killed in an air battle above the island, and his corpse floats down to rest on a mountainside. The appearance of the corpse is an ironic touch from Golding, who suggests that the increasingly violent world of the boys is not unique, but rather a mirror of what is going on in the adult world, where WWII still rages. The presence of this body is what finally convinces the boys on the islands that their fears are not unfounded--the "beastie" is real.