Literary devices allow a writer to describe events, people, places and so on in language which creates vivid images. Readers remember images more readily due to a picture in their heads or an apparent tone which establishes an atmosphere. This assists those readers to engage with the story and recognize and understand the characters. In Lord of the Flies, Golding uses literary techniques to create emotional responses in its readers who can then relate to the boys' fears. Readers become engrossed in the story, imagining their own responses to this situation.
In chapter 6, Beast from Air Golding foreshadows the tragic chain of events that will lead to the personification of the beast as the "figure seemed to peer across the brow of the mountain...and bowed and sank..." The reader knows how scared and vulnerable the boys are.
There is irony in the explanation of how the dead parachutist lands in the tree when Golding says, "A sign came down from the world of grown-ups..." Piggy has been trying to emulate all that he thinks his auntie might expect of him and laments the fact that there are no adults to help them make decisions and organize themselves because "grown-ups know things," says Piggy in chapter 5. The irony is in the fact that the boys' plight stems from the bad decisions of "grown ups" and shows how adults are not in fact the saviors Piggy thinks them to be.
Pathetic fallacy is a form of personification where inanimate objects or entities (such as the weather) are given human characteristics; the distinction being in using the natural surroundings not animals or creatures. Golding says that "the breeze hauled the figure through the blue flowers..." suggesting that the breeze is someone who is purposefully dragging the dead parachutist into position. It is effective and significant because readers can sympathize with the boys who are basically at the mercy of the elements and their own irrational fears.
There are a number of excellent literary devices in this chapter, and you might want to start by looking at the description given as Sam and Eric see the beast for the first time as they sit next to the fire:
Far beneath them, the trees of the forest sight, then roared. The hair on their forheads fluttered and flames blew sideways from the fire. Fifteen yards away from them came the plopping noise of fabric blown open.
Note the way in which the forest is personified through the way it is said to "sigh" and "roar." Clearly we imagine the forest as some kind of threatening creature, and the onomatopoeia in the words "sigh" and "roared" also add to the terror that Sam and Eric are experiencing. In the next paragraph, the "flailing fire" is refered to, which is an example of alliteration that again helps add to the tone of terror as Sam and Eric become ever more terrified with what they see and hear.
well there is the mention of the beast, the fire etcc