Interpret what "a sign" means in Lord of the Flies. What kind of message, figuratively speaking, are the grown ups sending?

In Chapter 5, as Ralph, Piggy and Simon sense the decay of order in the group, they momentarily wish for the comforts of the familiar adults that, until being stranded, had always provided guidance and discipline. Ralph abstractly wishes that the adults could send "a sign", meaning a message. Ralph doesn't articulate this thought, but it's pretty clear that he wishes that the adults could provide that same guidance and discipline, a sort of reaffirming...

In Chapter 5, as Ralph, Piggy and Simon sense the decay of order in the group, they momentarily wish for the comforts of the familiar adults that, until being stranded, had always provided guidance and discipline. Ralph abstractly wishes that the adults could send "a sign", meaning a message. Ralph doesn't articulate this thought, but it's pretty clear that he wishes that the adults could provide that same guidance and discipline, a sort of reaffirming of the right way to act and think, as well as assurance that the boys had not been forgotten and would be rescued if only they could keep their heads and wits.

The "sign" that comes arrives a few hours later, when all the boys are asleep and unable to see the contrails and explosions of what is evidently a fight between aircraft several miles above ground. The battle appears to culminate in the destruction of one aircraft and the parachuted body of its pilot lands on the island, and is later mistaken for the Beast. The figurative message this sends is that the adult world currently has its own problems, the war is ongoing, and it is the most sure source of death that the boys could possibly find. It is another reminder that the "Beast" is inside us, as well as a reminder to the boys (though they don't know it yet) that the "infinite cynicism" of adult life is what awaits them should they escape.