What does piggy overhear the pilot saying in lord of the files?

In chapter 1 Ralph and Piggy discuss whether anyone knows that they are on the island. Ralph suggests that his father will come and rescue them as soon as he can, telling Piggy that the people at the airport will tell him where they are. Piggy replies, and I quote... "Not then. Didn't you hear what the pilot said? About the atom bomb? they're all dead."