How did the boys happen to come to the island?

In chapter one of, "The Lord of the Flies," it's infered that the boys were on a plane. Piggy says, "There was that pilot. But he wasn't in the passenger cabin, he was up in the front." This suggests that they were in a plane as they continue to talk about who was on it and what happened. The boys said the plane was on fire due to conflict and they crashed on the island without any adults.