I still have not quite figured out the numbers yet and how they fit in. But, they could reference dates....2004,(when our crash occurred), 2008 etc....
I am also thinking that if the others are time travelers they could manipulate a chain of events to get certain people on a plane they know is going to crash on thier island. Such as a spinal surgeon that they need. Also, it seems to me that many of the main characters have come to a desperate point in life... a crossroads. Maybe headed for self destruction, in need of a new start. Also, most of them do not have any strong ties to the outside world. No one who is searching desperately for them........