Thank you to TPTB!
During the last Official LOST Podcast before the S4 mini-break, TPTB gave an analogy during the Q&A, on the snowglobe and magic coordinates. Combining the snowglobe aspect with the critical bearings for getting through the magnetic/atmospheric field around the island, passing through the barrier can be compared to a de-orbiting spacecraft re-entering the earth's atmosphere to land.
On TV news coverage during one of the early US space missions, someone (probably newsman Jules Bergman or astronaut Wally Schirra) explained the re-entry situation like this: if the earth was the size of a basketball, the window for re-entry would be as small as the thickness of a piece of paper. I believe that this was also featured in the movie "Apollo 13". As TPTB said in the OLP, if the angle of attack upon re-entry is not within the window, you either come in too shallow and bounce off of the atmosphere into space, or you come in too steep and burn up. Although we still don't know the nature of this mysterious barrier, or what causes it, this is an interesting way to look at the critical nature of staying on course when exiting or entering the island's boundary. Especially after Dan showed such grave concern about Frank staying on course flying back to the freighter, and, the way Dez was bounced right back toward the island while trying to sail away from it.
I'm sure that everyone heard this on the OLP, but I just thought that it was a pretty neat illustration of the island conditions.