In S03E12 of Lost, "Par Avion", Kate, Locke, Sayid and Danielle bypassed a sonic fence by going over it using a tree.
But in S03E15, "Left Behind", the smoke monster is not able to bypass it. It tried to go through it but is not going over it. Is this a loophole in the script?
There have been many instances when smoke monster penetrated ground, uprooted trees from deep underground and also flew to tree heights which is more than sonic fences.
Why didn't the smoke monster try to go over it? It was such an obvious way to bypass it, because it has the ability to fly and also go underground.