Lemme ask you something, Zorobabel.
OBL has been around for ten years and he's pulled off a string of evilly inventive and creative attacks on US assets both at home and abroad. He's never used the same attack method twice. And no-one foresaw the WTC attacks; no-one. Even now, they don't know whether they got him, or whether he escaped unscathed.
So knowing all that, do you really think that a bunch of Arab terrorists are going to walk into an airport and try to board a plane? Or do you think, on the basis of all the precedents, that if there is to be another attack it will come completely out of left field, like all the others?