No, pre-approval of passengers is actually more dangerous than random screening. Many people make this same mistake, in fact the government itself is getting ready to make it with CAPPS II. With pre-approval, the terrorists have to just keep trying until they find some of their number who can get approved. Then they waltz on the plane. With random screening, they can never be sure they won't be subject to a search. MIT folks did a good paper on this. Pre-approval is al-Quida's friend