It's not a huge safeguard, because the no-fly list in the U.S. does not, at this moment, disclose whether you're on the list or not. You may think you're not on the list, and show up at the airport, but once the information is transferred there may be a reason why you are stopped. You probably have heard about the stories where E. Kennedy was stopped; an 8-year-old boy was stopped because there was a case of mistaken identity. So that's the concern.
