Do you really think it's still possible to hijack an airplane? I don't give a damn if they've got UZIs with them. If they can still pull off hijacking a plane full of passengers given what we know about what happened on 9/11/2001, then this country no longer deserves to exist, because its people have become mindless and worthless drones incapable of rubbing 2 brain cells together.
However, if it is true as reported that Al Quaeda guys have infiltrated the pilot/crews of foreign airlines, it is still possible for an incoming plane from one of those airlines to enter the country, veer off target, and crash into a building.