I have a pretty good method for preventing bad people from getting on planes that doesn't require full body scans nor intrusive pat downs.
Follow a variant of the Israeli model and interview each passenger. Make each one show their passport and check it against the national passport data base. If the face, the passport photo and the photo on the national database all are similar, and you haven't visited Yemen or Pakistan etc. lately, then you get on the plane.
If you don't have a U.S. passport then you get to go through the more intrusive stuff.
John Culleton, Eldersburg