We use layers of security to ensure the security of the traveling public and the Nation's transportation system. Because of their visibility to the public, we are most associated with the airport checkpoints that our Transportation Security Officers operate. These checkpoints, however, constitute only one security layer of the many in place to protect aviation. Others include intelligence gathering and analysis, checking passenger manifests against watch lists, random canine team searches at airports, federal air marshals, federal flight deck officers and more security measures both visible and invisible to the public.
Each one of these layers alone is capable of stopping a terrorist attack. In combination their security value is multiplied, creating a much stronger, formidable system. A terrorist who has to overcome multiple security layers in order to carry out an attack is more likely to be pre-empted, deterred, or to fail during the attempt.