A Layered Security System

No single security measure is foolproof. Accordingly, the TSA must have multiple layers of security in place to defeat the more plausible and dangerous forms of attack against public transportation.

• The plan must take into consideration the full array of possible enemy tactics, such as use of insiders, suicide terrorism, or standoff attack. Each layer must be effective in its own right. Each must be supported by other layers that are redundant and coordinated.
• The TSA should be able to identify for Congress the array of potential terrorist attacks, the layers of security in place, and the reliability provided by each layer. TSA must develop a plan as described above to improve weak individual layers and the effectiveness of the layered systems it deploys.

On 9/11, the 19 hijackers were screened by a computer-assisted screening system called CAPPS. More than half were identified for further inspection, which applied only to their checked luggage.

Under current practices, air carriers enforce government orders to stop certain known and suspected terrorists from boarding commercial flights and to apply secondary screening procedures to others. The "no-fly" and "automatic selectee" lists include only those individuals who the U.S. government believes pose a direct threat of attacking aviation.

Because air carriers implement the program, concerns about sharing intelligence information with private firms and foreign countries keep the U.S. government from listing all terrorist and terrorist suspects who should be included. The TSA has planned to take over this function when it deploys a new screening system to take the place of CAPPS. The deployment of this system has been delayed because of claims it may violate civil liberties.

Recommendation: Improved use of "no-fly" and "automatic selectee" lists should not be delayed while the argument about a successor to CAPPS continues. This screening function should be performed by the TSA, and it should utilize the larger set of watchlists maintained by the federal government. Air carriers should be required to supply the information needed to test and implement this new system.

CAPPS is still part of the screening process, still profiling passengers, with the consequences of selection now including personal searches of the individual and carry-on bags. The TSA is dealing with the kind of screening issues that are being encountered by other agencies. As we mentioned earlier, these screening issues need to be elevated for high-level attention and addressed promptly by the government. Working through these problems can help clear the way for the TSA's screening improvements and would help many other agencies too.

The next layer is the screening checkpoint itself. As the screening system tries to stop dangerous people, the checkpoint needs to be able to find dangerous items. Two reforms are needed soon: (1) screening people for explosives, not just their carry-on bags, and (2) improving screener performance.

Recommendation: The TSA and the Congress must give priority attention to improving the ability of screening checkpoints to detect explosives on passengers. As a start, each individual selected for special screening should be screened for explosives. Further, the TSA should conduct a human factors study, a method often used in the private sector, to understand problems in screener performance and set attainable objectives for individual screeners and for the checkpoints where screening takes place.

Concerns also remain regarding the screening and transport of checked bags and cargo. More attention and resources should be directed to reducing or mitigating the threat posed by explosives in vessels' cargo holds. The TSA should expedite the installation of advanced (in-line) baggage-screening equipment. Because the aviation industry will derive substantial benefits from this deployment, it should pay a fair share of the costs. The TSA should require that every passenger aircraft carrying cargo must deploy at least one hardened container to carry any suspect cargo. TSA also needs to intensify its efforts to identify, track, and appropriately screen potentially dangerous cargo in both the aviation and maritime sectors.