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Monday, August 21, 2006

The Liquid Bomb Threat

Heathrow Plot Highlights Need for Improved Checkpoint Screening

By Norman Shanks and Steve Wolff

The London arrest of a terrorist team plotting to blow up multiple airliners over the Atlantic has brought into sharp focus the pressing need for a wholesale re-evaluation of how airports worldwide conduct checkpoint screening.

Major advances have been made in many areas of aviation security, but checkpoint screening has not kept pace with the developing threat. Existing equipment and procedures are better suited to preventing hijackings than detecting explosives and suicide bombers.

It is very unlikely that the recent plot could have been intercepted by current checkpoint technology and screening methods. The attack appears to have been foiled as a result of human intelligence and infiltration. Without an effective technology layer, along with robust and efficient screening, plots that are not uncovered through counterterrorism efforts will inevitably succeed. Human intelligence needs to be augmented with updated technology and processes to ensure a multi-layered defense is in place.

Expanding Vulnerabilities

The hijack threat after 9/11 remains high but past vulnerabilities that have allowed hijackers to take control of flights have now been largely addressed (i.e., secure cockpit doors, flight crew operating procedures and Air Marshals). In addition, passengers understand the role that they may have to play to protect themselves in any future attempt and a similar hijacking is now much less likely to succeed.

However, the overall spectrum of aviation security threats has broadened dramatically since the 1980s and 9/11, to include:

* A wider range of substances and the means of initiation or use, including liquid explosives, as used in the Yousef plot, Korean Airlines 858 and planned in the U.K., plus other threat materials, including improvised explosives such as TATP, sheet and distributed explosives, corrosives, gases, aerosols, and incendiaries.

* The growth of suicide attacks has dispelled previous assumptions that hijackers and bombers are unwilling to die to achieve their objectives.

* Bomb components carried by persons acting in consort are considered a major threat and may have played a role in the U.K. plot.

* The increased likelihood of explosive devices or components concealed on or in the body has become a critical area of concern. Recently, several governments have conducted trials of millimeter-wave, trace portals and X-ray backscatter systems in response.

Unfortunately, current screening methodologies for hand baggage and passengers do not adequately address the range and scope of these new threats. Terrorist groups have repeatedly demonstrated the ability to identify and exploit weaknesses in the checkpoint screening process, as reflected by the small weapons carried onboard on 9/11, the attempted shoe bombing and now liquid explosives. Liquids were first employed in Asia in 1995 (the Bojinka plot) and now appear to have been the material of choice for the plan curtailed by the arrests of August 10.

Terrorists will always return to the means used successfully in prior attacks to infiltrate explosives onto aircraft. Although the recent plot planned to use liquid explosives, and this vulnerability must obviously be dealt with, prior attempts have employed other materials. These include plastic and sheet explosives, which are both widely available and extremely difficult to detect using current techniques.

Measures to address the threat from liquid explosives alone will not prevent tragedies on the scale of 911, or the potential of the narrowly avoided U.K. plot. The piecemeal response of the past where screening processes have been adapted to narrowly counter the last incident is analogous to preparing to fight the last war. Terrorist groups will simply move on and exploit another perceived weakness in the system. The industry needs to move rapidly toward comprehensive screening of passengers and carry-on bags for a much wider range of explosives and novel weapons in various configurations, in addition to maintaining detection of conventional weapons.

Technology Solutions

It appears inevitable that allowing passengers to carry-on liquids, pastes and gels will now be reevaluated against the capabilities of existing and emerging technologies. Given the limitations of available technology and process options, stringent restrictions must be expected in the short to medium term. However, it is critical not to dwell solely on this menace at the expense of neglecting the wider range of anticipated threats.

The X-ray systems in use around the world today address the threat of hijack using handguns or knives. They are extremely effective when supported by the other measures mentioned above. However, despite many claims to the contrary, since the introduction of dual energy X-ray systems, these (conventional) X-ray systems cannot automatically or effectively detect a wide enough range of secreted explosives. Furthermore, even advanced technology X-rays and the costly cabin baggage computed tomography (CT) based systems under development would likely not by themselves detect the full threat spectrum, particularly if device components are distributed between multiple passengers or bags. To achieve robust explosives detection, a combination of technologies along with upgraded processes and procedures is required.

Given these gaping holes in the current checkpoint screening capability, there is a temptation to adopt the systems currently being used for hold baggage screening, but regulators must also take into account the fundamental differences between the threat in hold baggage versus the threat against the cabin.

Fortunately, the technology, processes and know-how to deal with this far more effectively are available today for both baggage and personnel screening. With the right equipment and measures, it is possible to dramatically boost checkpoint screening performance and realize a screening system that's both operationally viable and that lacks the systematic flaws that have permitted the tragedies and close calls of recent years.

A number of existing and near term technologies are available that, when combined appropriately with each other, can complement or replace existing systems. Examples are Thermal Neutron Analysis (TNA); millimeter-wave; X-ray backscatter; and Quadrupole Resonance (QR). Notably, TNA is being revisited as a complementary technology for the checkpoint as a means of screening items such as laptops, given its ability to penetrate dense metals that are difficult for other techniques, and to analyze liquids for elemental composition.

The incorporation of QR into X-ray systems is another example of how a new technology can be used to enhance the performance of existing systems without necessarily requiring widespread revamping of operator training and having only a minimal effect on operating procedures. The combined X-ray/QR systems now available represent the first example of combining mutually independent (i.e., orthogonal) technologies in a layered approach, as recommended after 9/11 by the U.S. National Academy of Sciences. Both General Electric and QRSciences have developed QR technology for passenger and baggage screening applications and have devices that have recently completed (or will soon complete) testing by the U.S. Transportation Security Administration. QR technology products for both shoe and baggage scanning are available and immediately deployable as part of this broader solution. As such, it is worth discussing QR further as a case study for improving checkpoint security.

Combining QR with other systems has demonstrated important synergies and advantages. Notably, QR is a "chemical fingerprint" technique that is tuned to detection of specific explosives resulting in high detection probability and a low intrinsic nuisance alarm rate. This is especially important for minimizing congestion at secondary search. Similarly, this forensic character makes QR particularly suited for detecting explosives transported as bomb components, because it is not dependent on the presence of other telltale signs of an assembled bomb such as a detonator, battery or other initiating means. This is a recognized limitation of X-ray technology and current primary screening processes.

Another example of where new and existing technologies can be integrated or used in concert to address current loopholes is in the area of passenger screening. Trials have been undertaken in the U.K. using new whole-body imaging systems such as millimeter-wave and X-ray backscatter. Such devices would benefit from the integration of QR or trace-based detection systems. For example, it is possible to operationally augment these technologies with a standalone QR based shoe-scanner. The capabilities can also be combined in a fully integrated unit. This would allow whole-body imaging systems to counter the strategy used by Richard Reid on December 22, 2001 when he breached security and attempted a shoe-bombing on American Airlines Flight 63, between Paris and Miami.

Screening Process Solutions

Some of the technologies mentioned above and others that are currently available may be too slow or costly to be used for every passenger, so it is important to explore effectively segregating and screening passengers to different standards according to passenger profiling and watch lists. A known/pre-approved passenger could be subject to a faster "standard" search whereas someone on a watch list might, if allowed to fly at all, be subjected to a much more detailed inspection using a combination of advanced technologies.

The remainder (the unknowns) would potentially be subject to a more thorough evaluation than known passengers, but nowhere near the screening detail to which profiled candidates might be exposed. This can be achieved either by implementing several lanes with a varying equipment mix or identical lanes with the ability to switch screening modes dynamically on a passenger-by-passenger basis based on profile. This approach would ideally be mixed with the random selection of passengers believed to be low threat for more detailed screening.

Taking this concept further to help address the potential threat from carry-on liquids, pastes and gels, the ability to carry-on these items, or any other specific items, might be dependent on the passenger profile with pre-approved passengers permitted to carry-on a wider range of these materials and cabin baggage items generally. Those passengers not pre-approved may end up being severely restricted in the type and amount of cabin baggage they are permitted.

Historically, there has been a tendency for governments to "make the perfect be the enemy of the good". They delay deployment of effective technology while waiting for the "perfect" system to be developed. With the recent U.K. attempt, terrorists have shown this contrived delay to be an unaffordable luxury. Available technologies can be effective for detection and deterrence of future exploits. By acting sooner rather than later, the industry can better meet the challenge of integrating different complementary technologies into an effective system-of-systems.

It is also important to evaluate both operational and detection capabilities simultaneously to ensure a fast-track deployment of updated systems and avoid the serial approach that has delayed new technology in the past. The current focus on assessing performance of individual devices in isolation must also give way to system-of-systems test processes and methods that evaluate entire systems, including operators and operational procedures.

After 9/11 checkpoint upgrades went only part way in addressing the increased range of cabin threats. A new or substantially revamped checkpoint is now needed to counter an expanded range of threats, sophisticated and organised adversaries and a new security landscape.

No perfect inspection technology is possible for such a broad range of threats. However, combining new and existing technologies with procedural changes will keep terrorists guessing, act as a deterrent, and improve detection of the wide assortment of attacks. Several mature technologies, including QR, millimeter-wave, X-ray backscatter and TNA can play complementary roles at the screening checkpoint and should be part of a reconfiguration of the screening system.

Targeted screening based on profiling coupled with tailored hand-baggage restrictions may be the most effective method in terms of cost, space requirements and throughput for upgraded security.

The U.K.'s "liquids plot" should serve as a wake up call for governments to move forward aggressively with development, operational trials and deployment of multi-technology, layered systems taking advantage of available technologies and processes to better defend against the omnipresent terrorist threat.

Norman Shanks is founder of Norman Shanks Associates International, an Aviation Security and Airport Management consultancy. From 1986-1991, he was Heathrow's Airport Security Manager.

Steve Wolff is president of Wolff Consulting Services. He helps security companies with product development and worldwide marketing.

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