Integrated application of various technologies to improve airport safety.
Aviation Week & Space Technology.- 1996 .- 145, №15-P. 50-52.
Integrated application of various technologies to improve airport safety.
The use of modern explosive detection systems and installations can significantly improve airport security, but even a perfect system for such purposes has limited capabilities and is very expensive, and the implementation of such systems on a national scale will require three to five years.
Many see new technologies as a means to strengthen the fight against terrorism. But without systems that can conduct unobtrusive screening of airline passengers and their checked and carry-on baggage, airport delays due to manual screening will increase. Airlines will be forced to cut flights by 30% to maintain accepted security levels.
Existing detection systems based on X-ray, computed tomography, and mobile ion spectroscopy have certain limitations. Some of these systems can detect well-hidden explosives, but they are expensive and have a high false alarm rate.
Establishing effective protection against terrorism is a complex issue, especially for the United States, which has a developed air transport system with a large number of airlines and airports with their own characteristics. The problem is also complicated by the unpredictability of terrorist actions. Of great importance is the presence of vulnerabilities in security systems that can be exploited by intruders. Such vulnerabilities include, for example, procedures for screening air passengers and their baggage, cargo and mail.
The U.S. Civil Aviation Safety Commission, created by President Clinton in response to the July 17, 1996, crash of TWA Flight 800, believes that the most important problem is preventing explosive devices from entering airline aircraft. This problem is not limited to civil aviation and industry, but should be considered a national problem to be solved by a joint effort of government and industry.
The panel's main recommendation is to rapidly implement dual-energy X-ray screening systems for 100% screening of checked baggage on all domestic routes. But to improve overall security, a combination of technologies is needed.
Some security system developers and manufacturers are skeptical that a nationwide move to such a significant security enhancement will be possible.
According to the vice president of Vivid Technologies, a manufacturer of dual-energy X-ray systems, the United States lacks the political will to change the way it fights air terrorists. In his opinion, the main task of developers of explosive detection systems is not to find the explosives themselves, but to detect their presence among the mass of other objects that fill the suitcases, briefcases and bags of airline passengers, or hidden in the confined spaces of portable radio devices or laptop computers. For example, the presence of organic compounds in luggage makes it difficult for the system to detect small objects that could potentially be explosive devices.
The Federal Aviation Administration (FAA) believes that checked baggage poses the greatest security threat to passengers and is focusing its efforts on accelerating the development and certification of new technologies to address this potential vulnerability. Currently, the FAA has 40 projects in development that involve developing more advanced explosive detection systems. Of these projects, 19 are to deliver prototype systems, while the remaining projects are to conduct fundamental research to improve components of existing detection systems.
Common plastic explosives such as Semtex (military designation C4, European PE4) and Detasheet can be formed into any shape. Conventional X-ray systems cannot detect these explosives, but more advanced technology systems such as dual energy X-ray systems can detect and identify some of these explosives.
Items that generate false alarms must be screened a second time by the operator or another person. As the false alarm rate increases, the importance of the human factor in making the final determination of whether or not an explosive is present in the baggage increases. Unfortunately, the increase in false alarm rates is associated with an increase in flight delays. Therefore, reducing false alarms is a major concern for airport and airline authorities interested in maintaining strict flight schedule compliance.
The dependence on the human factor, especially when terrorists are highly skilled at concealing explosives, is a weak point in the entire detection process. In an attempt to remedy this situation, the FAA supports the development of fully automatic and autonomous systems capable of positively identifying explosive devices.
The most promising technologies for detecting explosives at present include the following three: computed tomography, X-ray technology with two levels of radiation energy, and quadrupole resonance.
The prototype of CT-based X-ray screening systems was medical X-ray systems, which used CT scanning to examine patients. In a CT-based system, a rotating beam of X-rays creates layered images, or «slices,» of the contents of an item being inspected, taken from different angles. The system's computer uses these slices to reconstruct a complete image of the item, which is presented to the operator. These systems can detect explosives or metal objects. At airports, these systems work in conjunction with conventional X-ray screening systems, which perform a preliminary inspection and identify suspicious items sent for inspection by the CT-based system.
Computer tomography systems have certain advantages over conventional X-ray systems, but their throughput is about 600 pieces of baggage per hour, and the cost of one system is $965,000. The only system of this type certified by the FAA is the CTX 5000 system from In Vision. A new version of this system, the CTX 5000 SP, contains a preliminary screening device that performs an initial analysis to accurately select areas for tomographic scanning. The company produces only four systems per month, which is clearly not enough to meet all requests. As of August 1996, according to the FAA, four systems were operating in the United States, 14 in the UK, 7 in Israel, 4 in France, and one each in Belgium and Japan.
In dual-energy X-ray systems, when high or low voltage is applied to the anode of the X-ray tube, two separate beams of radiation are generated, revealing information that is used to detect materials with high nitrogen content. The computer analyzes the data and highlights areas on the image with colored glowing marks that the operator should pay attention to and decide whether or not the baggage being inspected contains explosives.
None of these systems meet the requirements for FAA certification, but they offer significant advantages over the conventional X-ray systems installed in the 1970s and 1980s to combat hijackings. The cost of a dual-energy system ranges from $27,000 to $500,000. It takes 6 seconds to screen a piece of luggage. Disadvantages include difficulty detecting some types of explosives and the inability to integrate with high-speed baggage conveyors.
In practice, the HI and VIS-W systems from Vivid Technologies and the Scan System 7 and Scan System 10 from EG fe G Astrophysics Research are used. Vivid has supplied 57 systems to the UK, two to the US, five to Switzerland and two each to Germany, Belgium, France and Canada. EG fe GA has supplied 12 systems to the UK.
Quadrupole resonance is a new technology that uses a radio frequency probe to obtain signatures of chemical substances that reflect their characteristic features. The detection of explosives by systems based on this technology is sensitive to the concentration of nitrogen in the environment, which is part of strong explosives. This makes it possible to detect potential explosive devices among other items and substances containing nitrogen. Quantum Magnetics is developing a Q-Scan Baggage Inspection System based on quadrupole resonance. The cost of this system ($ 200,000) is lower than systems using CT. Testing of the Q-Scan system at airports has shown that it quickly, reliably and effectively detects plastic explosives and, when operating in an automated mode, can inspect one piece of baggage in 30 seconds. However, it cannot detect all types of explosives listed in the FAA standard. However, it can detect RDX, which is part of plastic explosives. FAA officials say the Q-Scan system reliably detects most common plastic explosives used to make explosive devices.
Currently, the FAA is studying the possibility of using quadrupole resonance systems and X-ray systems with two energy levels of radiation together to detect various types of explosives and explosive devices, including sheet ones. However, the production of combined systems cannot yet exceed 5 units per month. Along with these systems, designed to detect explosives with a high concentration, portable devices and instruments are used to screen air passengers, their hand luggage, as well as portable electronic devices to detect explosives by microtraces of chemical elements. The cost of such devices and screening devices with a high level of detection is in the range from $30,000 to $180,000.
Currently, portable devices and devices for detecting explosives based on traces of the chemical elements they contain are produced by five companies: Thermedics Detection, Barringer Instruments, Ion Track Instruments, CPAD Technologies and Graseby Dynamics. The products produced by these companies, lonscan 400 (Barringer), Itemiser (Ion Track), Plastec Explosives Detector (Graseby), use ion mobility spectroscopy.
Despite their relatively low cost (from $43,000 to $150,000), ion mobility spectroscopy detection devices and systems have a significant drawback. At low vapor pressures of explosives, their detection reliability is lower than that of other systems, such as high-speed gas chromatography systems.
In ion mobility spectroscopy systems and devices, a sample is collected and then evaporated by rapid heating in the system. The detection process lasts 5 seconds.
More than 300 lonscan 400 systems are in operation at airports around the world, including La Guardia International and Dulles International in the US. Graseby has supplied two Plastec systems, and Ion Track has supplied four Itemiser systems, including one in Vietnam.
The best results for screening and detecting explosive vapors are achieved with systems based on high-speed gas chromatography and chemiluminescence, such as the Egis 3000 from Thermedics. The Orion Plus Horizontal system from CPAD uses ion mobility spectroscopy and high-speed gas chromatography to improve the accuracy of chemical analysis and reduce the false alarm rate.
The Egis system analyzes a sample in 18 seconds, while the CPAD system analyzes it in 6 seconds. The cost of these systems is $165,000 and $150,000, respectively. CPAD systems are installed in Saudi Arabia, Hong Kong, Israel, Japan and South Africa. More than 190 Thermedis systems are in operation, including 52 in Germany, four in the Middle East and 19 in the UK.
In addition to systems for detecting explosives by their mass and traces of chemical elements, there are systems for screening liquids and small items of baggage for the purpose of detecting explosives.
Inexpensive passenger screening portals are also being developed and will be available for use in 1997 or 1998.
A number of civil aviation security experts note that the FAA's desire to create a universal system capable of successfully detecting metal objects and explosives, the so-called «magic bullet», is associated with great difficulties. These difficulties are due to the need for large financial costs and the lack of a government decision to support these developments.
Experts believe that the FAA should recognize the futility of creating a «magic bullet» system in the foreseeable future and take a course on implementing the most advanced of the existing inspection systems, even with their individual shortcomings.
Vice President Gore's commission, created in response to the TWA Flight 800 crash, recommended spending $492 million over five years to improve U.S. civil aviation security. Of that amount, the commission recommended spending $161.3 million to field existing detection systems, including 54 CTX5000 SP CT systems and 20 X-ray systems. At the same time, research and development should be initiated to improve readiness to counter the ever-changing and increasingly complex threat posed by terrorists who will never stop looking for weaknesses in airport security. The Gore commission's proposal to spend $20 million on this research does not address the problem of significantly improving airport security. Experts estimate that at least $50 million should be spent annually on developing new means of enhancing security. Such means include forward- and side-scatter X-ray systems capable of detecting organic substances used to make explosive devices. New digital signal processing methods and image processing software also need to be developed.
Existing X-ray inspection systems process more than 1,000 pieces of baggage per hour, but their false alarm rate reaches 30%. New technologies and advanced image analysis tools can significantly reduce this rate.