Checked bags

Airports in the Middle East are handling increasing numbers of passengers and therefore need to screen a rapidly rising number of bags. However, new technologies are ensuring that these security checks do not create bottlenecks.

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By  Neil Denslow Published  May 31, 2005

|~||~||~|Most passengers grumble while queuing to get their carry-on bags screened at an airport, even if they recognise the importance of the checks, and the airports strive to keep the queues moving. Similarly, behind the scenes, checked luggage also needs to be screened as quickly as possible, so that security delays do not cause bags to miss their owners’ flights. However, ensuring that bags are screened both quickly and effectively clearly creates a major challenge and one that will get even worse, as more passengers pass through the region’s airports. “There is clearly a conflict between the operational and security requirements in any airport,” says Detlef Dau, director, marketing & sales, GE Infrastructure Security. “You can have hundreds of security checks, but if you do, then the whole flow of bags will collapse.” To ensure that this does not happen, new technologies are being introduced and tested for screening both checked luggage and carry-on bags. The aim in both cases is to increase the probability of a threat being detected while also reducing the number of false alerts raised by the system. However, different technologies are used in these two different areas because different types of threats are being looked for. “The threats in carry-on bags are very broad, whereas in checked bags it is much narrower,” explains Anthony Crane, vice president, business development, Rapiscan Systems. “For instance, you are not concerned if there is a knife in the hold of the aircraft, whereas you are concerned if someone has got one in their carry-on bag.” Because of this narrower range of threats, predominately explosives and contraband, screening systems for checked bags are much more automated than those for carry-on items. Transport Security Administration (TSA) regulations in the US, which are being replicated elsewhere in the world, lay down three levels of screening for checked luggage. “With the hold baggage, you first use automated machines that give an alarm if explosives are found. If the bag is rejected then you will have an operator interpret that image, and, if he passes it, then the bag moves on. However, if the bag is rejected again, then it goes to a higher level of automated detection. If it is again rejected, then the bag is reconciled with the passenger for further investigation,” explains Steve Williams, managing director, EMEA, L-3 Communications Security & Detection Systems. The aim for the security staff, of course, is to clear as many bags as possible with level 1 screening, so that only a limited number of items receive level 2 screening. Then, only as a last resort will the decision be made to open a bag because of the danger that this may entail to the security staff, and also because of the problems of finding the owner of the bag in the airport. “In some countries, security can open checked bags without the passenger being present. However, most people do not want to do this because of the risks it may involve,” explains Dau. “Generally, people prefer to get the owner of the bag to open it, but in bigger airports it is difficult to get the passenger to the bag, so you want a small reconciliation rate.” To get this low rate, the automatic screening needs to be as accurate and detailed as possible, while not slowing down the handling systems too much. Therefore, different technologies are combined and used for different tasks. Taking GE’s CTX 9000 DSi as an example, as the bag moves through the machine on the conveyor belt, a scan projection x-ray image is created using a Computed Tomography (CT) scanner, similar to the CAT scans used in hospitals. The machine then determines which areas, if any, need further inspection. ‘Slice’ images of these problem areas are then created using a rotating diffraction x-ray source, which can spot plastic explosives laid flat in the lining of a bag, for instance. The resulting images from the scans are then compared to a stored library of known explosives and other items to see if a match is found. The two technologies, CT scanning and diffraction x-rays, are combined in this way, as it creates the most accurate results. For, while CT has a high probability of detection, it generates an average false alarm rate. However, this is balanced out by the diffraction x-ray, which has a much lower false alarm rate and which can therefore resolve many of the issues raised by the CT. If there is still doubt about the contents of a bag after these two checks in the same machine, then it will be automatically routed to a level 2 machine. These are slower than the level 1 machines, which can process up to 542 bags per hour, but they are much more accurate. They are also placed on an offshoot of the main baggage handling system, so that they do not interrupt the flow of bags. Level 2 machines perform molecular analysis using coherent x-ray scatter (CXRS) to give an even more accurate reading of what is in the bag. The latest machines, such as GE’s Yxlon 3500, can also localise the screening so that it focuses on the areas flagged up by the level 1 machine. This then speeds up the level 2 screening, as not all of the bag needs to be examined by the machine. “We are starting to implement the Yxlon 3500 in the US, although it still needs to be certified by the TSA. This is expected to happen in the next couple of months, however, and we are now looking to install the system in Middle East airports as well,” comments Dau.||**|||~||~||~|However, while checked baggage screening is making greater use of automation to cut out the use of operators, the screening of carry-on bags, which uses conventional x-ray, is still reliant on human interpretation. An operator is needed, as a much wider variety of objects is being looked for, ranging from plastic explosives and guns to cigarette lighters and nail clippers. As such, even with the numerous advances made in the screening sector over recent years, such as explosive trace detection, automated systems alone cannot be relied on to accurately determine the contents of bags. “If the technology is infallible then you do not need an operator,” says Williams. “However, I do not think the technology is infallible just yet.” Smart technologies that could improve the effectiveness of carry-on screening are being tested though. Rapiscan, for instance, received funding from the TSA to develop a Nuclear Quadruple Resonance (NQR) explosives detection system for screening carry-on bags in the US. NQR, which is based on the magnetic resonance imaging technology used in hospitals, uses radio frequency energy instead of x-rays to screen bags, and it could make automatic explosive detection more effective. However, NQR will need to achieve a very high level of detection rates to be widely adopted, as adding automatic features can make the operator, who will still be needed, less effective. “If you tell an operator that a machine has an automated feature they become less attentive to the image,” says Crane. “And, because the range of threats is so wide, there is a reluctance to put automation into conventional machines, unless you can make it detect everything, which, of course, you cannot.” Operators therefore still play a key role in determining the contents of bags; however, because of the need for speed at the gate, they only have a few seconds to decided whether or not to clear an item. The main changes in carry-on baggage screening technologies are thus designed to make the operators’ job easier and more effective. “At the moment, 95% of the world’s installed carry-on machines are entirely operator-dependent. In that respect, we are looking for clearer images, better penetration and finer resolution to help the operator,” says Crane. One of the main trends is to make greater use of colour in the scan images. For instance, sugar may come up on the screen as orange, salt as green and steel as blue, while areas that cannot be penetrated are shown as black and, possibly, flashed up. However, while these machines can differentiate between organic and non-organic, they are not so good at telling if an organic is explosive, which may lead to a wave of false alarms and waning enthusiasm for the colour system from the operators. New machines are also being kitted out with threat image projection (TIP) technology, which is designed to keep the operators alert. These systems add a computer-generated image of a threat, such as a knife or explosive, to the scans of random bags. As the machine can record whether or not the virtual threat was spotted, it can be a good way of testing the effectiveness of operators. However, some argue that TIP images are sometimes not varied enough and that they need to be part of an overall training system for operators, not the sole element. “X-ray machine training, particularly for airports, is too much computer programme based,” comments Dr John Wyatt, a former British Army bomb disposal officer who is now technical director at SDS Group. “[Because of this,] operators generally have little idea of the proportions of devices and how combinations of components play a key role. I would therefore argue that practical hands-on experience of actual devices is needed in addition to other inputs and tests,” he adds. Training the personnel carrying out the checks thus remains the key for securing airports in the region and elsewhere, even with the development of more sophisticated technologies. However, the implementation of new systems can be a great aid for security staff both at the gate and in the baggage handling area, as the machines can clear most items and just flash up the bags — or even the areas of bags — that need special attention. Staff can then focus their efforts on just the suspect bags, while the majority of items are quickly processed. Passengers can also more quickly get through the checkpoints, without any compromise on security and, perhaps, without any grumbling either.||**||

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