As civil aviation emerged and started evolving in the second half of the 20th century, security-related concerns began appearing. Terrorists would sneak weapons on board of aeroplanes and hijack them for various purposes or utilise explosives to destroy aircraft mid-flight. As such, aviation security planners have begun considering and implementing security policies to prevent such incidents. The screening of passengers and their carry-on luggage for any dangerous items is one practice that was instituted as a result. Over time, it has evolved to become more sophisticated, involving varied and well-researched approaches as well as advanced scanning technology. However, questions regarding the effectiveness of the practice also arose, as there are claims that screening is both ineffective and inconvenient for passengers. This essay will provide a critical analysis of the strengths of screening, such as the prevention of crime, as well as the weaknesses, such as their congestion, bypassability and privacy concerns, that enable its failures to provide an informed view of the practice’s usefulness.
Screening Context and Practices
The term ‘screening’ can be applied to a variety of activities and areas in aviation, and it is essential first to delineate the meaning that will be used in this paper. It will apply the definition provided by Birkland (2006): “security staff inspects passengers at a security point before boarding to check for weapons, explosives, contraband, or other materials deemed to be a hazard to an aircraft” (p. 69). The scope of the search encompasses both the passenger’s body and clothes and their carry-on luggage. According to Stewart and Mueller (2017a), the practice was introduced in 1973, after a series of hijacking incidents that convinced the Federal Aviation Administration to overrule airlines’ objections against passenger searches. Since then, it has evolved considerably, becoming more sophisticated in terms of both technology and the methods used to conduct screenings efficiently.
A variety of methods and techniques exists for the performance of a screening procedure. Initially, it involved physical searches of each passenger and their carry-on luggage by the guards due to a lack of suitable equipment (Wallis, 2013). However, the practice was inconvenient for both passengers and security personnel due to its invasion of privacy and time requirements. Shortly after, airports started switching to metal detectors, both stationary and handheld, and X-ray scanners to detect guns and hand grenades, though both tools could only do so indirectly (Price & Forrest, 2016). Kearns (2018) adds that these measures are still at the centre of screening procedures nowadays, though modifications such as explosive detection via residue sampling and full-body scanners have been introduced at some airports. All of these technologies have considerable limitations, which aviation security providers try to address with other methods.
The lounges that are present at most airports, where passengers wait for their departure after checking in, are closely related to screening. Sweet (2009) describes them as a sterile area that is protected from danger because a person has to be checked to obtain permission to enter. To that end, passengers are expected to stay in the area once they pass the screening to minimise the risk of them interacting with an outside party that has not been vetted. Wallis (2003) describes two significant benefits to the usage of centralised sterile area-based screening over gate checks: cost savings and additional prevention opportunities. A single system for all passengers can use fewer security workers than would be necessary for providing a full screening crew for each gate without significant performance loss. Additionally, the sterile zone provides additional time for security personnel to find threats through methods other than screening, such as investigations by intelligence agencies, and respond to them before they have access to the aircraft. Such an intervention would not be possible if they were screened at the gate and proceeded to board immediately.
Trained security staff conduct screenings and make the final decision regarding whether the passenger’s belongings contain any dangerous items. Sauter and Carafano (2019) note that airports employed private companies for the purpose until, following the 9/11 attacks, the United States government formed the Transportation Security Administration and charged it with maintaining aviation security. The newly founded organisation would then introduce a variety of stringent policies, such as the restriction of screening positions to its workers. As a result, almost all of the private security providers lost their contracts with airports and were forced out of the screening process or subsumed by the TSA (Nemeth, 2017). Other nations followed the example of the United States, deeming airport protection a matter of national security and introducing a governmental security service that manages their operations.
The Failures of Screening
Over time, screenings have earned a reputation for being expensive and inefficient, leading to significant passenger dissatisfaction. Elias (2010) highlights how, despite the TSA’s objective of achieving waiting times of no more than ten minutes, passengers can spend upwards of forty minutes in screening queues at busy airports. As a result, their experience suffers considerably, which can create dissatisfaction, particularly when combined with the restrictions such as the liquid ban. Schneier (2003) describes complaints about public baggage searches and embarrassments and adds an account of how diabetics could not take their medication aboard planes for a year after 9/11. Tyler (2017) notes that screening is expensive, with the TSA’s security personnel being three times as numerous as their private counterparts were before 2001 at 60,000 (before the 2003 introduction of a 45,000 maximum limit). Moreover, despite all these issues, screening struggles to achieve its objective.
Metal detectors are ineffective against non-metallic weapons and explosives, and X-ray scanners only provide the general shapes of items without identifying their nature. Tyler (2017) notes that a non-metallic box cutter was used in the 9/11 attacks and proposes the scenario of the terrorist wearing body-conformal explosives while also stating that carry-on luggage inspections are inadequate. Advanced explosives are more readily available than before due to the advancement of technology, as are weapons that bypass scanners. As a result, numerous incidents occurred where terrorists and civilian testers took weapons through screenings undetected, leading to media exposé articles as well as extensive research into possible weaknesses (Cobb & Primo, 2003). All of these issues have combined to create a negative public perception of airport screening as an intrusive, slow and ineffective procedure.
Critical Analysis
Overall, passenger screening appears to have achieved its objective, at least partially. McCrie and Haas (2018) highlight how security personnel confiscate numerous dangerous items during checks daily despite their issues and disadvantages. Presumably, the people who carried these objects would have been able to sneak them on board the aeroplane and possibly use them to endanger the other passengers. However, as Hodwitz (2020) notes, while screening measures may have had a limited effect on the incidence of attacks on the aviation industry, it is challenging to separate any individual intervention and evaluate its effectiveness. As such, there are few quantitative evaluations of which approaches effectively improve the performance of screening procedures and which ones harm it. However, it is still possible to discuss the strengths and weaknesses of each aspect of screening.
Metal detectors will be the first item category that is featured in this essay. Alsaedi, Algizi, Iqbal and Resan (2016) note that most weapon detection devices use electromagnetic systems because of their ability to react to metals and produce assessments of the size, position and shape of the object. With that said, these claims do not necessarily correspond to the practical usage of metal detectors at airports. Skorupski and Uchroński (2017) find that a configuration that enables these advantages reduces the throughput of a metal detector significantly, compounding the procedure’s congestion issues, and that most managers set them to lower sensitivity as a result. Due to this decision, the scanners lose a significant portion of their effectiveness and begin manifesting effectiveness issues. These problems can be classified into false positives and negatives, with each happening for different reasons.
False positives occur when the scanner detects an object that is not a threat. They are particularly problematic when the passenger cannot remove the item in question. Kimura, Jinno, Tsukada, Matsubara and Koga (2019) supply the example of hip prostheses, with false alarm rates during screening reaching 86% for some categories of patients on international flights. The reaction is likely to prompt a more detailed search from the security staff, which wastes time and creates privacy concerns. A false negative is a situation where a dangerous item passes through the scanner undetected, letting the person take it to the aeroplane. Metal detectors have a significant limitation of being unable to react to non-metallic objects. However, Larson, Paulter Jr. and Troje (2019) also find that metals can sometimes pass through undetected by following non-linear trajectories, such as those that result from walking. As such, the technology is not entirely reliable even for its intended purposes.
Non-metallic threats warrant additional mention because of recent advances in technology that make them more widely available. Jacobs and Haberman (2017) explain how 3D printing technology can be used to produce working firearms from plastic. With that said, the ineffectiveness of metal detectors against these threats as well as other tools, such as ceramic knives, has led researchers to consider other methods of detecting hidden objects. In particular, terahertz imaging is a prospective method of non-invasive screening that is moving toward usability, being potentially able to see through clothing at adequate resolutions (Kowalski, 2019; Stantchev et al., 2016). With that said, the method’s non-discriminatory nature also creates privacy concerns, since the security personnel would likely be able to see the entirety of the person’s body.
Full-body scanners, which have been adopted in some airports throughout the world, tend to use either terahertz (or sub-terahertz) imaging or backscattering X-rays. Nugraha and Choi (2016) compare them to full undressing and add that strict legal and data protection frameworks should be applied to them to avoid misuse by security personnel. Full-body scanners can reveal features such as scars, amputated limbs, or medical devices that are located on the person’s body. In some locations, passengers are permitted to opt-out of going through these checks because of these concerns. However, as Windham (2016) observes, agencies such as TSA have made it mandatory for some people, chosen at the time of them receiving the boarding pass at the discretion of the agency, to undergo the check, endangering their privacy as a result. Overall, the technology is still controversial and not ready for adoption worldwide.
X-ray imaging is typically employed for the analysis of carry-on luggage. It is not used on passengers because of the health concerns associated with the radiation involved in the approach. As Arcúrio, Nakamura and Armborst (2018) note, the equipment has advanced considerably throughout its usage, becoming capable of providing high-resolution images and offering additional tools. However, it is still managed by a human operator, who is prone to errors because of factors such as positioning, lack of experience, or pressure to complete the task quickly. Skorupski and Uchroński (2018) add that it is possible to train personnel to achieve improved outcomes, though in doing so, their throughput will become lower. However, it is impossible to eliminate the human factor as long as people are involved in the process, and so, research is ongoing into alternate solutions.
Automation is one of the most prominent topics for the improvement of the overall quality of X-ray screening. Hättenschwiler, Sterchi, Mendes and Schwaninger (2018) state that automated explosive detection systems are already available for purchase, both in the form of decision aids and fully independent systems. Chavaillaz, Schwaninger, Michel and Sauer (2019) note that the first system type is effective at improving the performance of less experienced workers, though it has a negligible effect for experts. With that said, fully automated systems have higher overall potential because of their higher overall versatility and effectiveness that is enabled by big data approaches. Riffo, Flores and Mery (2017) have been able to produce promising results with a gun and razor detection algorithm over 360 inspections. However, fully automatic measures require additional development to mature to a stage where they can replace people.
Passenger reception of screenings tends to be negative for a variety of reasons, many of which involve anxiety. Maliwat (2018) discusses how over half of the passengers in his study feel frustration, fear, or humiliation during screenings, fearing mistreatment or lateness. Remarkably, Sakano, Obeng and Fuller (2016) connect perceptions of long waiting times with low confidence in the security provided by the screening. Passengers likely associate long waiting times with an overburdened system that cannot devote adequate attention to each case. Güreş et al. (2017) recommend improvements in the interpersonal competencies of the screening staff as a measure that can create a perception of competence and safety, increasing customer satisfaction. Friendly and competent workers would alleviate some of the passengers’ concerns over mistreatment or failure to apprehend a dangerous individual.
The final topic discussed in this essay will be the congestion of screening terminals that is prevalent in many large airports. Elias (2010) notes that space limitations mean that many airports cannot accommodate the increasing passenger flow with current screening procedures due to the design of their facilities. Other factors also slow down the process, such as the 20-minute continuous operation limitation for screener work (Buser, Sterchi, & Schwaninger, 2020). There are potential approaches that can help improve waiting times, such as that proposed by Rizk, Mora-Camino and Batatia (2018). However, the ultimate benefits of such methods are limited, especially if the regulating agencies retain the 100% screening rate requirement.
The only potential solutions to the issue of time usage and congestion that were found are increased automation, which was discussed above, and selective screening. An analysis of the TSA’s expedited screening program, PreCheck, has shown that it likely does not increase attack risk and may reduce it instead (Stewart & Mueller, 2017b). However, the issue of identification arises, which Hilton (2016) proposes to resolve through improved fingerprinting technology. It can enable passengers who are not considered a security concern to quickly pass the inspection, freeing up its resources and reducing congestion. However, as Haas (2019) counters, security gains that are currently enabled by biometrics technology do not warrant the reduction in privacy that is associated with it. Overall, the congestion and passenger dissatisfaction issues are likely to remain unaffected soon due to the lack of alternatives.
Conclusion
Overall, passenger screening at airports in its current form appears to be necessary and unavoidable despite its considerable drawbacks. The primary issues that face it are safety, throughput constraints and the invasion of privacy that is involved in the searching of one’s belongings. Current alternatives will generally harm one of these aspects to improve the other. However, technologies that are currently in development may help alleviate the issue by improving the speed and accuracy of the screening operations. With that said, they are also associated with specific issues; most importantly, the privacy considerations that are involved in sophisticated scanners and biometric technology. The research has led to the conclusion that the only currently feasible alternative would be to research all passengers to identify potential threats ahead of time and detain them, but this method creates concerns over privacy. Overall, aviation security professionals have to continuously observe new research and look for opportunities until they can identify feasible solutions to current issues that address the underlying concerns.
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