Aviation Physical Security

Problem Overview

Aviation is target number one for terrorists due to the complexity of a system that involves millions of people. This makes the problem of physical security particularly acute. Another reason is that airports have very valuable assets, allowing visitors to judge the economic status of a country. Since aviation requires the efforts of a large number of people to serve its purposes, attacks on it can destroy the functionality of the entire system (Stewart & Mueller 2013). The more complex the aviation system is, the more advanced a security protection model it needs to prevent such cases.

Since September 11, 2001, the Transportation Security Administration (TSA) has been developing a layered security program to oppose terrorism. The major goal of the new approach has been to ensure the prevention of terrorist attacks both on land and in the air. Twenty layers have been developed to stop individuals traveling domestically or internationally if they present a threat. The system has led to a number of positive changes. However, layers and new technologies cannot be added continuously, which means that this is not always the best solution to the problem. Terrorists still can succeed, especially in areas where human errors are likely to occur (Jackson & LaTourrette 2015). That is why an outcome-based approach to aviation security has been proposed to replace the outdated layered system. The paper at hand will compare and contrast the two approaches to the protection of physical assets and critically evaluate their pros and cons.

Layered Security System

Layers of US Aviation Security

Layers of US aviation security.
Figure 1: Layers of US aviation security (Wilkinson & Jenkins 2013, p. 37).

Before proceeding to the analysis of the layered security system, it is necessary to list and explain the layers in order to understand how the model is structured. As has already been mentioned, there are twenty layers (Figure 1) that can be summed up as follows (Wilkinson & Jenkins 2013):


This layer is represented by intelligence officers whose key duty is to identify the existence of any kind of threat to the security of the assets. They also cooperate with the federal government and some international agencies to discuss possible future issues and develop prevention strategies (Chatterjee, Hora & Rosoff 2015).

Customs and Border Protection

Customs and Border Protection (CBP) is the largest and one of the most complex sections in the Department of Homeland Security. Its aim is to safeguard and control passenger travel and commerce.

Joint Terrorist Task Force

The Joint Terrorist Task Force consists of various agencies and individuals (including immigration and customs enforcement, FBI, and many others). Their goal is to protect security at the regional level, ensuring that all the facilities comply with national and international standards of aviation security.

No-Fly List and Passenger Pre-Screening

The No Fly List was created immediately after September 11, 2001, when it became evident that the Computer Assist Passenger Pre-Screening System was unable to provide an appropriate level of security. The list is created through a profiling process. The US government decides what people should be prohibited from traveling in or out of the country on any commercial plane since they are considered capable of undermining aviation security. The number of such people has increased dramatically from 2001 (100 individuals) to more than 3000 in 2017 (Sewell, Lee & Jacobson 2013).

Crew Vetting

This layer is supposed to eliminate any threat potentially coming from airline crew members. They are obliged to submit their personal credentials (name, gender, date of birth, country of residence, etc.), while pilots and engineers also have to provide their license number so they can be easily found and tracked if necessary (Chatterjee, Hora & Rosoff 2015). Data collection is performed via Emergency Amendments (EAs) and Security Directives (SDs).

Visible Intermodal Prevention and Response (VIPR)

VIPR teams are supposed to increase the number of available resources in cooperation with regional security departments. The ultimate goal is to discover terrorists’ plans and increase the capacity to prevent attacks.


This layer unites over 500 local law enforcement agencies and security teams (coming from 17 mass transit systems and more than 70 airports) whose purpose is to prevent explosives from entering the airport interior with the help of canines (Chatterjee, Hora & Rosoff 2015).

Behaviour Detection Officers (BDOs)

Behavior Detection Officers are tasked with seeing whether passengers display any signs of suspicious behavior at the security checkpoint and detaining them for a more detailed check.

Travel Document Checker

TSA personnel cannot allow passengers to enter the departure zone unless they provide an ID and a boarding pass. In case they fail to provide the required documents, or if photo identification fails, passengers are subject to further inspection.

Checkpoint/Transportation Security Officers

Transportation Security Officers work at checkpoint counters to ensure that passengers do not have any banned items before they board the plane.

Checked Baggage

All luggage undergoes explosive trace and X-ray screenings before it is allowed to pass to the cargo compartment (Skorupski & Uchroński 2016).

Transportation Security Inspectors

Transportation Security Inspectors control all levels of threat both in the cargo area and airport interior.

Random Employee Screening

Some employees who enter the airport’s secure area (chosen randomly) may be asked to undergo a check or a thorough background screening.

Bomb Appraisal Officers (BAOs)

Bomb Appraisal Officers are involved in a more advanced and complex security process. Their task is to assist other staff in increasing security at checkpoints. These positions are occupied by people having experience in military Explosive Ordnance Disposal units (Chatterjee, Hora & Rosoff 2015).

Federal Air Marshal Service (FAMS)

In general, the major duties of the Federal Air Marshal Service officers are similar to those of VIPR. Like the latter, the former are trained to work for airlines and ensure safety. However, they typically work undercover and are entitled to carry arms on board.

Federal Flight Deck Officers

This category includes flight crew members who have a license to carry a firearm during flight operation onboard a plane.

Trained Flight Crew

To increase the level of safety in the air, cabin crews learn self-defense techniques to be able to protect themselves and passengers from a possible assault. Since TSA suggested adding this layer, such techniques have been taught within the crew member self-defense course (Ornato & Peberdy 2014).

Law Enforcement Officers

These are armed police officers whose task is to suppress or arrest individuals behaving aggressively, thereby ensuring airport security.

Hardened Cockpit Door

This is supposed to be an extra barrier against terrorists. This layer was introduced owing to the fact that after 9/11, it was discovered that cockpit doors were not secure enough and required improvement.


This is the last but one of the most important layers of defense. At every airport, undergoing a number of different screenings (metal detector, X-ray, trace explosive detector, etc.) is a regular procedure. The number of checks increases if an individual looks suspicious to officers.

Analysis of Advantages of Layered Security

Although layered security has had to face plenty of criticism, the introduction of the system still brought about some benefits. Its initial goal was to protect all parties involved in aviation while maintaining the maximum level of comfort for passengers. These are the results that it managed to achieve:

Airline improvement

The system is not only complex but also comprehensive and consistent. Airlines are required to cooperate closely not only with the airport of departure and its security teams but also with those of the destination. Depending on the success of this communication, some passengers give preference to particular airlines, especially if they demonstrate the lowest rates of failures or accidents (Wilkinson & Jenkins 2013). Thus the system made the security policies of airlines a point of competition, which has significantly improved their safety culture.

Passengers’ trust

Since passengers were made one of the most important layers of the system (through being thoroughly screened at every stage of their way to the plane), the possibility of threats that could potentially occur in the air has decreased dramatically. Despite the fact that the cost of a flight remains a decisive factor for the majority of customers, the level of security has also become one of the crucial points, as now some passengers are ready to pay extra to enjoy a reduced chance of an accident (Combs 2017).

Airport cooperation

As has already been mentioned, layered security brought airports that previously worked independently to cooperate on security issues. This made it much harder for a terrorist to pass through undetected.

Explosives trace detection

This new technology introduced by the system of layers makes it possible to identify if an individual’s hands or possessions have come in contact with even the smallest amounts of explosives or their components. The system is highly flexible, which makes it possible to use it in any location or environment, even beyond the checkpoint (Sewell, Lee & Jacobson 2013).

Wireless communication

Layered security maintains communication via radio equipment at checkpoints. This enables the staff to communicate wirelessly about any type of abnormality they discover when passengers undergo screenings; moreover, this type of communication reduces noise levels (Wilkinson & Jenkins 2013).

Advanced imaging technology

This technology was one of the key goals of the newly developed system of layers. It uses millimeter waves, which make it possible to detect not only metallic but also non-metallic threats under multiple layers of clothing without having to disturb passengers and strictly following privacy regulations (Sewell, Lee & Jacobson 2013). Furthermore, the technology is constantly developing and can protect even against evolving threats.

Advanced X-Ray

To be able to detect security threats stored in carry-on baggage, layered security involves thousand of such devices, which are upgradable and evolve together with threats. Currently, it has highly effective liquid detection capabilities and can screen sealed containers for explosive or dangerous liquids (Sewell, Lee & Jacobson 2013).

Analysis of Disadvantages of Layered Security

Despite the fact that the system appears to be highly reliable in protecting against terrorism, there are still reasons that have made aviation companies, airports, and customers think about other opportunities to ensure safety, which implies that layered security has not fully met its expectations. In fact, there have been many inconveniences and failures connected with its application, which include:


The system is excessively expensive for airlines since they have too many responsibilities towards it. Thus from a marketing perspective, it is much more profitable for them to invest in product development, innovation, and staff training instead of using all resources for security purposes (Gillen & Morrison 2015).

Unpleasant passenger experience

Since the introduction of the system, airports have become extremely paranoid about the consequences of insufficient security, which creates an unpleasant experience for passengers, who may have to miss or delay their flights because of being detained at checkpoints for no good reason.

Airport funding

Despite the fact that layered security was intended to cover the majority of airports, airport funding has not increased much. Since they have to purchase costly machines, many of them, having no additional funds from the government, have failed to meet all the new requirements imposed by the system (Wilkinson & Jenkins 2013).

Trusted Traveller program

This program allows passengers to submit an extensive amount of background information to reduce the number of checks at the airport (they are typically issued a biometric retinal card). The problem with this idea is that it is incredibly expensive while increasing the vulnerability of all layers (Chatterjee, Hora & Rosoff 2015). Furthermore, it does not prevent terrorists from entering security areas, since many of them do not have any criminal records and therefore can easily gain the necessary status.


This technology measures and analyses biological data; however, there are numerous countries that still have poor enforcement of this form of security owing to their low-security standards. For instance, for a group of employees, it is required to submit only one person’s fingerprint or card. This makes it possible for a dangerous individual to enter together with a group (Combs 2017).

Inadequate staff training

Despite the fact that every member of the crew is to have a minimum of 17 hours of defense techniques training, many airlines have reduced this to 2 hours of watching DVDs to avoid extra costs.

Ineffective international standards

ICAO Annex 17 requires all contracting states to establish their own system of security protection to maintain the appropriate level of terrorism prevention. Since the standards are unclear and nonbinding, there are still many airports that opt for maintaining the minimum security level, as their funding does not allow them to focus on this aspect (Wilkinson & Jenkins 2013).

Hardened cockpit doors’ ineffectiveness

The implementation of this layer is also quite expensive, which leads airlines to avoid the measure. In addition, despite the high cost of hardening the door with steel, it would be quite easy to memorize the duty schedule of flight attendants and rush into the cockpit while it is being opened.

Joint Terrorism Task Force vulnerability

The majority of Joint Terrorism Task Force members come from law enforcement units, including the FBI, but if a person working locally is interested in aviation security, he/she can also be accepted. This enables terrorists to get inside the system and obtain all the necessary information about its vulnerabilities to prepare for an attack (Combs 2017).

No-Fly List and pre-screening problems

CAPPS I & CAPPS II are used within the layered system to flag and pre-screen passengers. Since the information should be exhaustive (including names, backgrounds, ethnicities, criminal records, etc.), numerous mistakes in categorization are regularly made. For instance, surnames that sound Middle Eastern are often flagged, which creates inconvenience for passengers, decreasing their satisfaction with services provided (Harmon 2013). At the same time, a dangerous individual may not necessarily meet the criteria to be flagged as suspicious.

Failed behavior detection

Behavior detection cannot be reliable first and foremost because many passengers have aerophobia, which makes them avoid eye contact, have muscle tension, sweat more, or behave oddly. In contrast, a professional terrorist would have the proper preparation to pass this layer easily.

Baggage check problems

It is rather simple for any employee to smuggle a hazardous item inside a passenger’s baggage; in addition, the system is unable to detect all forms of explosives (Skorupski & Uchroński 2016).

Random employee screening ineffectiveness

Since the screening is random, its effectiveness is doubtful. Even a background check covers only five years before employees’ started working in their positions, which implies that people with harmful intent may not be stopped.

Federal Air Marshal Service decreased standards

This layer (which is supposed to provide planes with trained personnel to prevent attacks during the flight) is criticized as the most useless one since the high demand for marshals has led to very low training standards. Thus many of them cannot detect a terrorist and can easily reveal their own identity to them (Wilkinson & Jenkins 2013).

Passenger on-site screening subjectivity

The technologies used for screening often trigger a false alarm, which makes the decision excessively dependent on the operator’s judgment (which also delays the checkpoint progress). At the same time, it is possible to miss a truly dangerous chemical or a weapon (Sewell, Lee & Jacobson 2013).

Outcome-Focused Approach as Compared to Security Layers

Outcome-Focused Approach

New system of aviation security.
Figure 2: New system of aviation security (Wilkinson & Jenkins 2013, p. 53).

In order to overcome the existing problems of the layered system, TSA has developed a more proactive approach to aviation security, which is referred to as outcome-focused compliance. Unlike the layered system, which is based exclusively on the “gotcha” principle (trying to catch terrorists at different checkpoints), the new security model (Figure 2) will be focused on risk prevention (exercised with the help of artificial intelligence, differentiated screening, and networking principles), passenger facilitation (making the procedure more dynamic and flexible), and outcomes (cost-benefit, efficiency, user-friendliness, and security) (Ormerod & Dando 2015). Another great difference from security layers is the increased collaboration with the community. The new approach makes it possible for community members to identify a hole in the security system and decide whether it matters and how it can be patched. The idea is that the reason for its appearance is less important than ways to repair it and restore functionality (McFarlane & Hills 2013).

Analysis of Advantages of Outcome-Focused Approach

Within the framework of the proposed model, the desired outcomes reflect what standards are to be met by all countries to minimize security risks and increase the safety of passengers and assets. The new approach proposed by TSA, therefore, demonstrates the following advantages over layered security:


Unlike layered security, the outcome-based approach makes it possible to shift resources quickly from lower to higher-risk regions without having to distribute them equally. This capability is particularly valuable since terrorists tend to attempt attacks in the areas where they discover security gaps (Harmon 2013). The new system will allow such gaps to be filled in a short period of time and prevent possible threats without creating additional financial constraints (which cannot be said about the layered system, which is a prescriptive, one-size-fits-all approach).


The newly developed model ensures the long-term sustainability of the security system, which will allow aviation companies to address problems so that their solutions will not hinder the innovation and growth of aviation operations, which is impossible with the layered system as airlines have to direct substantial funding to security. Prescriptive standards of layered security cannot keep pace with evolving hazards and multiple terrorist groups since they are more process- than result-oriented and therefore act retrospectively (a development is based on the mistakes committed). Furthermore, such standards have to be reviewed and rewritten, adding new layers or making the existing ones more sophisticated, since new threats continue to emerge (Yadav & Nikraz 2014). The length and complexity of standards become excessive as they have to cover all possibilities for all kinds of airports.


Since the primary goal of the approach is to achieve a particular outcome, it makes it possible to determine the most effective use of available resources, which is specific to each region and airport, as well as to the level of threat (Cui & Li, 2015). The facility is not forced to allocate resources in a prescribed manner, as in the layered system.

Mutual validation and equivalence

Although each region will have its own standards, its desired outcomes will be shared and easily identifiable. System performance indicators can be compared in order to assess where outcomes are not being reached. This will allow not only quickly filling the gaps, but also understanding which of the numerous approaches to achieving the same outcome have proved to be the most productive so that they can be adopted in other states to mitigate future risks (Yadav & Nikraz 2014). At the same time, they will not have to rely on an exact replica of their practices since several different approaches can be equally effective if they manage to meet their objectives (which is impossible with layered security leading to a unified set of practices).


Mutual validation of the achieved outcomes leads to a better understanding between different aviation systems and creates incentives to track their influences on one another. This will make states more investigative and cooperative since they will have to conduct simultaneous evaluations.

Analysis of Disadvantages of Outcome-Focused Approach

Although the new system seems almost flawless to many people, there is no perfect security model that has no flaws whatsoever. The outcome-focused approach may present the following problems:


Using an outcome-focused approach is possible only when the required outcome can be clearly specified and when there are at least several possible ways of reaching it (Maurino et al. 2017). In this respect, the layered system is more reliable since it gives clear, universal guidelines for each type of threat.

Failure to meet complex challenges

The system works perfectly well provided that there is only one main hazard. In the event of multiple threats, it would be necessary to develop numerous strategies simultaneously, which is hardly possible to achieve with the same success as if they were developed in advance (Harmon 2013).

Unclear nature of the community assistance

It has been stated that the new approach was meant to increase cooperation between aviation and community members. Yet it is still unclear what criteria must be used to ensure that their intentions and capacities will make it appropriate and feasible to take part in the security process.

Hidden opposition

On the one hand, mutual assessment is aimed at increasing collaboration between different states. On the other hand, it is also possible they will be adversarial rather than supportive, which implies that they will not be willing to share their real strategies with competitors (Oster, Strong, & Zorn 2013).


In order to work properly, aviation companies will have to develop rich and versatile sources of metrics, information, and evidence, and be able to select the most appropriate instrument for each risk, choosing between soft or hard regulation. Furthermore, the agility of the approach will necessitate a continuous review of risks and objectives, which will lead to changes in security instruments each time these parameters change (Rashid, Place & Braithwaite 2014). This will make the outcome-focused approach even more complex than its predecessor.

High cost

Switching to new principles of networking, risk assessment, and security management will require additional training, equipment, and funding. All airports will have to transfer from one system to the other, which is inevitably connected with high expenses (Gillen & Morrison 2015). Airports will in addition become more vulnerable during the transitional phase.

No guarantees

Since the model has been developed by TSA only recently, it is now hard to say whether it is going to provide a better ratio of cost to lives saved than layered security.


Despite the overall acceptance of layered security, numerous critical responses to these measures have led TSA to think about vulnerabilities in the system. The fact that its pattern resembles an S-shape indicates that a terrorist does not need to breach all the levels for his/her attack to be successful, since it is unpredictable at what stage a failure may occur. To be able to conduct an attack, an individual only needs to be trained to recognize security gaps in the system and to perform a targeted action, choosing the most appropriate method. Thus the system is excessively dependent on each layer and the infallibility of technologies that can actually fail. In addition, it still needs humans to interact with machines, which increases the risk of attacks coming from aviation employees (as getting a job in this sector entails much less scrutiny than it should). No matter whether a mistake was unintentional or by design, layered security is unable to eliminate it until it is too late.

In contrast, the outcome-focused approach, which is proposed to replace the old system, seems to be more promising as it provides greater flexibility and a higher degree of sustainability. Moreover, it seems to be more resource-efficient, resilient, and effective since it makes it possible for states to identify for themselves what security measures should be taken to bridge their local gaps. Despite certain disadvantages of the system (that are likely to be eliminated with its further development), it makes it possible for aviation to not only acknowledge and eliminate threats but also to evolve simultaneously with them.

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