Security of Airports: Full Body Scanners and Walk Through Metal Detectors

This security review will cover the full-body scanners and metal detectors employed in airports in the United States and some airports internationally. A full-body scanner or Advanced Imaging Technology (AIT) as stated by the Transportation Security Administration (TSA), “uses millimeter wave AIT to safely screen passengers for metallic and nonmetallic threats, including weapons and explosives, which may be concealed under clothing without physical contact to help TSA keep the traveling public safe”(1 A Full-Body Scanner costs $250,000 per unit which has led to a multi-million dollar investment by the TSA. The other type of scanning employed by airports are Walk-Through Metal Detectors which detect any metal as a person passes through the detector, costing only $30,000 (1 These two devices are just some of the many forms of prevention tools that the TSA uses. Almost all of airport security is focused on the time a passenger goes from the airport lobby to the airplane. There are three areas in an airport. The lobby, the area where a passenger can freely walk between the airport and the rest of the world. There is no screening process to enter the lobby of an airport. The security checkpoint, the area in which passengers are screened for any hazardous materials or threats to the aircraft or to other passengers. The secure area where passengers wait before boarding the aircraft. And the aircraft.


At the security checkpoint all passengers completed a screening process. Passengers are first required to show proper identification such as a Driver’s License or a Passport. Once their identification is scanned for validity an employee then confirms that the name on their ID matches their boarding pass and signs the boarding pass. After this process is complete, all the passengers luggage will then be screened in an x ray machine and the passenger needs to pass through either a Full-Body Scanner or a Walk-Through Metal Detector. Once the process is completed a passenger is not subjected to any further security screening prior to boarding the aircraft. This process identifies a number of goals consistent with a multi-faceted authorization scheme. Identification, authentication, and authorization are all present. Authentication lies in confirming that a passenger has a boarding pass and has attained permission to fly. Authorization for a passenger is in the form of screening his luggage and his person confirming whether or not he is a threat to the rest of the passengers.

The screening process is a very controversial topic, specifically balancing the passenger’s right to privacy with the security of the airport. Airplanes are more vulnerable compared to other forms of transportation. A plane in flight is very isolated and nearly impossible to engage with no consequence to the passengers aboard. The Boeing 747 typically holds 416 passengers and is extremely mobile making it one of the biggest targets for terrorist attacks. The United States puts significant importance on the security of airplanes after the 9/11 attacks. Airplanes also hold significance because not only can each person be held hostage, but they can be transported potentially across international borders. Terrorists are the main threat to airport security and any persons wishing to enact a malicious attack against people in a populated area. The TSA and the companies that fly make very expensive investments into the planes and jet fuel to fly people around safely. The Transportation Security Administration (TSA) and the Federal Aviation Administration (FAA) are responsible for protecting the businesses that fly and the passengers that right them. As such there are many regulations for safety and regulation for the flights.


The purpose of the Walk-Through Metal Detectors and the Full-Body Scanners is to make sure that the passenger is not presenting a threat to the other passengers. The majority of weapons are in the form of metal. Guns, knives, scissors, razor blades, and other dangerous metals are detected by Walk-Through Metal Detectors (WTMD). However as technology of defense has progressed, the technology of attack has progressed as well. From plastic guns or knives to dangerous chemicals, an attacker is looking for the most effective means of attack with the smallest quantity. The Full-Body Scanner (FBS) is a direct answer to these types of attacks. The Full-Body Scanner completely reveals any and all items under clothing leaving only the body of a person. Any item external to the body is in view of the FBS. The more common materials seized by the TSA are in the form of contraband. The TSA makes many drug seizures and while they are not necessarily dangerous to the persons aboard they are still illegal substances.


The TSA has been attempting to employ Full-Body Scanners as their preferred device in all airports and replace Walk-Through Metal Detectors. And there are two main weaknesses in the Full-Body Scanners. The first is that they rely on an employee. FBS is a new technology and the device is not automated nor does it alert the employee to the presence of metals. The device displays a picture of a person with clothing removed and any external objects in black outline. The employee must identify any and all objects that the passenger may be carrying and call for further screening on said passenger. This dependence on an employee puts the system at risk because the employee must be paying attention to each and every passenger and manual identification of foreign objects is difficult when examining thousands of passengers each day. The second risk lies in the device itself and how it displays foreign objects. Unlike a Walk-Through Metal Detector, there is no audio or visual que that signals a passenger is carrying a metal device. The other risk is the manner in which these images are displayed. They present the front and back view of a person with their body as a light gray and any other objects as black on a black background. The presentation of black objects on a black background means that the objects a passenger carries, small metal or plastic objects, on their sides are difficult to detect. Although the United States asked other countries to employ the same technology, the former chief of security at Israel Airport Authority stated, “I can overcome the body scanners with enough explosives to bring down a Boeing 747″(2 Walk-Through Metal Detectors have weaknesses as well. The primary weakness being the inability to detect materials other than metal. This allows a passenger to potentially bring another non-metallic hazardous object through the security checkpoint.


There are some defenses in place to function in conjunction with FBS and WTMD. The first is that a passenger is required to remove all additional clothing such as jackets, sweatshirts, hats, and shoes to simplify the screening process. The second measure in place is the random screenings and profiling conducted by the TSA. While profiling does potentially jeopardize the liberties of a passenger it does prevent some small fraction of crime. Random screenings are conducted to ensure that a person who subverts a scanner does not bring hazardous materials into the airport. These both work in conjunction with the scanners in an attempt to balance out any potential inaccuracies. In recent years, many passengers have argued that these new devices invade the privacy of passengers. The Full-Body Scanner displays nude pictures of the passenger to an employee. The easiest way technology can evolve to prevent attacks is to sacrifice the privacy of the passenger. The way technology is evolving is to fully expose the passenger and all threats before letting the passenger pass through security. The Full-Body Scanner is a step in this direction for the price of $250,000 per machine (2). This is a very costly road and while the technology is not fully optimized it seems that most airports will not be as quick as the United States to adapt the same technology.