Background
What are backscatter scanners and how do they work?
The Transportation Security Administration, or TSA, uses full body scanners at airport security checkpoints to scan for prohibited items. The machines used on people are called backscatter passenger scanners, commonly referred to as Advanced Imaging Technology (AIT). They use ionizing radiation to detect items such as metal weapons or explosives. A low energy x-ray that is reflected back to the machine, which allows the TSA agents to see if any unusual items or materials are present. This is because as the radiation passes through the passenger's body, materials of different densities will result in different energies being received on the other side of the machine [EPA 2017]. If a density different than that what is expected of the body is detected in a certain area, the person will fail the screening. The image below gives a depiction of what is shown to the agent when a person is inside the scanner [Hodson].
The Transportation Security Administration, or TSA, uses full body scanners at airport security checkpoints to scan for prohibited items. The machines used on people are called backscatter passenger scanners, commonly referred to as Advanced Imaging Technology (AIT). They use ionizing radiation to detect items such as metal weapons or explosives. A low energy x-ray that is reflected back to the machine, which allows the TSA agents to see if any unusual items or materials are present. This is because as the radiation passes through the passenger's body, materials of different densities will result in different energies being received on the other side of the machine [EPA 2017]. If a density different than that what is expected of the body is detected in a certain area, the person will fail the screening. The image below gives a depiction of what is shown to the agent when a person is inside the scanner [Hodson].
Based on the gender selected for the passenger by the agent, which is either male or female, the scanner checks for variations at certain locations in the person's body using software called Automatic Target Recognition. As is shown in the image above, the orange squares denote in what locations on the body a prohibited item is suspected. The nature of the the item is not revealed. In such a case, the person must undergo additional screening in the form of a pat down by an agent. If a person were to refuse passing through the scanner, a full-body pat down is mandatory. Children 12 and under may receive a "less invasive" pat-down and be supervised by a parent [Trans Equality].
TSA scanning pre- and post-9/11
In the wake of the tragedies that occurred on September 11th, 2001, the processes used to screen at airports have changed greatly. In fact, the TSA did not exist. Airport security was managed by private contractors, and rigorous scanning was not necessary since threats to the safety of passengers were not common, and the FAA permitted blades up to 4 inches long. On November 19, 2001, the Aviation and Transportation Security Act was signed into law [TSA 2001]. One of the requirements of this law was that it was now required for federal security screeners to check passengers before boarding, as well as their bags. Many new items, such as liquids over 3.4 ounces, blades, and aerosols were now prohibited.
In the years since, the TSA has greatly expanded its scope. As of March 2014, TSA had deployed about 740 AIT systems at almost 160 airports, and we estimate that TSA will spend over $3.5 billion in life cycle costs on deployed AIT-ATR systems and future AIT systems. Now programs such as TSA PreCheck and Global Entry are available, where travelers can pay a fee for expedited screening that does not require them to remove certain items from their luggage or items such as shoes or belts. In addition, the TSA has begun to use facial recognition software and ID scanning instead of actual agents to analyze people at the security checkpoint.
How can personal characteristics lead to different treatment?
Some people may experience difficulties passing through TSA security, be denied entry for unidentified reasons, or have delayed airline boarding. This often occurs in cases where someone matches the demographics or name of that of a criminal or person on the terrorist watch list. It may also occur if the person has a history of additional private screenings. In this case, they are eligible to apply for the Department of Homeland Security Traveler Redress Inquiry Program, or DHS TRIP [TSA 2022]. This provides them with a number that allows them to enter a database which is supposed to reduce the likelihood of these events.
Why is this important?
Millions of people with different backgrounds and identities travel through airports in the United States every day. It is unfair that due to the algorithms in place today, some face inferior treatment. Bias in airport security should be eliminated to make travel more equitable. It is important to understand the causes of bias and how automation has contributed to disparities in travel procedures, which should be the same for everyone. By identifying the shortcomings of current algorithms and the variations between protocol and practice,
In the wake of the tragedies that occurred on September 11th, 2001, the processes used to screen at airports have changed greatly. In fact, the TSA did not exist. Airport security was managed by private contractors, and rigorous scanning was not necessary since threats to the safety of passengers were not common, and the FAA permitted blades up to 4 inches long. On November 19, 2001, the Aviation and Transportation Security Act was signed into law [TSA 2001]. One of the requirements of this law was that it was now required for federal security screeners to check passengers before boarding, as well as their bags. Many new items, such as liquids over 3.4 ounces, blades, and aerosols were now prohibited.
In the years since, the TSA has greatly expanded its scope. As of March 2014, TSA had deployed about 740 AIT systems at almost 160 airports, and we estimate that TSA will spend over $3.5 billion in life cycle costs on deployed AIT-ATR systems and future AIT systems. Now programs such as TSA PreCheck and Global Entry are available, where travelers can pay a fee for expedited screening that does not require them to remove certain items from their luggage or items such as shoes or belts. In addition, the TSA has begun to use facial recognition software and ID scanning instead of actual agents to analyze people at the security checkpoint.
How can personal characteristics lead to different treatment?
Some people may experience difficulties passing through TSA security, be denied entry for unidentified reasons, or have delayed airline boarding. This often occurs in cases where someone matches the demographics or name of that of a criminal or person on the terrorist watch list. It may also occur if the person has a history of additional private screenings. In this case, they are eligible to apply for the Department of Homeland Security Traveler Redress Inquiry Program, or DHS TRIP [TSA 2022]. This provides them with a number that allows them to enter a database which is supposed to reduce the likelihood of these events.
Why is this important?
Millions of people with different backgrounds and identities travel through airports in the United States every day. It is unfair that due to the algorithms in place today, some face inferior treatment. Bias in airport security should be eliminated to make travel more equitable. It is important to understand the causes of bias and how automation has contributed to disparities in travel procedures, which should be the same for everyone. By identifying the shortcomings of current algorithms and the variations between protocol and practice,