Prepared for Members and Committees of Congress
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Over the next several years, the Transportation Security Administration ( TSA) will likely face
continuing challenges to address projected growth in passenger airline travel while maintaining
and improving upon the efficiency and effectiveness of passenger screening operations. New
initiatives to expand the role of TSA personnel beyond screening operations, as well as initiatives
to improve screening efficiency and effectiveness through the deployment of new technologies,
will likely require additional investment. In addition to annual appropriations of $ 250 million in
FY2008 and FY2009, a portion of the $ 1 billion identified for aviation security in the stimulus
measure ( P. L. 111- 5) has been designated for acquiring and deploying technologies to screen
passengers for explosives.
However, policymakers and aviation security planners have not yet agreed upon a well- defined
strategy and plan for evolving airline passenger and baggage screening functions to incorporate
new technologies, capabilities, and procedures to more effectively and efficiently detect potential
threats to aviation security.
Ongoing challenges to maintaining and improving upon screening functions include: addressing
the potential impacts of projected airline passenger traffic growth on screening operations;
optimizing screening efficiency and minimizing passenger wait times; addressing potential airport
space constraints for screening checkpoints and equipment; improving the capability to detect
explosives at passenger checkpoints; optimizing inline explosives detection systems for checked
baggage; developing strategic plans for addressing screening technology and human factors
needs; and defining the funding requirements to implement these strategic plans.
A number of initiatives related to passenger and baggage screening are currently being evaluated
by the TSA. These include tests of new passenger checkpoint layouts and field testing of next-generation
checkpoint technologies for detecting explosives, including explosives chemical trace
detection devices, whole body imaging systems, and advanced technology ( AT) X- ray
capabilities.
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Policy Issues for Airport Passenger Screening................................................................................ 1
Airline Passenger Traffic Growth ............................................................................................. 2
Screening Efficiency and Passenger Wait Times ...................................................................... 2
Space Constraints at Airports .................................................................................................... 3
Improving Explosives Detection at Passenger Checkpoints ..................................................... 3
Strategic Planning for Addressing Technology and Human Factors Needs.............................. 4
Projected Costs and Funding Issues .......................................................................................... 5
Checkpoint Screening Human Performance.................................................................................... 6
Potential Impacts of Respecting Privacy on Screening Performance.............................................. 7
Covert Testing ............................................................................................................................... . 8
Threat Image Projection ................................................................................................................ 12
X- Ray Imagery and Carry- On Baggage Screening Performance.................................................. 13
Passenger Checkpoint Efficiency .................................................................................................. 15
Passenger Wait Times.............................................................................................................. 15
The Link Between Checkpoint Efficiency, Airport Terminal Design and Vulnerability
Reduction ............................................................................................................................. 17
Queuing Practices and Procedures .......................................................................................... 18
The Tailored Self- Select Screening Lane Initiative................................................................. 19
The Registered Traveler Program ........................................................................................... 20
Options for Further Streamlining Passenger Checkpoint Procedures ..................................... 22
Checkpoint Procedures for Liquids......................................................................................... 23
Passenger Education and Informational Materials.................................................................. 25
Checkpoint Evolution and Related Initiatives ............................................................................... 25
Next Generation Checkpoint Technologies ................................................................................... 27
Explosives Trace Detection Technologies............................................................................... 29
Explosives Trace Detection ( ETD) Machines................................................................... 29
Bottle and Liquid Explosives Scanners ............................................................................ 29
Walkthrough Explosives Trace Detection Portals............................................................. 30
Whole Body Imaging Technologies ........................................................................................ 30
X- Ray Backscatter Imaging Systems................................................................................ 32
Millimeter Wave Imaging Systems ................................................................................... 33
Advanced Technology X- Ray Equipment............................................................................... 34
Other Candidate Technologies and Applications for Aviation Security Screening ................. 34
Screening Airport Workers ............................................................................................................ 35
Screening and Vetting of Airline Crews ........................................................................................ 37
 	     
 
Figure 1. Average Peak Wait Times at Screening Checkpoints ..................................................... 17
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Table 1. Emerging Checkpoint Technologies ................................................................................ 28
       
 
Author Contact Information .......................................................................................................... 39
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istorically, airline passenger screening functions have focused on checkpoint screening
using magnetometers to detect metallic weapons on passengers and X- ray systems to
examine carry- on items. These methods have changed little since they were first
implemented at commercial airports in the United States during the early 1970s. Recently,
however, new initiatives to expand the role of TSA personnel beyond traditional physical
screening of passengers and their belongings, as well as initiatives to improve screening
efficiency and effectiveness through the deployment of new technologies, have been implemented
and are being tested. These changes are coming about largely in response to recommendations
and statutory requirements to address threats posed by explosives carried by passengers or in their
carry- on items.
Addressing the identified need to effectively detect explosives on passengers and in carry- on
items will likely require considerable investment and resources. However, policymakers and
aviation security planners have not yet agreed upon a clear strategy and well- defined plan for
evolving airline passenger screening functions to incorporate new technologies, capabilities, and
procedures to more effectively and efficiently detect explosives, weapons, and other threat objects
as well as individuals who may pose a threat to aviation security.
Over the next several years, the TSA will likely face continuing challenges to address projected
growth in passenger airline travel while maintaining and improving upon the efficiency and
effectiveness of passenger and baggage screening operations. Addressing these challenges raises a
number of significant policy issues related to allocating resources and funding passenger
screening initiatives, adequately addressing human performance issues in the design of future
passenger screening systems, and developing effective strategies for deploying next generation
screening technologies.
 
              
       
                       
The TSA faces a number of ongoing challenges to maintain and improve upon the effectiveness
and efficiency of passenger screening functions. These challenges include:
• Addressing projected airline passenger traffic growth and its potential impacts on
screening operations;
• Optimizing screening efficiency and throughput and minimizing passenger wait
times;
• Identifying and addressing potential airport space constraints for screening
checkpoints and equipment;
• Improving the capability to detect explosives at passenger checkpoints as
recommended by the 9/ 11 Commission and called for in legislation;
• Developing strategic plans for addressing identified technology and human
factors needs related to passenger screening; and
• Defining funding requirements to implement these strategic plans.
There are numerous policy issues regarding the strategies and approaches for addressing these
ongoing challenges. Some of the key issues are briefly discussed below.
H
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Currently, across the United States and its territories, passenger screening is conducted at about
450 airports. In total, there are more than 750 screening checkpoints and slightly more than 2,000
screening lanes at the nation’s commercial airports. 1 The Federal Aviation Administration ( FAA)
projects that domestic passenger traffic will increase at an average annual rate of about 3% from
2010 through 2020 and international passenger traffic will increase at a rate of approximately
4.5% per year. 2 Based on these projections, passenger volume at screening checkpoints is
expected to increase by more than 25% over the next eight years, although a prolonged economic
slowdown could moderate the pace of this growth to some degree.
In 2006, the TSA reported that it had screened over 700 million passengers and other individuals
accessing the secured areas of airports in the United States. If airline passenger traffic grows as
predicted, then the TSA will likely be screening over one billion people annually by 2024, or
perhaps sooner if initiatives to conduct random and targeted screening of airport employees,
currently being conducted under trial programs at selected airports, are expanded across the entire
aviation system. Significant resources will likely be needed to address future screening needs to
accommodate this growth without causing an operational impact on screening efficiency and
effectiveness.
      	       	  	            
 
         	    	   
 
With respect to screening efficiency, the TSA has set an objective of keeping average passenger
wait times to ten minutes or less ever since its inception in 2002. While the average wait times
aggregated across the entire aviation system have generally met this objective, wait times at
larger airports, particularly the busiest airports, often exceed ten minutes. 3 Passengers frequently
experience long waits in screening checkpoint queues, particularly during peak periods at the
nation’s busiest airports.
At many larger airports, space constraints and other design considerations have limited the TSA’s
ability to add additional screening lanes and reconfigure checkpoints to improve the flow of
passengers. This has resulted in lengthy wait times during peak periods, sometimes exceeding 40
minutes, at many of the nation’s largest airports.
Wait times are not just a problem at large airports, as smaller regional airports may also face
challenges with large seasonal fluctuations in passenger volume coupled with screening lane and
workforce constraints that may limit the ability to respond to spikes in passenger traffic.
Therefore, in addition to accommodating projected future growth in passenger volumes, the TSA
faces ongoing challenges at various airports to improve upon the overall efficiency of passenger
screening operations and meet stated wait time objectives without sacrificing performance.
1 United States Government Accountability Office. Aviation Security: TSA’s Staffing Allocation Model Is Useful for
Allocating Staff among Airports, but Its Assumptions Should Be Systematically Reassessed, GAO- 07- 299 ( February
2007).
2 Federal Aviation Administration, FAA Aerospace Forecast: Fiscal Years 2009- 2025.
3 United States Government Accountability Office. Aviation Security: TSA’s Staffing Allocation Model.
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Space constraints within airports are likely to become an increasing concern for the TSA as it
seeks to increase the number of screening lanes to meet projected growth in the number of airline
passengers. These constraints are also likely to become an increasingly important issue as the
TSA is seeking to reconfigure checkpoints over the next several years to accommodate new
screening technologies. The TSA is also seeking to expand the footprint of the screening
checkpoint queue and screening lanes to provide a more relaxed atmosphere for travelers and
provide behavioral detection officers ( BDOs) with additional space to mingle and interact with
passengers in an effort to improve the detection of suspicious behavior and possible hostile intent.
These factors may combine to result in a considerably larger footprint for screening checkpoints
compared to current configurations, particularly at older airports constructed when passenger
volume was considerably less and the footprint of screening checkpoints was quite small.
Optimizing the layout of screening checkpoints at these airports may require a considerable
investment in redesigning and expanding airport facilities to accommodate proposed future
changes to screening checkpoints that are intended to optimize efficiency and performance across
the entire network of commercial airports. 4 Particular challenges may be encountered at smaller
regional airports that have limited capability and access to resources to expand, as well as at large
airports with older terminals that were not initially designed with these new security challenges in
mind.
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The 9/ 11 Commission recommended that the TSA give priority attention to implementing
technology and procedures for screening passengers for explosives, something not currently done
routinely at screening checkpoints. Provisions to improve checkpoint technologies to detect
explosives were included in the Intelligence Reform and Terrorism Prevention Act of 2004 ( P. L.
108- 458, hereafter the “ Terrorism Prevention Act”).
To address the issue of detecting explosives carried by passengers, the TSA tested walk- through
trace detection portals, known as explosives trace portals ( ETPs), and has implemented
procedures for conducting pat- down searches of passengers for explosives. Full deployment of
the walk- through trace detection portals, or puffer machines, for use in secondary screening of
selected passengers had been part of the TSA’s strategy for screening passengers for explosives,
but this initiative has been put on hold due to maintenance issues with deployed systems. The
effectiveness of the strategy has also been brought into question by the foiled plot to bomb U. S.-
bound airliners using liquid explosives uncovered in August 2006. The TSA is working to identify
strategies and technologies that more completely address the explosives threat posed by
passengers and carry- on items.
In addition to keeping up with increased volumes of people passing through airport screening
checkpoints and improving upon screening efficiency, the TSA faces significant challenges in
4 The term “ optimize” is used extensively throughout this report. The term is broadly defined as improving or
developing as far as possible some measurable aspect of system performance or efficiency through the application of
new technologies, policies, procedures, and systems engineering principles. It should be noted, however, that there are
often inherent tradeoffs among certain measurable aspects of a system’s performance. For example, given current
technological capabilities, there are often tradeoffs between system efficiency and system detection capability.
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addressing 9/ 11 Commission recommendations and statutory mandates to improve the ability to
detect explosives and bomb- making components carried on passengers and in carry- on items.
There are lingering concerns that, without a significant investment to improve the detection of
concealed explosives and non- metallic weapons at passenger checkpoints, considerable
vulnerabilities will persist. The TSA is pursuing a wide variety of technologies to address the
challenge of detecting explosives at passenger screening checkpoints. These technologies include
walkthrough explosive trace detection portals, whole body imaging ( WBI) systems, bottle liquid
scanners, cast and prosthesis scanners, shoe scanners, advanced technology ( AT) X- ray systems,
and explosives detection systems ( EDS) tailored for carry- on screening applications. These
various technologies will complement, and in some cases replace, existing checkpoint tools such
as magnetometers, hand wands, and explosives trace detection ( ETD) equipment.
Under the TSA’s current budget plans, in the near term, deployment of this technology will be
concentrated at the nation’s largest airports and will often be limited to use on those passengers
selected for secondary screening or to resolve alarms set off during primary screening. Full scale
deployment of technologies to screen all passengers and carry- on items for explosives and other
concealed items will involve a considerably larger investment over the long term. However, a
specific long term investment and technology deployment strategy has not yet been agreed upon.
While these various technologies have reached a level of maturity where they can be
operationally deployed, achieving an end state in which all passengers are screened unobtrusively
to detect a broad range of threat objects raises a number of policy issues related to the privacy of
passengers as well as a long term investment strategy for implementing future checkpoint
concepts.
       	        	             
 
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The challenges to improving screening capabilities stem from the 9/ 11 Commission’s
recommendations to improve the detection of explosives on passengers and address human
factors considerations related to screener performance. 5 Four years after these recommendations
were issued, the Government Accountability Office ( GAO) reported that only limited progress
had been made in fielding explosives detection technologies at passenger checkpoints, and the
TSA lacks a strategic plan for the acquisition and deployment of screening technologies. 6
Moreover, covert testing at passenger checkpoints continues to provide evidence that, despite the
considerable federal spending on airline passenger screening since the 9/ 11 terrorist attacks, the
system remains vulnerable, particularly to the threat posed by adversaries attempting to sneak
improvised explosive devices ( IEDs) or components to assemble such devices through security
checkpoints and onboard passenger airliners. These vulnerabilities reflect the lack of adequate
technologies deployed at checkpoints capable of detecting explosives materials, as well as
limitations in screener performance that is influenced by a variety of human performance factors.
5 National Commission on Terrorist Attacks Upon the United States. The 9/ 11 Commission Report, Washington, DC:
July, 2004.
6 U. S. Government Accountability Office, Transportation Security Administration Has Strengthened Planning to Guide
Investments in Key Aviation and Surface Transportation Security Programs, but More Work Remains, Statement of
Cathleen A. Berrick, Director, Homeland Security and Justice Issues, Before the Committee on Commerce, Science,
and Transportation, U. S. Senate, May 13, 2008, GAO- 08- 487T.
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Provisions in P. L. 110- 53 ( see section 1607) required the TSA to finalize a strategic plan for
checkpoint explosives detection required by the Terrorism Prevention Act, and fully implement
the plan within one year of enactment. The act also contained provisions ( see section 1612) that
eliminate the cap on the system- wide number of TSA screeners, and require specialized training
for screeners on security skills such as behavioral observation and analysis, explosives detection,
and document examination. The act directed the TSA to hire sufficient personnel to ensure
adequate aviation security and reduce average security- related delays to less than 10 minutes. The
act also created a separate “ Checkpoint Security Screening Fund,” specifying that $ 250 million of
the security fees collected during FY2008 were to be deposited into this fund ( see section 1601),
and made available for research, development, deployment, and installation of equipment to
improve the detection of explosives at passenger checkpoints. The act also directed the TSA to
carry out a pilot study to examine technologies to improve the security at access control doors and
exit lanes for airport secured areas ( see section 1613).
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The Implementing Recommendations of the 9/ 11 Commission Act ( P. L. 110- 53) included a
provision establishing an Airport Checkpoint Screening Fund. The fund provided $ 250 million in
passenger security fees for the acquisition and deployment of technologies to improve the
detection of explosives at passenger screening checkpoints in FY2008. The FY2009 Department
of Homeland Security Appropriations Act ( P. L. 110- 329) provides $ 250 million for Checkpoint
Support, thus maintaining funding for checkpoint technologies, supplies, and equipment at the
level provided under the Airport Checkpoint Screening Fund in FY2008.
In addition to these appropriations, the American Recovery and Reinvestment Act of 2009 ( P. L.
111- 5) specifies an additional $ 1 billion for aviation security, designated for the procurement and
installation of checkpoint explosives detection equipment and checked baggage explosives
detection systems. This additional funding is expected to accelerate the deployment of checkpoint
explosives detection technologies over the next two years. Conference report language ( see
H. Rept. 111- 16) specifies that projects should be prioritized based on security risks.
Deploying new technologies and reconfiguring screening lanes to incorporate these technologies
and optimize performance and efficiency will likely cost more than $ 500,000 per screening lane
based on TSA average unit costs for candidate technologies. 7 This cost only considers the direct
costs for screening lane technology acquisition and installation, and does not include any costs
associated with expanding or reconfiguring airport terminals to accommodate new checkpoint
designs. Given that there are more than 2,000 screening lanes in operation throughout the United
States, the total cost to upgrade screening checkpoints is likely to exceed one billion dollars in
equipment costs alone.
Additionally, the costs to operate and maintain this screening equipment is likely to cost tens of
thousands of dollars each year per screening lane. Based on these rough estimates, it is apparent
that current funding levels for Checkpoint Support will not support a full- scale, near- term
deployment of emerging passenger checkpoint technologies. Congress may consider various
funding options to expand or accelerate the deployment of these checkpoint technologies. If such
7 CRS estimates based on unit costs provided in DHS TSA FY2009 congressional budget justification documents.
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options are not pursued, it will likely take ten years or more to achieve full system- wide
deployment.
At present, the TSA has adopted a strategy of focusing its efforts to deploy new checkpoint
screening technologies on larger airports. However, since the aviation screening system in the
United States operates using a single gateway concept, meaning that passengers are only screened
once at their originating airport, focusing investments solely on larger airports could result in
persisting vulnerabilities at smaller regional airports. These vulnerabilities may further persist
without a strategy and commitment to future funding for system- wide deployment of advanced
technology systems for detecting explosives and nonmetallic threat items at checkpoints.
	      
                         
       
The aviation security system is a human system involving extensive reliance on human
perception, performance, decision making, and judgment. This is particularly true with regard to
checkpoint screening functions where passenger and carry- on screening involve human resource
intensive activities to detect and resolve potential threat items. An underlying challenge related to
proposed checkpoint expansion and enhancements is addressing ongoing human performance
concerns to improve the detection of dangerous items at checkpoints and incorporate human
factors considerations in the design and operator training for next generation checkpoint
technologies and procedures.
Screener performance is a continuing concern as covert testing results have repeatedly
demonstrated existing weaknesses in screening procedures and capabilities that could potentially
be exploited by terrorists or criminals seeking to attack the aviation system. These weaknesses
may reflect a combination of policies, procedures, technology capabilities, and screener human
performance, although weakness in screener human performance has been emphasized as a
particular concern which can be affected by various factors. A wide range of human factors
considerations pertaining to screening procedures, training, fatigue and alertness, human
perception and detection capabilities, and judgment and decision making can have a significant
effect on the overall effectiveness of passenger checkpoint screening as well as baggage screening
operations.
Passenger checkpoint screening activities at all passenger airports are carried out by about 30,000
screeners who make up about 60- 65% of the total TSA screener workforce. The humans that
operate the system, particularly the screening workforce, have long been regarded as a potentially
highly fallible and vulnerable element of the aviation screening system. This should not be
construed as a reflection on the dedication and commitment of individual screeners to performing
this critical job function. Rather it reflects a combination of the complex challenges faced by
screeners, limitations in human perception and performance, resourceful adversaries who may
employ artful concealment methods, and competing job pressures to accurately detect threat
objects while maintaining an efficient flow of passengers through security checkpoints.
Adversaries seeking to carry out hijackings or bombings by carrying explosive devices, bomb
making components, or handheld weapons through screening checkpoints may attempt to exploit
various limitations on human perception and performance that may compromise security. A
variety of factors may contribute to these human performance limitations, including inadequate
training, lack of motivation and job satisfaction, fatigue, and workplace conditions, as well as
general human perception and performance limitations.
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Balancing individuals’ rights and expectations of privacy with screening effectiveness is a human
performance challenge. Criminals and terrorists have been known to conceal items in private
areas of the body, especially in the small of the back above the buttocks and high on the thigh.
Screeners are to carefully inspect these areas during pat downs to adequately check for dangerous
items. Also, underwire bras can set off magnetometers, and bras have been used to conceal
dangerous items. One of the most intrusive and most controversial aspects of secondary screening
is the use of pat- down inspections to check selected passengers or to resolve magnetometer
alarms. Specific complaints over pat- down techniques have centered on allegations of
inappropriate touching and unprofessional or rude conduct by screeners. More general complaints
have focused on privacy concerns and perceptions that the pat- down procedures were intrusive
and humiliating. 8
A 2005, DHS OIG investigation and audit of pat- down screening procedures found that the TSA
adequately advised passengers of their rights under the pat- down procedures, and appropriately
accommodated those rights. 9 The DHS OIG also found that TSA screeners were adequately
trained in pat down inspection procedures and, based on TSA records, additional screening
procedures were performed on proportionate numbers of male and female passengers. Finally, the
DHS OIG found that the TSA had implemented procedures to investigate and resolve passenger
complaints regarding the screening process.
The TSA maintains a screening Performance Management Information System ( PMIS) where
recorded complaints are logged. Operations research analysis teams and federal security directors
review complaints logged in the database to track trends and identify areas of concern and take
appropriate actions, including possible disciplinary actions, to resolve specific issues. Complaints
involving allegations of discrimination based on color, race, gender, religion, or national or ethnic
origin are forwarded to the TSA’s Office of Civil Rights for further investigation. Despite
considerable concern raised by some regarding inappropriate behavior during pat- down screening
procedures, the DHS OIG found no systematic problems with the technique.
Nonetheless, privacy groups, such as the American Civil Liberties Union ( ALCU), continue to
express concern over potential intrusion on individual rights and alleged cases of sexual
harassment and abuse of passengers, particularly female passengers, by TSA screeners. 10 These
concerns, however, raise a significant challenge for the TSA: to maintain high levels of security,
which necessitate resolving all alarms and screening in detail those passengers ascertained to pose
an elevated security risk, while maintaining the privacy rights and dignity of passengers identified
for these secondary screening measures. The principal option under consideration for addressing
these concerns is the use of whole body imaging technologies, discussed below. While these
technologies offer a potential alternative to pat- down screening techniques, they too, raise privacy
concerns because the images generated by these systems can reveal private areas, physical
8 Department of Homeland Security, Office of Inspector General, Review and Audit of the Transportation Security
Administration’s Use of Pat- Downs in Screening Procedures ( REDACTED), November 2005, OIG- 06- 10.
9 Ibid.
10 American Civil Liberties Union, TSA Pat- down Search Abuse, December 21, 2004, New York, NY.
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characteristics that individuals may wish to keep private, as well as prosthetics and other assistive
medical devices.
In the fast- paced environment of the passenger checkpoint, pat- down searches may be rushed and
certain areas may be overlooked. The difficulty in detecting threat items on passengers is
compounded by the requirements to respect the privacy of individuals discussed above, as well as
social and cultural norms and individual differences regarding interpersonal contact and
expectations of privacy and modesty. Some have also noted cultural sensitivities toward
handicapped and disabled individuals and point out that screeners are sometimes hesitant to
perform intrusive searches, particularly on individuals wearing various prosthetics. 11 Terrorists
and criminals can and have exploited these aspects of individual privacy by concealing prohibited
items in body cavities and near private areas of their bodies, and could also exploit a screener’s
reluctance to perform thorough searches of prosthetic devices. Covert testers also use these
methods to conceal simulated threat items in an effort to test screeners’ abilities to detect items
under real- world conditions and identify vulnerabilities in checkpoint screening that can
potentially be reduced through procedural modifications and/ or changes to screener training.
These covert tests have revealed weaknesses in screener performance to detect weapons,
simulated explosives, and components of explosive devices.
	 
             
Much of the concern over the performance of airport screening operations has arisen from
information that has been made public regarding the results of covert testing operations. Covert
testing using rudimentary mock bombs and guns started soon after screening checkpoints were
first established in the early 1970s. Following the bombing of Pan Am flight 103 in December
1988, the FAA began more sophisticated “ red team” tests to identify weaknesses in screening
performance and other aspects of aviation security. The term red team harkens back to the Cold
War era military exercises where red teams – so designated in reference to the Soviet Union’s red
flag and the association of red with communist groups – adopted strategies and tactics of an
enemy force in simulations and war games.
The use of aviation security red team testing was suspended for a period of time following the
9/ 11 attacks, largely over concerns that red team practices could potentially put testers in danger
or cause significant panic among passengers because of the acute focus on aviation security and
the lingering public fear following the attacks. In 2003, the TSA’s Office of Internal Affairs and
Program Review ( OIAPR) resumed covert testing of passenger screening checkpoints, checked
baggage screening operations, and airport access control measures. At present, this function falls
under the responsibility of the TSA’s Office of Investigations ( TSA- OI). In addition to nationwide
covert testing conducted by the TSA- OI, Federal Security Directors ( FSDs) at each airport are to
perform local covert testing. The local testing was initially called the Screener Training Exercises
and Assessments ( STEA), but is now known as the Aviation Screening Assessment Program
( ASAP) and has been revamped to better reflect the types of threat objects that may be used by
terrorists based on the latest intelligence and threat information.
11 Jeanne Meserve and Mike M. Ahlers. “ TSA Tester Slips Mock Bomb Past Airport Security.” Cable News Network
( CNN), January 28, 2008.
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While specific performance metrics for covert testing are considered security sensitive, various
media reports of test results suggest that failure rates are often quite high, particularly with
respect to screeners missing simulated improvised explosive devices and explosive components.
For example, it has been reported that during tests conducted in 2006, TSA screeners missed fake
bombs 75% of the time at Los Angeles International Airport ( LAX), and 60% of the time at
Chicago O’Hare Airport ( ORD). 12 The TSA contends that the results, on the surface, appear
discouraging, but are a reflection of highly sophisticated concealment methods being used by
testers to uncover specific system vulnerabilities so that corrective action can be taken.
According to the TSA “... as security officers adapt and begin to consistently discover covert
testing methods, testers start all over again, creating more difficult and harder- to- detect tests. This
years’ long game of cat and mouse more closely simulates real terrorist probing and operations
and keeps officers alert and informed of the latest techniques and improvements.” 13 The TSA
points out that this type of testing is fundamentally different from the static, unchanging
performance evaluations that were employed prior to the 9/ 11 attacks. Since the present day test
protocols are constantly changing, the TSA has primarily used them to provide a snapshot of
specific vulnerabilities in the system. It has not systematically assessed whether screener
performance is improving or getting worse over time, although it asserts that improvements have
been made. According to the TSA, the covert testing methods are primarily used as a tool for
assessing and identifying areas where performance improvements are needed and are potentially
achievable through additional training, operational emphasis, or procedural redesign.
The TSA plans to complete more than 2,500 covert tests of passenger screening checkpoints
annually during FY2008 and FY2009 in an effort to continually identify vulnerabilities and take
corrective action to improve checkpoint screening based on the latest intelligence and information
regarding terrorist weapons and explosives that pose a threat to commercial aviation and methods
for concealing these threat objects. 14 While specific test results are considered security sensitive
information, it has been reported that current failure rates are comparable to those observed in
1987 when screeners failed to detect about 20 percent of concealed items during on- the- job
performance testing. 15 However, the TSA asserts that the testing methods used at that time was in
no way comparable to current covert testing methods.
Concerns over advance warning given prior to covert testing and screener performance
evaluations has been a longstanding issue. While media reports have suggested that some recent
TSA covert tests were leaked to screeners, the TSA maintains that its procedures are designed to
minimize the likelihood that screeners will be tipped off regarding a covert test operation, while
providing appropriate notification to TSA airport level management and local law enforcement to
ensure that the tests are conducted safely. Nonetheless, cases of screeners being tipped off
regarding covert testing have been documented. For example, in 2004, the DHS IG found that
screeners at the Jackson- Evers International Airport in Mississippi had been given information
regarding upcoming covert tests, including details about the gender and race of the testers, the
type of test items being used, and the location of test items on the tester and in carry- on and
12 Ibid.
13 Transportation Security Administration, Covert Testing: Why is Covert Testing Important?
14 Transportation Security Administration, Fiscal Year 2009 Congressional Justification, Transportation Security
Support.
15 Sara Kehaulani Goo. “ Airport Screeners Do Poorly, Panel Told.” The Washington Post, April 23, 2004, p. A8.
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checked baggage. 16 Also, it was revealed that in April 2006, TSA headquarters staff used an
internal electronic communications system to provide field level personnel with heads up
information regarding possible covert testing operations, providing details regarding testing
methods. 17 The TSA responded that it was investigating the allegations, but preliminary findings
indicated that the internal communication regarding the testing was considered suspicious by a
headquarters official who decided to forward it to federal security directors at airports across the
country, but the email was recalled 13 minutes after it was sent. Based on these findings, the TSA
concluded that the dissemination of information regarding the upcoming covert test did not
appear to be a deliberate attempt to tip off screeners or screening supervisors. Former TSA
Administrator Kip Hawley testified that there was nothing to indicate that anyone within the TSA
attempted to tip off airport security screeners regarding covert testing in this incident. 18
In addition to concerns over possible advance warning of covert tests, concerns have also been
raised that the TSA does not have adequate processes in place to systematically document causes
of covert testing failures and carry out appropriate remedial action. A GAO audit of TSA’s covert
testing programs, including covert testing of passenger screening, baggage screening, and airport
access control systems, found that the TSA- OI has failed to systematically record, document, and
inform management of causes for test failures as would be expected if federal government
standards for internal control were fully implemented. 19 The GAO further noted that the TSA
lacks a systematic process to ensure that recommendations by TSA- OI are fully considered, and
management decisions for adopting or rejecting these recommendations are appropriately
documented.
While the TSA- OI made numerous recommendations to the TSA’s Office of Security Operations
during the period reviewed ( March 2003- June 2007), the GAO found that often, in more than
40% ( 18 out of 43) of cases, TSA management either took no action or it was unclear how the
action taken addressed the recommendation. The lack of a formal process made it difficult to
assess how the recommendations related to covert testing results, and in turn, how actions taken
remedied problems identified by the TSA- OI. The GAO concluded that without such a process,
the TSA’s ability to strengthen aviation security based on the findings and recommendations of
covert testers is limited, and it recommended that the TSA establish a system for documenting the
results and recommendations stemming from covert testing and to track actions taken in response
to these recommendations.
In addition to the internal covert testing by the TSA’s Office of Inspections, both the Department
of Homeland Security Office of Inspector General and the GAO independently conduct periodic
audits and inspections of TSA screening functions that often include covert testing methods.
While many of the details of these audits are considered security sensitive, the results of these
tests have provided Congress and observers with important insights regarding the persisting
vulnerabilities at airport passenger screening checkpoints.
16 Department of Homeland Security, Office of Inspector General. Letter Report: TSA’s Management of Aviation
Security Activities at the Jackson- Evers International Airport, August 2007, OIG- 07- 73.
17 Honorable Bennie G. Thompson, Chairman, Homeland Security Committee, U. S. House of Representatives, “ Cover
Blown: Did TSA Tip Off Airport Screeners about Covert Testing.” Statement Released November 14, 2007.
18 “ TSA: Airport Screeners Weren’t Tipped Off,” Air Safety Week, November 19, 2007.
19 United States Government Accountability Office. Transportation Security: TSA Has Developed a Risk- Based Covert
Testing Program, but Could Better Mitigate Aviation Security Vulnerabilities Identified Through Covert Tests, August
2008, GAO- 08- 958.
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Most notably, in a series of covert tests conducted in 2007, GAO investigators demonstrated that,
even when proper procedures were followed, checkpoint screening often failed to detect
concealed explosives and components that could be used to construct an explosive device
potentially capable of downing an airliner. 20 For these tests, the investigators constructed two
improvised devices: an improvised explosive device ( IED), consisting of a liquid explosive that
would be triggered by a low- yield detonator ( i. e., a blasting cap); and an improvised incendiary
device ( IID), constructed from commonly available products including a liquid component. The
investigators obtained the materials to construct these devices at local stores and over the Internet,
spending less that $ 150. The investigators then employed various methods to conceal these items
on their persons and in carry- on baggage, demonstrating that it is possible to pass either a
constructed device or the components to build an IED or an IID through airport screening
checkpoints without detection. In all cases, screeners failed to detect or prohibit the carriage of
IED and IID components, including liquid components.
The GAO noted that the specific security weaknesses exploited in these covert tests, which were
not divulged for security reasons, were identified by reviewing publicly available information,
including information often shared through the Internet and readily available to terrorist groups.
By exploiting these weaknesses, the investigators were able to pass these components, including
banned liquid items, through various security checkpoints. While the investigators were subjected
to secondary screening for unrelated reasons in some instances, pat- down searches and other
secondary screening methods failed to detect the improvised explosives or prohibited items. In
other instances, screeners challenged the investigators for failing to fully comply with various
procedures, including procedures regarding permissible quantities and packaging of liquids.
The GAO concluded that its “ tests clearly demonstrate that a terrorist group, using publicly
available information and few resources, could cause severe damage to an airplane and threaten
the safety of passengers by bringing prohibited IED and IID components through security
checkpoints.” 21 In reviewing these results, the TSA has acknowledged checkpoint vulnerabilities
related to human performance, screening procedures, and checkpoint technologies. The GAO
asserted that improvements in these areas may further reduce the risks to commercial aviation
posed by IEDs and IIDs.
While the GAO’s specific recommendations focusing on ways to improve screener detection of
threat objects made to the TSA were not publicly divulged, the GAO also urged the TSA to take
the following actions to enhance checkpoint screening operations:
• Establish dedicated airport screening lanes to handle those passengers posing an
elevated risk and for those passengers with special needs;
• Introduce more aggressive, visible, and unpredictable checkpoint procedures,
such as random pat- down and hand- wand screening; and
• Continue to develop new technology at checkpoints to better detect concealed
items.
20 United States Government Accountability Office. Statement of Gregory D. Kutz, Managing Director, Forensic
Audits and Special Investigations, and John W. Cooney, Assistant Director, Forensic Audits and Special Investigations.
Aviation Security: Vulnerabilities Exposed Through Covert Testing of TSA’s Passenger Screening Process. Testimony
Before the Committee on Oversight and Government Reform, House of Representatives, November 15, 2007.
21 Ibid., p. 10.
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  	              ! 
These recommendations for action reflect a continuing concern that, despite considerable
investment in checkpoint screening technologies and personnel since the terrorist attacks of
September 11, 2001, significant vulnerabilities persist in checkpoint screening operations. In
testimony before the House Committee on Homeland Security on November 14, 2007, former
DHS Inspector General Clark Kent Ervin stated that “[ t] he sad fact is that for all the dollars and
attention that has been focused on screener performance since 9/ 11, study after study ... shows
that it is just as easy today to sneak these deadly weapons past screeners [ as] it was on 9/ 11.” 22
While Ervin’s conclusions have been somewhat controversial and widely disputed by the DHS
and the TSA, his general recommendations parallel various initiatives put forward by Congress
and the Bush Administration to improve screener performance. Specifically, Ervin recommended
extensive training and frequent retraining of screeners under simulated real- world conditions;
remedial action for screeners and supervisors that fail performance tests and termination of those
employees that habitually perform on a sub- par level; and systemwide deployment of next
generation screening technologies, such as whole body imaging and advanced X- ray systems.
These recommendations reflect specific needs for improvements in human factors and training for
screening personnel as well as investment in screening technologies. The TSA is actively
pursuing an approach to address checkpoint screening technology and human factors through its
recently launched checkpoint evolution initiative.
               
      
  
In addition to covert testing, which tests screener performance in detecting concealed threat items
on passengers and in carry- on items under operational conditions, the performance of screeners
that inspect X- ray images of carry- on items is routinely monitored and evaluated using a
technology called Threat Image Projection ( TIP). This technology provides the capability to
overlay virtual, computer- generated, threat objects over X- ray images of passenger’s screened
property during normal screening operations or to present virtual images of baggage containing
concealed threat items. TIP was first fielded by the FAA in 1999.
Following the terrorist attacks of September 11, 2001, TIP was discontinued as an operational
performance tool over concerns that screener responses to TIP images would increase delays
amidst the heightened focus on aviation security threats. However, viewing the technique as a
valuable operational testing and performance tool, the TSA reintroduced TIP in 2003 using a
greatly expanded database of threat images said to be more representative of weapons and
concealment tactics that may be used by terrorists. In comparison to the FAA TIP system prior to
the 9/ 11 attacks which had about 200 images in its database, the TIP system in use by the TSA
today has over 2,000 images, 23 with new images constantly being added based on identified
threats and concealment methods identified through intelligence and field operations. Fielded X-ray
equipment in use at screening checkpoints is TIP- ready. That is, these machines are designed
to store and display TIP database images, and are therefore referred to as TIP- Ready X- ray or
TRX equipment. These systems are networked, and linked into TSA laboratories that create and
distribute new TIP imagery periodically based on intelligence regarding new threat items and
concealment methods.
22 Statement of Clark Kent Ervin Before the Committee on Homeland Security, House of Representatives, Cover
Blown: Did TSA Tip Off Airport Screeners About Covert Testing?, November 14, 2007.
23 Transportation Security Administration, Aviation Security System of Systems: THEN and NOW.
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  	              " 
On TRX equipment, images of weapons and explosives are projected on the X- ray images of
actual bags being screened. This is done for several purposes. First, by providing periodic threat
images to the screeners, the system promotes alertness and acts as a mitigation for boredom and
complacency, two factors that can have a significant negative impact on human performance.
Second, the ability to collect data regarding screening performance and screener sensitivity in
real- world settings serves as an invaluable tool for human factors researchers studying screener
performance. For example, these researchers can look at performance as a function of time of day
and time on shift, to optimize the scheduling of shifts and breaks for screeners. Researchers can
also use the TIP data to identify particular threat items or methods of concealment that are often
missed, and in response can tailor recurrent screener training and re- qualification to emphasize
and correct specific weaknesses, either on a systemwide, an airport- by- airport, or even on an
individual screener level. Third, TIP provides a quantifiable means to evaluate the performance of
screeners at individual, work group, airport, or systemwide levels of analysis. As such, it can be
used to track progress over time and can be used to document deficient levels of individual
performance that establish grounds for dismissal. TIP has been one of the most significant
technology changes to carry- on screening since X- ray screening techniques were first
implemented in the early 1970s, and directly addresses human performance aspects of checkpoint
screening functions.
However, TIP is limited in its scope and provides data on only one aspect of screening operations:
screener preliminary threat identification of X- ray images. TIP does not provide data on whether
proper procedures were carried out once a threat object was suspected and flagged by the X- ray
screener, whether explosive trace detection ( ETD) systems were properly used to conduct
secondary evaluations of suspected explosives, and so on. Also, TIP does not provide any data on
the screening of passengers themselves or their checked baggage; it only provides data on the
screening of carry- on baggage. Nonetheless, TIP is widely regarded as an important screener
evaluation tool, and it will likely remain an integral part of advanced technology ( AT) X- ray
equipment deployment in the future.
                 !  	       "   #                 
    
       
Current generation X- ray systems provide significantly higher resolution than systems that were
deployed at airports in the 1990s and prior. However, these systems only provide a single view
angle, typically an overhead view, of screened items. Nonetheless, in addition to increased image
resolution, image coloration and other image enhancement features allow screeners to more easily
differentiate organic and metallic materials and provide the capability to use color contrast to
better differentiate certain elements of the X- ray image. For example, the coloration allows
organic materials to stand out from inorganic materials making it easier to detect dense organic
matter that may be indicative of an IED, and provides differential coloration of metals to allow
for easier detection of metallic weapons.
In addition to selective coloration, newer X- ray systems allow for a wide array of image
enhancement functions to highlight or turn off and declutter certain features in a process known
as image “ stripping.” However, some research has shown that individual image enhancements do
not necessarily improve IED detection compared to viewing of the original X- ray image,
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suggesting that the greatest advantage derived from current single- view X- ray systems may be
their improved image resolution. 24 Nonetheless, viewing multiple image enhancements in
combination – such as stripping out organic items or metallic items, or displaying a negative
image – can potentially help resolve image ambiguities and possibly improve detection. While
currently deployed X- ray systems have these capabilities, time pressures at busy screening
checkpoints may often preclude detailed examination using various combinations of these image
enhancement capabilities.
Object orientation in the X- ray view is often a key determinant to whether an object will be
recognized or detected. Prohibited items, such as guns and knives, presented at odd viewing
angles can often be missed, even by highly trained screeners. At present, the main tool to address
detection performance of objects presented at difficult- to- recognize view angles is through the
use of computer- based training using TIP imagery of threat items presented at various view
angles. Since threat object recognition and detection is a skill that is likely to continually improve
with experience and exposure to both TIP imagery and artfully concealed real- world threat items,
retention of high- performing experienced X- ray screeners is likely to remain a key component of
maintaining high levels of screening performance.
Research has also shown that pre- employment screening to assess aptitude for interpreting X- ray
images, recognizing objects and detecting prohibited items can substantially increase X- ray
screening performance. 25 Thus, with regard to establishing and maintaining effective X- ray image
screening performance, it appears that a specific emphasis should be placed on screener selection
and training, as well as initiatives to retain high- performing X- ray image screening personnel.
Besides improvements in screener selection and training in methods of performing pat- down
searches and interpreting X- ray images, addressing additional human factors issues related to the
screener work setting – including fatigue, motivational factors, and environmental considerations,
such as lighting, noise, and operations tempo – may also yield improvements in the ability to
detect threat items and individuals with hostile intent.
With regard to advancements in screening technology, next generation advanced technology ( AT)
X- ray systems are capable of providing multiple image views, usually two views that provide
both a overhead view and a profile view of the X- rayed item. Some of these systems also
incorporate computer image interpretation algorithms that automatically search for, and either
highlight or alert the operator to, suspected threat items such as explosives and weapons. These
features, however, can often be viewed negatively by operators and can slow the screening
process if they generate high numbers of false alarms or false positives. The specific performance
characteristics of AT X- ray systems being acquired and deployed by the TSA, including
information about their false alarm rates, is not publicly available, but remain important
considerations in the selection of systems and system features for operational deployment. Policy
considerations regarding the acquisition and deployment of AT X- ray systems are further
discussed in the section on “ Next Generation Checkpoint Technologies.”
24 Adrian Schwaninger, “ X- ray Imagery: Enhancing the Value of the Pixels,” Aviation Security International, October
2005, pp. 16- 21.
25 Ibid.
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     $          
While the ability to detect threats is the primary metric for evaluating passenger checkpoint
system performance, maintaining checkpoint efficiency has also been given a high priority.
However, the well documented phenomenon of speed- accuracy trade- offs in human performance
highlight the fact that increasing system throughput can lead to missed threats and a deterioration
of system effectiveness. Therefore, policymakers and aviation security strategists have generally
focused on striking a balance between maintaining reasonable wait times and high levels of threat
detection. While research and engineering has focused on optimizing screening lane efficiency
and effectiveness, longstanding wait time objectives have been set by policy, largely based on
what is regarded as reasonable to expect by the traveling public.
  
 
         	    	   
 
It has been the Department of Transportation’s and the TSA’s longstanding goal that passengers
should not wait, on average, more than 10 minutes to pass through an airport security checkpoint.
This can be traced back to the objectives laid out for checkpoint efficiency by then Secretary of
Transportation Norman Mineta in 2002 as responsibility for checkpoint screening functions was
being turned over to the TSA. 26
The challenge in determining the number of checkpoints that will meet specified wait time
criteria largely derives from the variability and fluctuation in daily and hourly passenger volumes.
Typically a representative busy hour is picked to model the passenger demand for screening. The
TSA has identified a variety of methods for selecting the busy or peak hour to be used in
modeling passenger screening demand. Data can be derived from either annual enplanement
forecasts or from airline flight schedules, with adjustments made for the percentage or amount of
passengers that are transferring from other flights and do not impose demand on the screening
checkpoints.
The number of checkpoints required can then be estimated based on the modeled passenger
demand for checkpoint screening for a representative busy hour divided by the hourly throughput
achievable from a single checkpoint. For example, if the model predicted 3,000 passengers per
hour, and the achievable throughput per screening lane was 300 passengers per hour ( five
passengers per minute), then ten screening lanes would provide an optimal number with no
excessive queuing. However, this may result in excessive capacity during non- peak periods. To
better balance resources with reasonable wait times, space requirements for queuing passengers
awaiting to pass through screening checkpoints, known as queue length requirements, can be
assessed by determining passenger average arrival rate over the selected busy hour, multiplied by
the average or expected wait time, divided by the number of checkpoint lanes to process these
passengers.
For example, if it were expected that 3,000 passengers would arrive during the hour, the arrival
rate would be 50 passengers per minute. If the target wait time was 10 minutes, then the total
queue size would be 500 passengers, and in a ten screening lane configuration, that would
translate to 50 passengers in queue per lane. According to design guidelines issued by the TSA,
26 Remarks of Norman Y. Mineta, Secretary of Transportation, Travel and Tourism Industry Unity Dinner, March 6,
2002, Washington, DC.
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space allocation for queues should provide somewhere between seven and 15 square feet per
person, 27 resulting in a total square footage allocation for queuing passengers of between 3,500
and 7,500 square feet in this example.
In this manner, the TSA can determine the optimum number of screening lanes and gauge the
space allocation requirements for queuing passengers to meet peak passenger demand loads.
However, space constraints at airports may prevent achieving these objectives, at least without
overcrowding passengers in queue which can heighten aggravation and tension making it more
difficult to spot suspicious individuals, and it can also heighten security risk because these
overcrowded queues could become prime targets for a shooting or bombing attack. In various
locations, unique airport factors may have a notable impact on the optimum number of screening
lanes as well as the configuration of those lanes. More significantly, airport space limitations and
other factors limiting available resources to set up and staff screening lanes may result in less than
optimal numbers of screening lanes.
Wait time objectives are a key consideration in determining the number of screening lanes and
screeners needed across the nation’s airports. The screening lane requirements, in turn, drive
space requirements at airports for housing security checkpoints and terminal layouts to
accommodate passenger screening operations. The TSA models its staffing allocation and
screening lane requirements using a model that attempts to screen 85% of passengers within the
10 minute target time frame based on passenger volumes projected for each airport’s peak travel
month. 28 The TSA notes that on only about 7 percent of days out of the year will passenger
volumes exceed these levels, resulting in expected wait times of more than 10 minutes.
Predictably, many of these days occur during peak travel periods during the Thanksgiving and
Christmas holiday times. While this model, which forms the basis of the TSA’s staffing
allocation, is designed to minimize the number of passengers experiencing waits of more than 10
minutes, in practice many more passengers experience waits of longer than 10 minutes.
At the busiest airports, designated as security category X and category I airports, 29 average wait
times have consistently exceeded the 10 minute goal ( See Figure 1). Since these larger airports
account for more than three- quarters of passenger boardings, a good portion of airline travelers
routinely experience wait times in excess of the 10 minute goal. While the average wait times at
these large airports are a few minutes greater than the 10 minute target, lengthy wait times,
sometimes exceeding 40 minutes, are not uncommon during peak travel periods at major airports.
However, consistent peak period waits of more than 40 minutes are often grounds for further
examination from a TSA optimization team to identify staffing, screening lane, or other resource
issues that may be contributing to these long waits. 30 The GAO has recommended that the TSA
establish a mechanism for periodically assessing the assumptions of its screener staffing
27 Transportation Security Administration. Recommended Security Guidelines for Airport Planning, Design and
Construction, Revised June 15, 2006.
28 U. S. Government Accountability Office. Aviation Security: TSA’s Staffing Allocation Model Is Useful for
Allocating Staff among Airports, but Its Assumptions Should Be Systematically Reassessed. February 2007, GAO- 07-
299.
29 Commercial passenger airports are assigned to one of five security categories ( Category X, I, II, III, or IV) based on
consideration of passenger volume and other risk factors. The nation’s busiest airports are assigned to either Category
X or Category I.
30 U. S. Government Accountability Office. Aviation Security: TSA’s Staffing Allocation Model, February 2007.
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allocation models as it continues to refine and optimize screener staffing and screening lane
lanes. 31
Figure 1. Average Peak Wait Times at Screening Checkpoints
FY2004- FY2006
5
10
15
Fiscal Year
Average Peak Wait Time ( Minutes)
Category X 13 12 12.6
Category I 11.8 11.2 10.4
Category II 8.5 8.3 7.7
Category III 9.1 8.7 8
Category IV 8.6 8.2 7.2
FY2004 FY2005 FY2006
Airport Security
Category:
TSA Target
Source: U. S. Government Accountability Office ( GAO). Aviation Security: TSA’s Staffing Allocation Model Is
Useful for Allocating Staff among Airports, but Its Assumptions Should Be Systematically Reassessed. February
2007, GAO- 07- 299.
    ) 	  %              %    	       	  	     *   	            	     $  
 	   
    +        	  	    ,      	   
Despite various efforts to improve checkpoint efficiency and reduce passenger wait times,
checkpoint lines remain vulnerable terrorist targets for bombings, shootings, or the potential
release of chemical or biological agents because they often consist of large congregations of
individuals in the “ non- sterile” portion of the airport terminal, that is prior to screening for
possible threat items. Inefficiencies at screening checkpoints that result in long screening queues
and congestion in airport terminals introduce unique vulnerabilities that may be mitigated through
various efforts to increase checkpoint efficiency, but may also be mitigated by specific design
considerations to minimize congestion and isolate long screening queues from open, accessible
areas of the airport terminal.
31 Ibid.
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Toward this objective, airport and security checkpoint queue design considerations might
consider options for better restricting access to security screening lines and better controlling
access to the areas in and around checkpoint lines to address these vulnerabilities. Additional
streamlining of passenger screening checkpoints may further reduce these vulnerabilities. In
addition to streamlining checkpoint procedures, the TSA is examining ways to integrate next
generation screening technologies as part of its new “ checkpoint evolution” initiative.
-    	         	   
               
 
For some time, the responsibility for the passenger screening checkpoint queues has been an
issue. Previously, the TSA had taken a much more limited role in controlling and monitoring the
lines that formed in front of security checkpoints. Airports had the primary responsibility for
controlling access to these lines, and on an airport- by- airport basis, procedures varied for
queuing, including whether to set up dedicated lines for elite travelers ( e. g., first and business
class travelers), and for airline crews. Access controls for security screening queues was primarily
a function carried out by airport contract employees serving as document checkers. More
recently, the TSA has been hiring and deploying Transportation Security Officers ( TSOs) to serve
as document checkers, eliminating the need for airport document checkers to control access to
screening lines. The TSA has adopted the title of TSOs for the TSA screener workforce to better
reflect the more diversified job functions and roles of these employees, including document
checking, behavioral observation, and bomb appraisal functions. In addition, the continued
expansion of the Registered Traveler program, which potentially offers the opportunity for
streamlined checkpoint processing for passengers who voluntarily submit background
information for vetting by the TSA, is also changing the manner in which screening lines operate.
At many airports, queues to enter checkpoint screening lanes have been designed to provide
“ elite” flyer lanes that the airlines make available to first class, and sometimes business class
travelers, as well as to their best customers who have reached certain status levels in airline
frequent flyer programs. 32 While the airlines maintain that they have the right to offer elite
passengers curbside- to- curbside perks, including dedicated queues to enter checkpoint screening
lanes, some people have complained that security screening is paid for equally by everyone
through equivalent passenger security fees and general fund contributions, and therefore, all
passengers should receive equal treatment. However, the TSA contends that separating seasoned
passengers familiar with screening procedures from others benefits everyone through better
efficiency and resource allocation at the screening checkpoints. 33
More recently the TSA has moved forward with a system of lane self- selection or tailored
screening lanes, allowing expert travelers to select expedited lanes, while families traveling with
small children and individuals needing additional assistance are funneled through screening lanes
better equipped to handle these traveler’s special needs. Also, the Registered Traveler ( RT)
program offers paying RT members who have been vetted and issued biometric identity cards
either preemptive queuing or dedicated checkpoint lanes. Whether these concepts will replace or
complement “ elite” flyer lanes remains an issue for the TSA, airlines, and airports as they seek to
determine the best model to accommodate travelers and expedite the screening process. The
tailored screening lane initiative and the RT program are described in further detail below.
32 Sara Kehaulani Goo, “ First Class Fast Lane,” The Washington Post, August 2, 2005, p. D01.
33 Ibid.
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      	           .              	    )     !  	  	   	 "  
In an effort to explore ways to make checkpoint screening queuing processes more efficient and
expedient for passengers, the TSA has field tested an initiative for passengers to self- select among
one of three designated screening lanes based on their knowledge and experience with TSA
screening procedures and the number of carry- on items in their possession. In field tests of this
concept at the Salt Lake City, Utah, airport and Denver International Airport, the TSA has
adopted a skiing analogy, setting up a “ Black Diamond” fast lane for expert travelers that are
completely familiar with screening procedures and are traveling with a single carry- on bag. A
“ Blue Square” lane has been designated for frequent flyers somewhat familiar with TSA
procedures, or more experienced flyers that have multiple carry- on items. Finally, a “ Green
Circle” lane has been established for families with small children, parents carrying infants and
toddlers in strollers, others needing special assistance, as well as those unfamiliar with checkpoint
security procedures that require additional guidance.
For some travelers, lane selection is constrained. For example, those carrying multiple bags
would not be allowed to choose the Black Diamond lane, and those traveling with small children
or strollers would be routed to the Green Circle lane. However, other travelers would be free to
self- select their lane. For this reason, choosing a Black Diamond lane might not always be the
fastest route if it is often chosen, particularly if it is chosen by individuals that really don’t have a
full understanding of the security screening procedures and restrictions. This could lead to
frustration and aggravation among delayed passengers expecting a streamlined process by
choosing the expert lane. While this is a difficult issue to address, passenger checkpoint
experiences among all travelers, including expert travelers, may be improved though passenger
education.
Nonetheless, the TSA has noted that in the trial program, passengers choosing the Black Diamond
lanes have experienced significantly reduced wait times. Smoother operations in other lanes have
also been observed. For example, the TSA attributes a reduction in the confiscation of prohibited
items to families feeling less rushed and having more time to prepare for the screening process.
The TSA contends that “[ s] ecurity is best served by a calm screening environment ...” 34 and has
indicated that it is seeking to expand this initiative to additional airports that will be selected
based on airport and airline support, and consideration of checkpoint configuration and passenger
characteristics. 35 By the end of FY2008, the TSA had expanded the use of these self- select lanes
to 32 airports. According to TSA observations, since implementing the program, expert lanes
have seen an average 21 percent increase in throughput ( with some as high as 40 percent), while
alarm rates for lanes designated for families and those needing extra assistance have been reduced
by an average of 11 percent. 36 Based on these results, the TSA has expanded the use of self- select
lanes at several airports throughout the United States.
34 Transportation Security Administration, TSA Announces Expansion of ‘ Diamond’ Self- Select Lanes. Press Release,
March 5, 2008.
35 Ibid.
36 Transportation Security Administration, Black Diamond Self Select Lanes, Helping Passengers Move at Their Own
Pace.
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    ,   	 
          "             
In addition to the tailored self- select screening lane initiative, the TSA regards the Registered
Traveler ( RT) program as another potential means to streamline checkpoint processing of
participating passengers that pose a known low risk, allowing the TSA to better concentrate its
resources on screening passengers of unknown or elevated risk ( e. g., conducting secondary
screening of passengers selected based on similar name matching to suspected terrorists, terrorist
sympathizers, or supporters of terrorist organizations; resolving alarms that occur during primary
screening; and assessing the risk of passengers exhibiting suspicious behaviors). The registered
traveler concept was recommended by airlines and airports soon after the 9/ 11 attacks as a means
to vet trustworthy travelers and allow security screening efforts to concentrate on those
passengers of unknown risk, or particularly, passengers posing an elevated risk. It was initially
believed that such a system could encompass most of the flying public, allowing security
screening efforts to be highly focused on those travelers that were not part of the program. Within
weeks after the 9/ 11 attacks, the DOT’s Airport Security Rapid Response Team included among
its recommendations the urgent need to establish a nationwide program for voluntarily submitting
information for vetting passengers who would be issued “ smart” credentials, to expedite
processing of the vast majority of travelers, thus allowing aviation security resources to be
focused most effectively, an idea that became known as the “ trusted traveler” concept. The
recommendation was reflected in statutory language included in the Aviation and Transportation
Security Act ( ATSA; P. L. 107- 71) and gave the TSA the authority to pursue a voluntary system
for passenger vetting and identity authentication using biometrics.
To date, the RT program has been quite limited in its scope, available primarily to frequent
travelers at a small number of airports under a trial program. As of December 2007, the TSA
estimated that about 64,000 individuals were participating in the RT trial program, only a very
small fraction of the tens of millions of annual airline travelers. The TSA, however, began
expanding the RT program in the summer of 2008 beyond the original 19 airports that
participated in the trial program. RT is now available to any airport that requests it.
The RT program was originally implemented under a public- private partnership model, in which
volunteer passengers, who submit background information for vetting along with biometric data,
are issued biometric identity cards issued by private service providers once cleared through the
background check process, which is coordinated by the TSA. The TSA has since dropped the
background check process and now describes the RT program as strictly a private sector
enterprise. 37 The RT vendors are responsible for card issuance and identity verification of
program participants as they enter screening checkpoints, however security screening remains the
responsibility of the TSA.
In some airports, RT participants are simply given preemptive queuing into screening lanes used
by all other passengers, while other airports have dedicated screening lanes for RT program
participants. Additionally, at some airports, like Orlando International Airport ( MCO), RT
program participants have been used to test out emerging technologies, like shoe scanners,
allowing them to reduce or eliminate some of the hassles associated with passenger screening.
The concept has been to provide RT participants with some sort of expedited screening
experience as an incentive for participation. In turn, the TSA was expected to benefit by
37 Transportation Security Administration, “ Registered Traveler Interoperability Pilot Program,” Federal Register,
73( 147), July 30, 2008, pp. 44275- 44278
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maintaining basic screening requirements for RT participants, thus allowing it to better focus
more extensive resources on non- participating passengers that pose an unknown or elevated risk.
However, the TSA has largely concluded that current technologies are not advanced enough to
offer RT participants an opportunity to bypass minimal screening requirements, because the
required background checks do not eliminate the possibility that an RT participant could take
hostile action threatening aviation security, and that the main benefits of the RT program are its
identity verification capabilities. 38
From its experience during pilot testing, the TSA determined that the security threat assessment
conducted on RT applicants is largely redundant with terrorist watchlist checks conducted on all
passengers each time they fly, and found that other elements of the background check performed
“ are not core elements in determining threats.” 39 Therefore, under the fully deployed RT program,
the TSA decided to eliminate the additional elements of the background check process and do
away with the $ 28 fee it passed on to RT applicants to offset related costs. 40 While the RT
program is now available to all airports, its future now seems uncertain as the benefits to both the
TSA and program participants based on experience during testing appear to be much more limited
than originally anticipated.
Moreover, just as the TSA announced nationwide availability of the RT program in the summer of
2008, it took action to suspend Verified Identity Pass, Inc., which serves as a vendor for the RT
program under the brand name Clear ® , from processing new applications after a laptop computer
containing unencrypted applicant personal data from about 33,000 RT applicants was reported
missing from San Francisco International Airport ( SFO). This potential data breach prompted the
TSA to suspend further enrollment in the Clear ® Identity Pass RT program while it conducted
audits of Verified Identity Pass, Inc., data security procedures. The suspension was quickly lifted
after the laptop was recovered and the company put in place procedures to encrypt all enrollee
personal data. 41 The incident and the potential threat of data breaches, however, raise considerable
questions about the protection of private information under such programs during a time when
there is considerable anxiety over identity theft. Security breaches such as this may cause
potential applicants to reconsider whether the potential benefits of moving more quickly through
security lines with fewer hassles are worth the risk of potential identity theft. Data security,
therefore, appears to be another key issue for the future direction of the RT program.
Questions also remain regarding how hassle- free RT security lines are and how much time RT
participants really save at security checkpoints. According to the TSA, it is up to individual
airports to determine if they wish to participate in this program. As TSA moves forward with RT,
the airline industry, which once backed this program as a means to reduce hassles for frequent
fliers, now characterizes the manner in which it is being implemented as having limited and
questionable benefit. The use of the program as a testbed for streamlined screening technologies
and procedures has thus only provided limited benefits and reductions in travel hassles to
participants. Nonetheless, some RT vendors have been pushing forward with the concept of
38 Ibid.
39 Transportation Security Administration, “ TSA Lifts Cap and Eliminates Fee on Registered Traveler,” Press Release,
July 24, 2008.
40 Transportation Security Administration. “ Registered Traveler Interoperability Pilot Progam,” Federal Register, 73
( 147), July 30, 2008, pp. 44275- 44278.
41 Transportation Security Administration, “ Update On Verified Identity Pass, Inc. Clear ® ’ s Registered Traveler
Enrollment,” Press Release, August 11, 2008.
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promoting the RT program as an opportunity to stimulate the development of advanced screening
technologies, particularly technologies that can improve checkpoint efficiency. For example,
Verified Identity Pass, Inc., has offered technology developers a $ 500,000 prize for the
development of technologies that can further streamline checkpoint processes, focusing on the
scanning of shoes, laptops, and outer garments. 42 The company indicates that it would pursue
partnerships with the winning developer to obtain TSA certification of promising new
technologies and would ultimately seek to purchase systems for screening RT participants.
While the potential benefits of the RT program have not been fully realized, Congress included
language in the FY2008 Consolidated Appropriations Act ( P. L. 110- 161) directing the TSA to
establish an international RT program that incorporates biometrics and e- passport technologies to
be used in conjunction with US VISIT and the Visa Waiver Program. Under the existing RT
program, some international carriers have been participating for outbound flights originating from
JFK and Newark Liberty airports. The future of both domestic and international RT
implementation remains an issue of particular interest with regard to how this program may be
able to someday work in coordination with other screening initiatives to streamline the process
for certain passengers, thereby facilitating a risk- based allocation of screening resources to focus
on those passengers that present an unknown or elevated risk.
/    	   
                     	  	      
 
           %    	   
         
 
Additional efficiencies may be gained in passenger checkpoint screening if some current
requirements could be met using more expedient alternatives. Two procedural requirements in
particular are believed to be major factors in decreasing passenger throughput and increasing the
so- called hassle factor: the requirements to remove shoes for X- ray screening and the requirement
to remove laptops and other large portable electronics, such as portable DVD players, from carry-on
baggage so that they can be screened separately. Eliminating these requirements, or taking
steps to streamline these aspects of the screening experience, is therefore seen as having a
potentially significant impact on improving checkpoint efficiency.
Shoe scanners that may eliminate the need to remove shoes for scanning were initially tested on
participants in the Registered Traveler ( RT) pilot program in 2007. However, the model
manufactured by GE tested under the RT program was found to not meet TSA’s detection criteria
and further testing of the systems was suspended. 43 In August 2008, the TSA initiated field testing
of a different model shoe scanner, the L3 PassPort, at Los Angeles International Airport. The shoe
scanner systems currently under evaluation use explosives trace detection methods and puff air
over the shoes to collect samples for analysis. 44 The systems are designed to detect traces of
nitrate- based and peroxide- based explosives, but they do not generate an image of the shoe or
screen for metals. 45 During these trials, the TSA will still require passengers to remove their shoes
after being scanned by the machines to make sure the technology does not miss any explosives
42 “ Clear Offers 500K Prize for New Checkpoint Technology,” Aviation Week’s Airports, 26( 1), January 8, 2008, pp.
1- 2
43 Transportation Security Administration. “ Status Update on Testing of General Electric Kiosk for Registered
Traveler,” News & Happenings, TSA, October 9, 2007.
44 Benet Wilson, “ TSA Tests L3 Shoe Scanners at LAX Airport Checkpoints,” Aviation Daily, August 7, 2008.
45 Steve Surjapurta, “ May We Leave Our Shoes On at Airport Security?,” Tripso Travel News, August 1, 2008.
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threats. 46 However, pending the outcome of these trials, shoe scanners may eventually be
deployed to airports nationwide potentially allowing most passengers to keep their shoes on
during the entire screening process.
The TSA is also in the process of approving designs for laptop carrying cases that are specifically
designed to allow laptop computers to remain in the bag as they pass through the X- ray scanner.
The TSA requires that the bag designs provide an unobstructed X- ray image of the laptop
computer by itself. 47 This is accomplished through the use of a pull out or flip out laptop sleeve or
compartment that allows the laptop to be scanned by itself, away from the other compartments
and contents of the carry- on. Passengers will be instructed to place only the laptop in this sleeve
to avoid the laptop image from being obscured by power cords, peripheral devices, or other items
stowed in the carry- on bag. Since use of the TSA- approved laptop cases is voluntary and requires
an investment by travelers, it may be some time before this has any meaningful impact on
improving checkpoint efficiency. For laptop- toting travelers, however, the reduced hassle of not
having to remove then re- pack laptop computers may been seen as a considerable incentive by
itself to purchase one of these cases, even if it doesn’t guarantee shorter wait times at screening
checkpoints in the near term.
    %    	             
      ) 	 0  	  
 
In addition to checkpoint delays caused by laptop and shoe screening requirements, the TSA
limitation on liquids carried through security checkpoints, implemented in 2006, has resulted in
considerable confusion, delays, and hassles for airline passengers and has had a significant impact
on checkpoint efficiency and passenger wait times.
Immediately following the detection of the terrorist plot targeting airliners bound for the United
States and Canada from London’s Heathrow Airport in August 2006, the TSA responded by
banning the carriage of all liquids and gels by passengers through airport screening checkpoints.
The total ban on liquids and gels remained in effect for several weeks. During this period, limited
exceptions were made for breast milk for babies, liquid medicines, and other liquids regarded as
being medically necessary. Beverages purchased beyond the screening checkpoint were not
included in the ban, largely because the threat of passing bomb- making materials to an airline
passenger using liquids purchased from vendors in the secured areas of airport terminals was
considered minimal, and other security measures, such as background checks for airport workers,
were viewed as limiting the possibility that terrorists might exploit beverage distribution to
airport vendors as a means to get liquid explosives beyond airport security checkpoints.
In September 2006, the TSA relaxed the passenger liquid ban to some degree, establishing
specific quantity limits and special procedures for carrying liquids through screening checkpoints.
The TSA ultimately settled on a procedural approach for passengers to carry limited quantities of
liquids through checkpoints and onto aircraft in a manner facilitating screening and inspection of
those liquid items. The TSA refers to these procedures as the “ 3- 1- 1 for carry- ons” concept, with
the objective of providing a simple- to- remember memory aid for travelers. Under 3- 1- 1, travelers
are allowed to carry through the checkpoint liquids in bottles with a liquid volume of three
46 Art Marroquin, “ Airport Security to Test Shoe Scans,” LA Daily News ( Los Angeles, CA), August 2, 2008.
47 Transportation Security Administration, “ New Security Simplifying Laptop Bag Procedures,” TSA News &
Happenings, July 29, 2008.
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ounces or less, are limited by how many of these bottles will comfortably fit within a one quart
clear plastic bag, with a limit of one such bag per traveler.
By November 2006, the European Union, along with Canada and other countries in Europe, Asia,
and the South Pacific, adopted the 3- 1- 1 protocols in an effort to harmonize international aviation
security procedures with TSA procedures. The TSA believes that roughly half of the world’s
aviation travelers must adhere to these procedures for carrying liquids through security screening
checkpoints.
The 3- 1- 1 procedures were designed to allow the carry- on of liquid toiletry items in specified
quantities for those passenger traveling on short trips and not checking baggage and for making
reasonable accommodations to allow for accessible liquid medicines and toiletry items on longer
flights. However, placing liquids in checked baggage is still preferred by the TSA. In addition to
these allowable liquids, passengers are allowed to bring on board liquid medicines, as well as
baby formula and food, breast milk, and juices to provide for a traveling infant. These items are
allowed in reasonable quantities exceeding the three ounce limit imposed on other liquids and are
not required to be placed in the quart- sized bag. While these procedures have been designed to
provide reasonable accommodations for passengers traveling on short trips or with special needs
for access to liquid medicines, necessary dietary supplements, and items to care for infants, the
procedures often cause confusion and delays at airport screening checkpoints. The TSA has made
extensive efforts to educate and inform the public regarding these procedures, and has been
exploring the use of tailored screening lanes to separate passengers that might be unfamiliar with
these procedures from seasoned air travelers seeking an expedited process to get through airport
screening.
The TSA has responded to public criticism over the liquids ban and subsequent 3- 1- 1 procedures
by pointing out the significance of the liquids explosives threat. However, an aspect of the liquids
ban that has raised considerable criticism of the TSA is that the threat posed by liquid explosives
was widely understood prior to the U. K. liquids bombing plot. Liquid explosives had been used
in the downing of Korean Airlines flight 858 in November 1987, and Ramsi Yousef used an
improvised liquid explosive device to bomb Philippine Airlines Flight 434 in December 1994,
smuggling the chemicals onboard in a contact lens solution bottle. He and his co- conspirators
were plotting to use similar liquid explosive devices, assembled in the aircraft lavatory, to destroy
as many as twelve U. S.- bound aircraft from Asia as part of the so- called Bojinka plot concocted
by Yousef and his uncle, Khaled Sheikh Mohammed. Authorities believe that the U. K. liquids
explosives plotters similarly sought to assemble liquid explosive devices in aircraft lavatories, but
unlike the Bojinka plot, intended to carry out suicide attacks, killing themselves along with all on
board these aircraft. Despite the previous attacks involving liquid explosives, it was only after this
plot was uncovered by British authorities that the TSA felt compelled to take action and impose
significant constraints on the carriage of liquids through screening checkpoints and onboard
aircraft.
While it appeared unlikely that security procedures for carrying liquids on board aircraft would be
significantly modified or relaxed anytime soon – until new technologies capable of reliably
detecting liquid explosives could be developed, tested, and fully deployed at airports – the TSA
announced that it would begin phasing out restrictions on carry- on liquids by the fall of 2009.48
Former TSA Administrator Kip Hawley indicated that, by the end of 2010, passengers should be
48 Thomas Frank, “ TSA likely to ease restrictions on liquids in 2009,” USA Today, October 28, 2008.
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able to again carry liquids through screening checkpoints, but would be required to place bottles
and other liquid containers through X- ray machines separately.
  
 
             	        !        	      1     	   
 
The TSA has launched several initiatives to inform the public regarding specific checkpoint
requirements, procedures, and limitations. The efforts to inform passengers regarding the 3- 1- 1
policy on liquids serves as an example of how the TSA has made considerable efforts to provide
the traveling public with adequate information regarding screening and security procedures to
make passengers experiences as efficient and hassle- free as possible, given current policies,
strategies, and approaches to screening. However, many security procedures remain confusing, in
part, because they have changed in response to changing threat assessments, or have been applied
inconsistently in the past.
Public education is likely to increase in importance as the TSA rolls out various new checkpoint
screening technologies over the next several years. While some of these technologies have been
field tested on a limited basis at various airports across the country, ongoing initiatives to deploy
these systems nationwide represent the most significant change to the passenger checkpoint
experience since mandatory use of magnetometers and X- ray screening of carry- on items was
implemented 35 years ago.
	      
     $  
     
     !        !             
To address the challenges of improving screening performance, enhancing the capability to detect
explosives, and increase checkpoint efficiency and throughput, the TSA is testing new checkpoint
concepts that integrate emerging screening technologies and address various operational and
human factors needs. In March 2008, the TSA launched an initiative called Checkpoint Evolution
encompassing a variety of planned improvements to airport screening checkpoints. Former TSA
Administrator Kip Hawley noted that “[ t] his is the first significant change to the checkpoint since
the 1970s,” a reference to the fact that the layout of airport screening checkpoints in the United
States, has remained relatively unchanged since they were first implemented in the early 1970s.
A Checkpoint Evolution Team at the TSA has developed a prototype concept for the checkpoint
of the future that is showcased on the TSA website. 49 The prototype future checkpoint concept
entered operational testing and evaluation at Baltimore Washington International Thurgood
Marshall Airport ( BWI), in Terminal B, which services Southwest Airlines, in April 2008. This
prototype includes multiview AT X- ray equipment, millimeter wave whole body imaging ( WBI)
portals used for continuous random screening, and liquid bottle scanners. 50 However, the
investment strategy and deployment schedule for deploying various future checkpoint concepts
currently under evaluation remains unclear.
In addition to potentially improving the efficiency and effectiveness of the screening process,
proposed changes to the screening checkpoint may help reduce congestion at “ soft target”
49 See [ http:// www. tsa. gov/ evolution/ index. shtm]
50 Transportation Security Administration. “ Checkpoint Changes to Improve Security and Calm Process,” TSA News &
Happenings, April 28, 2008.
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locations such as airport lobbies. Various design elements of the proposed future checkpoint
provide potential mitigation of the threat of explosives carried through the security checkpoint
and possibly for the threat of shootings or bombings in and near the checkpoint queue. By
designing more streamlined queuing process, and queuing areas that are better separated from the
public spaces in the airport terminal, the TSA hopes to achieve enhanced capabilities for
surveillance and behavioral detection of potential threats of this kind.
The TSA is also seeking to implement methods to make the screening checkpoint a calmer, less
chaotic environment in hopes that this will allow screeners and behavioral detection officers
( BDOs) to more easily spot suspicious behaviors. Former TSA Administrator Kip Hawley noted
that “[ c] alm allows things to stand out more. It creates a better environment to observe hostile
intent.” 51 According to the TSA, a calmer checkpoint environment can also help to ease perceived
time pressures and other distractions that may hinder screener performance.
Elements of the future screening checkpoint queuing area design include mood lighting, soothing
music, improved signage to direct and instruct passengers, and museum- style storyboards that
convey personal stories of various TSA screeners. In the prototype, panels and informational
boards also function as barriers to better separate the checkpoint queue from the rest of the
passenger terminal. The queuing area also includes a “ prep stop,” giving passengers a location to
discard or recycle any trash or prohibited items, such as beverages, and organize and bag other
items prior to screening. Travel document checking stations, staffed by TSA document checkers,
are to be positioned at the transition between the queue and the screening lanes.
In the screening lanes, various technologies and procedures to streamline the screening process
are included in the future checkpoint concept. For processing carry- on bags, the prototype system
integrates an automatic conveyor and bin return system. The proposed automated conveyor
system is to have the capability to separate alarm items ( i. e., suspicious items that require
additional scrutiny) from cleared carry- on items. Cleared items are to proceed down the conveyor
to a collection area where passengers can gather their possessions.
One highlighted feature of the prototype system is the use of sensitive cameras in the collection
area to identify and alert passengers when items, including items as small as coins, are left behind
in the conveyor bins. Once the bins are emptied, the system would automatically return them via
a reverse- direction conveyor belt to the beginning of the conveyor for reuse, thus eliminating the
labor- intensive function of moving and stacking bins currently performed by TSOs.
On the back end of the future checkpoint configuration, the TSA plans to install “ re- composure
benches,” to allow passenger to reassemble their items that may have been removed or opened
during the screening inspection process, and an “ end zone” where travelers can regroup with their
families or others traveling with them before proceeding to their boarding gate.
Two significant challenges to implementing the proposed checkpoint evolution concept are
acquisition and sustainment costs and airport space requirements. The Bush Administration’s
Budget Request for FY2009 specified $ 11.5 million for checkpoint reconfiguration and expansion
costs, matching FY2008 levels. However, much of this has been slated for expanding the number
of screening lanes at various airports across the country to meet the expected growth in passenger
air travel rather than for reconfiguring existing screening lanes. Future funding needs to
51 Thomas Frank, “ TSA Tries Soothing Screening Process,” USA Today, March 30, 2008.
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implement checkpoint evolution concepts beyond initial field testing is yet to be determined.
These checkpoint evolution concepts are currently being field tested in conjunction with other
initiatives to deploy next generation checkpoint screening technologies aimed at addressing
lingering concerns over the limited ability to detect explosives on passengers and in carry- on
items.
%  &   '        
   	      
          
  
     
Since the early 1970s, passenger screening checkpoints have relied almost exclusively on the use
of magnetometers, or walk- through metal detectors ( WTMDs), as the sole means for primary
screening for weapons or other prohibited or dangerous items being carried by passengers. These
machines induce pulsed magnetic fields and sense any interruption or disturbance in those fields,
usually caused by the presence of metallic objects, as individuals pass through these fields. 52
These devices, however, are not capable of detecting explosives or nonmetallic threat items. Also,
checkpoint screening of carry- on items for explosives, weapons, and other threats is carried out
using X- ray systems are limited in their ability to assist human operators detect objects or make
determinations regarding potential threat objects based on the X- ray image.
In its final report, the 9/ 11 Commission recommended that “[ t] he TSA and the Congress must
give priority attention to improving the ability of screening checkpoints to detect explosives on
passengers.” 53 Congress responded by including language in the Intelligence Reform and
Terrorism Prevention Act ( P. L. 108- 458), directing the Department of Homeland Security to “...
give a high priority to developing, testing, improving, and deploying, at airport screening
checkpoints, equipment that detects nonmetallic, chemical, biological, and radiological weapons,
and explosives, in all forms, on individuals and in their personal property.” 54 The legislation also
directed the TSA to develop a strategic plan for deployment of explosives detection equipment at
airport checkpoints, including technologies such as walkthrough explosives detection portals,
document scanners, shoe scanners, and X- ray backscatter devices. These various technologies are
discussed in further detail below. The Implementing Recommendations of the 9/ 11 Commission
Act of 2007( P. L. 110- 53) reiterated the requirement for developing this strategic plan, and also
established a Checkpoint Screening Security Fund, requiring that $ 250 million collected from
passenger and airline security fees be deposited in this fund in FY2008. Funding for Checkpoint
Support, which encompasses checkpoint technology acquisition has been maintained at the $ 250
million level for FY2009 ( See P. L. 110- 329).
Over the past few years, the TSA has been field testing a wide variety of checkpoint technologies
aimed at improving the screening of passengers and carry- on items, particularly to address the
need for improving the detection of explosives at passenger checkpoints. A summary of some of
the key emerging checkpoint technologies that are now reaching technical maturity for field
testing and deployment in airport settings is provided in Table 1. A more comprehensive
examination of screening technologies and technical approaches follows. These technical
approaches include explosives chemical trace detection methods; whole body imaging systems;
52 Tim L. Hudson and Matthew J. Frankel, “ Staying Ahead of the Game: The Future is Now for Advanced Passenger
Screening,” Airport Magazine, April/ May 2007, pp. 46- 50.
53 National Commission on Terrorist Attacks Upon the United States. The 9/ 11 Commission Report ( Authorized
Edition). New York, NY: WW. Norton & Company. p. 393.
54 P. L. 108- 458, Sec. 4013; 49 U. S. C. § 44925.
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advanced technology X- ray capabilities; and other methods, such as computed tomography ( CT)-
based explosives detection systems ( EDS) and the use of magnetic resonance imaging ( MRI)
technologies for detecting explosives and other threat objects in carry- on items.
Table 1. Emerging Checkpoint Technologies
Emerging Technology Description
Estimated Per Unit Acquisition
Cost
Advanced Technology ( AT) X- Ray X- ray systems with advanced visual
detection capabilities including multi-view
imaging and automated
explosives detection algorithms
$ 199,845
Whole Body Imagers ( WBIs) Imaging systems using X- ray
backscatter or millimeter wave
( mmW) imaging technologies to
inspect for concealed weapons and
explosives under passenger clothing.
These units can be used in place of
metal detection wands and physical
pat- down inspections
$ 256,872
Bottle Liquid Scanners ( BLS) A new handheld detection capability
to discriminate explosives or
flammable liquids from common
benign liquids carried by passengers
or in carry- on items
$ 42,419
Cast and Prosthesis Imagers Specially designed low dose X- ray
backscatter devices to screen casts
and prosthetic limbs for possible
concealed weapons and certain
explosives
$ 56,567
Shoe Scanner Systems Devices to scan shoes for explosives
using nuclear quadrupole resonance
imaging techniques. Field tested
under the Registered Traveler
Program but found to not yet meet
minimum detection standards
$ Not Specified
Explosives Trace Detection Portals Walkthrough portals using explosive
trace detection methods to inspect
passenger for trace indicators of
explosives.
$ 211,924
Automated Carry- On Bag Explosives
Detection System
Automated detection capability for
inspecting bags for explosives and
weapons using computed
tomography ( CT) based solutions.
Seen as a possible means for either
complementing or replacing current
manual X- ray image analysis
processes
$ 506,778
Source: Transportation Security Administration, Congressional Justifications – Aviation Security, FY2008 and
FY2009.
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 #     
 	 "  
        $      	             	  
 
Several technologies that use various explosives trace detection methods are available for
screening passengers and carry- on items for explosives. Available explosives trace detection
technologies that may be considered for checkpoint use include explosives trace detection ( ETD)
machines tailored for checkpoint screening lane use to screen carry- on items; handheld bottled
liquids scanners that use explosive trace detection screening methods; and walk- through
explosives trace detection portals for screening individuals.
       	 
       
   
  
                   
 
ETD machines have been a fixture at aviation screening checkpoints and for checked baggage
screening at smaller regional airports since the TSA assumed responsibility for passenger
screening. These systems are capable of detecting minute quantities of elements found in
explosive compounds using a variety of techniques, including mass spectrometry, gas
chromatography, chemical luminescence, and ion mobility spectrometry, 55 to measure the
chemical properties of vapor or particulate matter sampled from passengers, carry- on items,
checked baggage, or cargo. It is generally believed that ETD systems will continue to play a
central role in the screening of carry- on items to detect traces of explosives for items belonging to
individuals singled out for secondary screening, or items flagged for additional screening based
on the analysis of the TSA screener viewing the X- ray image of the item during the primary
screening process.
     
                    	 
        
   
Following the August 2006 U. K. aircraft liquid bombing plot, the TSA has been keenly interested
in identifying an effective technology for detecting explosives in liquids and flammable liquids
without requiring direct contact with a sample. Observers have noted that it would have been
extremely difficult to detect liquid explosives, like those the terrorists had planned to use,
employing checkpoint screening technologies and techniques in place at that time. 56 Since then,
the TSA has been working with a number of vendors of bottled liquid scanner ( BLS) technology
to identify candidate systems for field testing.
So far, two handheld units, the Fido PaxPoint developed by ICx Technologies and the SABRE
4000 developed by Smiths Detection have been acquired by the TSA for field testing. The
SABRE 4000 relies on ion mobility spectrometry, a common trace detection method proven
effective in detecting minute quantities of explosives and chemical weapons. The Fido PaxPoint
uses a different trace detection technology that relies on amplifying fluorescent polymers, a
technique that utilizes a film lining that reacts when exposed to minute quantities of explosives.
The sensitivity of these devices is considered to be sufficient enough to detect explosive traces
and vapors through bottles and other sealed containers, including peroxide- based explosives as
well as nitrogen- based explosives. These units cost roughly $ 43,000 each. Under the TSA’s
proposal for FY2009, it intends to deploy a cumulative total of 250 of these units, which would
enable them to be available at roughly two- thirds of all screening lanes at Category X and
55 These terms refer to a variety of techniques used to identify unknown chemical compounds that are applied in the
aviation security setting primarily, and often exclusively, to test for the presence of explosives.
56 Norman Shanks and Steve Wolff. “ The Liquid Bomb Threat.” Air Safety Week, August 21, 2006, p. 1.
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Category I airports. This, however, is considerably scaled back from earlier estimates that the
TSA would acquire a cumulative total of 800 of these units by the end of FY2008.57 Both devices
have been deployed in field tests at several large airports.
While these devices also have the capability of detecting chemical warfare agents, it appears that
the TSA is primarily interested in the explosives detection capabilities of these devices and has
not formally addressed the potential threat of chemical attacks in airline passenger cabins,
although chemicals like Sarin and VX nerve agent have been used in non- aviation terrorist attacks
in the past.
The TSA has also considered various other technologies capable of detecting liquid explosives
through a sealed container that use X- ray quadrupole resonance imaging, acoustic/ ultrasound,
Raman spectroscopy, and electromagnetic resonance techniques. Researchers are also working on
laser irradiation techniques for detecting peroxide- based explosives. 58 These various techniques,
however, can encounter difficulty in accurately identifying explosives through opaque containers
and tend to yield relatively high numbers of false positives making them impractical for
deployment at airport screening checkpoints given the current state of technology maturity of
these systems. 59
                   	 
       
   
  
              
In 2004, the TSA initiated pilot testing of walkthrough explosives trace detection portals. When
passengers pass through these semi- enclosed portals, puffs of air are blown at them to provide
airborne samples of elements on their person. The samples are automatically collected and
analyzed by the unit to detect the presence of explosives using explosives trace detection
techniques. The system relies on an ion mobility spectrometry process that provides versatile
detection of both positive and negative ions using a proprietary ion “ trap.” 60 The system is
capable of detecting a broad spectrum of explosives in a matter of a few seconds. However, citing
reliability problems, the TSA suspended further deployment of these systems, and was reportedly
reassessing how to proceed. 61 The TSA has not sought to acquire additional trace portal systems,
focusing instead on testing and deployment of whole body imaging ( WBI) technologies, which
are discussed in further detail below.
           !    	             	  
 
As part of the TSA’s overall approach to improving the detection of explosives and nonmetallic
weapons at passenger screening checkpoints, it is currently exploring the use of whole body
imaging technologies for detecting concealed items carried by passengers. Whole body imaging
solutions offer an integrated approach to passenger screening insofar as these technologies can
reveal concealed items carried on a person, including traditional metallic weapons, non- metallic
57 “ TSA Adds More Bottle- Screening Devices at Airport Checkpoints.” Aviation Daily, November 16, 2007.
58 “ New Analytical Tool Developed for Liquid Explosives Detection.” Science Daily, October 13, 2006.
59 Kevin Bullis, “ A Better Liquid- Explosives Detector,” MIT Technology Review, December 1, 2006.
60 General Electric, “ The United States Transportation Security Administration ( TSA) has installed the GE EntryScan ³
Walk- through Explosives Detector to Screen Passengers at Boston Logan Airport’s Terminal a Security Checkpoint.”
September 9, 2006.
61 Eric Lipton, “ Screening Tools Slow to Arrive in U. S. Airports,” The New York Times, September 3, 2006.
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weapons, and explosive devices. These systems, however, cannot provide an indication of
whether a concealed item is made of explosives material. Nonetheless, detection of a concealed
item can alert screeners to conduct more thorough screening to determine the specific
characteristics of the item through methods such as explosives trace detection or walkthrough
explosives detection portals.
The TSA is continuing to study specifically how whole body imaging technologies could be
integrated with other technologies in future checkpoint screening solutions. The Transportation
Security Laboratory ( TSL), a component of the DHS Science and Technology Directorate, has
been mulling a concept it refers to as the “ tunnel of truth.” This future checkpoint concept, which
would submit passengers to a battery of screening techniques while being transported on a
moving walkway, incorporates whole body imaging technologies along with trace detection portal
technologies. 62
Because of the ability to detect a broad array of concealed items, many view whole body imaging
systems as a candidate technology for primary screening as part of a system such as the future
“ tunnel of truth concept,” although in current field testing the TSA is providing this technology
solely as an option for passengers selected for secondary screening as an alternative to a pat- down
search, and as a procedure applied to individuals randomly selected for secondary screening.
Since whole body imaging technologies are regarded by some as highly invasive, critics of these
systems have argued that they should only be used in limited circumstances. For example, the
American Civil Liberties Union ( ACLU) has urged Congress to ban the use of whole body
imaging technologies as a method for primary screening. The ACLU mai