Aviation Security: Vulnerabilities Exposed Through Covert Testing of TSA's Passenger Screening Process
Published: 2007-11-15T00:00:00

Fast Facts:

Highlights:
section_title: Why GAO Did This Study
paragraphs: In August 2006, the Transportation Security Administration (TSA) substantially modified its passenger screening policies based on the alleged transatlantic bomb plot uncovered by British authorities. With the aim of closing security gaps revealed by the alleged plot, the revised policies severely restricted the amount of liquids, gels, and aerosols TSA allowed passengers to bring through the checkpoint. At the Committee's request, GAO tested whether security gaps exist in the passenger screening process. To perform this work, GAO attempted to (1) obtain the instructions and components needed to create devices that a terrorist might use to cause severe damage to an airplane and threaten the safety of passengers and (2) test whether GAO investigators could pass through airport security checkpoints undetected with all the components needed to create the devices. GAO conducted covert testing at a nonrepresentative selection of 19 airports across the country. After concluding its tests, GAO provided TSA with two timely briefings to help it take corrective action. In these briefings, GAO suggested that TSA consider several actions to improve its passenger screening program, including aspects of human capital, processes, and technology. GAO is currently performing a more systematic review of these issues and expects to issue a comprehensive public report with recommendations for TSA in early 2008.
section_title: What GAO Found
paragraphs: GAO investigators succeeded in passing through TSA security screening checkpoints undetected with components for several improvised explosive devices (IED) and an improvised incendiary device (IID) concealed in their carry-on luggage and on their persons. The components for these devices and the items used to conceal the components were commercially available. Specific details regarding the device components and the methods of concealment GAO used during its covert testing were classified by TSA; as such, they are not discussed in this testimony. Using publicly available information, GAO investigators identified two types of devices that a terrorist could use to cause severe damage to an airplane and threaten the safety of passengers. The first device was an IED made up of two parts--a liquid explosive and a low-yield detonator. Although the detonator itself could function as an IED, investigators determined that it could also be used to set off a liquid explosive and cause even more damage. In addition, the second device was an IID created by combining commonly available products (one of which is a liquid) that TSA prohibits in carry-on luggage. Investigators obtained the components for these devices at local stores and over the Internet for less than $150. Tests that GAO performed at a national laboratory in July 2007, in addition to prior tests in February 2006 that GAO performed in partnership with a law enforcement organization in the Washington, D.C., metro area, clearly demonstrated that a terrorist using these devices could cause severe damage to an airplane and threaten the safety of passengers. Investigators then devised methods to conceal the components for these devices from TSA transportation security officers, keeping in mind TSA policies related to liquids and other items, including prohibited items. By using concealment methods for the components, two GAO investigators demonstrated that it is possible to bring the components for several IEDs and one IID through TSA checkpoints and onto airline flights without being challenged by transportation security officers. In most cases, transportation security officers appeared to follow TSA procedures and used technology appropriately; however, GAO uncovered weaknesses in TSA screening procedures and other vulnerabilities as a result of these tests. For example, although transportation security officers generally enforced TSA's policies, investigators were able to bring a liquid component of the IID undetected through checkpoints by taking advantage of weaknesses identified in these policies. These weaknesses were identified based on a review of public information. TSA determined that specific details regarding these weaknesses are sensitive security information and are therefore not discussed in this testimony. GAO did not notice any difference between the performance of private screeners and transportation security officers during our tests.

section_title: Letter
paragraphs: Thank you for the opportunity to discuss our latest test of airport security.  In March 2006, we reported on the results of covert security vulnerability  testing at 21 airports across the country. These tests clearly demonstrated  that our nation’s airlines were vulnerable to a suicide bomber using  commercially available materials to detonate an explosive device onboard  an airplane. During these covert tests, our investigators passed through  airport security checkpoints carrying prohibited explosive components  without being caught by Transportation Security Administration (TSA)  security officers. Later that year, in August 2006, British authorities  uncovered the alleged transatlantic bomb plot. The discovery of this bomb  plot, in which terrorists allegedly sought to detonate improvised explosive  devices (IED) in airplanes as they crossed the Atlantic Ocean, caused TSA  to substantially modify its screening procedures—all liquids, gels, and  aerosols with some exceptions were banned from being carried through  passenger screening checkpoints and onto aircraft until the plot was  further investigated. These restrictions were later relaxed to allow small  amounts of liquids, gels, and aerosols through the checkpoint.
This report responds to your request that we test whether security  vulnerabilities exist in the TSA passenger screening process. To perform  this work, we attempted to (1) obtain the instructions and components  needed to create devices that a terrorist might use to cause severe damage  to an airplane and threaten the safety of passengers and (2) test whether  investigators could pass through airport security checkpoints undetected  with all the components needed to create the devices.
To obtain instructions on creating devices a terrorist might use, we  reviewed publicly available information and performed Internet searches.  We obtained components for these devices at local stores and over the  Internet. We devised methods to conceal the prohibited components using  public information about TSA policies and procedures and obtained items  to conceal the components at local stores and over the Internet. We then  conducted our covert tests at a nonrepresentative selection of 19 airports  across the country. The criteria we used to select the airports resulted in  our testing a variety of U.S. commercial airports, some of which employed  private screeners.
Our work was not intended to evaluate the overall design and  effectiveness of TSA’s airport security program, which contains multiple  layers of security. Rather, our work was performed to test specific security  vulnerabilities related to the three major elements of TSA’s passenger  screening process—human capital (i.e., people), processes, and  technology employed at the checkpoint. We tested the effectiveness of our  explosive device at a national laboratory in July 2007. We had previously  tested the effectiveness of less powerful explosive and incendiary devices  in the Washington, D.C., metro area with help of a local law enforcement  organization. We conducted work for this investigation from March 2007  through July 2007 in accordance with quality standards for investigations  as set forth by the President’s Council on Integrity and Efficiency.
subsections: section_title: Background
paragraphs: TSA is responsible for securing all modes of transportation while  facilitating commerce and freedom of movement for the traveling public.  In performing its responsibilities, TSA is guided by risk-based planning,  which generally involves a consideration of threats, vulnerabilities, and the  criticality or consequence of an attack if it were to be carried out.
Specifically, in its approach to securing the domestic aviation sector, TSA  maintains numerous programs that provide a layered approach to security,  including intelligence gathering and analysis, checking passenger  manifests against watch lists, and assigning undercover air marshals to  certain flights. The general public associates TSA mainly with its security  effort at airport passenger checkpoints. One primary goal of the passenger  checkpoint screening program is to provide for the safety and security of  persons and property on an aircraft against the introduction of an  unauthorized weapon, explosive, or incendiary. As we reported in April  2007, TSA continues to modify its checkpoint screening program based on  a number of factors including passenger feedback, risk-based planning,  and its own internal review and testing process. TSA’s well-publicized  recent policy change in response to the alleged transatlantic bomb plot of  August 2006 is an important example of risk-based planning. Known as the  3-1-1 rule, this procedural change prohibits liquid, gel, or aerosol items  over 3.4 fluid ounces in carry-on luggage; in addition, all liquid and gels  should be placed in a 1-quart bag, and only one 1-quart bag is allowed per  passenger.
subsections: section_title: Passenger Screening Process
paragraphs: TSA focuses on the checkpoint screening process as a primary means of  detecting prohibited items. Items that TSA has prohibited passengers from  bringing aboard an aircraft include, among other things, firearms and  knives; gasoline and lighter fluid; disabling chemicals, including chlorine  and liquid bleach; and many additional items that may be seemingly  harmless but could be used as weapons. During the passenger screening  process, transportation security officers follow standard operating  procedures and utilize technology such as walk-through metal detectors  and X-ray machines to detect prohibited items either on a passenger’s  person or in his or her carry-on luggage. The passenger checkpoint  screening process is composed of the following three elements:    Transportation security officers (also known as TSOs) screen all  passengers and their carry-on luggage prior to allowing passengers  access to their departure gates. Among other responsibilities,  transportation security officers attempt to detect prohibited items that  passengers may try to carry beyond the security checkpoint.
Technology is used during the screening process, which primarily  consists of walk-through metal detectors, X-ray machines, handheld  metal detectors, and explosive trace detection (ETD) equipment.
Standard operating procedures establish the process and standards  by which transportation security officers are to screen passengers and  their carry-on items at screening checkpoints.
The process of screening a passenger who continues to alarm the walk- through metal detector provides an example of how these three elements  intersect. According to TSA’s Screening Checkpoint Standard Operating  Procedures manual, a passenger who continues to alarm the walk-through  metal detector must be screened using a hand-wand search. Passengers  may alternatively request a full-body pat-down search. The manual  describes the process that transportation security officers are to follow  during the additional screening, which includes the use of ETD swabbing  and a pat-down of the passenger to detect any irregularities in their body  contour that could represent concealed items.
section_title: TSA Efforts to Improve the Passenger Screening Process
paragraphs: TSA faces a significant challenge in balancing security concerns with  efficient passenger movement. In our April 2007 report, we described how  TSA monitors transportation security officer compliance with passenger  checkpoint screening procedures through its performance accountability  and standards system and through testing. Compliance assessments  include quarterly observations of transportation security officers’ ability to  perform particular screening functions in the operating environment,  quarterly quizzes to assess their knowledge of procedures, and an annual  knowledge and skills assessment. TSA conducts tests to evaluate, in part,  the extent to which transportation security officers are able to detect  simulated threat items hidden in accessible property or concealed on a  person. TSA modifies its standard operating procedures based on the  professional judgment of TSA senior-level officials and program-level staff,  daily experiences of airport staff, complaints and concerns raised by the  traveling public, and an analysis of risks to the aviation system. For  example, in December 2005, TSA modified its prohibited items list to allow  passengers to carry certain scissors and tools as long as they did not  exceed a certain length. TSA’s stated purpose in removing certain scissors  and tools from the prohibited items list was to shift the focus of  transportation security officers from items considered by TSA to pose a  low threat to items considered to pose a high threat.
section_title: Creating Functioning IED and IID Devices
paragraphs: Investigators found instructions on the Internet for creating both an IED  and IID and purchased the components from the Internet and from a local  store for approximately $150. The IED was conceived as a two-part  device—a detonator component that, on its own, could function as an IED,  and a mixture of fuel and oxidizer that would require the explosion of the  detonator. Although the detonator component could be considered an  IED, for the purposes of this report, we are referring to the combination of  the detonator and the liquid explosive as a single IED. Information about  liquid explosives was publicly available on several Web sites and  discussed in media articles related to various terror plots, including the  failed London subway bombing of July 21, 2005, and the transatlantic  bomb plot of August 2006. In addition, we obtained information about  creating an IID from the Internet. We also found videos on the Internet of  the intense fire resulting from an IID. One of the components for the IID is  a liquid that TSA prohibits passengers from bringing through security  checkpoints. Specific details regarding the device components and the  methods of concealment we used during our covert testing are classified  by TSA; as such, they are not discussed in this testimony.
A group of tests conducted in February 2006 and July 2007 show that the  IED proposed for this investigation functions as intended. In 2006, within  the scope of our original covert testing report, we worked with a law  enforcement organization in the Washington, D.C., metro area to confirm  that the detonator would function as an IED. A test performed by local law  enforcement officials confirmed that the detonator would cause damage to  an aircraft and threaten the safety of passengers. Because our proposed  IED for this investigation was composed of two parts (the detonator and  the liquid explosive), in July 2007 we sought assistance to confirm that this  more complex IED would function as intended. Several tests conducted at  a national laboratory demonstrated that this IED can function as intended,  with the initial explosion by the detonator successfully causing the liquid  explosive to detonate in several tests. Explosion data indicate that this  device exploded with a force sufficient to cause severe damage to an  aircraft. The IID is a far simpler device. Our work with a law enforcement  organization in the Washington, D.C., metro area in February 2006  confirmed that the components of the IID (one of which is a liquid) could  function as intended, causing damage to an aircraft and threatening the  safety of passengers.
section_title: Testing at 19 Airport Security Checkpoints
paragraphs: Our investigators devised methods that would allow them to conceal the  prohibited components for these devices from transportation security  officers. During this planning phase, they considered publicly advertised  TSA policies related to liquids and other items, including prohibited items.  They also judged that some components could be hidden in either their  carry-on luggage or on their persons. They developed covert test  procedures to challenge TSA screening measures using these components  and methods. Specific details regarding the methods of concealment we  used are classified by TSA; as such, these details are not discussed in this  testimony.
By using various concealment methods, our investigators demonstrated  that it is possible to bring the components for several functioning IEDs  and one functioning IID through checkpoints and onto airline flights  without being challenged by transportation security officers. In most  cases, transportation security officers appeared to follow TSA procedures  and used technology appropriately; however, we uncovered weaknesses in  TSA screening procedures and other vulnerabilities as a result of these  tests. For example, although transportation security officers generally  enforced TSA’s 3-1-1 rule, we were able to bring a liquid component of the  IID undetected through checkpoints by taking advantage of weaknesses  we identified in TSA’s policies based on a review of public information.  TSA determined that specific details regarding these weaknesses are  sensitive security information and are therefore not discussed in this  testimony. We did not notice any difference between the performance of  private screeners and transportation security officers during our tests.
subsections: section_title: Covert Test Series One
paragraphs: From March 19 through March 23, 2007, two investigators tested the TSA  checkpoint screening process at a number of U.S. airports. Transportation  security officers did not interact with our investigators at every airport.  Interactions that did occur included the following:    On March 19 and March 20, 2007, transportation security officers  advised our investigators to use a 1-quart clear plastic bag rather than  the larger bags they were using, but did not require them to do so  before passing through the checkpoint.
Also at another airport, on March 23, 2007, a transportation security  officer did not allow one investigator to bring a small, unlabeled bottle  of medicated shampoo through the checkpoint. This was a legitimate  toiletry item used by one of our investigators. The officer cited TSA  policy and stated that since the bottle was not labeled, “it could contain  acid.” She did not allow our investigator to bring the unlabeled  medicated shampoo bottle through the checkpoint. However, a liquid  component of the IID—despite being prohibited by TSA—was allowed  to pass undetected through the checkpoint. We had identified this  weakness based on a review of public information before performing  our tests.
section_title: Covert Test Series Two
paragraphs: From May 7 through May 9, 2007, two investigators tested the TSA  checkpoint screening process at a number of U.S. airports. Transportation  security officers did not interact with our investigators aside from the  following:    On May 8, 2007, one investigator deliberately placed coins in his  pockets to ensure that he would receive a secondary inspection. The  transportation security officer used a hand-wand and performed a pat- down search of our investigator. However, the transportation security  officer did not detect any of the prohibited items our investigator  brought through the checkpoint.
section_title: Covert Test Series Three
paragraphs: From June 5 through June 8, 2007, two investigators tested the TSA  checkpoint screening process at a number of U.S. airports. Transportation  security officers did not interact with our investigators at every airport.  Interactions that did occur included the following:  Inclement weather forced our investigators to change their flight plans  at one airport. After changing their plans, they were selected for  secondary inspection at the TSA security checkpoint. Transportation  security officers performed pat-downs at the checkpoint. However, the  transportation security officers did not detect any of the prohibited  items our investigators brought through the checkpoint.
section_title: Corrective Action Briefings
paragraphs: We briefed TSA officials on August 16, 2007, and September 5, 2007, to  discuss our findings. Officials from TSA’s Security Operations Office were  present during our second briefing. At these briefings, we suggested that  TSA consider how the results of our covert testing should affect its risk- based approach to airport security. This could include implementing one  or more measures to reduce the likelihood that terrorists could  successfully bring IED and IID components through checkpoints using a  similar methodology to ours in the future.
The specific nature of our suggestions to TSA is considered sensitive  security information. Put generally, we suggested that, among other things,  TSA (1) establish, depending on airport capacity, one or more special  passenger screening lines to screen individuals based on risk and  individuals with special needs; (2) introduce more aggressive, visible, and  unpredictable deterrent measures into the passenger screening process at  airports nationwide, to potentially include the implementation of  enhanced individual search procedures (e.g., pat-downs and hand-wand  screening) to detect concealed components; and (3) continue to develop  and deploy new technology to be used at passenger screening checkpoints  that would be able to better detect concealed components.
TSA officials indicated that they did not disagree with our suggestions in  principle and that they would examine them closely to determine whether  and how they should be implemented. They acknowledged vulnerabilities  in human capital, processes, and technology. They also indicated that they  are deploying additional specialized personnel to enhance security at  existing checkpoints and that they are exploring methods for enhancing  transportation security officer training and transforming the culture of  their workforce. Regarding standard operating procedures, officials said  that they are continuously revisiting and revising their policies. They also  indicated that they were moving forward to develop a “checkpoint of the  future” that would incorporate new and emerging technology to address  terror threats. Such technology could include innovative imaging  techniques.
section_title: Conclusion
paragraphs: Our 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. Given our degree of  success, we are confident that our investigators would have been able to  evade transportation security officers at additional airports had we  decided to test them. We understand the challenges TSA faces in balancing  security risks with the efficient movement of passengers; however, from a  strict security standpoint, current policies allowing substantial carry-on  luggage and related items through TSA checkpoints increases the risk of a  terrorist successfully bringing an IED, an IID, or both onto an aircraft  undetected. Even if current carry-on luggage policies are left unchanged,  our testing shows that risks can be reduced through improvements in  human capital, improved processes, and continued advances in  technology.
GAO is currently performing a more systematic review of these issues and  expects to issue a comprehensive public report with recommendations for  TSA in early 2008.
Mr. Chairman and Members of the committee, this concludes our  statement. We would be pleased to answer any questions that you or other  members of the committee may have at this time.
section_title: GAO Contacts
paragraphs: For further information about this testimony, please contact Gregory D.  Kutz at (202) 512-6722 or kutzg@gao.gov. Contact points for our Offices of  Congressional Relations and Public Affairs may be found on the last page  of this testimony.
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