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entitled 'Aviation Security: TSA's Change to Its Prohibited Items List 
Has Not Resulted in Any Reported Security Incidents, but the Impact of 
the Change on Screening Operations Is Inconclusive' which was released 
on April 25, 2007. 

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April 25, 2007: 

The Honorable Robert C. Byrd: 
Chairman: 
The Honorable Thad Cochran: 
Ranking Minority Member: 
Subcommittee on Homeland Security: 
Committee on Appropriations: 
United States Senate: 

The Honorable David E. Price: 
Chairman: 
The Honorable Harold Rogers: 
Ranking Minority Member: 
Subcommittee on Homeland Security: 
Committee on Appropriations: 
House of Representatives: 

The Honorable Hillary Rodham Clinton: 
United States Senate: 

Subject: Aviation Security: TSA's Change to Its Prohibited Items List 
Has Not Resulted in Any Reported Security Incidents, but the Impact of 
the Change on Screening Operations Is Inconclusive: 

The alleged August 2006 terrorist plot to detonate liquid explosives 
onboard multiple commercial aircraft bound for the United States from 
the United Kingdom has highlighted both the continued importance of 
securing the civil aviation system and the potential that improvised 
explosive devices (IED) may be smuggled onboard passenger aircraft. The 
Transportation Security Administration (TSA) has primary responsibility 
for ensuring the security of civil aviation, which includes the safety 
of passengers and flight crew.[Footnote 1] 

One measure TSA uses to protect the aviation system is prohibiting 
individuals from carrying items that it determines to be a threat to 
the aircraft and its passengers into an airport sterile area or onboard 
an aircraft either in their carry-on bag or on their person.[Footnote 
2] To implement this measure, TSA maintains a prohibited items list 
that informs both the Transportation Security Officers (TSO) who 
conduct passenger screening and the traveling public of items that will 
not be allowed into an airport sterile area or onboard an aircraft. In 
December 2005, TSA revised its prohibited items list to allow 
passengers to carry: (1) metal scissors with pointed tips and a blade 4 
inches or less in length as measured from the fulcrum; and (2) tools-- 
such as pliers, screwdrivers, and wrenches--7 inches or less in length 
(excluding crowbars, drills, hammers, and saws).[Footnote 3] 

TSA considers any incident that threatens the security or safety of an 
aircraft or its passengers and flight crew to be a security incident. 
These could include a range of activities onboard an aircraft such as 
disruptive passenger behavior, violence against a passenger or crew 
member, hijacking attempts, or the use of an improvised explosive 
device. By examining the security impacts of the change to the 
prohibited items list, this report considers the impacts that could 
result from a passenger attempting to use scissors or tools to hijack 
an aircraft or to commit other forms of violence onboard a flight. Such 
actions fall within TSA's statutory responsibility to ensure the safety 
and security of passengers and crew aboard aircraft. In accordance with 
Conference Report 109-699, which accompanied the fiscal year 2007 
Department of Homeland Security (DHS) appropriations act,[Footnote 4] 
this report addresses the following questions: (1) What was TSA's basis 
for removing certain scissors and tools from the prohibited items list 
and what are stakeholder views on the change? (2) What have been the 
impacts, if any, of the removal of certain scissors and tools from the 
prohibited items list on the security of aircraft passengers and flight 
crew and on the effectiveness of checkpoint screening operations? 

To address these objectives, we analyzed TSA documentation and data, 
including TSA security incident reports, TSA written analyses related 
to the prohibited items list change, results of Threat Image Projection 
(TIP) testing,[Footnote 5] and data on training hours completed by 
TSOs. Although the TIP data we received had limitations, we believe 
that they are sufficiently reliable for the purposes of this report and 
that the data on training hours are sufficiently reliable as well. We 
also met with two Federal Security Directors (FSD) to obtain their 
views on the impact of the prohibited items list change on checkpoint 
screening operations.[Footnote 6] However, information obtained from 
our interviews with these FSDs cannot be generalized because we did not 
use random selection or representative sampling when determining which 
FSDs should be interviewed. In addition, we met with officials at the 
Federal Aviation Administration (FAA) and the Federal Air Marshals 
Service (FAMS)--a component of TSA--to obtain their views regarding the 
prohibited items list change. We also met with TSA officials to obtain 
information on their rationale behind the change. We spoke with 13 
stakeholders within the aviation industry, including representatives of 
4 domestic aviation associations, the largest association representing 
airline pilots in the United States, the largest association 
representing flight attendants in the United States, an association 
representing federal air marshals and other federal law enforcement 
officers, an international aviation association, and 5 aviation 
security experts. We also met with a major aircraft manufacturer to 
determine whether there are any major safety concerns related to the 
change to the prohibited items list. Finally, we incorporated aspects 
of a recently issued GAO report on passenger checkpoint screening 
procedures, which included a review of the factors TSA considered in 
modifying the prohibited items list and TSA's analysis supporting the 
December 2005 prohibited items list change.[Footnote 7] We conducted 
our work from November 2006 through March 2007 in accordance with 
generally accepted government auditing standards. More details about 
the scope and methodology of our work are presented in enclosure I. 

Results in Brief: 

TSA's stated purpose in removing certain scissors and tools from the 
prohibited items list was to shift TSO focus from items considered by 
TSA to pose a low threat (including certain scissors and tools) to 
items considered to pose a high threat, such as explosives. The change 
also was intended to better allocate TSA resources to implement other 
security measures that target explosives--a change supported by the 
majority of aviation industry stakeholders that we interviewed. TSA's 
decision to remove these items from the prohibited items list was based 
on the professional judgment of TSA officials that these items do not 
pose a significant threat to the security of the cockpit or to 
passengers and flight crew as well as internal studies that sought to 
examine, among other things, risks to flight security and 
considerations of customer concerns and screening efficiencies. As part 
of these internal studies, TSA collected data on the number and types 
of prohibited items surrendered at checkpoints and the time it takes 
for TSOs to conduct carry-on bag searches. In March 2007, we reported 
that TSA did not analyze these data to determine the extent to which 
TSO resources would actually be freed up to implement other security 
measures, nor did TSA analyze other relevant factors such as the amount 
of time taken to search for small scissors and tools and the number of 
TSOs conducting these searches. We recommended that TSA develop sound 
evaluation methods, when possible, that can help TSA determine whether 
proposed procedures would achieve their intended purpose.[Footnote 8] 
TSA concurred with the recommendation and stated that it plans to make 
better use of generally accepted research design principles and 
techniques when operationally testing proposed changes to screening 
procedures. Based on our analysis of TSA data for the third and fourth 
quarters of fiscal year 2005 (a 6-month period), we determined that 
TSOs spent, on average, less than 1 percent of their time--about 1 
minute per day over the 6-month period--searching for the approximately 
1.8 million sharp objects, other than knives and box cutters, that were 
found at passenger screening checkpoints between April 2005 and 
September 2005. Therefore, it may not have been accurate for TSA to 
assume that no longer requiring TSOs to search for small scissors and 
tools would significantly contribute to TSA's efforts to free up TSO 
resources that could be used to implement other security measures. TSA 
acknowledged that its data collection and analysis effort may not have 
been methodologically rigorous but stated that it did serve to provide 
insights regarding the type and quantity of items collected at the 
passenger checkpoint. TSA officials also stated that even if TSO 
resources were not freed up as intended, they continue to view their 
decision to allow small scissors and tools onboard aircraft as sound, 
particularly because their review of threat information determined that 
small scissors and tools do not pose a significant threat to aviation 
security. Additionally, 9 of the 13 aviation industry stakeholders whom 
we interviewed supported the removal of small scissors and tools from 
the prohibited items list because they believe small scissors and tools 
do not pose a risk to the security of the aircraft and stated that the 
change will increase TSA's focus on IEDs; the remainder disagreed, 
citing potential increased security risks. TSA officials acknowledged 
that small scissors and tools, as well as other items permitted onboard 
commercial aircraft, may potentially be used as weapons against 
passengers and flight crew, but stated that these items cannot be used 
to hijack an aircraft given the other layers of security in place, such 
as hardened cockpit doors that prevent unauthorized access to the 
flight deck. 

Based on our review of TSA security incident reports from the time 
period following the prohibited items list change (December 2005 
through February 2007), there have been no reported security incidents 
onboard an aircraft involving the use of small scissors or tools. 
However, the impact of the prohibited items list change on security is 
uncertain because the absence of an event occurring involving the use 
of these items does not preclude the possibility that future 
occurrences could happen. In addition, with respect to the 
effectiveness of the change on checkpoint screening operations, it is 
not possible to determine this because the available data are 
inconclusive. As we reported in March 2007, TSA conducted informal 
studies 30, 60, and 90 days following the change and concluded that TSO 
time was freed up to focus on high-threat items, but our analysis of 
TSA data does not support this conclusion.[Footnote 9] TSA agrees that 
the agency could have conducted a more methodologically sound 
evaluation of the impact of the prohibited items list change, but 
continues to believe that the change nevertheless significantly 
contributed to the agency's efforts to free up TSO resources to focus 
on detecting high-threat items, such as explosives. It also is not 
clear whether the change had any impact on TSOs' ability to detect 
explosives--a key goal of the change. One way TSA measures the 
effectiveness of the passenger screening system in detecting threat 
items, such as explosives, is the results of threat image projection 
testing.[Footnote 10] However, TSA does not claim nor do the data 
definitively support that TSA's change to the prohibited items list had 
any impact on threat image projection results because TSA implemented 
other changes to checkpoint screening operations at or around the same 
time as the prohibited items list change. With regard to TSA's efforts 
to increase training for identifying explosives as part of its overall 
effort to become a more risk-based organization, TSA data between 
October 2004 and January 2007 show an increase in the average number of 
hours spent in training per TSO, but this trend began before the change 
to the prohibited items list and there are other factors that may have 
contributed to this increase. 

Background: 

In accordance with applicable laws and regulations, TSA prohibits 
weapons, explosives or incendiaries, and other items that TSA believes 
pose a significant threat to civil aviation security onboard commercial 
aircraft.[Footnote 11] TSA has divided these prohibited types of items 
into seven categories. Individuals are prohibited from carrying these 
items into an airport sterile area or onboard an aircraft either in 
their carry-on bag or on their person. Table 1 provides a description 
of the items included in the seven categories. 

Table 1: Categories and Descriptions of Prohibited Items. 

Category of prohibited item: Guns and firearms; 
Description of items included in the category: BB guns; compressed air 
guns; firearms; flare pistols; gun lighters; parts of guns and 
firearms; pellet guns; realistic replicas of firearms; spear guns; 
starter pistols; stun guns/cattle prods/ shocking devices. 

Category of prohibited item: Sharp objects; 
Description of items included in the category: Axes and hatchets; bows 
and arrows; ice axes/ice picks; knives of any length, except rounded-
blade butter and plastic cutlery; meat cleavers; razor-type blades, 
such as box cutters, utility knives, and razor blades not in a 
cartridge, but excluding safety razors; sabers; scissors, metal with 
pointed tips and a blade length greater than 4 inches as measured from 
the fulcrum; swords; throwing stars (martial arts). 

Category of prohibited item: Club-like items; 
Description of items included in the category: Baseball bats; billy 
clubs; blackjacks; brass knuckles; cricket bats; golf clubs; hockey 
sticks; lacrosse sticks; martial arts weapons, including nunchucks, and 
kubatons; night sticks; pool cues; ski poles. 

Category of prohibited item: All explosives; 
Description of items included in the category: Ammunition; blasting 
caps; dynamite; fireworks; flares in any form; gunpowder; hand 
grenades; plastic explosives; realistic replicas of explosives. 

Category of prohibited item: Incendiaries; 
Description of items included in the category: Aerosol, any, except for 
personal care or toiletries in limited quantities; fuels, including 
cooking fuels and any flammable liquid fuel; gasoline; gas torches, 
including microtorches and torch lighters; lighter fluid; strike-
anywhere matches; turpentine and paint thinner; realistic replicas of 
incendiaries; all lighters. 

Category of prohibited item: Disabling chemicals and other dangerous 
items; 
Description of items included in the category: Chlorine for pools and 
spas; compressed gas cylinders (including fire extinguishers); liquid 
bleach; mace; pepper spray; spillable batteries, except those in 
wheelchairs; spray paint; tear gas. 

Category of prohibited item: Tools; 
Description of items included in the category: Crowbars; drills and 
drill bits, including cordless portable power drills; hammers; saws and 
saw blades, including cordless portable power saws; other tools greater 
than 7 inches in length, including pliers, screwdrivers, and wrenches. 

Source: TSA. 

[End of table] 

Passenger screening is a process by which personnel authorized by TSA 
inspect individuals and property to deter and prevent the carriage of 
any unauthorized explosive, incendiary, weapon, or other items included 
on TSA's prohibited items list onboard an aircraft or into a sterile 
area.[Footnote 12] Passenger screening personnel--TSOs--must inspect 
individuals for prohibited items at designated screening 
locations.[Footnote 13] As shown in figure 1, the passenger screening 
functions are: 

* X-ray screening of property, 

* walk-through metal detector screening of individuals, 

* hand-wand or pat-down screening of individuals, 

* physical search of property and trace detection for explosives, and: 

* behavioral observation. 

Figure 1: Passenger Checkpoint Screening Functions: 

[See PDF for Image] 

Source: GAO and Nova Department Corporation. 

Notes: Explosive trace detection (ETD) works by detecting vapors and 
residues of explosives. Human operators collect samples by rubbing 
swabs along the interior and exterior of an object that TSOs determine 
to be suspicious, and place the swabs in the ETD machine, which then 
chemically analyzes the swab to identify any traces of explosive 
materials. 

Bomb Appraisal Officers (BAO) are available to respond to unresolved 
alarms at the checkpoint that involve possible explosive devices. The 
BAO may contact appropriate law enforcement or bomb squad officials if 
review indicates possible or imminent danger, in which case the BAO 
ensures that the security checkpoint is cleared. The BAO approves 
reopening of security lane(s) if no threat is posed. 

[A] BDOs are TSOs specially trained to detect suspicious behavior in 
individuals approaching the checkpoint. Should the BDO observe such 
behavior, he or she may refer the individual for individual screening 
or to a law enforcement officer. As of April 2007, BDOs are not present 
at all airport checkpoints. 

[B] The hand-wand or pat-down is conducted if a passenger is identified 
or randomly selected for additional screening because he or she met 
certain criteria or alarmed the walk-through metal detector. 

[C] Manual or ETD searches of accessible property occur if the 
passenger is identified or randomly selected for additional screening 
or if the screener identified a potential prohibited item on X-ray. 

[End of figure] 

Typically, passengers are only subjected to X-ray screening of their 
carry-on items and screening by the walk-through metal detector. 
Passengers whose carry-on baggage alarms the X-ray machine, who alarm 
the walk-through metal detector, or who are designated as selectees-- 
that is, passengers selected by the Computer-Assisted Passenger 
Prescreening System (CAPPS[Footnote 14]) or other TSA-approved 
processes to receive additional screening--are screened by hand-wand or 
pat-down and have their carry-on items screened for explosives traces 
or physically searched. 

In addition to passenger checkpoint screening, other layers of aviation 
security recognized by TSA include, among other things: 

* Hardened cockpit doors to prevent unauthorized access or forced entry 
to the flight deck. 

* Deployment of federal air marshals on certain flights to provide 
physical security should an incident occur. 

* Federal Flight Deck Officers (FFDO) Program to train pilots on 
commercial passenger and cargo aircraft on how to use lethal force 
against an intruder on the flight deck.[Footnote 15] 

* Security training for flight and cabin crews to handle potential 
threats onboard aircraft. Flight and cabin crews are expected to defend 
the flight deck in accordance with a TSA and FAA-developed guidance 
manual known as the Common Strategy.[Footnote 16] 

In addition, TSA considers the vigilance of able-bodied passengers to 
be an important layer of aviation security. Able-bodied passengers are 
those passengers who may engage in self-defense actions should an 
incident occur onboard commercial aircraft. 

TSA Changed the Prohibited Items List to Shift TSO Resources to Higher- 
Threat Priorities and Most Aviation Industry Stakeholders Interviewed 
Supported TSA's Change: 

TSA Conducted Various Studies to Determine Whether Changing the 
Prohibited Items List Would Free Up TSO Resources, but Some Efforts 
Lacked Methodological Rigor: 

As we reported in March 2007,[Footnote 17] TSA changed the prohibited 
items list in an effort to shift TSO resources to focus on higher 
threats, such as explosives, and based on its determination that small 
scissors and tools do not pose a risk to aviation security.[Footnote 
18] TSA's decision was informed by the conclusions reached by an 
Explosives Detection Improvement Task Force established in October 2005 
by the TSA Assistant Secretary to respond to the threat of IEDs being 
carried through the checkpoint. The goal of the task force was to apply 
a risk-based approach to screening passengers and their baggage in 
order to enhance TSA's ability to detect IEDs. As part of its analysis, 
the task force considered a number of factors including threat 
information, TSO effectiveness, and overall screening performance. 
According to TSA officials, the task force also considered the results 
of a Prohibited Items Working Group that was established in February 
2005 by the then-TSA Assistant Secretary to develop recommendations for 
modifying the prohibited items list to better reflect the current 
aviation security environment. 

The Prohibited Items Working Group assessed each item on the prohibited 
items list using four criteria: (1) risks to flight security (i.e., can 
the item be used to take down an aircraft in flight); (2) legal 
restrictions (i.e., hazardous and other materials that are prohibited 
from the aircraft or from the flight cabin); (3) public concern and 
screener effectiveness (i.e., would permitting the item onboard an 
aircraft cause significant passenger and flight crew concern regarding 
their safety); and (4) international standards (i.e., international 
protocols recommend that the item be prohibited from the aircraft or 
the flight cabin). At the conclusion of its analysis, the working group 
recommended that scissors with pointed tips less than 6 centimeters 
(2.36 inches) and tools less than 7 inches be removed from the 
prohibited items list because these items were not considered to 
represent a risk to the aircraft or cockpit security. Although the 
working group based its size restriction for scissors on the size 
parameters recommended by the International Civil Aviation Organization 
(ICAO)--which is to provide for the safe, orderly, and efficient 
development of international civil aviation--the working group deviated 
from ICAO's recommendation to prohibit all pointed/edged 
scissors.[Footnote 19] A TSA representative from the working group 
stated that this change was recommended because the working group 
concluded that pointed/edged scissors could not be used to gain access 
to the cockpit to take down an aircraft in flight. In addition, the 
working group stated that concentrating on such items diminished TSA's 
efforts to focus on identifying objects that pose the greatest threat 
to aviation security, such as IEDs. 

Subsequent to the analysis of the working group, TSA's Explosives 
Detection Improvement Task Force collected information from several 
sources to test its assumption that a disproportionate amount of TSO 
resources was being spent searching for small scissors and tools. 
First, TSA reviewed data maintained in TSA's Performance Management 
Information System,[Footnote 20] which showed that during the third and 
fourth quarters of fiscal year 2005 (a 6-month period), TSOs collected 
a total of about 1.8 million sharp objects other than knives or box 
cutters and about 468,000 tools. The sharp objects constituted 19 
percent of all prohibited items surrendered at the checkpoint during 
this period and tools constituted 5 percent of the items. Second, based 
on information provided by FSDs, TSOs, and other screening experts, TSA 
determined that scissors constituted a large majority of the total 
number of sharp objects found at passenger screening checkpoints. TSA 
also concluded that small screwdrivers, wrenches, and pliers make up a 
large majority of the tools found at checkpoints. Third, TSA 
headquarters officials searched through surrendered items bins at four 
airports and found that most of the scissors had blades less than 4 
inches in length and a very large percentage of the tools that were 
surrendered were 7 inches or smaller. 

Based on these collective efforts, TSA's Explosive Detection 
Improvement Task Force concluded that a significant number of items 
found at the checkpoint were low-threat, easily identified items, such 
as small scissors and tools, and that a disproportionate amount of time 
was spent searching for these items--time that could have been spent 
searching for high-threat items, such as explosives. The task force 
also concluded that because TSOs can generally identify scissors and 
tools on X-ray images easily, if small scissors and tools were no 
longer on the prohibited items list, TSOs could avoid conducting time- 
consuming physical bag searches to locate and remove these items. TSA 
ultimately concurred with the recommendations provided by the Explosive 
Detection Improvement Task Force and decided to remove scissors less 
than 4 inches and certain tools less than 7 inches from the prohibited 
items list. 

Although TSA's rationale for its December 2005 change to the prohibited 
items list was to reduce focus on low-threat items in order to free up 
TSO time, attention, and resources to implement screening practices 
that better focus on high-threat items--such as Screening Passengers by 
Observation Technique (SPOT) and Unpredictable Screening Process 
(USP)[Footnote 21]--we reported in March 2007 that TSA had not 
conducted the necessary analysis of the data collected to determine the 
extent to which the removal of small scissors and tools from the 
prohibited items list could free up TSO resources. Specifically, we 
found that TSA had not analyzed the data on sharp objects surrendered 
at the checkpoint along with other relevant factors, such as the amount 
of time taken to search for scissors and the number of TSOs at the 
checkpoint conducting these searches. Based on our analysis of TSA's 
data for the third and fourth quarters of fiscal year 2005 (a 6-month 
period), where we considered these other relevant factors, we 
determined that TSOs spent, on average, less than 1 percent of their 
time--about 1 minute per day over the 6-month period--searching for the 
approximately 1.8 million sharp objects, other than knives and box 
cutters, that were found at passenger screening checkpoints between 
April 2005 and September 2005. If the average amount of time TSOs spent 
searching for sharp objects per day over a 6-month period was less than 
1 minute per TSO, and sharp objects constituted just 19 percent of all 
prohibited items surrendered at checkpoints over this period, then it 
may not be accurate to assume that no longer requiring TSOs to search 
for small scissors and tools would significantly contribute to TSA's 
efforts to free up TSO resources that could be used to implement other 
security measures. TSA stated that the decision to remove small 
scissors and small tools from the prohibited items list was not only 
based on an analysis of data but was also firmly rooted in its 
assessment of risk, professional judgment, and experience. According to 
TSA, this included interviews with FSDs who unanimously indicated the 
change would free up TSO resources, as well as examinations of the 
prohibited items surrendered at several airports and a study to 
determine the amount of time taken to conduct bag searches. 

TSA acknowledged that this particular data collection and analysis 
effort may not have been methodologically rigorous, but stated that it 
did serve to provide insights regarding the type and quantity of items 
collected at the passenger checkpoint and the analysis effort generally 
supported the decision. Additionally, the TSA Assistant Secretary 
stated that even if TSA determined that the proposed prohibited items 
list modification would not free up existing TSO resources to conduct 
explosives detection procedures, he would have implemented the change 
anyway considering that such items no longer posed a significant 
security risk given the multiple layers of aviation security. 

In our March 2007 report, we recommended that TSA develop sound 
evaluation methods, when possible, that can help TSA determine whether 
proposed procedures that are operationally tested would achieve their 
intended purpose, such as enhancing TSA's ability to detect prohibited 
items and freeing up existing TSO resources that could be used to 
implement proposed procedures.[Footnote 22] TSA concurred with the 
recommendation and stated that it plans to make better use of generally 
accepted research design principles and techniques when operationally 
testing proposed changes to screening procedures. For example, TSA 
agreed to consider using random selection, representative sampling, and 
control groups in order to isolate the impact of proposed changes to 
screening procedures from the impact of other variables. 

Most Aviation Industry Stakeholders We Contacted Supported TSA's 
Changes to the Prohibited Items List: 

The majority (9 of 13) of the aviation industry stakeholders that we 
interviewed supported the removal of small scissors and tools from the 
prohibited items list. In general, these stakeholders said that they 
believe that the layers of aviation security reduce a passenger's 
ability to access the cockpit with low-threat items, and further noted 
that passengers may carry other items onboard an aircraft (such as 
glass bottles, pens, and sharpened credit cards) that may also be used 
as weapons. Stakeholders also stated that TSOs will be able to better 
focus on detecting IEDs if low-threat items such as small scissors and 
tools are removed from the prohibited items list. However, 4 out of 13 
aviation industry stakeholders that we interviewed were opposed to the 
prohibited items list change, stating that permitting scissors 
increases the risk of violence against passengers and flight crew 
onboard an aircraft. Some of these stakeholders also stated that 
scissors also increase the risk that hijackings could be successfully 
implemented because scissors have bladed edges and pointed tips and 
therefore can be used as knives, and because terrorists can train with 
scissors to perfect their use as weapons. These stakeholders further 
stated that unlike other items that can be improvised to create a 
cutting surface (such as broken glass bottles), terrorists would not 
need to alter scissors onboard aircraft to use them as weapons. This 
could also allow a passenger to use the cutting edge and/or the 
sharpened tip of a scissor as a weapon without alerting other 
passengers or flight crew, as compared with the attention that could be 
drawn to a passenger that breaks a glass bottle. 

TSA acknowledges that scissors and tools may be used as weapons against 
passengers and flight crew. However, TSA stated that other items that 
are permitted onboard commercial aircraft, such as pens and glass 
bottles, may also be used as weapons against passengers and flight 
crew. TSA also maintained that its focus is on detecting explosives or 
items that can be used to breach the cockpit and potentially hijack the 
aircraft, which TSA and the majority of the aviation industry 
stakeholders that we spoke with view as a significant threat to 
aviation. TSA maintained that small scissors and tools cannot be used 
to hijack an aircraft, particularly given the other layers of security. 

Although stakeholders who both supported and disagreed with TSA's 
change stated that the layers of security implemented since September 
11, 2001--particularly the hardened cockpit door--have decreased the 
likelihood of a successful hijacking, stakeholders generally stated 
that the risk of a hijacking is highest when the cockpit door is 
opened. In an attempt to mitigate this potential vulnerability, and in 
accordance with the air carrier's responsibility to ensure that no 
passenger can access the flight deck when the cockpit door needs to be 
opened during flight, air carriers will typically place a beverage cart 
between passengers and the cockpit with a flight attendant standing 
behind the cart. The beverage cart and the flight attendant serve as a 
"secondary barrier" between passengers and the cockpit door. However, 
two aviation stakeholders--a former law enforcement officer who 
provides self-defense training and a representative from the 
association of flight attendants--stated that this secondary barrier 
can be circumvented by a determined terrorist using a scissor to attack 
the flight attendant who is manning the beverage cart, which could 
allow the terrorist to negotiate around the beverage cart and then 
access the open cockpit door. A senior TSA official stated that flight 
crew protocols are sufficient to ensure passengers cannot breach the 
cockpit and that mechanisms are in place to ensure that cockpit doors 
are opened for brief periods of time. 

No Security Incidents against Passengers or Crew Using Scissors or 
Tools Have Been Reported to TSA Since the Change to the Prohibited 
Items List, but the Impact of the Change on Screening Operations Is 
Inconclusive: 

No Onboard Incidents Involving Small Scissors or Tools Reported to TSA 
Since Prohibited Items List Change and FAA Does Not Believe These Items 
Pose a Risk to the Integrity of an Aircraft: 

Based on our review of TSA security incident reports from the time 
period following the prohibited items list change (December 2005 
through February 2007), there have been no reported security incidents 
onboard an aircraft involving the use of small scissors or 
tools.[Footnote 23] However, TSA and aviation security stakeholders we 
spoke with acknowledged that the absence of an onboard incident 
involving scissors or tools as weapons does not preclude the 
possibility of such an incident in the future. In addition, based on 
aircraft vulnerability and system safety and security analyses 
performed to date by government and industry, neither FAA nor a major 
aircraft manufacturer we interviewed perceive any meaningful increase 
in risk to the integrity of an aircraft associated with TSA's decision 
to permit small scissors and tools onboard aircraft.[Footnote 24] FAA 
officials also stated that aircraft are designed so that there are many 
layers of protection to prevent damage to the integrity of an aircraft 
from within (e.g., hardened cockpit doors and separate and redundant 
wiring for critical systems with few internal access points). The 
aircraft manufacturer stated that while it is possible that terrorists 
or others intending to do harm to the aviation system could use these 
items in ways not currently foreseeable, given current risk mitigation 
activities, the ability to inflict major damage to an aircraft with 
them is extremely remote. 

Impact of Prohibited Items List Change on Checkpoint Screening 
Operations Is Inconclusive: 

TSA conducted informal studies 30, 60, and 90 days after the prohibited 
items list changes went into effect to determine whether the change had 
resulted in reductions in the percentage of carry-on bags that were 
searched and overall screening time. However, in a prior report, we 
identified limitations in TSA's methodology for conducting these 
studies and concluded that it may not be accurate to assume that the 
prohibited items list change freed up resources.[Footnote 25] TSA 
agrees that the agency could have conducted a more methodologically 
sound evaluation of the impact of the prohibited items list change, but 
TSA continues to believe that the change did significantly contribute 
to the agency's efforts to free up TSO resources to focus on detection 
of high-threat items, such as explosives. TSA officials stated that 
that they have not conducted or planned any additional studies on the 
prohibited items list change to determine the impact of the change on 
the effectiveness of screening operations. Officials continue to view 
the change as sound based on their professional judgment and assessment 
of risk, and state that the change allowed the agency to shift focus 
from low risks to areas such as increased focus on explosive devices 
and increased training. 

In February 2007, a TSA official stated that some FSDs interviewed 
several TSOs after the prohibited items list change went into effect, 
and these TSOs reported that the change did save screening time. 
However, TSA could not identify how many TSOs were interviewed, at 
which airports the TSOs were located, and how the TSOs were selected 
for the interview; nor did TSA document the results of these 
interviews. As TSA did not use random selection or representative 
sampling when determining which TSOs should be interviewed, the 
interview results cannot be generalized. 

Most of the FSDs we interviewed in August 2006 as part of our passenger 
screening procedures review stated that the prohibited items list 
change, in addition to another change, did not collectively free up TSO 
resources to perform screening activities focused on threats considered 
to pose a high risk, such as explosives.[Footnote 26] Specifically, 13 
of 19 FSDs we interviewed at airports that tested USP and SPOT said 
that TSO resources were not freed up as a result of the prohibited 
items list change and another change made by TSA during this time 
frame.[Footnote 27] In addition, 9 of the 19 FSDs said that in order to 
operationally test the procedures, TSOs had to work overtime, switch 
from other functions (such as checked baggage screening), or a 
screening lane had to be closed. Moreover, 13 of the 19 FSDs stated 
that TSOs did not experience more time to conduct explosives 
training.[Footnote 28] 

In addition to the lack of clarity about the impact of changes to the 
prohibited items list on TSO's available time, it also is not clear 
whether the change had any impact on TSOs' ability to detect IEDs--a 
key goal of the change. The results of threat image projection (TIP) 
testing are one way that TSA measures the effectiveness of the 
passenger screening system in detection of threat items, such as 
explosives. The results of TSA TIP testing are considered sensitive 
security information and thus could not be included in this report. 
Nevertheless, it is not clear whether TSA's change to the prohibited 
items list had any impact on TSOs' ability to identify IEDs during TIP 
testing because multiple factors could have accounted for the changes 
in TIP scores over time. For example, TSA implemented other changes to 
checkpoint screening operations at or around the same time as the 
prohibited items list change. These changes include both new and 
revised procedures, such as: revising the USP to include selected 
screening process elements like explosive trace detection of footwear 
and accessible property; screening 100 percent of passengers' footwear; 
banning liquids and gels; revising bulk-item pat downs to include the 
waistline down to the ankles; targeting threat area searches within 
baggage; revising the CAPPS rules; and implementing the new SPOT 
procedure. In fact, FSDs we interviewed at two category X 
airports[Footnote 29] in February 2007 as well as other TSA officials 
stated that at this time it is not possible to isolate the effect of 
the prohibited items list change from these additional changes in order 
to determine its impact on checkpoint screening operations and whether 
the prohibited items list change freed up TSO resources.[Footnote 30] 

With regard to TSA's efforts to increase training for identifying IEDs 
as part of its overall effort to become a more risk-based organization, 
TSA data between October 2004 and January 2007 show an increase in the 
average number of hours spent in training per TSO, but this trend began 
before the change to the prohibited items list and there are other 
factors that may have contributed to this increase. Our analysis of 
these data show an increase of an average of 1.68 hours per TSO in 
monthly IED training over the 29-month period, from an average of 0.42 
hours per TSO in October 2004 to an average of 2.10 hours per TSO in 
February 2007. According to TSA's TSO training officials, there are two 
primary explanations for the increase: (1) in October 2005 TSA provided 
a 4-hour IED training course to 18,000 TSOs over a 3-week period, and, 
according to TSA, about 98 percent of the 48,236 TSOs on board had 
received classroom, checkpoint, or computer-based improvised explosive 
device recognition training as of February 6, 2007; and (2) in May 2006 
TSA instituted a new monthly requirement of 4 hours of IED training per 
TSO. Thus, although a goal of the prohibited items list change was to 
increase TSO training hours for detecting IEDs, TSA program officials 
acknowledge, and we agree, that it is not clear whether the change to 
the prohibited items list had any impact on time spent in training. 

Concluding Observations: 

TSA is faced with the challenge of addressing numerous threats to 
commercial aviation security, as demonstrated by the alleged August 
2006 terrorist plot to detonate liquid explosives onboard multiple 
commercial aircraft bound for the United States from the United 
Kingdom. TSA's December 2005 change to the prohibited items list is one 
of several efforts TSA has made to focus its resources on addressing 
the threat posed by explosives, which TSA considers to be the most 
significant threat to commercial aviation security. While TSA's 
consideration of threat information, the professional judgment of TSA 
personnel, data analysis, and international standards all constitute 
reasonable inputs to making informed decisions on how to best 
anticipate and address threats given its available resources, the 
impact of the prohibited items list change on security and screening 
effectiveness is inconclusive. Nevertheless, we are encouraged that TSA 
recognized the limitations in its analysis of data used to help inform 
the prohibited items list change and plans to improve the 
methodological rigor for evaluating proposed changes to passenger 
screening procedures in the future, as we recommended in our March 2007 
report. This effort will be particularly important as additional 
changes to passenger screening procedures--including future revisions 
to the prohibited items list--are considered and implemented. 

Agency Comments: 

We provided a draft of the report to DHS for its review and comment. 
TSA provided technical comments, which we incorporated as appropriate. 

We will send copies of this report to the Secretary of the Department 
of Homeland Security; the Assistant Secretary, TSA; and interested 
congressional committees as appropriate. We will also make this report 
available at no charge on GAO's Web site at http://www.gao.gov. If you 
or your staff have any questions about this report, please contact me 
at (202) 512-2757 or goldenkoffr@gao.gov. Contact points for our 
Offices of Congressional Relations and Public Affairs may be found on 
the last page of this report. Key contributors to this report are 
listed in enclosure II. 

Signed by: 

Robert Goldenkoff: 
Acting Director, Homeland Security and Justice Issues: 

Enclosures: 

Enclosure I: Scope and Methodology: 

To describe TSA's basis for removing certain scissors and tools from 
the prohibited items list and stakeholder views on the change, we 
obtained and analyzed TSA documentation of the proposed prohibited 
items list change considered by TSA's Explosives Detection Improvement 
Task Force, which was the deliberating body for proposed TSA procedural 
changes that were considered between October 2005 and December 2005. We 
also obtained and analyzed a draft TSA Prohibited Items Working Group 
analysis, as well as TSA public statements and testimonies regarding 
the rationale for the prohibited items change. We also met with TSA 
officials to obtain information on their rationale behind the change. 
In addition, we met with officials at the Federal Aviation 
Administration (FAA) and the Federal Air Marshals Service (FAMS)--a 
component of TSA--to obtain their views regarding the prohibited items 
list change. We spoke with organizations within the aviation community 
including four domestic aviation associations, one international 
aviation association, a major aircraft manufacturer, the largest 
association representing airline pilots in the United States, the 
largest association representing flight attendants in the United 
States, and an association representing federal air marshals and other 
federal law enforcement officers.[Footnote 31] In addition, we met with 
five aviation security experts to obtain their views on TSA's change to 
the prohibited items list.[Footnote 32] We selected these experts based 
on their depth of experience in the field of aviation, employment 
history, and their recognition in the aviation security community. We 
also met with a major aircraft manufacturer to determine whether there 
are any major safety concerns related to the change to the prohibited 
items list. Finally, we incorporated aspects from our recently issued 
report on passenger checkpoint screening procedures,[Footnote 33] which 
included a review of the factors TSA considered in modifying the 
prohibited items list and TSA's analysis supporting the December 2005 
prohibited items list change. 

To determine the impacts, if any, that the removal of certain scissors 
and tools from the prohibited items list had on security and on the 
effectiveness of screening operations, we obtained and reviewed TSA 
documentation and data including the results of threat image projection 
(TIP) testing and data on training hours completed by Transportation 
Security Officers (TSO). We sent written questions about data quality 
control and reporting procedures to TSA officials responsible for 
collecting and analyzing these data, and received responses to these 
questions. The TIP data TSA provided contained limitations. First, the 
data contained only monthly averages for tests in which improvised 
explosive devices (IED) images had been successfully identified by 
TSOs, according to individual airports in each airport category; we did 
not receive the raw numbers of image presentations from which the 
percentages were derived. Therefore, to compute an average percentage 
of successful TIP tests across all airports, we computed an average of 
averages. Computing an average in this manner can provide a result that 
is slightly different than if raw data had been used. For example, we 
could not adjust our computations to account for differing numbers of 
image presentations or the rate of image presentations by airport. 
Second, there were missing values, or no test results, for some 
airports in certain months. Despite these limitations, we believe the 
TIP data were sufficiently reliable to provide an indication of TSOs' 
abilities to identify IED images. In addition, we interviewed Federal 
Security Directors (FSD) from Boston Logan Airport and Washington 
Dulles International Airport to obtain anecdotal information about 
their views on the impact of the prohibited items list change on 
checkpoint screening operations. However, the perspectives of these two 
FSDs cannot be considered to be representative of the views of FSDs 
nationwide or generalized because we did not use random selection or 
representative sampling when determining which FSDs should be 
interviewed. 

To determine whether the change to the list of prohibited items had any 
impact on TSO time spent in training, we also analyzed training data 
provided by TSA on the average number of hours spent in training per 
TSO for the period from October 2004 through February 2007. TSA uses a 
dynamic system to capture training data called the Online Learning 
Center, and TSA offers several reasons for the dynamic nature of this 
system. First, TSA employees and contractors are continuously allowed 
to update training history hours. As a result, data on training hours 
and attendance extracted from the database at two different points in 
time may vary as employees and contractors update their training 
history. Second, there can be a delay in updating training data due to 
manual entry of student results. TSA policy is that final reports are 
generated on the 10TH of each month in order to permit time to collect 
and consolidate airport data for manual data entry. The training hour 
data were sufficiently reliable for our purpose in showing a general 
increase in IED training over time. Our results are based on the data 
TSA provided to us on March 21, 2007. 

To determine if any security incidents onboard an aircraft involving 
the use of small scissors or tools were reported to TSA, we reviewed 
and analyzed TSA security incident reports from the time period 
following the prohibited items list change (December 22, 2005--the 
effective date of the prohibited items list change--through February 
28, 2007). Because TSA is the agency with primary responsibility for 
aviation security and maintains records of aviation security incidents, 
TSA security incident reports were our primary source of information 
for identifying incidents involving small scissors or tools. We 
followed a two-step process to identify incidents appropriate to our 
review. During the first step, one analyst reviewed all incidents in 
each daily TSA security incident report to identify any incidents that 
he or she discerned involved small scissors or tools based on key words 
or phrases in the incident title or description. A log was created for 
each incident report reviewed. In the second step, a random sample of 
10 percent of the incident reports was selected, and these reports and 
their accompanying logs were reviewed by a second analyst to verify the 
accuracy of the first analyst's judgments. We limited the scope of our 
TSA security incident report review to incidents that occurred on 
commercial passenger aircraft in-flight. We defined "in-flight" as the 
time between aircraft take-off and landing. Although it is possible 
that there were some incidents involving small scissors or tools that 
occurred during the time period of our review that were not reported to 
TSA, and thus not recorded in the incident reports, we found the 
incident reports sufficiently reliable for our purposes. 

We conducted our work from November 2006 through March 2007 in 
accordance with generally accepted government auditing standards. 

Enclosure II: GAO Contact and Staff Acknowledgments: 

GAO Contact: 

Robert Goldenkoff (202) 512-2757 or goldenkoffr@gao.gov. 

Staff Acknowledgments: 

Key contributors to this report were Maria Strudwick, Assistant 
Director; David Alexander; Christopher Backley; Amy Bernstein; Tony 
Cheesebrough; Adam Hoffman; Stanley Kostyla; Tom Lombardi; and Brian 
Sklar. 

(440557): 

FOOTNOTES 

[1] See 49 U.S.C. §§ 114(d), 44903(b). 

[2] Sterile areas are located within the terminal where passengers are 
provided access to boarding aircraft. 

[3] 70 Fed. Reg. 72,930 (Dec. 8, 2005). 

[4] See H.R. Conf. Rep. No. 109-699, at 139 (2006) (accompanying H.R. 
5441, enacted into law as the Department of Homeland Security 
Appropriations Act, 2007, Pub. L. No. 109-295, 121 Stat 1355 (2006)). 

[5] The Threat Image Projection system is designed to test TSOs' 
detection capabilities by projecting threat images, including guns, 
knives, and explosives, onto carry-on bags as they are screened during 
actual operations. TSOs are responsible for identifying the threat 
image and calling for the bag to be searched. Once prompted, TIP 
identifies to the TSO whether the threat is real and then records the 
TSO's performance in a database that could be analyzed for performance 
trends. 

[6] FSDs are the ranking authorities responsible for leading and 
coordinating security activities at U.S. commercial airports at which 
TSA provides for or oversees the provision of screening activities. 

[7] GAO, Aviation Security: Risk, Experience, and Customer Concerns 
Drive Changes to Airline Passenger Screening Procedures, but Evaluation 
and Documentation of Proposed Changes Could Be Improved, GAO-07-57SU 
(Washington, D.C.: Mar. 7, 2007). The information in this report is 
considered sensitive security information in accordance with 49 C.F.R. 
part 1520 and is not available to the public. A public version of this 
report (GAO-07-634) is expected to be issued in May 2007. 

[8] Ibid. 

[9] Ibid. 

[10] The results of TSA TIP testing are considered sensitive security 
information and thus could not be included in this report. 

[11] See 49 U.S.C. § 44902; 49 C.F.R. §§ 1540.111, 1544.201(d). 

[12] Access to sterile areas is controlled by TSOs (or by nonfederal 
screeners at airports participating in the Screener Partnership 
Program) at checkpoints where they conduct physical screening of 
individuals and their carry-on baggage for weapons, explosives, and 
other prohibited items. 

[13] TSOs must deny passage beyond the screening location to any 
individual or property that has not been screened or inspected in 
accordance with passenger screening standard operating procedures. If 
an individual refuses to permit inspection of any item, that item must 
not be allowed into the sterile area or onboard an aircraft. 

[14] CAPPS is a computer-assisted system that, based on information 
obtained from airline reservation systems, identifies passengers that 
may pose a high risk to aviation security. These high-risk passengers, 
along with other individuals selected for secondary screening, and 
their carry-on baggage are subject to additional and more thorough 
screening. 

[15] Administered by TSA, the FFDO Program deputizes volunteer pilots 
of commercial passenger aircraft as armed federal law enforcement 
officers for the purpose of defending the flight deck "against acts of 
criminal violence or air piracy." Since the program was officially 
established on February 25, 2003, TSA has deputized thousands of 
eligible flight crew members as FFDOs. 

[16] The Common Strategy is a detailed guidance manual developed by TSA 
and FAA for pilots and other crewmembers to identify their 
responsibilities and the appropriate responses during in-flight 
security threats. In January 2005, TSA and FAA issued a revised version 
of the Common Strategy. The previous version, referred to as Common 
Strategy #1, was the strategy in effect on September 11, 2001. Common 
Strategy #1 was developed jointly by industry, FAA, and FBI, and 
presumed a hijacker whose motive might be ransom, escape from the law, 
political asylum, or publicity. According to the Common Strategy, the 
terrorist attacks of September 11, 2001, demonstrated that Common 
Strategy #1 was not effective in dealing with a new breed of hijacker 
whose motives are terrorism, mass murder, and suicide. 

[17] GAO-07-57SU. 

[18] The change to the prohibited items list was one of several other 
changes to TSA procedures intended to focus more TSA resources on 
higher threats, such as explosives. The Explosive Detection Improvement 
Task Force recommended seven proposed procedures that were ultimately 
implemented by TSA. These procedures were considered by senior TSA 
officials as especially important for enhancing the detection of 
explosives and for deterring terrorists from attempting to carry out an 
attack. According to TSA, some of the proposed procedures, such as the 
prohibited items list change, could also free up TSOs so that they 
could spend more time on procedures for detecting explosives and less 
time on procedures associated with low security risks, such as 
identifying small scissors in carry-on bags. The seven proposed 
procedures tested by the task force reflect both new procedures and 
modifications to existing procedures. The procedures are discussed in 
detail in GAO-07-57SU. 

[19] Nations that are members to ICAO agree to cooperate with other 
member states to meet standardized international aviation security 
measures. ICAO recommends that pointed/edged scissors of any size 
should be prohibited from the flight cabin, while rounded or blunt 
scissors less than 6 cm should be permitted in the flight cabin. The 
TSA Prohibited Items Working Group utilized the ICAO size parameters, 
but applied the parameters to both rounded/blunt scissors as well as 
pointed/edged scissors, thus deviating from the ICAO recommendation to 
ban all pointed/edged scissors. 

[20] TSA's Performance Management Information System is designed to 
collect, analyze, and report passenger and baggage screening 
performance data, such as wait times at selected airports, workload 
data, and the performance and utilization of passenger and baggage 
screening equipment. TSA headquarters uses the Performance Management 
Information System data to support external reporting on performance 
and internal decision-making processes. 

[21] Screening Passengers by Observation Technique involves specially 
trained TSOs observing the behavior of passengers and resolving any 
suspicious behavior through casual conversation with passengers and 
referring suspicious passengers to selectee screening. Unpredictable 
Screening Process entails random selection of passengers across two 
screening lanes to be subjected to a predetermined element of the 
selectee screening process. 

[22] GAO-07-57SU. 

[23] Because TSA is the primary agency responsible for aviation 
security and maintains records of aviation security incidents, TSA 
security incident reports were our primary source of information for 
identifying incidents involving small scissors or tools. These security 
incident reports summarize transportation security incidents-- 
including aviation--that are reported to TSA and include descriptions 
of the incident. We used the December 2005-February 2007 time period 
because it was after the effective date of the prohibited items list 
change. Pursuant to TSA-issued Security Directive 1544-04-15, all 
aircraft operators are required to immediately report all threats that 
could affect the security of commercial aircraft to TSA. 

[24] The Federal Aviation Administration has primary responsibility for 
ensuring the safety of civil aviation operations, including the 
operation of air traffic control and regulating the manufacture, 
operation, and maintenance of aircraft. See 49 U.S.C. § 44701. 

[25] The results of the informal follow-on studies, which were 
conducted at 6 to 9 airports, show that the percentage of carry-on bags 
searched increased by about 0.1 percentage point at the time of the 30- 
day study, then decreased by 2.3 and 0.7 percentage points at the time 
of the 60-day and 90-day studies, respectively. However, the results of 
these informal studies may not be reliable due to the limitations in 
the methodology TSA used to conduct the studies. Specifically, TSA did 
not use a methodology that would control for factors other than the 
prohibited items list change that may influence the percentage of carry-
on bags searched by TSOs. To do this, TSA would have had to develop a 
formal, systematic methodology for randomly selecting various times of 
day, location of checkpoints, number of checkpoints, and so on for data 
collection. By not controlling for such factors, TSA may not know the 
extent to which a reduction in the percentage of carry-on bags searched 
is due to the prohibited items list changes. See GAO-07-57SU. 

[26] See GAO-07-57SU. An additional measure intended to free up TSO 
resources involved changes to CAPPS rules to reduce the number of 
passengers selected for secondary screening. TSA's assumption is that 
these changes could allow TSOs who were normally assigned to selectee 
screening duties to be reassigned to new procedures, which may require 
new screening positions. 

[27] Since we did not use random selection or representative sampling 
when determining which FSDs should be interviewed, the interview 
results cannot be generalized. 

[28] Of the remaining 6 FSDs, 5 said that TSO resources were freed up 
as a result of the prohibited items list and CAPPS rules changes, and 1 
was uncertain whether TSO resources were actually freed up. 

[29] TSA classifies the over 400 commercial airports in the United 
States into one of five categories--X, I, II, III, and IV. Generally, 
category X airports have the largest number of passenger boardings and 
category IV airports have the smallest number. 

[30] The views of the two FSDs we interviewed may not be representative 
of the views of the population of FSDs. 

[31] Specifically, we met with the Air Transport Association (ATA), the 
National Air Carrier Association (NACA), the Regional Airline 
Association (RAA), the Air Carrier Association of America (ACAA), the 
International Air Transport Association (IATA), the Air Line Pilots 
Association (ALPA), the Association of Flight Attendants (AFA), and the 
Federal Law Enforcement Officers Association (FLEOA). 

[32] The views of these five experts may not necessarily represent the 
general view of other experts in the field of aviation security. 

[33] GAO-07-57SU. 

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