This study deals with issues that could arise, should the Federal Aviation Administration (FAA) mandate the implementation in airports of new passenger screening technologies that are currently available or are being developed. The objectives of this study were (1) to review all potential automated instrumental methods currently under FAA consideration for passenger screening, (2) to assess aspects of each method that could cause concerns over health risks (e.g., exposure to radiation), privacy, and traveler comfort, in light of current and anticipated health regulations, privacy laws, and public concerns, (3) to consider ways to maintain effectiveness while increasing public acceptance and minimizing health risks, (4) to determine key factors that could affect airport implementation and suggest mitigating strategies, (5) to suggest alternate screening methods for passengers who wish to avoid the automated system, and (6) assess mechanisms for clearing alarms.
Ensuring the safety of the U.S. air travel system and of American and foreign air carriers traveling to and from the United States is a monumental task. Currently, in the United States this involves screening more than 1.5 million passengers and their carry-on baggage every day for the presence of metallic weapons and other dangerous materials. To address current security requirements, the FAA is examining new technologies designed to enhance the effectiveness of existing screening procedures. At the same time, the FAA is investigating other technologies that would enable existing systems, which, at present, can detect only metallic weapons, to detect other types of dangerous objects and substances (e.g., plastic explosives). These improvements are necessary as preparation for anticipated changes in security requirements.
An ideal passenger screening technology would be capable of detecting both metallic and nonmetallic threat items in less than six seconds, with a high degree of accuracy (including a high detection rate with a low false-alarm rate). In addition, an ideal system would give the operator enough information in an appropriate format to allow for the speedy and accurate resolution of alarms.
Current passenger security-screening requirements were developed in response to an increase in hijackings prior to 1972. Passenger screening procedures in place today focus on finding passengers carrying metallic weapons that might be used to intimidate the crew into changing the destination of an aircraft. However, because of increasing international political unrest and the attractiveness of U.S. aircraft as terrorists targets, the FAA has recognized the need to improve the capabilities of existing airport security screening systems and processes. These improvements include (1) enhancing the ability of metal-detection portals to operate effectively in an electrically noisy environment, (2) providing better information to security screening personnel on the type and location of potential weapons on individuals who trigger metal-detection portal alarms, and (3) increasing the detection capabilities of existing systems by adding the ability to detect a broader spectrum of metals and alloys, plastic explosives, and other threat materials.
Trace-detection technologies, which detect the presence of explosive materials by reacting to their vapors or particles, can be used to supplement existing metal-detection technologies to build more comprehensive security systems. Metal detection portal systems can be replaced by technologies that can produce images that reveal objects concealed under layers of clothing and that enable security personnel to identify both metallic and nonmetallic threat objects.
These potential improvements to current screening technologies, as well as new technologies that meet anticipated future screening requirements, have technical features that strengthen their detection capabilities. However, the acceptance or rejection of a technology both by the people required to use it (e.g., airport operators and air carriers) and by the people affected by it (e.g., passengers and crews) is just as important as the performance and effectiveness of the technology. Air carriers will resist the implementation of a detection technology (no matter how perfect), if it is unacceptable to the traveling public. Thus, a technology could fail for largely nontechnical reasons. The panel identified the following nontechnical issues of potential public concern in relation to new passenger screening technologies:
· Health. Will the technology harm or injure people? Will people perceive the technology as dangerous?
· Legal. (other than health-related lawsuits, subsumed in ''Health" above). Do certain aspects of the technology violate the rights of individuals under the Fourth Amendment to the Constitution of the United States, which guarantees against unreasonable search and seizure? Does it violate the legal right to privacy? Will people perceive either of these possibilities to be true?
· Operational. Will the technology require additional space in airport terminals? Will air carriers be able to screen passengers accurately and rapidly enough to maintain flight schedules?
· Privacy. Even if not a legally cognizable invasion of privacy, will the technology make people feel as though their privacy is being invaded? Will the screening process reveal personal information that passengers would rather keep to themselves?
· Convenience. Will passengers be able to proceed quickly through the system and to their gates? Will the new technology take more time to screen passengers than current procedures?
To examine these issues, the panel conducted three information-gathering meetings, including a workshop on new technologies for passenger screening. The workshop was attended by representatives of air carriers, airport operators, specialists in aviation security screening systems in other countries, and individuals interested in the legal aspects of passenger screening. With input from this wide variety of sources, panel members were able to address the five nontechnical issues listed above, along with other questions that emerged in the course of the study.
The major conclusions of the panel are as follows:
· The level of discomfort, inconvenience, cost, and personal intrusion air carriers and travelers are willing to tolerate is strongly influenced by their perceptions of the severity of the threat, the urgency of the situation, and the effectiveness of the efforts to deter the threat.
· Even without adding more advanced screening equipment, current screening systems and procedures can be improved significantly by placing greater emphasis on human factors.
The panel makes the following general recommendations to aid the FAA for determining which new technologies are appropriate for passenger screening:
· Emphasize the link between the invasiveness and inconvenience of the screening technology and the threat being addressed in a strategy for implementing new passenger screening technologies.
· Emphasize programs that improve the effectiveness of the operator as a part the security system.
LINKS BETWEEN PASSENGER INCONVENIENCE AND LEVEL OF THREAT
The panel determined that air carriers and the traveling public relate the extent of passenger screening they consider acceptable and adequate to the severity of the threat they believe is being averted by the screening process. For example, air carriers and passengers accept the more intensive security procedures used for international flights because they perceive a higher likelihood of terrorists targeting international flights. Passengers would probably resent the application of similarly tight security measures to domestic flights, unless authorities could prove that the level of threat was higher than usual. The temporary intensification of security screening procedures, such as the procedures instituted in response to threats to air travel security at New York airports, appear to have been received by air carriers and the traveling public with little clamor.
Because of the strong relationship between public acceptance and the perception of risk, the panel believes the FAA should make this link explicit in a strategy for implementing new passenger screening technologies. Because it is impossible to predict the course that terrorism will take in the coming years, the FAA plan should include relating specific technologies to specific threats. As threat scenarios shift with changing national and international climates, this information would make it possible for the FAA to implement technologies quickly in response to specific threats. The FAA plan should also include information on how new technologies will be implemented over time in the absence of specific threats against U.S. air carriers or airports.
By immediately addressing the link between the perceived level of threat and the acceptance of more intrusive security screening processes, the FAA will help air carriers react more quickly to specific threats. Air carriers will also be able to plan for the purchase of equipment based on new technologies as part of their routine efforts to upgrade security screening equipment.
ASSESSMENT OF PUBLIC ACCEPTANCE
The panel can formulate some general conclusions and recommendations about new technologies for passenger screening. However, further steps must be taken to assess public acceptance and to incorporate information from these assessments into screening procedures for each technology under investigation to ensure that it is suitable for use in passenger screening. Assessing public attitudes is also important because, as the panel workshop clearly revealed, limited data are available on public opinion even regarding the implementation of current screening technologies. Because the successful implementation of a new screening technology will be influenced by the public attitude, data on public
opinion must be obtained for all proposed screening technologies. Identifying possible blocks to implementation early in the development process will cost less than retrofitting a fully developed system to address particular concerns.
Assessing the potential for public acceptance of a new screening system or procedure is a complex problem for two main reasons. First, it is more difficult to determine public reaction to an abstract, proposed system than to a real, here-and-now piece of equipment. Therefore, it will be important for the FAA to assess public reaction to new screening systems and procedures while the systems are still being developed and when prototypes are available for demonstration. Second, the previously discussed link between the level of threat and the acceptability of more intrusive screening procedures must be taken into account. The results of surveys or other measures of potential public acceptance will be affected by the prevailing level of threat. A carefully designed survey may be able to account for the influence of perceived threat.
Insight can be gained from studies of public reactions to, and acceptance of, current metal detectors and baggage screening systems when they were first introduced. More recently, imaging systems were introduced in correctional institutions to screen individuals entering the facility by producing images of their bodies beneath their clothes. Experience with these systems can provide insight on public reactions to, and acceptance of, this type of passenger-system interface.
Finally, armed with information about public reactions to specific screening technologies, a public education campaign to address specific concerns can be formulated to improve acceptance of a new technology. Information about specific technologies must be presented in a way that is understandable to a variety of audiences. Analogies to other common or familiar experiences are often effective.
A major problem with current passenger screening technologies and procedures is that they do not provide the operator with specific information about the nature and location of potential threat items. New technologies designed to assist operators to locate and identify objects identified by the equipment as potential threats should address the following concerns:
· Convenience. Passengers will experience less delay if operators can quickly determine whether or not the item that triggered the alarm is a threat.
· Privacy. Operators will be less likely to encounter external medical devices or other nonthreat objects that passengers consider personal, if the equipment is designed to identify the location of the item that triggered the alarm.
· Legal. Information about nonthreat items will be minimized by limiting the search area. This will also lessen the need for a policy on discovery of illegal, but nonthreat, items.1
Improvements to Current Technologies
Improvements to current metal-detection technologies are not likely to be apparent to the traveling public or to operators of the screening equipment. However, screening systems that will improve the ability of the operator to identify threat objects quickly and accurately could address concerns identified above. The panel did not identify other concerns related to improvements in metal-detection technology.
Technologies to Address Future Passenger Screening Requirements
The trade-off between technology performance and public acceptance is an issue for all technological improvements in airport security screening. Any changes to the now-familiar metal-detection portals will cause concerns over health effects, the invasion of privacy, and passenger convenience.
Imaging technologies can see through clothes and produce an image of the human body underneath. The images vary in the amount of detail they present, depending on the technology, but none is of photographic quality. Operators then view and interpret these images. Concerns about improving operator effectiveness for current screening systems, discussed below, may apply to using imaging technologies as well.
Imaging technologies can be classified as either passive or active. In passive screening, the natural radiation emitted by the human body is detected and analyzed. This procedure minimizes concerns about radiation. Active imaging entails irradiating the body with x-rays or millimeter waves and analyzing the radiation scattered from the body. In both imaging procedures, objects (e.g., metallic weapons or explosive materials) that emit or scatter radiation differently from the human body will appear different from the background on the image. At the current level of development of imaging technologies, images must be viewed and interpreted by an operator. Many of the concerns discussed below would be
1 Current legal interpretation holds that the screening of passengers and others as they enter an airport or concourse is allowable only when the search is performed to identify items that are a threat to aviation security. Air carriers are not authorized to search for other illegal or suspicious items, such as drugs or large amounts of cash, that do not endanger the aircraft.
mitigated by the development of effective, automated image-interpretation capabilities that would eliminate the operator from the routine screening process.
The panel concluded that the images produced by these technologies are of sufficiently high quality to make them effective for screening passengers. However, when the perceived level of threat is low, passengers, crews, and others passing through screening checkpoints are likely to object to having images of their bodies displayed. There are also likely to be concerns about the use and storage of the data used to generate images. Procedures, such as having operators of the same sex view the images or moving operators away from the screening checkpoints, could allay concerns. However, for financial and logistical reasons, these procedures are likely to make imaging technologies extremely unattractive for use as primary screening systems at all checkpoints. Quantifying the level of threat at which people are likely to accept this kind of invasion of privacy is difficult but necessary prior to mandating the use of any imaging technology for screening passengers at airports.
Because active imaging technologies use the detection of various forms of radiation to create the images, there are also likely to be concerns about health effects. The panel concluded that the levels of radiation exposure required for image production are insignificant compared to the levels experienced during many other common activities, including airplane flights. Therefore, health concerns associated with imaging technologies have more to do with the perception among certain segments of the population, such as frequent travelers or pregnant women, that these radiation levels are harmful. These perceptions can be addressed by a public education campaign and by offering equally effective alternative screening procedures for those who do not want to be irradiated.
Trace-detection technologies physically collect samples of air or material from clothing or bodies of individuals and use the samples to infer the presence of dangerous materials. Sample collection can entail sampling the air around individuals or touching them to remove particles of explosive materials from them or their belongings. Chemical compounds of interest can be identified using many techniques. The specifics of the chemical-identification technologies are less likely to cause passenger concern than the sample collection techniques.
Unlike imaging technologies, where the technologies themselves are mature and the equipment is commercially available, trace-detection technologies are still in the development phase, especially with regard to methods of sample collection and matching appropriate sampling techniques with chemical-identification technologies. Therefore, it is more difficult for the panel to comment on specific passenger screening scenarios involving trace-detection technologies.
However, sample collection for trace-detection technologies must entail the physical transfer of material from the person being screened to the screening equipment. Sampling the air around a person is less intrusive, but likely to be less effective, than touching the person to collect a sample. For technologies that require touching, one concern is people's aversion to being touched either by inanimate objects, such as bars or fronds, or by operators wielding hand-wand devices. This concern is difficult to address because the desire to preserve distance from strangers is deeply ingrained and is often influenced by basic cultural and religious beliefs. The optimum distance people maintain between themselves and others varies greatly from person to person and from culture to culture, and it is not likely to be changed by public information campaigns. Concerns about privacy, about initiating physical contact, and the transmission of disease may prove to be significant hurdles to implementing new technologies.
Trace-detection technologies are also being considered for use in screening hand-carried baggage and personal electronic devices. Objections to touching these items are likely to be less intense than objections to touching people themselves. Collecting samples from areas that a person is likely to have touched may be an effective way of transporting material from that person to the screening equipment. Collecting samples from boarding cards may be a practical way of implementing trace-detection technologies in passenger screening.
ROLE OF OPERATORS IN PASSENGER SCREENING
The panel determined that the involvement of security personnel and the quality of their performance are critical elements in the successful implementation of a security system. Operators are responsible for the decision-making component of the security system. The sound analytical capability of operators is a major requirement for accurately determining the potential danger to the aircraft.
The FAA Human Factors Program has begun to formulate objective criteria for selecting, training, and motivating screening personnel. It is frequently assumed that poor performance of current security systems can be attributed to the low wages paid to operators. It is further assumed that higher wages would attract better personnel and result in significant improvements in performance. However, the panel members believe that other more powerful reasons are to blame for the less-than-desirable operator performance reported by the FAA (Fobes, 1995). At best, higher wages may mean less turnover among operators (a severe problem in itself), providing opportunities to apply better selection, training, and motivational methods.
Competent operator performance in new passenger screening systems will depend on the combined effect of programs
dealing with operator ergonomics, selection, training, and motivation. Techniques for measuring operator performance are critical to the success of a program for assessing prototype systems, validating operator selection methods, evaluating new training techniques, monitoring and analyzing the on-line effectiveness of security-screening systems and personnel, and providing feedback to individual operators.
The allocation of functions between machine and operator is likely to have a significant influence on the effectiveness of future systems. In an apparent paradox, as screening systems become more automated, operator performance is likely to become even more important to the successful implementation of these systems. Operators will be performing more difficult and complex tasks that defy automation, and increased automation will introduce a host of new human performance issues. In developing new screening technologies, it would be more practical to integrate the proper allocation of functions into the technology development cycle itself, rather than to address the integration of the human operator into the system after the equipment has been designed and tested.
To aid air carriers and screening companies in selecting, training, and motivating passenger screening personnel and to provide direction on the use of ergonomics in designing security-screening equipment, the panel recommends that the FAA accelerate its program in human factors. The program can assist in developing effective measurements of operator performance, determining the optimal allocation of functions in new systems during development, and integrating research on operator ergonomics, selection, training, and motivation into the explosives-detection program. Successful implementation of any passenger screening system, based on current technologies or on a proposed new technology, requires the effective integration of human operators into the overall security system.