After the terrorist attacks of September 11, 2001, the President signed the Aviation and Transportation Security Act (ATSA) into law on November 19, 2001, with the primary goal of strengthening the security of the nation’s civil aviation system. ATSA created TSA as the agency with responsibility for securing all modes of transportation, including civil aviation. As part of this responsibility, TSA performs or oversees the performance of security operations at the nation’s nearly 440 commercial (i.e., TSA-regulated) airports, including passenger and checked baggage screening operations. FSDs are TSA officials responsible for overseeing TSA security activities, including passenger and checked baggage screening, at one or more commercial airports. TSA classifies commercial airports in the United States into one of five security risk categories (X, I, II, III, and IV) based on various factors, such as the total number of takeoffs and landings annually, and other special security considerations. In general, category X airports have the largest number of passenger boardings and category IV airports have the smallest. TSA periodically reviews airports in each category and, if appropriate, updates airport categorizations to reflect current operations. Figure 1 shows the number of commercial airports by airport security category as of July 2015. TSA uses a multilayered security strategy aimed to enhance aviation security. Within those layers of security, TSA’s airport passenger checkpoint screening system includes, among other things, (1) screening personnel (i.e., TSOs); (2) SOPs that guide screening processes conducted by TSOs; and (3) technology, such as advanced imaging technology systems (often referred to as body scanners) or walk-through metal detectors, used to conduct screening of passengers. To carry out passenger and checked baggage screening operations, TSA employs TSOs at the vast majority of the nation’s commercial airports. There are several levels of screening officers deployed at the passenger checkpoint: Transportation Security Officer (TSO): Performs the majority of security functions to screen people and property to mitigate threats. Screening may include pat downs, search of property, and operating technology including walk-through metal detectors, X-ray machines, and explosives detection equipment, among other things. Lead Transportation Security Officer (LTSO): Leads a staff of TSOs, including distributing and adjusting workload and tasks among employees and oversees the security screening team on a daily basis. Implements security procedures and provides coaching and guidance to TSOs in performing screening duties, among other things. LTSOs also perform screening functions along with added responsibilities, such as resolving alarms and supervising screening locations when a supervisor is not available. Supervisory Transportation Security Officer (STSO): Oversees screening checkpoints and/or baggage screening, supervises LTSOs and TSOs in performance of security screening and ensures all required screening is performed in accordance with SOPs. Reviews and evaluates work and performance of LTSOs and TSOs, approves leave, and recommends corrective or disciplinary actions, among other things. STSOs also perform screening functions and resolve passenger alarms. Transportation Security Manager (TSM): Coordinates and facilitates TSA security activities and manage one or more programs as assigned by the Federal Security Director. A TSM assigned to oversee screening checkpoints manages security activities, including recognizing and correcting improper use or application of equipment or screening procedures, monitors screening operations, and implements changes to enhance security and efficiency at screening locations. TSOs inspect individuals and property as part of the passenger screening process to deter and prevent the carriage of any unauthorized explosive, incendiary, weapon, or other prohibited items on board an aircraft or into the airport sterile area—in general, an area of an airport that provides passengers access to boarding aircraft and to which access is controlled through the screening of persons and property. Ordinarily, screening of accessible property at the screening checkpoint begins when an individual places accessible property on the x-ray conveyor belt or hands accessible property to TSA personnel. As shown in figure 2, TSOs then review images of the property running through the X-ray machine and look for signs of prohibited items. The passengers themselves are typically screened via a walk-through metal detector or an advanced imaging technology machine, and passengers generally have the option to request screening by a pat down if they do not wish to be screened by these technologies. Passengers will also be subject to a pat down if they are screened by the walk-through metal detector or advanced imaging technology system and the equipment alarms (in order to resolve the alarm). TSOs also inspect checked baggage to deter, detect, and prevent the carriage of any unauthorized explosive, incendiary, or weapon onboard an aircraft. Figure 3 shows the general process used to screen checked bags. Checked baggage screening is accomplished through the use of explosives detection systems or explosives trace detection systems, and through the use of alternative means, such as manual searches and canine teams when the explosives detection systems are unavailable. In accordance with ATSA, screeners must complete a minimum of 40 hours of classroom instruction, 60 hours of on-the-job training, and successfully complete an on-the-job training examination before they are certified as security screeners. Screeners can be certified to conduct passenger screening or checked baggage screening, or they may be certified as dual function and can then conduct passenger and checked baggage screening. ATSA also requires that TSA provide operational testing of screening personnel, and any individual who fails an operational test must successfully complete remedial training on that specified security function before returning to duty. In addition, screeners must also undergo an annual proficiency review to ensure they continue to meet all qualifications and standards required to perform a screening function. TSA also requires remedial training for TSOs who fail an annual proficiency review. Covert tests recently conducted by the DHS-OIG highlighted areas of concern for TSA regarding the effectiveness of the passenger screening process. Specifically, the DHS-OIG conducted covert testing to determine the effectiveness of TSA’s Advanced Imaging Technology screening equipment, its related automated target recognition software, and checkpoint screener performance in identifying and resolving potential security threats at airport checkpoints. TSA has responded to the DHS Secretary’s direction regarding the results of the DHS-OIG covert testing, in part, by updating its screening SOPs and retraining TSOs to address the Inspector General’s findings. Also in response to the DHS-OIG findings, TSA has developed new measures of effectiveness that it expects will better emphasize the agency’s goals for improving security effectiveness by focusing the measures on both the screening system and workforce in the areas of readiness and performance. For example, improved workforce measures, now being reported monthly, include those to track TSOs’ progress against training requirements, absences due to injuries or other reasons, and whether they are meeting performance thresholds on various tests of performance and job proficiency. TSO training is comprised of a compendium of courses that includes basic training for initial hires, recurrent training, remedial training, and return-to-duty training. For example, all new hires receive a combination of classroom, hands-on, and web-based training. After TSOs finish their initial new hire training, they receive recurrent and specialized training courses throughout the year that are provided either via classroom instruction or through the TSA Online Learning Center. Recurrent training typically focuses on core screening skills and policies such as X-ray image interpretation, detection techniques, and screening SOPs. TSOs receive remedial training when they have failed an operational or certification test, or if a supervisor identifies a need for further training, among other things. Further, according to TSA, TSOs who are absent from their screening duties for a period of time must undergo some level of “return-to-duty” training based on the amount of time they were absent. For example, TSOs certified in a screening function but who have not performed that function for a period of 15 consecutive days or more are required to complete a return-to-duty training program before being allowed to perform that function independently. Table 1 describes the various types of training TSOs receive. The Office of Training and Development (OTD), within TSA headquarters, oversees the development, delivery, and evaluation of training programs for TSA employees. The National Training Plan (NTP), developed jointly by OTD and the Office of Security Operations, contains the core curriculum for TSOs to meet their annual training, including the classes and hours required for TSOs to complete for the year. TSA headquarters officials implement the NTP to provide ongoing training throughout the year aimed at continually improving screeners’ knowledge, skills, and abilities. However, the responsibility for managing the individual training of TSOs is largely decentralized and it primarily falls on Security Training Instructors at individual airports to train TSOs on parts of the NTP by certain dates throughout the year. Managers in the field track the percentage of the NTP curriculum that TSOs have completed on a monthly basis using the Online Learning Center database. In addition, TSA officials at all 10 airports we contacted stated that they monitor various testing results for their TSOs and observe screening operations at their airports’ checkpoints, to determine any local, specialized training needs their screening force may need—over and above that included in the NTP issued by TSA headquarters. TSA headquarters can also add training requirements throughout the year as needed, such as the recently completed “Mission Essentials—Threat Mitigation” training discussed later. TSA officials we spoke with at airports noted challenges associated with completing not only the required training under the NTP, but also training associated with frequent changes to the screening SOPs for how particular screening practices are to be conducted at the checkpoint.