Measuring and maintaining performance in x-ray baggage inspection at security checkpoints: methodological and practical considerations

Inspecting X-ray images of passenger baggage for prohibited items at security checkpoints is crucial to ensuring aviation security. To prevent performance declines during inspection, the EU allows screeners to perform this task for only 20 min, although little is known about how this performance actually evolves over time. For many airports, longer screening durations would be practical, and this raises the question of the ideal screening duration in terms of both performance and screener well-being. To measure screeners’ performance, airports typically implement threat image projection (TIP). TIP projects fictional threat items (FTIs) onto the X-ray images of passenger baggage; and by recording the screeners’ decisions, it allows measurement of their detection rate. To draw meaningful conclusions from these data, it is essential for them to be reliable and valid.However, their reliability and validity are still poorly researched and not confirmed. This thesis addresses the question of how time on task affects performance in X-ray image inspection of cabin baggage, and it asks whether TIP performance data collected at airports provide a reliable and valid measure of operational threat detection. Manuscript 1 investigated how performance evolves with time on task in two groups of screeners who performed a 1-hr X-ray image inspection task in the laboratory. One group took 10-min breaks every 20 min; the other group screened continuously without breaks. To assess the validity of measurements of detection performance, we varied target prevalence. Results confirmed the typical target prevalence effect and showed that da is a valid measure of detection performance for X-ray images inspection. Manuscript 1 provides evidence that screeners were able to maintain performance for a full hour, and that breaks had no effect on performance. However, time on task caused a shift in response tendency and might cause more distress. In Manuscript 2, we investigated the effects of time on task on performance under real working conditions by analyzing performance data from a 4-month field study. A group of screeners at a European airport were asked to analyze X-ray images from a remote screening room for up to 60 min. Only when task load was high (number of images analyzed per min), did the screeners' hit rate decrease with time on task. The efficiency, in terms of the reject rate and processing time, increased with time on task. Screeners who conducted longer screening durations did not report more distress. Yet, there were marked individual differences in performance, in performed screening durations, and in preferred screening durations. In Manuscript 3, we examined the reliability and validity of TIP performance by analyzing a large data set from a European airport. We showed that TIP data can be a reliable and valid measure of operational threat detection, and that around 100 TIP events per screener should be considered to attain minimum reliability values of 0.7. The manuscript further provides recommendations on how to increase the reliability of TIP data.Taken together, these findings show that TIP data, which are in frequent use, can provide a reliable and valid measure of operational threat detection and that screeners can maintain performance for more than 20 min. Manuscripts 1 and 2 provide evidence that time on task in X-ray image inspection leads to a shift in response tendency rather than a decline in sensitivity. Based on performance and survey results, screening sessions could be designed more flexibly and an extension to 30–40 min could be considered. The manuscripts provide meaningful theoretical insights into performance in X-ray image inspection, especially with regard to the effect of time on task. They further provide methodological and practical contributions on appropriate detection performance measures, on how to measure performance reliably and validly, and on the design of screening durations

Human factors in X-ray image inspection of passenger Baggage – Basic and applied perspectives

The X-ray image inspection of passenger baggage contributes substantially to aviation security and is best understood as a search and decision task: Trained security officers – so called screeners – search the images for threats among many harmless everyday objects, but the recognition of objects in X-ray images and therefore the decision between threats and harmless objects can be difficult. Because performance in this task depends on often difficult recognition, it is not clear to what extent basic research on visual search can be generalized to X-ray image inspection. Manuscript 1 of this thesis investigated whether X-ray image inspection and a traditional visual search task depend on the same visual-cognitive abilities. The results indicate that traditional visual search tasks and X-ray image inspection depend on different aspects of common visual-cognitive abilities. Another gap between basic research on visual search and applied research on X-ray image inspection is that the former is typically conducted with students and the latter with professional screeners. Therefore, these two populations were compared, revealing that professionals performed better in X-ray image inspection, but not the visual search task. However, there was no difference between students and professionals regarding the importance of the visual-cognitive abilities for either task. Because there is some freedom in the decision whether a suspicious object should be declared as a threat or as harmless, the results of X-ray image inspection in terms of hit and false alarm rate depend on the screeners’ response tendency. Manuscript 2 evaluated whether three commonly used detection measures – ${d}'$, ${A}'$, and ${d}_{a}$ – are a valid representation of detection performance that is independent from response tendency. The results were consistently in favor of da with a slope parameter of around 0.6. In Manuscript 3 it was further shown that screeners can change their response tendency to increase the detection of novel threats. Also, screeners with a high ability to recognize everyday objects detected more novel threats when their response tendency was manipulated. The thesis further addressed changes that screeners face due to technological developments. Manuscript 4 showed that screeners can inspect X-ray images for one hour straight without a decrease in performance under conditions of remote cabin baggage screening, which means that X-ray image inspection is performed in a quiet room remote from the checkpoint. These screeners did not show a lower performance, but reported more distress, compared to screeners who took a 10 min break after every 20 min of screening. Manuscript 5 evaluated detection systems for cabin baggage screening (EDSCB). EDSCB only increased the detection of improvised explosive devices (IEDs) for inexperienced screeners if alarms by the EDSCB were indicated on the image and the screeners had to decide whether a threat was present or not. The detection of mere explosives, which lack the triggering device of IEDs, was only increased if the screeners could not decide against an alarm by the EDSCB. Manuscript 6 used discrete event simulation to evaluate how EDSCB impacts the throughput of passenger baggage screening. Throughput decreased with increasing false alarm rate of the EDSCB. However, fast alarm resolution processes and screeners with a low false alarm rate increased throughput. Taken together, the present findings contribute to understanding X-ray image inspection as a task with a search and decision component. The findings provide insights into basic aspects like the required visual-cognitive abilities and valid measures of detection performance, but also into applied research questions like for how long X-ray image inspection can be performed and how automation can assist with the detection of explosives

Sleep loss and fatigue among commercial airline pilots

Today’s flight operations work on a pressurised 24/7 timetable as a result of the unrelenting escalation in international long-haul, short-haul, regional and overnight flights within commercial aviation. Air traffic around the world has doubled every 10 years for the last 30 years. Whilst there have been considerable advancements in aviation technology and operational demands, the human operators need for sleep remains. Commercial airline pilots are presently highly suspectible to sleep loss and fatigue due to these demanding, round-the- clock requirements. Whilst flight and duty time limitation regulations are in place to prevent pilot fatigue, they are not based on sound scientific evidence regarding their ability to do so. Furthermore, various European-based investigations have reported very high levels of sleep disruption and fatigue in European cockpits. Therefore, this study aimed to examine the influence of sleep deprivation and associated fatigue on incidents in flight and mental health and to investigate its effects on performance in commercial airline pilots. Firstly, this research found a critical pathway from duty hours through to self-reported incidents in flight with sleep disruption and feelings of fatigue in the cockpit found to be key factors contributing to this pathway (Study 1). This research also found very high incidences of self-reported sleep disturbance, feelings of fatigue in the cockpit, and consequential errors and incidents in flight as a result of fatigue. Further to this, self-reported sleep disruption and feelings of fatigue were also found to significantly influence pilots’ self-reported perceived depression or anxiety with those who reported higher incidences of sleep disturbance and fatigue being more likely to report feeling depressed or anxious (Study 2). Additionally, 24 hours’ sleep deprivation and subsequent fatigue was found to significantly impair mood and airline pilot core competencies, specifically cognitive flexibility, hand-eye coordination, multi-tasking ability, sustained attention, problem-solving, situation awareness and perceived workload with significant impairments becoming evident following 20 hours of continuous wakefulness (Study 3 & 4). Flying performance was not significantly impaired. Sleep disruption and fatigue is a highly serious and prevalent problem in European cockpits. It negatively impacts flight safety and pilot mental health and well-being. Further investigation in to the current flight and duty time limitation regulations as well as in to potential measures which could act as early detection and warning indicators of declining performance, as a result of sleep loss and fatigue, would enhance flight safety and promote pilot mental health and well-being

Standardization Roadmap for Unmanned Aircraft Systems, Version 2.0

This Standardization Roadmap for Unmanned Aircraft Systems, Version 2.0 (“roadmap”) is an update to version 1.0 of this document published in December 2018. It identifies existing standards and standards in development, assesses gaps, and makes recommendations for priority areas where there is a perceived need for additional standardization and/or pre-standardization R&D. The roadmap has examined 78 issue areas, identified a total of 71 open gaps and corresponding recommendations across the topical areas of airworthiness; flight operations (both general concerns and application-specific ones including critical infrastructure inspections, commercial services, and public safety operations); and personnel training, qualifications, and certification. Of that total, 47 gaps/recommendations have been identified as high priority, 21 as medium priority, and 3 as low priority. A “gap” means no published standard or specification exists that covers the particular issue in question. In 53 cases, additional R&D is needed. As with the earlier version of this document, the hope is that the roadmap will be broadly adopted by the standards community and that it will facilitate a more coherent and coordinated approach to the future development of standards for UAS. To that end, it is envisioned that the roadmap will continue to be promoted in the coming year. It is also envisioned that a mechanism may be established to assess progress on its implementation

A Risk-Based Optimization Framework for Security Systems Upgrades at Airports

Airports are fast-growing dynamic infrastructure assets. For example, the Canadian airport industry is growing by 5% annually and generates about $8 billion yearly. Since the 9/11 tragedy, airport security has been of paramount importance both in Canada and worldwide. Consequently, in 2002, in the wake of the attacks, the International Civil Aviation Organization (ICAO) put into force revised aviation security standards and recommended practices, and began a Universal Security Audit Program (USAP), in order to insure the worldwide safeguarding of civil aviation in general, and of airports in particular, against unlawful interference. To improve aviation security at both the national level and for individual airport, airport authorities in North America have initiated extensive programs to help quantify, detect, deter, and mitigate security risk. At the research level, a number of studies have examined scenarios involving threats to airports, the factors that contribute to airport vulnerability, and decision support systems for security management. However, more work is still required in the area of developing decision support tools that can assist airport officials in meeting the challenges associated with decision about upgrades; determining the status of their security systems and efficiently allocating financial resources to improve them to the level required. To help airport authorities make cost-effective decisions about airport security upgrades, this research has developed a risk-based optimization framework. The framework assists airport officials in quantitatively assessing the status of threats to their airports, the vulnerability to their security systems, and the consequences of security breaches. A key element of this framework is a new quantitative security metric ; the aim of which is to assist airport authorities self-assess the condition of their security systems, and to produce security risk indices that decision makers can use as prioritizing criteria and constraints when meeting decisions about security upgrades. These indices have been utilized to formulate an automated decision support system for upgrading security systems in airports. Because they represent one of the most important security systems in an airport, the research focuses on passenger and cabin baggage screening systems. Based on an analysis of the related threats, vulnerabilities and consequences throughout the flow of passengers, cabin baggage, and checked-in luggage, the proposed framework incorporates an optimization model for determining the most cost-effective countermeasures that can minimize security risks. For this purpose, the framework first calculates the level of possible improvement in security using a new risk metric. Among the important features of the framework is the fact that it allows airport officials to perform multiple “what-if” scenarios, to consider the limitations of security upgrade budgets, and to incorporate airport-specific requirements. Based on the received positive feedback from two actual airports, the framework can be extended to include other facets of security in airports, and to form a comprehensive asset management system for upgrading security at both single and multiple airports. From a broader perspective, this research contributes to the improvement of security in a major transportation sector that has an enormous impact on economic growth and on the welfare of regional, national and international societies

To investigate the feasibility of predicting, identifying and mitigating latent system failures in a UK NHS paediatric hospital

The aim of this study was to investigate the feasibility of identifying latent system failures in a paediatric National Health Service hospital in the England (NHS). Medicine related errors affect up to 9% of all patients in NHS hospitals. The theoretical basis included error causation theory, the functioning of short-term memory and how the brain manages multiple stimuli. The literature review covered error causation and prevention research, undertaken in healthcare settings and other high-risk industries. The study environment was the dispensary of Birmingham Children’s Hospital (BCH) and a busy ward. The study instrument was non-participant, direct observation of routine dispensing and medicines administration tasks. The first phase identified latent risks in a specific readily observable task set in a specialist paediatric hospital pharmacy department. Having identified a major latent risk, interruption, the investigation then established the significance that interruptions had on operatives. The second phase investigated the efficiency and effectiveness of the current Incident and error reporting system (IR1s) in supporting learning from incidents and changing practice. The first phase identified “interruptions” as a latent error and demonstrated, for what appears to have been the first time in healthcare research, the impact these have on operatives. The second phase confirmed that a gap existed in healthcare error reduction strategies. From the outcomes of the first two phases a completely new strategy, to predict latent system errors and then to reduce them was devised. The strategy was then implemented in another area of the hospital, with different staff, on a high-risk task, IV medicine administration and was shown to reduce medicine errors