Technology continues to improve the effectiveness of passenger and bag screening, however the human remains a critical part of the screening system, both in the detection of threats and the resolution of alarms. Significant variations can be found in the effectiveness and efficiency of security screening systems even where the same technology and similar processes are deployed. Antony Bridges and Alison McGuffog, from QinetiQ’s Human Performance team, examine the difference that a high performing screener can make and identify what makes a quality screener and a quality screening organisation.
A ‘quality screener’ has a high threat detection rate at whatever form of screening they are conducting (e.g. X-ray, pat-down, bag search) whilst maintaining an acceptable false alarm rate. They are expected to deliver their task within appropriate timescales and provide excellent traveller experience in their interactions.
In X-ray screening, as with other security tasks such as pat-down, we know there is variation between screeners in their ability to determine whether an item requires additional search, either because it contains a threat or prohibited article, or because the screener is not able to quickly resolve the image as clear and other methods need to be deployed (e.g. hand search or trace detection).
In a quality screening workforce, a lower level of false alarms can be achieved without compromising threat detection as the screener workforce is able to discriminate more effectively between those trays that require additional search and those which are clear. This has implications for other parts of the system, e.g. the number of screeners required to conduct further searches on the bags rejected by the X-ray screener.
Screener decision-making time varies significantly across the same screener’s performance. Whilst typical decision-making time might be around five seconds, this is clearly influenced by the complexity of the images viewed. Many images can be very quickly dismissed as clear by both high quality and less effective screeners, e.g. a coat in a tray. The graph shows that there is a long ‘tail’ on decision making time, showing that some images can take much longer to resolve as clear than others. Importantly, there does not appear to be a strong relationship between the accuracy of decision-making and time taken. Effective and ineffective screeners can make quick decisions; the difference is in the outcome.
Can Anyone Do The Job?
There is evidence that a ‘quality screener’ requires certain innate skills that are not achieved through training alone. One of the challenges facing employers in selecting for those skills is that the current structure of a security screening checkpoint requires screeners to be rotated between different tasks, e.g. loading, X-ray screening, bag search, pat-down body search, and the skills that contribute to an individual performing well in one area may not support higher levels of performance in others. For example, a study on pat-down found that certain personality measures were predictive of performance on this task, specifically that “the variable extroversion reliably improves the prediction of overall body search performance, accounting for 13.5% of the variance in body search scores” (Bridges, 2004). However, an earlier study (Learoyd and Bridges, 2001) found that those who scored higher on the 16 PF5 dominance score (which relates to extroversion) would perform less effectively on the X-ray screening task.
Both these studies suggest that the variability in performance that can be observed in any screening pool can be partly accounted for by personality factors, which can be assessed during the recruitment process. However, how can those other innate skills be assessed?
As Dr Craig Donald noted, “using traditional methods as a basis for selection gives aspects that are important to the overall profile, but may ignore many people who have the intrinsic capacity for quick and effective visual analysis of X-ray images that are going to drive effective performance”. Donald worked with a team to create a selection tool specifically designed to assess X-ray screening skills – ScreenX has been deployed for many years at major international airports. It allows organisations to assess the skills needed of ‘quality screeners’ so that they only select those people who have enough innate ability to be trained to perform at an acceptable level.
Understanding what makes a quality screener should not just be seen as a ‘nice to have’. The organisations that understand the characteristics of those staff that get the best results develop a competitive advantage. They are better positioned to recruit, select, train, manage, and reward the best people and therefore get the best performance.
A Quality Screening Organisation
The attitude towards security of the organisation’s board of management will be reflected throughout the organisation. Significant improvements in performance have been observed when performance metrics are made available to boards, allowing them to understand the impact of changes on security outcomes and to send out a clear message to their staff that security performance is a board-level issue. Organisational decisions impact on resources allocated and therefore on individual workloads. The provision of appropriate rest areas will affect the extent to which screeners feel valued by the organisation and will also have a significant impact on fatigue. Poorly designed shift patterns result in unnecessary fatigue, degrading detection performance as well as the screener’s ability to interact appropriately with passengers, thereby damaging the traveller experience. Also, frequently changing shift patterns interfere with a security screener’s ability to plan a life outside work, and backward shift patterns (shift patterns that move to earlier rather than later times of the day) have been found to be particularly disturbing to shift workers and to have health implications.