A multi-method approach towards identifying situational factors and their relevance for X-ray screening

In the last decade, large investments have been made to improve airport security for safeguarding air transportation. X-ray screening of passenger bags is a key component of airport security procedures. State-of-the art X-ray screening systems provide high quality images, yet the decision whether a passenger bag has to be further investigated (e.g. using manual search) still relies on human operators (X-ray screeners). The primary work task of X-ray screeners is to visually inspect X-ray images of passenger bags for prohibited items and decide whether a bag is OK or not in a reasonable amount of time. It is well-known from scientific research that human performance depends on a variety of situational factors. Understanding which situational factors are relevant for X-ray screening at airports can provide important insights for increasing efficiency and effectiveness at airport security checkpoints. A multi-method job analysis was developed to identify situational factors which influence X-ray screeners' primary work task in cabin baggage screening (CBS) at a European airport. First, qualitative work observation was applied to identify situational factors. Then, interviews with experts were conducted to gain further insights on which situational factors could be relevant for X-ray screening by human operators. These methods provided the basis for a survey conducted with X-ray screeners in order to obtain ratings of how relevant situational factors are and how often they occur. A list of main situational factors that influence X-ray screeners' primary work task was elaborated throughout the process and summarized in a categorical system using impact and frequency. Factors of high impact and frequency were bag content depending on different kinds of materials; bag complexity and how bags and trays are packed and put on the conveyor belt. Factors of medium relevance were factors of the work environment (noise, light, air, temperature and quality of X-ray images), team specific factors (communication, time pressure and team atmosphere) and other factors affecting X-ray screening (operational processes of secondary bag search, loading of bags, passengers causing fuss and hassle). The reported results indicate the presence of several situational factors affecting X-ray screeners' primary work task.