## 4 Discussions and Conclusions
Conversely, in the case of system-limit failures, higher proficiency levels have a greater facilitative effect on reducing response time. This suggests that proficiency levels had varying effects on the response time for resolving failures in different failure types, with higher proficiency being more effective in dealing with system-limit failures but less effective in addressing system-malfunction failures. Therefore, further research may be needed in order to explore the underlying mechanisms and factors influencing the effectiveness of higher proficiency in resolving system-malfunction failures. Previous studies have extensively demonstrated that expert pilots exhibit more systematic and efficient eye movement patterns compared to intermediate and novice pilots [29; 32; 33]. This study further revealed that eye movement patterns vary in high proficiency (expert) participants depending on the type of failure. For instance, in the case of system-malfunction failures, the proficiency ratio of fixation duration monotonically increased, while in the case of system-limit failures, this ratio initially decreased and then increased (see Table 3). The trends in saccade duration and fixation rate varied in system-failure and system-limit failure as well (see Tables 4 and 5). This inconsistent pattern of proficiency ratio changes suggested differences in eye movement patterns, attention allocation and monitoring behavior of participants at different proficiency levels for system-malfunction and system-limit failures. It also implied that different cognitive and coping strategies may have been employed for different types of failures. The existence of such inconsistencies provided clues for further investigating the cognitive and coping strategies for different types of failures, aiming to enhance pilots' understanding and response capabilities to automation system failures. Given the substantial variations in response performance and monitoring behavior across different proficiency levels, depending on the type of failure, it is important for the literature to distinguish between system-malfunction and system-limit failures and not overlook the influence of proficiency. The findings of this study not only emphasize the importance of distinguishing between system-malfunction and system-limit failures but also support the significance of pilots' mental models of automated systems and the improvement of pilot training. System-limit failures are predictable because pilots receive training and have knowledge of specific system failure scenarios. However, if they have not received sufficient training or their proficiency level is not adequate, system-limit failures may become difficult and unpredictable for them. Additionally, there are system-malfunction failure conditions that even the designers themselves may not have anticipated, making the situations even more unpredictable. Practitioners responsible for system operations may encounter an increasing number of abnormal events, sometimes even unprecedented ones. Research findings on how to predict, respond to, and train for rare, uncertain, and unexpected events will help them succeed in these challenging and difficult processes [34]. The results of this study also support this perspective. Therefore, in addition to recognizing the distinction between system-malfunction and system-limit failure, it is crucial to focus on the development of pilots' mental models of automated systems and training theories, fostering their core competencies and enhancing their overall abilities to deal with complexity, uncertainty, and unknown situations. This ensures that they can effectively cope with system failures when they occur, and it is of paramount importance to enhancing the quality of pilot training and improving the safety design of aircraft automation systems. One limitation of this study is its relatively small sample size, consisting of only 24 participants. It is important to acknowledge that this sample may not fully represent the diverse population of commercial aircraft pilots.