Development and Validation of a Pilot Activity Load Index (PALI) based on NASA-TLX template

Abstract Introduction: Workload can be defined as the hypothetical construct that represents the cost incurred by a human operator to achieve a particular level of performance. Each job has specific needs and demands. The better measurement tool assessing that estimate the workload, it’s need to identify the requirements of a task, the circumstances under which it is performed, and the skills, behaviors, and perceptions of the operator. Heretofore, several methods have has been providing to assess the workload. One of the most common methods of assessing mental workload is NASA-TLX method. The present study was therefore conducted to Develop and Validate of a Pilot Activity Load Index (PALI) based on NASA-TLX template.   Method: The study is a cross-sectional and descriptive-analytical that was carried out among airline pilots of Civil Aviation Organization. At first, task analysis was conducted to pilot proffession using Hierarchical Task Analysis (HTA) technique by literature review, documentation and semi-structured interviews whit 8 expert pilots. Then requirements and interactions related to piloting tasks extracted according to duties. In next step, “Pilot Activity Load Index” or PALI subscales were developed based on NASA-TLX template. Validity of the subscales were evaluated by Content Validity Ratio (CVR) and content validity index (CVI).The content validity was carried out using Lawshe’s table. Finally, to determine the internal consistency of the subscales, 30 pilots airliner completed the final version of the PALI in typical flight phases. The data obtained were then analyzed in SPSS using Cronbach's alpha to measure the reliability of the subscales and considering an acceptance level of 0.7. Result: the first results led to the emergence of an initial list with 17 subscales. 11 subscales were irrelevant, redundant and impractical to use in operational environment, Because of these items had CVR less than 0.75 were omitted from the subscales list. Finally, six items were approved for the final subscales that related to pilot tasks (CVI=0.79). The Verified subscales had a Cronbach's alpha value of 0.88 and was therefore considered a reliable tool. Conclusion: The PALI developed in this study has a good validity and reliability and therefore be can used to assess the workload in airline pilots.The results revealed that the activity load index developed in this study has a good validity and reliability and can therefore be used to subjective rating workload assessment in airliner pilots. According to the results obtained in this study, PALI can be an index as a useful tool, simple, low-cost and without interfering to the duties and assess sources of pilot workload then to matching job demands and pilot capabilities In order to prevention of human errors and aviation accidents.