In this study, three Line Operations Safety Audits (LOSAs) on an airline are carried out, their results are compared with each other, and a comparison is also made between domestic and international fleets. The LOSA is a proactive and predictive method in the Safety Management System that detects the strengths and weaknesses of airline performance under normal operations. Furthermore, it is a tool to improve the safety margin. The LOSA process is implemented on the basis of ten operating

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... eristics. Once the data for each LOSA was gathered and processed, the results for the three were compared. Surveys show that LOSAs provide a monitoring system for the Threat and Error Management of old generation aircraft. Domestic and international airline fleets confront different types of threats and errors in different flight phases. It is concluded that the syllabuses of training courses should be different for flight crew with respect to their fleet and the threat and error types. That are most common the obtained results can promote the importance of airlines' Threat and Error Management based on their fleet type in the future.