This research delves into the analysis of various factors affecting the organisational citizenship behaviour of First Officers within Koarmada-I. Specifically, the study explores the impact of trust, leadership, environment, and organisational commitment on this behaviour. The research sample consists of 143 First Officers based in Jakarta's Koarmada-I. The study uses descriptive analysis, validity and reliability tests, and Structural Equation Modeling for hypothesis testing. The study findings indicate that trust significantly impacts Organizational Commitment, whereas its effect on Organizational Citizenship Behavior is not statistically significant. Military leadership, on the other hand, does not demonstrate a substantial influence on Organizational Commitment, but it does have a considerable effect on Organizational Citizenship Behavior.