Absract. In the context of increasing air traffic intensity and the growing proportion of night and long-haul flights, the management of crew fatigue is becoming a critically important factor in ensuring flight safety. Crew fatigue is recognized as a significant factor affecting the reliability of flight operations and decision-making processes. At the same time, traditional working time limitations do not provide a comprehensive assessment of fatigue-related risks, which necessitates the implementation of integrated approaches. Modern methods, including heart rate variability (HRV) analysis and simulation modeling, enable a more accurate assessment of the functional state of crew members and facilitate the identification of fatigue formation patterns. The research problem lies in the limitations of the prescriptive approach based on Flight Time Limitations (FTL), which does not account for physiological and circadian characteristics of humans. The aim of this study is to develop recommendations for assessing crew fatigue levels in airlines of the Republic of Kazakhstan based on an integrated model consistent with international standards of ICAO, IATA, and EASA. The objectives include the analysis of international fatigue management approaches, the development of a mathematical model of the fatigue index, its statistical validation, and the formulation of practical recommendations. The research methods include multiple and logistic regression, ROC analysis, calculation of sensitivity and specificity, Monte Carlo simulation, and heart rate variability (HRV) analysis. The results demonstrated the superiority of the integrated FRMS model (AUC = 0.623) compared to the prescriptive FTL-based model (AUC = 0.574). Simulation modeling showed a reduction in fatigue risk by up to 17% under optimized scheduling conditions. A statistically significant relationship between fatigue, night workload, and decreased HRV was identified. It is concluded that the implementation of an integrated fatigue index within the safety management systems of airlines in the Republic of Kazakhstan is justified. The proposed recommendations enable a transition to proactive fatigue risk management and are consistent with international standards.

Keywords: crew fatigue, fatigue risk management, safety management system, working time limitations, heart rate variability, biomathematical modeling analysis, aviation safety.