This paper examines the psychophysiological stress experienced by flight crews during a standard landing approach, a phase considered one of the most critical in aviation operations. Elevated levels of cognitive and emotional strain can significantly influence pilot performance, including situational awareness, decision-making accuracy, and reaction time. The study emphasizes the pivotal role of timely and precise avionics diagnostics in mitigating risks associated with equipment failure or misinterpretation of instrument data. In this context, a method for calculating the reliability of critical onboard instruments during landing is proposed. The approach integrates both technical reliability factors and operational stressors to provide a comprehensive evaluation framework. The findings aim to support enhanced safety protocols and inform the development of more resilient avionics systems.