To address the absence of standardized lower bounds for avoidance angles in independent parallel instrument approaches under the “parallel + open V-shaped” hybrid runway configuration, as well as the insufficiency of the conventional 45° avoidance strategy, which does not fully account for variations in runway spacing and potential secondary collision risks, Monte Carlo simulation with a three-dimensional positional error probability model was employed to systematically investigate the optimization and safety implications of avoidance angles. A dynamic model of independent parallel approaches under varying runway spacing conditions was constructed, and the relationship between runway spacing and the lower bound of avoidance angles was precisely quantified through Monte Carlo simulations. Furthermore, for the specific risk profile of the hybrid runway configuration at Chengdu Tianfu International Airport, a three-dimensional positional error probability model was applied to evaluate the potential collision risks between deviating aircraft and departing aircraft on the lateral runways under different avoidance angles. The results show a negative correlation between runway spacing and the lower bound of the avoidance angle. When the runway spacing is extended to 2 400 meters, the lower bound of the avoidance angle can be reduced to 35°, leading to an approximate 50% reduction in the peak collision risk on critical flight segments and a decrease of about 10.4% in the upper boundary of the arrival-departure window. This improvement enhances airspace utilization efficiency while ensuring compliance with collision risk requirements. Based on the operational characteristics of hybrid runway configurations, a quantitative relationship between the avoidance angle and runway spacing was establisher, providing theoretical support for refining operational standards for such configurations.