In conditions of high airspace congestion, the safety of modern air transportation requires continuous control in a mode close to real time. An important component of air traffic safety is the risk of collision, which depends on the airspace congestion, the air traffic control system and the reliability of the equipment. The article assesses the risk of aircraft collisions during en-route flight within a specific airspace region. The proposed methodology is based on the fragmentation of airspace into elementary zones using a hierarchical spatial indexing system to identify potential conflict points and uses risk assessment models that are suitable for a pair of aircraft based on the direction of flight of the aircraft. Open data on the position of civil aircraft obtained using the concept of automatic dependent observation in the broadcast mode are used to assess the risk of collision for a specific airspace. The risk assessment is proposed based on a combined model of air traffic on intersecting and parallel courses. A priori data on aircraft deviations from the specified trajectories of movement were obtained based on statistical analysis of trajectories from past route implementations. The data collected during the study are given in tables. Calculations and data collection are performed using a program developed in the Python programming language with the involvement of appropriate libraries that are responsible for connecting to the network of automatic dependent observation transmitters, calculating risks using the appropriate model and visualizing data. The proposed approach was verified using open data on air traffic within German airspace for a certain time frame. The results of the study include both a statistical assessment of aircraft deviations and recommendations for using the methodology in FRA areas and recommendations for applying the assessment results