Impact of GNSS Outage on Mid-Air Collision Risk

Abstract

Automatic dependent surveillance broadcast technology is transforming aviation by providing air traffic controllers with fast and accurate surveillance capabilities which rely on aircraft broadcasting their position obtained typically through the global navigation satellite system. While satellite navigation enables accurate positioning, it remains vulnerable to external disturbances, which can be triggered by multiple causes, such as intentional jamming or ionospheric events. In such cases, navigation systems revert to less accurate navigation techniques, such as inertial sensors or ground-based radio navigation aids. This study comes with two main objectives: (i) to study the impact of an outage of satellite navigation systems on mid-air collision risk due to navigation performance degradation, and (ii) to translate collision probabilities due to navigation error into minimum spacing requirements. In this context, this study simulates navigation errors of real world trajectories by using a probabilistic radio navigation error model. Results show that the risk of mid-air collisions is increased in case of a degradation of the navigation performance. However, it stays well below the target level of safety when ground-based navigation aids are used instead of satellite navigation.