Risk Assessment of Loss of Control In-Flight Trajectories for Urban Air Mobility Safety

In Urban Air Mobility (UAM), maintaining a minimum separation between aircraft is a safety requirement, which becomes challenging amidst congested air traffic and off-nominal conditions, such as Loss of Control In-flight (LOC-I). This paper assesses the risk of separation loss due to aircraft trajectories in LOC-I scenarios, associated with the integration of UAM into the national airspace system. To accomplish this, simulation-based and analytical approaches have been integrated into the risk assessment mechanism for collision involving LOC-I aircraft to enhance UAM safety. Automatic Dependent Surveillance-Broadcast (ADS-B) data obtained from the accident reports were used to simulate LOC-I trajectories within the UAM operational environment. In addition, data acquired from the Generic Transport Model (GTM), a specialized model designed to simulate the LOC-I scenario, was employed to generate LOCI trajectories. The safety of the UAM aircraft is evaluated by checking the separation loss encounters resulting from LOC-I and UAM aircraft trajectories. The UAM aircraft trajectories were generated using simulation software for those flying below 4000 ft, considering vertiports in Atlanta City. The simulation software, developed for UAM traffic management purposes, was also used to detect conflicts and simulate various separation loss scenarios. The conflict detection simulated in the UAM simulation software was quantitatively evaluated by calculating the probabilities of mid-air collisions, near mid-air collisions, and well-clear violations due to LOC-I, combining LOC-I and UAM aircraft trajectories. The assessment suggests that the UAM aircraft in congested settings could be affected by LOC-I trajectories. By leveraging realistic ADS-B data and the GTM model, this information can guide the development of planning algorithms and safety protocols in congested UAM environments.