Building a Performance Comparison Framework for Urban Air Mobility Airspace Management Concepts

Kurzfassung

The demand for air transportation service using Urban Air Mobility (UAM), as both competitive and complementary transportation means, is expected to increase in the near future to save travel times in urban areas. Thus, an adequate set of services for airspace network management supporting their operations will be needed. Despite the numerous emerging topics of UAM being widely researched, an analysis of this need is yet to be explored. Research institutions and newly founded and well-established companies of the aerospace sector all over the world are actively engaged in three research pillars: vehicle technology, infrastructure, and business models to pave the way for UAM deployment. Whereas a multitude of UAM vehicle types and airspace management concepts are still in the experimental phases, some contenders are close to certification. However, this multitude of stakeholders involved in the novel UAM industry consequently leads to several different viewpoints based on the respective background and to individual goals with no universal way of comparing them for assessment. A lot of research regarding UAM airspace network design and management is being conducted, and various approaches for it have been suggested. However, it appears hard to assess them qualitatively, and quantitatively. This might pose a problem, as claims published by companies and institutions cannot be easily validated, and consequently hinder the decision-making for the most suitable approach to be adopted. Thus, building a performance comparison framework, based on common metrics, becomes essential for evaluating different network designs and management concepts for UAM operations. This paper aims to find a unified method for comparing, evaluating, and assessing different UAM airspace management approaches based on appropriate metrics. Selected metrics should therefore be simple, quantitative, and generally applicable, enabling a comparison of different network topologies, regardless of their differences. Inspiration for suitable metrics can be drawn from common transportation means that are constantly in use such as commercial air, rail, and road transportation. A subset of Key Performance Indicators and Areas (KPIs and KPAs, respectively) from those three domains are considered suitable for UAM applications, as this newly emerging means of transportation inhibits some major aspects of conventional air traffic management, rail traffic management systems, and road network performance. Within this paper, three newly developed concepts are presented first as examples of possible airspace management approaches for UAM. They are labeled as “slot-based approach”, “trajectory-based approach” (both developed by DLR), and “strategic conflict management approach” (developed by NASA). The slot-based approach is designed with a rigid route structure and time slot management in mind, whereas the trajectory-based approach is based on a free-route and direct flight concept with an on-demand character. NASA’s strategic conflict management approach provides UAM flights with demand-capacity balancing and spacing at vertiports and control waypoints along the routes defined within UAM-specific corridors. These approaches are applied to the representative scenarios in two different urban areas, namely Hamburg in Germany and Dallas/Fort Worth in the United States. Then, after careful consideration of the two other industries’ benchmarks and check-up of applicability to UAM, a non-exhaustive, yet detailed list of metrics will be provided to cover network, aerodrome, safety, and human-centered aspects. For initial investigation, only network specific metrics will be further analyzed and elaborated in this paper. The resulting network specific metrics mainly concern time and energy efficiencies, the complexity of associated traffic management, and robustness of schedule, as well as intuitive measurements for comparison to ground transportation modes. This paper serves as a basis for an international UAM framework comparison, which is one of the meaningful topics addressed by Air Traffic Management-eXploration (ATM-X) collaboration between NASA and DLR. A subset of the selected metrics can be chosen in order to evaluate and objectively compare the presented three air traffic management concepts for safe and efficient UAM operations, but can also be applied to other traffic management approaches.