Development and Evaluation of a U-space Route Structure for the City of Frankfurt Connecting Airport and Trade Fair Via Fast-Time Simulation

In the course of the European project CORUS-XUAM, a very large-scale demonstration was conducted for the metropolitan area of Frankfurt, for which a newly developed U-space route structure was conceptually elaborated. The demonstration exercise focuses on the initial definition and a near-term implementation of urban U-space corridors inside controlled airspace (class D) connecting terminal 2 of the Frankfurt Airport and the Frankfurt Trade Fair via air taxi services operating as airport shuttles. With advancements in navigation performance, monitoring, surveillance, communication technology and increasing operating experience, U-space corridors can transition to free flight trajectories. Local constraints such as approaching fixed-wing traffic, flights operating under visual flight rules (VFR) including helicopter emergency medical services, heliport operations, and a VFR holding pattern were taken into account in order to elaborate the course of the U-space corridors. Of special interest is the harmonization of airspace users inside and outside of U-space while ensuring safe and efficient conflict detection and resolution. A set of fast-time simulations have been conducted to evaluate the developed U-space route structure and its operating concept based on historic air traffic data for the metropolitan area of Frankfurt. Following the hypotheses that every 120 seconds an air taxi departure can be performed without causing a negative impact on airport operations, we evaluate the metrics U-space corridor usage, occupancy, throughput, number of resolved conflicts and occurring/imposed delay. In addition, we elaborate where conflicts occur and whether another air taxi or the background traffic caused them. Furthermore, we show how they can be resolved, i.e., how often and to what extend delaying and/or re-routing is applied throughout different scenarios. Using the selected separation values, it is possible to have air taxis departing every 90 s at both vertiports. This certainly changes when different separation thresholds are used. Additionally, we showed that all conflicts can be solved by applying a small ground delay or by simply choosing a different U-space corridor.