Urban Air Mobility (UAM) has the ability to reduce ground traffic congestion by enabling rapid on-demand flight through three-dimensional airspace with zero operational emissions by using electric Vertical TakeOff and Landing (eVTOL) vehicles. In the long term with more UAM flights, air traffic control is expected to limit further growth of such operations. Therefore, a first research has been performed on energy-efficient trajectory optimisation for a given required time of arrival, as the arrival phase is the most safety-critical flight phase with much higher air traffic density and limited battery energy. However, research on the computation of the optimal required time of arrival (RTA) for eVTOL aircraft has not yet been performed. Unlike fixed-wing aircraft or helicopters in commercial aviation, eVTOL aircraft have different flight dynamics, limited battery energy supply and a limited number of landing spots at a vertiport such as the top of high-rise buildings. This work is the first to utilise a mixed-integer linear program that computes the optimal RTAs for eVTOLs to safely separate them for minimum delay based on remaining battery state of charge and vertiport capacity. A concept of operations for vertiport terminal area airspace design is also proposed while making use of the existing energy-efficient trajectory optimisation tool. The research serves as a basis for further development of safe and efficient UAM operations. The mathematical model can also be applied to Unmanned Aircraft System Traffic Management (UTM) by inserting new separation requirements and flight dynamics for smaller drones when optimising a high density arrival terminal airspace.

Urban air mobility with electric Vertical TakeOff and Landing (eVTOL) vehicles is envisioned to become a fast and flexible urban transportation mode. Apart from technical challenges for eVTOLs regarding vehicle design and manufacturing, airspace design and traffic control mechanisms are most desired on the operation side. In particular, from an operational point of view, the arrival phase is expected to be the main bottleneck, with restricted vertiport resources, high air traffic density, frequent flight manoeuvres, and limited eVTOL remaining battery energy, all leading to complex operational constraints. This work provides a framework to enable optimal and efficient on-demand eVTOLS arrivals in the context of on-demand urban air mobility. We investigate the throughput of a double landing pad vertiport by proposing a new vertiport terminal area airspace design and a novel rolling-horizon scheduling algorithm with route selection capability to compute the optimal required time of arrival for eVTOLs in a tactical manner. Finally, a case study on arrivals in a hexagonal vertiport network is performed to show the algorithm performance with different configurations. Our simulation results show that up to 50 seconds delay per eVTOL is expected during the commuter peak hours and less than 10 seconds delay is expected during off-peak hours.