Increasing urbanization and a growing need for mobility are pushing the transport infrastructure in many cities to its limits. Many different mobility solutions are being investigated to solve this problem. In addition to ground-based transportation, Urban Air Mobility (UAM) is discussed as a possible solution to create a new type of urban transport mode, which could fulfill different transport needs in several application fields. The cross-institutional and interdisciplinary research project "HorizonUAM - Urban Air Mobility Research at the German Aerospace Center (DLR)" brings together a wide variety of DLR departments to research on the vision of Urban Air Mobility. In order to coordinate the different research focuses of the project partners, it is necessary to create a common basis for the upcoming work. Therefore, five different use cases were defined. All use cases are selected in order to cover a broad spectrum of challenges for vehicles, safety, air traffic management, infrastructure and operations. In addition, different types of ground-based infrastructure (vertidromes) and their characteristic properties as well as two different concepts of operation (ConOps) for an on-demand and a scheduled UAM service are considered. For each use case and based on the ConOps, application-specific mission profiles, which form the basis for the design of the vehicles, are outlined. As the future of UAM also strongly depends on technological advances, a short-term (2025+) and a long-term (2050+) scenario capture the development of the most important fields of technology for UAM until 2050. Based on the defined use cases, missions and technology scenarios, various aspects regarding to technical feasibility, efficiency, sustainability, market development potential and social acceptance will be investigated in the course of the project
