With the rising interest from big investors and manufacturers in UAM solutions, many vehicle prototypes and ground infrastructure designs are beginning to appear and being tested in real-world scenarios. This mode of air transportation could be a game-changer if the different milestones are achieved. While there are many challenges to be covered, from noise pollution to airspace management, safety is probably one of the main elements to be assessed. And while much effort has been given into designing and promoting UAM vehicles, little research has been published or conducted about safety considerations. This study provides with a discussion on different findings related to safety based on a root cause analysis of reported and documented helicopter accidents involving similar environments and conditions to those UAM will face. By assessing these hazards in similar VTOL aircraft such as helicopters, an extrapolation to UAM vehicles is made for different types of vehicles, depending on their characteristics and performance capabilities observed in various prototypes. The analysis is divided in two main parts. The first part focuses on the different occurrences involved in the accidents, following the CICTT standard definitions for reporting aviation accidents and incidents. The second part goes deeper and analyses the causes involved that lead to those occurrences, and how these could apply to UAM vehicles. The discussion considers the identified hazards in different levels, depending on factors such as human presence and automation, and their impact on criticality, prevention and mitigation. The overall study provides with some guidelines on safety issues that are considered relevant for future research in the field of UAM, as well as for the future standardization of the necessary elements to implement and regulate these systems in urban centers
