  This paper studies the problem of scheduling urban air mobility trips when
travel times are uncertain and capacity at destinations is limited. Urban air
mobility, in which air transportation is used for relatively short trips within
a city or region, is emerging as a possible component in future transportation
networks. Destinations in urban air mobility networks, called vertiports or
vertistops, typically have limited landing capacity, and, for safety, it must
be guaranteed that an air vehicle will be able to land before it can be allowed
to take off. We first present a tractable model of urban air mobility networks
that accounts for limited landing capacity and uncertain travel times between
destinations with lower and upper travel time bounds. We then establish
theoretical bounds on the achievable throughput of the network. Next, we
present a tractable algorithm for scheduling trips to satisfy safety
constraints and arrival deadlines. The algorithm allows for dynamically
updating the schedule to accommodate, e.g., new demands over time. The paper
concludes with case studies that demonstrate the algorithm on two networks.
