The conceptualized and uprising market of urban air mobility requires flight operations in constrained volumes of airspaces. In this paper, we address the concept of performance-based navigation in the context of future electric vertical takeoff and landing vehicles. We discuss measures for an onboard monitor that supervises the navigation system integrity and flight control accuracy, and we use these metrics for the trajectory selection and contingency logic of the flight guidance system. As a second aspect of this paper, we propose a method for adjusting the followed trajectory during flight to increase the safety level of the landing maneuver. Therefore, we estimate the probability of violating requirements on the position of the aircraft through offline simulation and evaluate critical parameters that are sensitive to causing flight path deviations. For this, we utilize the efficient subset simulation methodology employing Markov chain Monte Carlo algorithms to reduce the computational burden. The findings of the offline simulations, i.e., the joint probability density functions, are parametrized and stored for onboard use. Finally, the control law for adjusting the trajectory leverages the knowledge gained by subset simulation, current sensor measurements or state estimates, and the available authority computed by the onboard monitor. An example demonstrates the feasibility of the proposed approach and shows the increased level of safety due to trajectory variation during landing.     «

The conceptualized and uprising market of urban air mobility requires flight operations in constrained volumes of airspaces. In this paper, we address the concept of performance-based navigation in the context of future electric vertical takeoff and landing vehicles. We discuss measures for an onboard monitor that supervises the navigation system integrity and flight control accuracy, and we use these metrics for the trajectory selection and contingency logic of the flight guidance system. As a...     »