Energy-Optimal 4D Guidance and Control for Terminal Descent Operations

During the descent phase, an aircraft transits from quasi-cruise to approach conditions, while dissipating both kinetic and potential energy as it loses altitude and velocity. With a shift towards trajectory-based operations (TBOs), aircraft flying the descent phase will need to meet strict time and space constraints in the form of 4-dimensional (4D) waypoints. Compared with legacy paradigms, TBO offer a safer and more efficient exploitation of the terminal airspace capacity. This chapter presents a guidance and control strategy to support the use of 4D trajectories (4DTs) in descent operations. It also addresses the possible need for human pilot involvement and intelligent system adaptation. As such, it is part of a larger research project tackling the development of cognitive human machine interfaces and interactions (HMI²) in aviation. The lack of established HMI ² formats and functions for 4DT following was identified as a major limitation to be addressed, which creates significant potential synergies with collision avoidance.