Demand control law for total energy angle tested at manual steep approaches
With rising demands on flight precision and more complex flight trajectories, pilots' workload during manual flight is increasing. This is especially the case for flight path and speed control with thrust and spoilers during approach and landing. The objective of the nxControl system is to enable pilots to manually control the longitudinal load factor nx instead of engine parameters and spoiler deflections. This load factor is equivalent to total energy angle. It is directly influenced by engine thrust and aerodynamic drag. The nxController shall complement the existing fly-by-wire control laws of today's commercial airliners. It aims at higher precision with lower workload during manual flight. The pilots set and monitor the controller input and impact by an adapted human-machine interface consisting of a thrust-lever-like inceptor and additional display elements to enhance energy awareness. This paper describes the nxControl system with focus on the demand control law and an evaluation study with 24 airline pilots in a research flight simulator. The task was a demanding, steep, and curved approach in the mountainous area of Salzburg airport with required navigation performance RNP 0.1. The results show that despite minimal training the pilots achieved higher precision in speed and energy control with lower physical workload with the nxControl system.
Published in: Journal of Guidance, Control, and Dynamics, 10.2514/1.G003194, American Institute of Aeronautics and Astronautics