Feasibility study on fixed flight-path angle descent for wide-body passenger aircraft

Abstract

This study proposes the use of fixed flight-path angle (FPA) descent as a potential alternative for eco-friendly air traffic operations. Additionally, given that the proposed descent procedure follows a fixed, assigned flight-path angle, with the aircraft continuously descending toward the runway threshold with near-idle thrust, the trajectory should be more predictable for air-traffic controllers. As such, the proposed approach is expected to contribute significantly toward decreasing the air traffic fuel consumption, while simultaneously facilitating the air traffic controllers' task of maintaining the required time spacing between concurrent traffic. Furthermore, FPA descent does not require any retrofits in the fundamental components of current ground systems and/or onboard avionics. This paper clarifies the feasibility of fixed flight-path angle descent for B777-200 and B787-8 wide-body jet passenger aircraft, envisaging its implementation in near-term operations. A total of 30 trials were carried out in a series of experiments designed to evaluate the proposed descent method, considering arrivals at two major international airports in Japan-the Tokyo and Kansai International Airports-using B777-200 and B787-800 full flight simulators of a national airline. The pilots' procedures, cockpit operability, assigned vertical path tracking performance, and fuel efficiency associated with the proposed FPA descent are discussed and compared with those of conventional arrival operations. The analysis results indicate that the fixed flight-path angle descent is feasible for large-sized jet aircraft within the assumed operational environment, and that its combined use with speed control has the potential to result in even better energy-saving performance in future air traffic management operations. Keywords Air traffic management • Continuous descent operation • Flight simulator experiments • Fuel reduction • Asian economic growth Abbreviations ATCo Air traffic controller ATM Air traffic management CAS Calibrated airspeed CDO Continuous descent operation CDU Control display unit CI Cost index ETA Estimated time of arrival FAF Final approach fix FIM Flight-deck interval management FMC Flight management computer FMS Flight management system FPA Fixed flight-path angle ISA International Standard Atmosphere OPD Optimized profile descent PD Profile descent RTA Required time of arrival TOD Top of descent

Reducing speed commands in interval management with speed planning

“…The vertical profile for all runs is initialised at 38,000ft (FL380). From top of descent until capturing the −3.0-degree glideslope, a continuous descent approach with a fixed geometrical flight path angle of −2.2degrees (18,28) was used, as shown in Fig. 8.…”

Traffic synchronization with controlled time of arrival for cost-efficient trajectories in high-density terminal airspace

“…More recently, Itoh et al (2018a) and Itoh et al (2018b) also studied the operational feasibility of CDOs from the point of view of pilots when flying fixed flight-path angle descents. Results showed that this technique improves the efficiency of the flight and, according to the pilots, operationally stable flights for B777-200 aircraft could be achieved providing the flight path angle is around 2.5 degrees.…”