Energy-optimized approaches: a challenge from the perspectives of pilots and air traffic controllers

Abstract

Carrying out an approach that is as economical and safe as possible remains a challenge for flight crews, with a multitude of requirements to meet simultaneously. For an aircraft to descend from cruise altitude to touchdown with the lowest possible fuel consumption and noise signature, an approach is required that is both at idle thrust in the ideal speed and follows an ideal vertical profile without using speed brakes, extending the landing gear too early, or flying unnecessary horizontal segments with high thrust settings. In September 2019, a total of 90 test approaches were carried out at Zurich Airport on DLR's Airbus A320 Advanced Technology Research Aircraft (ATRA) using the low noise augmentation system (LNAS) pilot assistance system for the most economical and quiet approaches possible. The aim of this paper is to present the challenges from the pilots' and controllers' point of view for an idle approach and its execution by means of LNAS, to show the potential for fuel savings and noise reduction on the basis of flight test data and to discuss the next development steps. The assistance system reduces the crew's workload and provides support for all these tasks during an approach. The key information needed to perform optimum approaches is the expected distance from the actual aircraft position to the runway. The approaches carried out with the assistance system were significantly more economical and quieter on average than the approaches performed by a pilot group tasked with conducting minimum-fuel and low-noise approaches without the assistance system.