Looking for the best flight efficiency indicators for arrivals

This study, conducted as part of an official working group with European air navigation service providers, explores various multi-dimensional flight efficiency indicators for arrivals. The objective is to find simple and intuitive indicators, easy to process and reproduce, that can best approximate fuel burn. We identified eleven indicators, covering the three dimensions (horizontal, vertical and speed), and decomposed them in two sub-indicators to capture permanent vs variable inefficiencies as proxies for airspace vs operations. We then considered all combinations and integrated each in a linear regression, calibrated per aircraft type on the top 30 European airports in the last 50NM, over 2.8 million flights. Predicting fuel burn in excess with a single indicator leads to diverse performances (mean absolute error ratio ranging from 25% to 66%). Combining indicators can improve performances (22% with two, 20% with three, 18% with four and 16% with the eleven) but adds complexity. The simplest indicators on the three dimensions (time, altitude and speed differences) show fair performances combined (24%). A good compromise may be with the two of the top 3 indicators (altitude average and time difference, 23% combined) possibly complemented by the corresponding speed indicator (speed average, 21% combined). Future work should investigate whether the prediction performance may be further improved.