Fuel-based flight inefficiency through the lens of different airlines and route characteristics. A post-operational analysis for one day of traffic at the ECAC area.

In the light of the ambitious environmental targets for future air traffic management paradigms, there is a need in the enhancement of current (key) performance indicators, with the objective to facilitate the identification of different sources of environmental inefficiencies, and to enable large scale and systematic post-operational analyses. Based on a previously published methodological framework to compute fuel-based performance indicators, this paper aims at exploring these inefficiencies at different granularity of the results. For this purpose, a set of filters has been applied on a data-set of 24h of traffic within the ECAC (European Civil Aviation Conference) area, encompassing different airspace users categories, route length and flight frequencies. The results show that the carriers prone to low-cost business models have, on average, the highest value of total fuel inefficiency in absolute terms with a median around 530 kg (17%); compared to full-service carriers with a median around 432 kg (20%); observing as well that relative fuel inefficiency significantly drops as the stage length of the routes increases. Moreover, results reveal that the busiest the routes are, the higher fuel inefficiencies they accrue. For routes with less than 5 departures per day, the fuel inefficiency accounts for 19.1% in relative terms, if compared with the total fuel burnt; whereas for the routes from the category between 12 and 20 daily departures the relative fuel inefficiency rises to 22.6%. These figures are obtained when the reference trajectory used to derive fuel inefficiency is a full free route trajectory at maximum range operations and without considering en-route charges. The paper also explores other reference trajectories, constrained to the airway network in force and/or considering the (estimated) cost index chosen by the airspace users. It is acknowledged, however, that a larger data-set needs to be considered in the future to generalise the validity of the obtained results.