Assessing the environmental impact of Continuous Descent Operations based on Quick Access Recorder and surveillance data

Continuous Climb Operations (CCOs) and Continuous Descent Operations (CDOs) are aircraft operating techniques enabled by airspace design and facilitated by Air Traffic Control (ATC) that allow aircraft to follow a flexible, optimum flight path which brings reduced fuel burn, costs, emissions and noise levels without reducing safety. EUROCONTROL has estimated the implementation of these operations in an annual reduction of 340k tons of fuel, 1M tons of CO2, C150M in cost and an average of 1-5dB per flight in noise. Deploying CCOs and CDOs is an ongoing task that different Air Navigation Service Providers (ANSPs) are undertaking globally, but assessing the number of CCOs and CDOs flown worldwide is challenging. The accurate evaluation of these operations in terms of performance and environmental impact is not trivial. In this work, multiple performance metrics proposed to measure fuel efficiency of continuous operations are evaluated using Quick Access Recorder (QAR) data. Over 50 % of flights with some degree of inefficiency would be classified as efficient if metrics solely based on vertical profiles are utilized. After quantifying the limitations of these metrics, this paper presents new performance indicators, whose combination allows an improved classification of flights in terms of fuel efficiency. Inaccurate metrics can hide operational inefficiencies and delay the investigation of the actual root cause for such inefficiencies.