Operational Fuel Inefficiency in Cruise Flight: A Worldwide Geospatial Analysis

Aircraft often deviate from fuel-optimal trajectories during the cruise phase of flight, which accounts for approximately 70% of aviation fuel consumption. Deviations in horizontal route, altitude, and speed lead to excess fuel burn, increased CO₂ emissions, and higher operational costs. This study provides a global assessment of cruise fuel inefficiency using trajectory data from over 32 million flights between November 2022 and November 2023. We estimate global cruise fuel inefficiency at 7.5%, representing 12.9 million metric tons of excess fuel consumption, with associated fuel costs and 40.7 million metric tons of CO₂ emissions. Regional variation is notable, ranging from 4–7% in oceanic regions to 19.5% in China. By analyzing trajectory dimensions, we identify key inefficiency sources: horizontal inefficiency (3.3%) driven by geopolitical constraints and rigid airspace structures, vertical inefficiency (2.4%) caused by altitude constraints and congestion, and speed inefficiency (2.2%) resulting from operators prioritizing speed over fuel efficiency.