Vertical and Horizontal Flight (In)Efficiency and Optimisation of Flight Trajectories – A Literature Review

A review of recent academic and professional literature on flight efficiency reveals that vertical and horizontal inefficiencies persist as significant challenges to the performance and sustainability of the air traffic management (ATM) system. While these inefficiencies have been widely studied, there remains a lack of comprehensive insight into their full range of impacts, as well as the underlying factors that hinder effective optimisation efforts across different operational contexts. To address this gap, this study examines and synthesises the current body of research related to vertical and horizontal flight (in)efficiency. The review synthesises findings from diverse sources, identifying recurring themes such as fuel consumption, environmental impact, monetary effects, ATM operational constraints and trajectory optimisation strategies. Additionally, the analysis underscores key differences in methodological approaches and thematic priorities between vertical and horizontal efficiency studies. The results contribute to a more holistic understanding of flight (in)efficiency and aim to inform the future development of integrated, context-sensitive models that can improve operational efficiency and support the sustainable evolution of the ATM system.