Modeling combined and separated sequencing legs in Point Merge: impact on capacity, vertical profile, and continuous descent

Abstract

The object of research is the process of arrival sequencing in terminal maneuvering areas under the Point Merge concept. One problematic aspect is ensuring stable time-based intervals and maintaining continuous-descent profiles under peak demand and wind perturbations, as well as the lack of simple rules for choosing between combined and separated sequencing legs and for switching between them. The study used analytical modelling of arc geometry and direct-to-merge rules; parameterization of procedures and target intervals; probabilistic models of demand and ground-speed variation; Monte Carlo simulations using open traffic, weather and Aeronautical Information Services sources; statistical analysis; construction of a proxy controllability index; a hysteresis-based switching rule; and sensitivity analysis. It was proposed to obtain a reproducible framework for designing and comparing combined and separated sequencing legs with unified metrics. This follows from combining transparent geometry parameterization with a simple hysteresis-based switching rule that avoids frequent back-and-forth configuration changes. As a result, medians are practically identical on identical geometry, while differences appear in the tails: separated legs reduce the probability of long loops and extreme low-altitude horizontal segments. Compared with static alternatives, hysteresis-based switching under peak demand reduces separation-interval violations by up to ≈17.5 percentage points and shortens median low-altitude horizontal time by ≈4–9 s, at the cost of ≈0.57 NM of added median distance, providing better operational support without heavy optimizers. Limitations include a single case, environmental inference via extra distance, and a proxy controllability index. Future work will include human-in-the-loop experiments and coupling with detailed aircraft-performance models.