Analysis of the Relationship Between Runway Occupancy Time (ROT) and Aircraft Separation on Final Approach as a Constraint on Runway Capacity Under High-Demand Operations

Runway throughput at high-density European airports is governed not only by the aircraft interarrival separation on final approach but also by runway occupancy time (ROT). As reduction of Separation Minima (SM) becomes operationally and technically feasible and as Air Traffic Control Officers (ATCOs) improve delivery accuracy, ROT is expected to play a progressively larger role as the capacity-limiting mechanism. This study provides the first quantitative evidence of this effect through an analysis of a saturated traffic scenario operating under the RECAT-EU wake turbulence separation scheme and reduced surveillance minima of 2.5 nautical miles, based on ADS-B surveillance data. For each RECAT-EU leader–following sequence, ROT distributions were compared against the actual approach-to-approach times and the applicable SM to derive the probability that ROT becomes the binding constraint. Results show that, when arrival separation is governed by the reduced surveillance-based separation rather than by wake turbulence constraints, ROT is significantly more likely to become the limiting factor for runway capacity. This evidence provides a quantitative basis to guide future research, which should focus on ROT reduction strategies tailored to aircraft performance, including flexible exit taxiway concepts and adaptive exit allocation, prioritising those aircraft sequences identified by this study as most ROT sensitive.