Toward Time-Based Separation Rules for Landing Aircraft

Abstract

Aircraft landing on the same runway are potentially exposed to a similar wake vortex hazard, under either instrument meteorological conditions (IMC) or visual meteorological conditions (VMC) when the air traffic control (ATC) distance-based instrument flight rules (IFR) and visual flight rules (VFR) are applied, respectively. Since IFR are stricter than VFR, the runway landing capacity is lower under IMC than under VMC. Possibilities are investigated for introducing time-based ATC separation rules instead of the current distance-based ATC separation rules between landing aircraft as an option for increasing the runway landing capacity under IMC and consequently decreasing the existing gap between IFR and VFR capacity. A model for calculating the landing capacity of a single runway on the basis of ATC time-based separation rules was developed. In addition to these rules, which would be set up by using the current ATC distance-based separation rules and the advanced knowledge on the current and predicted behavior of the wake vortex influenced by the weather conditions, the model uses other inputs, such as the structure of fleet mix in terms of the proportion of particular aircraft categories, which are represented by their wake vortex parameters (the approach speed, wingspan, and weight), and the geometry of the approach corridor, which enables landing on a given runway. The model output is the matrix of the standardized time-based separation rules for different combinations of landing aircraft sequences, which would be applicable to both VMC and IMC, and the runway landing capacity calculated for combinations of the time-based separation rules depending on the current and predicted wake vortex characteristics and behavior. The model is applied to calculating the landing capacity of a single airport runway.