Steeper Approach Procedure for Increasing Ultimate Capacity of Closely Spaced Parallel Runways

Abstract

The steeper approach procedure (SAP) is investigated as an innovative option for increasing the ultimate arrival capacity of closely spaced parallel runways under the instrument metrological conditions and instrumental flight rules. SAP is based on the two pairs of instrumental landing systems, each enabling the certified aircraft to approach a given parallel runway at either the standard (3°) or steeper (5° to 7°) glide slope (GS) angle. The difference in the GS angles allows application of the air traffic control (ATC) vertical separation rules between the arriving aircraft; this can mitigate the impact of wake vortices on the aircraft in trail separation while on the same or different approach trajectories. A combination of these with the ATC longitudinal and horizontal–diagonal separation rules has the potential to increase the ultimate arrival capacity of closely spaced parallel runways. An analytical model was developed for calculating the arrival ultimate capacity of closely spaced parallel runways. The model inputs are the geometry of given parallel runways, the ATC minimum separation rules, and the aircraft fleets mix characterized by the aircraft wake vortex types and categories, capability of using different GS angles, final approach speeds, and the arrival runway occupancy time. The model output consists of the ultimate capacity of closely spaced parallel runways and its variations in dependence on the mixture of arrivals and departures for a large U.S. airport.