Increasing airport capacity with modified IFR approach procedures for close-spaced parallel runways

Because of wake turbulence considerations, current instrument approach procedures treat close-spaced (i.e., less than 2,500 feet apart) parallel run-ways as a single runway. This restriction is designed to assure safety for all aircraft types under all crosswind conditions. Restricting crosswinds and/or aircraft types can permit safe operations for runways with smaller spacings than 2,500 feet. An alternative safety paradigm can be based on the pairing procedure commonly used for visual approaches to close-spaced parallel runways. In this case, wake turbulence is not a factor if there are appropriate limits on allowed longitudinal pair spacings and/or allowed crosswinds. This paper examines how these concepts can be formulated into safe instrument approach procedures.