ABSTRACT
Due to space limitations at most airports an increased airport capacity can often only be accomplished by using existing parallel runways more effectively or by building additional parallel runways. This paper focuses on the collision risk related to independent parallel approaches and the minimum required parallel runway spacing for which the collision risk may be judged acceptable. The suitability of several risk measures and methods for Target Level of Safety (TLS) assessment is studied. Application of two methods provide a TLS-area, defining a range from which the TLS may be chosen by policy makers. A risk model is developed for determination of the collision risk. Numerical evaluations show that the collision probability between two aircraft can be considerable under various operational conditions, especially near turn on to the localizer and during a dual missed approach. For trying to maintain the collision risk at a low and acceptable level, three risk reducing measures are identified. Provided that these measures are applied and assuming that a TLS from the specified TLS-area is used, independent parallel approaches may be judged adequately safe if the runway spacing is greater than 1270 m, and unsafe if the spacing is lower than 930 m.
