Midair Collision Risk when Executing an Incorrect Approach during Established on Required Navigation Performance Operations

Providing improved efficiency in the terminal environment around high-capacity airports, Established on RNP leverages Required Navigation Performance technology to safely allow reduced aircraft-to-aircraft separation during curved simultaneous approaches. As one element in a comprehensive safety analysis, this paper describes the methodology and results used to estimate the mid-air collision risk when at least one aircraft leaves the intended approach path by inadvertently selecting an unintended flight procedure. The analysis considers three possible cases where an aircraft could be put at risk of collision during such an event: one where the trailing aircraft flying to the intended runway may be put at risk; a second where an aircraft flying to the incorrectly selected runway is put at risk; and, a third case, which only occurs when more than three parallel runways are available, where an aircraft flying to a runway between the intended runway and the incorrectly selected runway is put at risk of collision. The analysis concludes that all three cases could pose significant risk if not appropriately mitigated with controller monitoring and procedure design, but the third case is the most severe.