Dynamic Event Trees for Aircraft Collision Risk Assessment

The air transportation system provides an extremely safe mode of transportation. Maintaining adequate separation ensures safety but limits the capacity of the airspace. In addition to the expected growth in commercial flights, the number and diversity of other aircraft types will also increase significantly. A diversity of collision avoidance technologies may also exist together in future architectures of the National Airspace System. This article proposes a dynamic event tree (DET) framework and its evaluation methodologies to assess collision risk in airspace with a variety of aircraft types. Several methods are applied to a DET example, which models a midair collision scenario using the framework, and the performance and limitations of each method are discussed.