Framework for airspace planning and design based on conflict risk assessment

This paper presents a framework for airspace planning and design based on a conflict risk assessment developed for the purpose of preventing aircraft conflicts and collisions. The paper also presents a conflict risk assessment model developed for airspace strategic planning, as a first step of the proposed framework. The model is intended to facilitate comparisons and sensitivity analyses of different airspace designs and organizational scenarios under different traffic flow levels. Risk is assessed using two variables: the conflict probability and the number of conflicts in the observed airspace under the given circumstances. The model is based on the concept of critical sections, which are traversed by the aircraft during level flight, or while climbing or descending through these sections. For a given pair of aircraft conflict probability is defined as product of the probability that one aircraft is in a critical section of its own trajectory, and the conditional probability that another aircraft is in its own critical section while the first aircraft is already in it. The number of conflicts is defined as the product of conflict probability and estimated traffic flows for the given airway. The final values for conflict numbers are determined taking into account all available flight levels and airway combinations in the given airspace. The model provides an analysis of influence of separation reduction on conflict risk and could be used in both en-route and terminal manoeuvring airspace.