Framework for airspace planning and design based on conflict risk assessment: Part 2: Conflict risk assessment model for airspace tactical planning

This paper presents a conflict risk assessment model developed for the purpose of airspace tactical planning under the framework for airspace planning and design based on conflict risk assessment. The model is intended for comparison of different alternative flight scheduling scenarios for a given airspace sectorisation, from a risk and safety point of view. Conflict risk is assessed using duration and severity of conflict situation in the observed airspace under given circumstances. The model is based on the assumption that conflict between pair of aircraft exists when either horizontal or vertical separation minima are violated. For the purpose of risk assessment at the tactical planning level, a term “elementary risk” is introduced. It is defined as the ratio between: (1) the surface limited by minimum separation line and function representing the change of aircraft separation and the surface limited by minimum separation and time moments presenting the conflict duration, and (2) abscissa. The risk is then defined as the ratio between the “elementary risk” and the observed period of time. Apart from the risk between aircraft pair, an assessment of the total risk is also considered. A simple illustration of the model application shows that in addition to airspace geometry, the conflict risk between aircraft pair and total conflict risk also depends on traffic demand, aircraft speed, spatial and temporal distribution of traffic in the airspace as well as the applied separation minima. The developed model is intended for use both in en-route as well as terminal airspace and allows for the determination of the most suitable flight schedule which would be balanced with risk and capacity requirements (lower risk, greater capacity).

► A conflict risk assessment model was developed for airspace tactical planning.
► The risk is defined as combination of the conflict duration and severity.
► It is designed to be used for scheduling purposes in the given airspace.
► The model is intended for use in both en-route as well as in the TMA airspace.
► Numerous factors influencing risk values are identified.