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[Abstract] This paper evaluates through Monte Carlo (MC) simulation an airborne self separation concept which has been developed for use in en-route traffic conditions such as encountered over the Mediterranean area. For three different encounter scenarios, probabilities for violating minimum separation and for near-mid-air and mid-air events are estimated by applying powerful novel MC simulation approaches in rare event estimation. This provides great new insight in the efficacy of airborne conflict resolution management. The paper shows several quantitative risk estimates and presents an interpretation of these results in terms of safety. It shows that airborne self separation can be very effective, but also has its limitations for dense traffic conditions when conflict resolution is done in a sequential and un-coordinated way.

Airborne Separation Assistance System (ASAS) is seen as a promising option for the future ATM concept to increase capacity and flight efficiency while maintaining flight safety. One idea of recent interest in ASAS applications is Airborne SPacing Application using enhanced Sequencing and Merging (ASPA-S&M). The S&M is expected to support energy saving arrivals, commonly referred to as Continuous Descent Arrivals (CDA). The motivation for our study is the need to clarify how safety and capacity depend on the setting of spacing criteria and in combination with specific S&M design aspects, and to identify any potential emergent behavior that should be taken into account in the operation design. For this purpose, a preceding study has designed initial mathematical models of the ASAS application for two aircraft trailing. This research develops the models to multiple aircraft trailing under stochastic wind conditions. In this paper, ASAS core components and their interactions are captured to build an integrated model using a Stochastically and Dynamically Colored Petri Net (SDCPN). Through Monte Carlo simulation based on the SDCPN model, we evaluate the performance of ASAS speed control for CDA operation considering the wind effect and multiple trailing aircraft.

With increasing traffic there often are environmental and economical reasons to optimise Simultaneous Converging Instrument Approaches (SCIA) without sacrificing the high safety levels realised in air traffic. One of the well known safety issues of SCIA is the risk of a mid air collision due to a double go around. The aim of this paper is to show through a working example that there is a clear advantage to accomplish the safety protection through support of advanced accident risk assessment methodology. In this paper such methodology is applied to a specific example of SCIA at Schiphol airport. Comparison of the obtained results against FAA established SCIA criteria shows that there are situations in which these FAA criteria are not met, while the collision risk is not higher than for other situations that satisfy these criteria. The implication for Schiphol airport is that a specific change can be introduced as being risk neutral. The implication for other busy airports with converging runways might be that there is room to develop new or improved SCIA without compromising safety.

Airborne separation assurance is seen as a promising option for the future air traffic management concept to provide an increase in capacity and flight efficiency while maintaining flight safety. So-far, studies or expectations are largely based on assumptions about the achievable spacing and separation criteria. These assumptions range from optimistic to reserved, when comparing these separation criteria to currently used radar surveillance-based values. In any case, there is a clear knowledge gap on this subject. Thus, it is important to assess the relationship between spacing and separation distances on one hand and safety on the other hand. This relationship directly affects the effectiveness of airborne separation assurance. The aim of this paper is to address this issue by conducting an accident risk assessment, including a bias and uncertainty assessment and an assessment of risk sensitivity to spacing and separation values. Each stage in the methodology used is illustrated by examples. It is shown that the methodology provides valuable feedback on both the airborne separation assurance operation and the accident risk assessment.