Helicopter Wake Encounters in the Context of RECAT-EU

This work presents a first attempt to apply the RECAT-EU (European Wake Turbulence Categorisation and Separation Minima) methodology of fixed-wing aircraft separation to helicopters. The approach is based on a classification of helicopters in categories using their rotor diameter and weight combined with wake comparisons between different classes of fixed-wing aircraft and helicopters. Where necessary the upset caused by a wake encounter to a simple helicopter model is used to establish safe separation distances. The work is based on a very limited amount of data for wake strengths but shows that the principles of the RECAT-EU methodology are directly applicable to helicopters at least for landing and take-off. This research calls for further measurements of helicopter wakes with modern methods so that the suggested separation distances can be further ascertained and ultimately refined allowing for better and safer integration of fixed and rotary-wing traffic at airports

Assessment of dynamic pairwise separation benefits using an Airport-in-a-Lab concept

Today dynamic pairwise separations are considered the last evolutional step of research in order to alleviate the capacity reducing effects of wake-vortex-related aircraft separations. Within the L-bows project we employed DLR German Aerospace Center’s wake vortex prediction and monitoring system WSVBS to predict safe minimum separations between arriving aircraft pairs depending on aircraft parameters and weather conditions. Based on an actual parameter set the dynamic pairwise separation values may be lower than separations from other frameworks. One resulting potential benefit is the possibility to accommodate more actual landings per time unit or to reduce arrival delay if demand is kept unchanged. Compared to other separation rule sets the challenge in utilizing and assessing this benefit is the short forecast lead time of the crucial weather conditions. We developed an assessment of the potential benefits of dynamic pairwise separations using an Airport-in-a-Lab concept. The paradigm of the concept is to combine real world airport data and future concepts in order to demonstrate the benefits in a laboratory environment. The results as exemplary benefits in terms of average arrival delays and their translation into direct cost savings were showing a range of 25% to 43%. Thus benefits were measurable within the Airport-in-a-Lab scenario but their realization in real life will strongly depend on the specific weather situation at an airport and the underlying demand-to-capacity ration for arrivals

Flexible runway use modeling using pairwise RECAT-EU separation minima

If we would take fuel consumption and noise annoyance into account in the runway allocation process,runway allocation can take place more efficiently, both in terms of fuel cost as well as noise annoyance. In this research, the focus is on the further development of a model in order to make the calculationsmore refined. Moreover, the improvements conducted in this research relate to the methodologies to compute the cost of the decision variables and the level of complexity of specific linear programming constraints in the optimization model. Consequently, the aim of this research is to answer the following research question: Can the performance of Standard Flex be further optimized by applying pairwise flight dependencies, while ensuring and contributing to a valid trade-off between runway capacity, noise emission, fuel burn and safety. By means of this research, the flexible runway allocation model has been improved on many aspects. The computation strategy of both objectives has moved from a reference aircraft based computation strategy to an analysis based on each unique aircraft on its own. This refined computational approach has resulted in a better understanding and modeling strategy of the operations that take place at an airport. Finally, the implementation of RECAT-EU separation minima has resulted in a reduction of 5-10% in overall separation times with respect to the regular ICAO WTC strategy, based on multiple air traffic demand mixture scenarios, based on a specific demand of flights?.Aerospace Transport & Operation