Alexander Lau

Potential for Fuel Reduction through Electric Taxiing

In this study the potential for fuel savings through electric taxiing is investigated. Therefore simple models are used to investigate the difference of fuel consumption during the ground phase and the flight phase of a gate-to-gate mission. By using these models the fuel savings can be estimated, which are the sum of the fuel saved during ground operations and the additional fuel required during the flight phase due to an increased Operating Empty Weight. The models are applied to actual data of flights conducted by domestic carriers within the United States National Airspace System. Results show that electric taxiing offers the potential for fuel savings depending on the flight mission, i.e. the ratio of time an aircraft spends on ground and the flight distance. A parametric analysis is conducted to investigate the sensitivity of the results for different constraints. The study concludes with a comparison of the concept compared to other operational or technological measures aiming to reduce fuel consumption on ground.

Impact of Cloud Encounter Mitigation Procedures on Operational and Economic Effectiveness of HLFC Aircraft

The objective of this paper is to investigate the effect of cloud encounter mitigation procedures on operational and economic effectiveness of aircraft with hybrid laminar flow ncontrol (HLFC) based on real-world flight routes and weather data. The objective is to evaluate whether cloud mitigation procedures are an appropriate measure to maximize the expected benefit of HLFC-technology under realistic meteorological boundary conditions. A global analysis of cloud encounter on typical airline routes has been conducted based on atmospheric data provided by the European Centre for Medium-Range Weather Forecasts. nDifferent routing procedures have been benchmarked against each other and the most appropriate procedure for daily flight operation will be discussed. For optimizing the daily route planning of HLFC aircraft with respect to cost (direct routing with cloud Encounter and performance losses vs. re-routed flightpath) models for lateral trajectory optimization and calculation have been applied.

Individual Wake Vortex Separations: Capacity and Delay Impact on Single and Dual Dependent Runway Systems

Airport capacity constraints and growing traffic demand in air transportation cause congestion and delay on the ground and in the air. Conservative wake turbulence separation minima in the approach phase guarantee a minimum of in-flight wake encounters of trailing aircraft. On the other hand, in many situations weather-based separation minima could support more efficient runway utilization. This work estimates delay reduction and capacity gains of DLRs Wake Vortex Prediction and Monitoring System (WSVBS) through the application of reduced time-based approach separations for a single and dual dependent runway system. The system dynamically adjusts approach separations without compromising safety. Delay calculations are conducted with a dynamic runway queuing model, which is capable to process time varying approach separations. It provides the relevant delay data, where several representative operational scenarios enabled through the application of reduced separations on a single and dual dependent runway system are considered. Capacity profiles are created by processing WSVBS separation data with the actual traffic demand. The results give insight about possible delay reductions as well as related operational impact under given implementation assumptions. It is shown that the WSVBS provides efficiency gains on both runway systems, whereas operational requirements regarding the single runway system need to be taken into account applying reduced individual separations. Regarding the dual dependent runway system, an average hourly delay reduction up to 15 minutes maximum is revealed for the defined scenario setup.

Assessment of a Convective Weather Nowcasting and Tracking Algorithm Based on Delay Reduction Potential at Munich Airport (Part I)

This work presents the first part of an economic assessment of Rad-TRAM, which detects, tracks and predicts up to one hour heavy precipitation cells by using weather radar data. Rad-TRAM has been developed at DLR and will be assessed by analyzing delay data at Munich Airport during convective weather events. Delay reduction potential underlying operational adaptation through advanced weather information serves as assessment metric to quantify the economic benefit of the algorithm. Advanced weather information refers to the tracking, nowcasting and visualization of severe areas within thunderstorms. Delay data is evaluated during convective impact within the boundaries of terminal airspace of Munich airport and coverage areas within this airspace are considered regarding delay behavior. Arrival traffic is affected by mean individual delay rates of up to 21 minutes whereas departure traffic is more evenly impacted during convective impact. A delay analysis of time periods before and after convective impact reveals that there is potential for delay reduction, if advanced weather information is provided in these periods as well as in the period of convective activity.

European Air Traffic Flow Management with Strategic Deconfliction

To guarantee a safe journey for each aircraft, air traffic controllers make sure that separation minima are maintained. To prevent controller overburdening, each controller team is responsible for one confined sector. Furthermore, sectors limit the number of flights entering each hour. Compliance to all sector and airport capacity constraints in daily business is ensured by EUROCONTROL’s Network Management. This function balances the flights’ demand of airspace with available capacity by re-allocating departure timeslots. However, when minimum separation between two aircraft may become compromised, a conflict occurs. Conflicts are solved by controllers who provide pilots with instructions to maintain separation. Hence, conflicts increase controller workload and thus tighten sector capacity. The aim of this work is a prevention of actual conflicts by strategic deconfliction. Strategic conflicts refer to planned trajectories which violate separation minima in any future point in space and time. Mimicking a future Network Management, departure times are re-allocated to reduce the number of strategic conflicts while satisfying both sector and airport capacity constraints. As a basis for the deconfliction, actual datasets of planned trajectories, sector bounds and airport features are aggregated to model the European Air Traffic Flow Management. The allocation problem of departure timeslots is formulated as a Quadratic Binary Problem with linear delay costs, quadratic conflict costs and linear constraints. In an optimal solution, all strategic conflicts are solved. Finally, a trade-off between conflict reduction and delay is performed.