Optimization of Weather Adaptive Noise Abatement Trajectories

As projected air travel is expected to increase up till 2030, future airports are faced to deal with the impact of (rising) noise hinder within their environment and the resulting allowed attainable throughput capacity. To date, several proposed techniques are able to lower the noise contribution. This thesis study focusses on weather-adaptive trajectory optimization, in which departure trajectories - subjected to day-to-day meteorological variations - are reshaped in such a way that inhabited areas are (partly) avoided to exposed noise areas generated by the aircraft. Incorporating day-to-day meteorological variability into trajectory optimization leads to an enhancement over reference-day trajectory optimization. This enhancement allows for improved accuracy with respect to the aircraft performance- and noise footprint calculations. The accuracy increase can be used to generate opportunities to improve the reference-day optimized trajectories even further. This led to the following purpose statement: The aim of this thesis work is to accurately represent the noise footprint by means of quantifying the influence of meteorological variability of the effects in wind and temperature variations on the shape and extent of aircraft acoustic footprints and use this information to optimize aircraft trajectories for diverse objectives. For this purpose, the FORT reference-day optimization tool is extended with weather dependent effects in an accurate and computationally tractable manner. The enhanced, weather-adaptive, FORT tool is able to optimize flight trajectories with respect to time, fuel, emissions, and awakenings objectives at any given airport for several departure procedures. Within FORT, the noise submodel is based on the INM methodology and enhanced with daily varying excess attenuation. This day-to-day varying excess attenuation replaces the lateral attenuation correction, which represented average yearly excess attenuation. The day-to- day excess attenuation is accessed for various noise-observer distances by means of an EA-database. In this way, the noise submodel employs a table lookup approach for both its NPD- and EA-calculations, maintaining simple and fast lookup table calculations while allowing complex evaluation of atmospheric effects on noise contours. Aircraft and acoustic performance is significantly influenced by varying temperature, relative humidity, wind speed, and wind direction layers. A positive temperature lapse rate distribution leads to upward ray path refraction, causing shadow zones, where a negative lapse rate results in downward refraction, causing caustics formation. Furthermore, the combination of temperature and relative humidity have a significant effect on the amount of acoustic absorption. Finally, the combination of temperature and wind layers induce greater speed of sound differences. This greater difference leads to a stronger presence of shadow zones and caustics phenomena, which can be used to eliminate noise at populated areas. Meteorological phenomena, which are seasonal dependent, cause the temperature, relative humidity, and wind profile distribution in the troposphere to vary, which results into different day-to-day aircraft and acoustic performance. The impact of weather-adaptive optimization is assessed by means of a case study in which two departure trajectories are optimized for multiple objectives, while being subjected to several atmospheric profiles. The two departures are based on standard instrument departures currently in use at AAS. The weather-adaptive trajectory optimization model complies with all the regulations and guidelines applicable to departure trajectories prescribed by PANSOPS and AAS in order to create a realistic and feasible trajectory. The atmospheric profiles incorporate temperature-, relative humidity-, wind speed-, and wind direction distribution differences to show the impact of seasonal effects on the optimization outcome. The weather-adaptive optimization results are compared to both reference-day optimization results and standard departure trajectories executed at AAS. For both cases, significant differences in aircraft- and acoustic performance are obtained for all objectives (time, fuel, emission, and awakenings). Firstly, when comparing the reference-day optimization to the results of the weather-adaptive optimization, it is concluded that the true impact of reference-day optimized trajectories on time, fuel, emission, and awakenings objectives differ significantly when subjected to a nonreference- day atmospheric profile. The time, fuel, and emission objectives are dependent on aircraft performance and are therefore affected by the varying wind speed and direction profile. The awakenings objective is both affected by the aircraft- and acoustic performance and therefore influenced by the full atmospheric profile. Secondly, for both standard AAS departure trajectories and reference-day optimized trajectories, it is concluded that the weather-adaptive optimization is able to generate an opportunity to further decrease the objectives. FORT utilizes the atmosphere in a positive manner, by means of aircraft performance advantages and acoustic focussing effects (e.g. directing shadow zones towards unpopulated areas). Finally, it can be concluded that the inclusion of meteorological variability into trajectory optimization leads to improved accuracy of the aircraft- and acoustic performance in general. These results create a better understanding about the atmospheric effects in terms of aircraft performance and subsequent noise contours. Furthermore, the weather-adaptive model is able to use the accuracy increase to further decrease the awakenings impact. For future work, the results can be further improved by analyzing different aircraft types on trajectory optimization output. Furthermore, the combination of multiple simultaneous optimized arrival- and departure trajectory optimizations could be researched in order to improve the feasibility of the current established trajectories with respect to separation requirements. Last but not least, societal costs play a major role when optimizing the awakenings objective. In certain cases, the total number of awakenings can be reduced significantly. This decrease however, may be at the expense of accompanying societal costs as new trajectories could induce complaints and other forthcoming societal costs when flying over different populated areas. The impact of changing the trajectories with respect to social aspects could be researched in more detail to establish societal feasibility of the optimized trajectories.Air transport and Aerospace OperationsControl and SimulationAerospace Engineerin