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Item type:Publication, Access status: with files , Mitigation of aviation’s climate impact through robust climate optimized trajectories in intra-european airspace(ICAS, 2022-09); ; ; ; Aircraft trajectories are currently flown and optimized to reduce operating costs, keeping engine CO2-emissions from burnt fuel at a minimum by following fuel optimized routes under consideration of wind. However, research has shown that the location and time of non-CO2 emissions such as NOx, water vapor or the formation of contrail cirrus contribute to about two thirds of aviation’s induced climate impact [1]. Consequently, one option to reduce this impact on a short time horizon is operational measures that aim to optimize aircraft trajectories with regard to climate impact by avoiding atmospheric regions that are especially sensitive to non-CO2 emissions from aviation. For this purpose, the effects of individual emission species need to be quantified in order to assess the mitigation potential by climate-optimized routing. For this reason, multi-dimensional algorithmic climate change functions, which allow for the quantification of the climate impact of emissions, based on meteorological parameters which a e available from weather forecast data is used. These algorithmic climate change functions are integrated into the cost functional of a trajectory planning algorithm which is based on an optimal control approach and applied in order to estimate climate optimized aircraft trajectories trading climate impact reduction against cost increase. Since the climate impact and therefore the algorithmic climate change functions are highly dependent on the prevailing atmospheric conditions, particularly the formation of contrail cirrus, weather prediction uncertainties are considered in order to determine robust eco efficient trajectories. Within this study, the methodology and optimization applied to determine such a robust solution are presented and results are analyzed for an exemplary intra-European flight route.Publicationtype: Conference PaperScopus© Citations 1 116 205 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , A comprehensive survey on climate optimal aircraft trajectory planning(Multidisciplinary Digital Publishing Institute (MDPI), 2022-03-07); ; ; ; The strong growth rate of the aviation industry in recent years has created significant challenges in terms of environmental impact. Air traffic contributes to climate change through the emission of carbon dioxide (CO2) and other non-CO2 effects, and the associated climate impact is expected to soar further. The mitigation of CO2 contributions to the net climate impact can be achieved using novel propulsion, jet fuels, and continuous improvements of aircraft efficiency, whose solutions lack in immediacy. On the other hand, the climate impact associated with non- CO2 emissions, being responsible for two-thirds of aviation radiative forcing, varies highly with geographic location, altitude, and time of the emission. Consequently, these effects can be reduced by planning proper climate-aware trajectories. To investigate these possibilities, this paper presents a survey on operational strategies proposed in the literature to mitigate aviation’s climate impact. These approaches are classified based on their methodology, climate metrics, reliability, and applicability. Drawing upon this analysis, future lines of research on this topic are delineated.Publicationtype: Journal ArticleScopus© Citations 28 97 198 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Climate impact mitigation potential of formation flight(Multidisciplinary Digital Publishing Institute (MDPI), 2021-01-08); ; ; ; The aerodynamic formation flight, which is also known as aircraft wake-surfing for efficiency (AWSE), enables aircraft to harvest the energy inherent in another aircraft’s wake vortex. As the thrust of the trailing aircraft can be reduced during cruise flight, the resulting benefit can be traded for longer flight time, larger range, less fuel consumption, or cost savings accordingly. Furthermore, as the amount and location of the emissions caused by the formation are subject to change and saturation effects in the cumulated wake of the formation can occur, AWSE can favorably affect the climate impact of the corresponding flights. In order to quantify these effects, we present an interdisciplinary approach combining the fields of aerodynamics, aircraft operations and atmospheric physics. The approach comprises an integrated model chain to assess the climate impact for a given air traffic scenario based on flight plan data, aerodynamic interactions between the formation members, detailed trajectory calculations as well as on an adapted climate model accounting for the saturation effects resulting from the proximity of the emissions of the formation members. Based on this approach, we derived representative AWSE scenarios for the world’s major airports by analyzing and assessing flight plans. The resulting formations were recalculated by a trajectory calculation tool and emission inventories for the scenarios were created. Based on these inventories, we quantitatively estimated the climate impact using the average temperature response (ATR) as climate metric, calculated as an average global near surface temperature change over a time horizon of 50 years. It is shown, that AWSE as a new operational procedure has a significant mitigation potential on climate impact. For a global formation flight scenario, we estimated the average relative change of climate response to range between 22% and 24% while the relative fuel saving effects sum up to 5–6%.Publicationtype: Journal ArticleScopus© Citations 6 177 305 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Climate-optimized trajectories and robust mitigation potential : flying ATM4E(Multidisciplinary Digital Publishing Institute (MDPI), 2020-10-30); ; ; ; Aviation can reduce its climate impact by controlling its CO2-emission and non-CO2 effects, e.g., aviation-induced contrail-cirrus and ozone caused by nitrogen oxide emissions. One option is the implementation of operational measures that aim to avoid those atmospheric regions that are in particular sensitive to non-CO2 aviation effects, e.g., where persistent contrails form. The quantitative estimates of mitigation potentials of such climate-optimized aircraft trajectories are required, when working towards sustainable aviation. The results are presented from a comprehensive modelling approach when aiming to identify such climate-optimized aircraft trajectories. The overall concept relies on a multi-dimensional environmental change function concept, which is capable of providing climate impact information to air traffic management (ATM). Estimates on overall climate impact reduction from a one-day case study are presented that rely on the best estimate for climate impact information. Specific weather situation that day, containing regions with high contrail impact, results in a potential reduction of total climate impact, by more than 40%, when considering CO2 and non-CO2 effects, associated with an increase of fuel by about 0.5%. The climate impact reduction per individual alternative trajectory shows a strong variation and, hence, also the mitigation potential for an analyzed city pair, depending on atmospheric characteristics along the flight corridor as well as flight altitude. The robustness of proposed climate-optimized trajectories is assessed by using a range of different climate metrics. A more sustainable ATM needs to integrate comprehensive environmental impacts and associated forecast uncertainties into route optimization in order to identify robust eco-efficient trajectories.Publicationtype: Journal ArticleScopus© Citations 30 273 227 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , A concept for multi-criteria environmental assessment of aircraft trajectories(Multidisciplinary Digital Publishing Institute (MDPI), 2017-08-01); ; ; ; Comprehensive assessment of the environmental aspects of flight movements is of increasing interest to the aviation sector as a potential input for developing sustainable aviation strategies that consider climate impact, air quality and noise issues simultaneously. However, comprehensive assessments of all three environmental aspects do not yet exist and are in particular not yet operational practice in flight planning. The purpose of this study is to present a methodology which allows to establish a multi-criteria environmental impact assessment directly in the flight planning process. The method expands a concept developed for climate optimisation of aircraft trajectories, by representing additionally air quality and noise impacts as additional criteria or dimensions, together with climate impact of aircraft trajectory. We present the mathematical framework for environmental assessment and optimisation of aircraft trajectories. In that context we present ideas on future implementation of such advanced meteorological services into air traffic management and trajectory planning by relying on environmental change functions (ECFs). These ECFs represent environmental impact due to changes in air quality, noise and climate impact. In a case study for Europe prototype ECFs are implemented and a performance assessment of aircraft trajectories is performed for a one-day traffic sample. For a single flight fuel-optimal versus climate-optimized trajectory solution is evaluated using prototypic ECFs and identifying mitigation potential. The ultimate goal of such a concept is to make available a comprehensive assessment framework for environmental performance of aircraft operations, by providing key performance indicators on climate impact, air quality and noise, as well as a tool for environmental optimisation of aircraft trajectories. This framework would allow studying and characterising changes in traffic flows due to environmental optimisation, as well as studying trade-offs between distinct strategic measures.Publicationtype: Journal ArticleScopus© Citations 41 455 518