45 research outputs found

    Aircraft Cruise Phase Altitude Optimization Considering Contrail Avoidance

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    Contrails have been suggested as one of the main contributors to aviation-induced climate impact in recent years. To reduce the climate impact of contrails, mitigation policies such as taxation will be necessary in the future to incentivize jet aircraft operators to reduce contrail production. Contrails form in regions of the atmosphere with the right ambient conditions and they can be avoided by flying around these regions; this research investigates one such contrail avoidance strategy that uses flight level optimization to minimize contrail formation. A cruise phase flight profile system model was developed in this research that optimizes for environmental objectives such as contrails, CO2, and NOx, alongside traditional objectives such as fuelburn and flight time. Using this system model and 11 different aircraft types on 12 weather days, a preliminary study was done to determine the price range of contrail taxation that would incentivize airlines to operationally avoid contrails. Result suggests a price range of 0.12/NMto1.13/NM to 1.13/NM on contrail tax would effectively incentivize contrail avoidance. Furthermore, since operating costs differ depending on the type of aircraft, a single price on contrail tax may incentivize contrail avoidance on a small aircraft, but not larger ones. To account for this difference, a method of assigning contrail tax to different aircraft types is introduced using the aircraft maximum takeoff weight. Assuming airlines are incentivized to fly contrail avoidance strategies, the climate impact of the flight profiles was evaluated for 287 flights along 12 O-D pairs for the 24 hour day of April 12, 2010. Under various assumptions of contrail radiative forcing and time horizon of climate impact evaluation, the flight level optimization reduced the average climate impact per flight by as much as 39.1% from a baseline of wind-optimal flight at optimal cruise altitude. In comparison, a complementary lateral optimization method reduced 13.3% from the same baseline. Furthermore, flight level optimization shows to be more fuel efficient by reducing the climate impact of contrails by as much as 94% from the baseline, compared to 60% using the lateral approach. In terms of the CO2 emission from the additional fuelburn, the climate impact of lateral method was 4 times higher than the flight level approach. Lastly, result shows that designing for long-term environmental objectives is more energy efficient (reduction in climate impact per additional kilogram of fuel used) than short-term, which suggest reducing CO2 emission is favored over contrail avoidance in designing for climate impact optimal flight profiles

    Aircraft cruise phase altitude optimization considering contrail avoidance

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    Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (pages 76-77).Contrails have been suggested as one of the main contributors to aviation-induced climate impact in recent years. To reduce the climate impact of contrails, mitigation policies such as taxation will be necessary in the future to incentivize jet aircraft operators to reduce contrail production. Contrails form in regions of the atmosphere with the right ambient conditions and they can be avoided by flying around these regions; this research investigates one such contrail avoidance strategy that uses flight level optimization to minimize contrail formation. A cruise phase flight profile system model was developed in this research that optimizes for environmental objectives such as contrails, COâ‚‚, and NOx, alongside traditional objectives such as fuelburn and flight time. Using this system model and 11 different aircraft types on 12 weather days, a preliminary study was done to determine the price range of contrail taxation that would incentivize airlines to operationally avoid contrails. Result suggests a price range of 0.12/NMto1.13/NM to 1.13/NM on contrail tax would effectively incentivize contrail avoidance. Furthermore, since operating costs differ depending on the type of aircraft, a single price on contrail tax may incentivize contrail avoidance on a small aircraft, but not larger ones. To account for this difference, a method of assigning contrail tax to different aircraft types is introduced using the aircraft maximum takeoff weight. Assuming airlines are incentivized to fly contrail avoidance strategies, the climate impact of the flight profiles was evaluated for 287 flights along 12 O-D pairs for the 24 hour day of April 12, 2010. Under various assumptions of contrail radiative forcing and time horizon of climate impact evaluation, the flight level optimization reduced the average climate impact per flight by as much as 39.1% from a baseline of wind-optimal flight at optimal cruise altitude. In comparison, a complementary lateral optimization method reduced 13.3% from the same baseline. Furthermore, flight level optimization shows to be more fuel efficient by reducing the climate impact of contrails by as much as 94% from the baseline, compared to 60% using the lateral approach. In terms of the COâ‚‚ emission from the additional fuelburn, the climate impact of lateral method was 4 times higher than the flight level approach. Lastly, result shows that designing for long-term environmental objectives is more energy efficient (reduction in climate impact per additional kilogram of fuel used) than short-term, which suggest reducing COâ‚‚ emission is favored over contrail avoidance in designing for climate impact optimal flight profiles.by Hang Gao.S.M

    4D trajectory optimization of commercial flight for green civil aviation

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    For the current development of green civil aviation, this study aims to optimize the green four-dimensional (4D) trajectory of commercial flight by taking into account conventional cost and environmental cost. Some fundamental models, efficient processing methodologies, and conventional objectives are proposed to construct the framework of trajectory optimization. Based on the environmental cost including greenhouse gas cost and harmful gas cost, green objective functions are presented. The A* algorithm and the trapezoidal collocation method are employed to optimize the lateral path and vertical profile for 4D optimization trajectory generation. A case study for the A320 from Barcelona Airport to Frankfurt Airport yields the results that the optimal costs can be obtained under different objectives and the total cost can be more optimized by adjusting the weights of environmental cost and conventional cost. The study builds an aided tool for 4D trajectory optimization and demonstrates that environmental factors and conventional factors should be taken into comprehensive consideration when constructing the flight trajectory in the future, as well as it can underpin the green and sustainable development of the air transport industry

    Robust 4D Climate Optimal Flight Planning in Structured Airspace using Parallelized Simulation on GPUs: ROOST V1.0

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    The climate impact of the non-CO2 emissions, being responsible for two-thirds of aviation radiative forcing, highly depends on the atmospheric chemistry and weather conditions. Hence, by planning aircraft trajectories to reroute areas where the non-CO2 climate impacts are strongly enhanced, called climate-sensitive regions, there is a potential to reduce aviation induced non-CO2 climate effects. Weather forecast is inevitably uncertain, which can lead to unreliable determination of climate-sensitive regions and aircraft dynamical behavior and, consequently, inefficient trajectories. In this study, we propose robust climate optimal aircraft trajectory planning within the currently structured airspace considering uncertainties in the standard weather forecasts. The ensemble prediction system is employed to characterize uncertainty in the weather forecast, and climate-sensitive regions are quantified using the prototype algorithmic climate change functions. As the optimization problem is constrained by the structure of airspace, it is associated with hybrid decision spaces. To account for discrete and continuous decision variables in an integrated and more efficient manner, the optimization is conducted on the space of probability distributions defined over flight plans instead of directly searching for the optimal profile. A heuristic algorithm based on the augmented random search is employed and implemented on graphics processing units to solve the proposed stochastic opti- mization computationally fast. The effectiveness of our proposed strategy to plan robust climate optimal trajectories within the structured airspace is analyzed through two scenarios: a scenario with large contrails&rsquo; climate impact and a scenario with no formation of persistent contrails. It is shown that, for a night-time flight from Frankfurt to Kyiv, a 55 % reduction in climate impact can be achieved at the expense of a 4 % increase in cost.</p

    A Comprehensive Survey on Climate Optimal Aircraft Trajectory Planning

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    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&#34;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.This research was carried out as a part of the project EU-project FlyATM4E. FlyATM4E has received funding from the SESAR Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 891317. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and the SESAR JU members other than the Union

    Comparison of actual and time-optimized flight trajectories in the context of the In-service Aircraft for a Global Observing System (IAGOS) programme

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    Airlines optimize flight trajectories in order to minimize their operational costs, of which fuel consumption is a large contributor. It is known that flight trajectories are not fuel-optimal because of airspace congestion and restrictions, safety regulations, bad weather and other operational constraints. However the extent to which trajectories are not fuel-optimal (and therefore CO2-optimal) is not well known. In this study we present two methods for optimizing the flight cruising time by taking best advantage of the wind pattern at a given flight level and for constant airspeed. We test these methods against actual flight trajectories recorded under the In-service Aircraft for a Global Observing System (IAGOS) programme. One method is more robust than the other (computationally faster) method, but when successful, the two methods agree very well with each other, with optima generally within of the order of 0.1%. The IAGOS actual cruising trajectories are on average 1% longer than the computed optimal for the transatlantic route, which leaves little room for improvement given that by construction the actual trajectory cannot be better than our optimum. The average degree of non-optimality is larger for some other routes and can be up to 10%. On some routes there are also outlier flights that are not well optimized; however the reason for this is not known

    Can we successfully avoid persistent contrails by small altitude adjustments of flights in the real world?

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    This paper describes the first-ever operational contrail avoidance trial in the real world, which took place in the region of Maastricht Upper Area Control (including the northwest of Germany, the Benelux countries and part of the North Sea) in the year 2021. Contrail avoidance could be an efficient method for mitigating the climate impact of aviation. Applying a deliberate experiment design, air traffic was deviated every other day by changing the flight altitude by up to 2000 ft up or down if potential persistent contrails were predicted. Whether deviations were successful on average was checked using satellite images of high clouds and by application of a contrail detection algorithm, which makes use of the properties of contrails. Despite the fact that forecasting persistent contrails remains a challenge, the trial was successful at a significance level of 97.5 %, i.e., on average persistent contrails can be avoided for regular flights in the real world with a small intervention in the vertical flight path. The experiment is an important step towards a regular operational reduction of the aviation climate impact by means of air traffic management. Nevertheless, many open questions need to be solved prior to an operational implementation of contrail avoidance or climate optimised flight trajectories in legal ATM procedures

    UAS in the Airspace: A Review on Integration, Simulation, Optimization, and Open Challenges

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    Air transportation is essential for society, and it is increasing gradually due to its importance. To improve the airspace operation, new technologies are under development, such as Unmanned Aircraft Systems (UAS). In fact, in the past few years, there has been a growth in UAS numbers in segregated airspace. However, there is an interest in integrating these aircraft into the National Airspace System (NAS). The UAS is vital to different industries due to its advantages brought to the airspace (e.g., efficiency). Conversely, the relationship between UAS and Air Traffic Control (ATC) needs to be well-defined due to the impacts on ATC capacity these aircraft may present. Throughout the years, this impact may be lower than it is nowadays because the current lack of familiarity in this relationship contributes to higher workload levels. Thereupon, the primary goal of this research is to present a comprehensive review of the advancements in the integration of UAS in the National Airspace System (NAS) from different perspectives. We consider the challenges regarding simulation, final approach, and optimization of problems related to the interoperability of such systems in the airspace. Finally, we identify several open challenges in the field based on the existing state-of-the-art proposals

    An Approach to Analyze Tradeoffs for Aerospace System Design and Operation

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    There are important tradeoffs that need to be considered for the design and operation of aerospace systems. In addition to tradeoffs, there may also be multiple stakeholders of interest to the system and each may have different preferences as to the balance amongst the tradeoffs under consideration. A tradeoff hyperspace is created when there are three or more tradeoff dimensions and this increases the challenge associated with resolving the hyperspace in order to determine the best design and operation of a system. The corresponding objectives of this research are to develop a framework to analyze tradeoff hyperspaces and to account for the preferences of multiple stakeholders in this framework.This work was supported by the National Aeronautics and Space Administration (NASA) under grant NRA- #NNX10AN92A (NASA Ames). The authors are grateful to Dr. Neil Y. Chen and Dr. Banavar Sridhar in the Aviation Systems Division at NASA Ames for their valuable guidance and feedback in managing this project

    Reformulating aircraft routing algorithms to reduce fuel burn and thus CO2 emissions

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    During the UN Climate Change Conference (COP26), in November 2021, the international aviation community agreed to advance actions to reduce CO2 emissions. Adopting more fuel efficient routes, now that full global satellite coverage is available, could achieve this quickly and economically. Here flights between New York and London, from 1st December, 2019 to 29th February, 2020 are considered. Trajectories through wind fields from a global atmospheric re-analysis dataset are found using optimal control theory. Initially, time minimal routes are obtained by applying Pontryagin’s Minimum Principle. Minimum time air distances are compared with actual Air Traffic Management tracks. Potential air distance savings range from 0.7 to 16.4%, depending on direction and track efficiency. To gauge the potential for longer duration time minimal round trips in the future, due to climate change, trajectories are considered for historic and future time periods, using an ensemble of climate models. Next, fixed-time, fuel-minimal routes are sought. Fuel consumption is modelled with a new physics-driven fuel burn function, which is aircraft model specific. Control variables of position-dependent aircraft headings and airspeeds or just headings are used. The importance of airspeed in finding trajectories is established, by comparing fuel burn found from a global search of optimised results for the discretised approximation of each formulation. Finally, dynamic programming is applied to find free-time, fuel-optimal routes. Results show that significant fuel reductions are possible, compared with estimates of fuel use from actual flights, without significant changes to flight duration. Fuel use for winter 2019–2020 could have been reduced by 4.6% eastbound and 3.9% westbound on flights between Heathrow and John F Kennedy Airports. This equates to a 16.6 million kg reduction in CO2 emissions. Thus large reductions in fuel consumption and emissions are possible immediately, without waiting decades for incremental improvements in fuel-efficiency through technological advances
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