Air traffic is an important part of our mobility with an increasing rate in transport volume of around 5% per year. Air traffic also contributes to anthropogenic warming by around 5%. Here we present a climate impact assessment tool AirClim and give an overview on the recent technology assessments. Finally, we present a best practice for a robust climate impact assessment, which combines a comprehensive four-layer approach to model the air traffic system with AirClim and includes aspects of atmospheric uncertainties, sensitivities, and verification procedures.@en

Impacts of commercial aircraft operation upon the environment, which are caused primarily from emissions of CO2, NOx and the formation of contrails, are matter of growing concern, as aviation is one of the fastest developing industrial sectors worldwide and the awareness of its effects is expanding. Recent research has focused on the cost-benefit potential of different mitigation strategies, which optimize flight trajectories with respect to climate and economy, but most of these mitigation strategies cannot be implemented in the near future due to technical challenges.The objective of this paper is to present an interim mitigation strategy, which bridges this time period. In analogy to military exclusion zones, climate restricted airspaces (CRA) are defined based on 3-D climate change functions, characterizing the environmental impact caused by an aircraft emission at a certain location. Regions with climate costs greater than a threshold value are closed in the corresponding month; others are cleared for air traffic. To estimate the cost-benefit potential of this strategy, a preliminary analysis is conducted on the route from Helsinki (EFHK) to Miami (KMIA). Affected flight trajectories are re-routed optimally around resulting CRA with regard to monetary costs for varying threshold values. Therefore, flight simulation algorithms are developed, which solve a non-linear optimal control problem. For each optimized flight trajectory corresponding average temperature response (ATR) and cash operating costs (COC) are expressed relative to a reference great circle trajectory with constant Mach number and compared with the climate mitigation potential of climate optimized trajectories.@en

Climate optimized flight trajectories are considered to be a promising measure to mitigate non-CO₂ emissions’ environmental impact, which is highly sensitive to locus and time of emission. Within this study, optimal control techniques are applied in order to determine 2D (lateral) and 3D (lateral and vertical) cost-optimized flight trajectories while mitigating their climate impact by minimizing emissions and flight time in highly climate sensitive regions. Therefore, monetary and 4D-climate cost functions, describing the climate sensitivity in dependency of the emission location, altitude, time and weather situation, are integrated into the optimization algorithm. For both, 2D- and 3D-optimization, the cost-benefit potential (climate impact mitigation vs. rise in operating costs) is investigated for nine fictitious North Atlantic routes for eastbound and westbound directions in the presence of winds. The conducted study shows large potential for both measures as the reduction of climate sensitivities along the trajectory often predominates the additional emissions caused by headwinds, additional climb-and descent phases, additional flight distance, and off-design altitudes. Flight trajectories optimized within the horizontal plane can reduce the average temperature response (ATR) by approximately 15 % for a two percent increase in cash operating costs (COC). This mitigation potential is significantly improved by superposition of lateral and vertical optimization. 3D-optimized trajectories which are comparable in cost increase achieve a 20-35 % higher ATR reduction than their 2D-optimized counterparts. Further, they reduce global warming more efficiently (higher ATR reduction per unit cost increment) and to a higher extent. However, achieving maximum climate impact mitigation is linked with an disproportional rise of cash operating costs in both cases. Therefore, a careful consideration of the required climate impact savings as well as the accepted surcharges is necessary.

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