## 3 Results: Comparing Different Operational Mitigation Measures in Aviation
### Generalization and Comparison within Measure Types
#### 3.2.1 Comparison of Trajectory-Related OIs  
Scaling of the LOSL results to the European target flight plan can be performed for different application scopes. We find a mitigation potential of 1.3% in ATR100 for implementation of LOSL on all North Atlantic flights of the target sample of European flights (associated with 0.4% increase in DOC). Scaling the results to implementation on all long-range flights from and to Europe, we observe a reduction potential in ATR100 by 1.8% (+1.0% in DOC) for the European target flight plan. In general, we see higher mitigation potentials for North Atlantic flights compared to other long-distance flights from or to the ECAC area caused by the specific weather situation on the considered day.  
Implementation of FREE or WIND in the considered airspace only leads to limited mitigation potentials in relation to the target flight plan (between 0.3% and 0.4% depending on the selected objective function, associated with a slight DOC decrease of 0.1%). However, it can also be assumed that the concept can be expanded to further European airspaces. The reports by Functional Airspace Block Europe Central (FABEC) [72; 73; 74] show that the overall routing inefficiency defined by comparing the great-circle distances and planned flight distances is around 5.8% in FABEC airspaces in 2021, and it is around 5.6-5.9% in the investigated German Airspace between 2018 and 2021. Therefore, obtained results can be considered representative of the European region in terms of efficiency and fuel-saving potential. Nevertheless, the representativity of the found climate mitigation potentials is limited due to the specific meteorological conditions in this airspace on the investigated day. For this example, almost no CiC are expected to form in the considered temporal and spatial scope. For the target sample, we observe a significantly higher non-CO\({}_{2}\) climate impact for the target flight plan compared to the individual airspace reference (CO\({}_{2}\)-Eq of 4.87 compared to 2.65), which is among other effects explained by limited climate impact from CiC in the selected airspace (contribution of 11.5% to ATR100 for the target flight plan compared to 0.6% in the selected airspace). Therefore, we expect a smaller mitigation potential when scaling FREE and WIND concepts to a broader scale.  
Modeling climate-optimized trajectories (CLIM) on average shows large mitigation potentials of 9.9% in the North Atlantic region while keeping cost increase below 4.4% for the investigated reference flights. If these mitigation potentials can be transferred to all North Atlantic flights, we find a climate mitigation potential of 1.1% and a climate mitigation potential of 3.3% when implementing climate-optimized flight planning for all European long-haul flights (+1.1% and +2.7% in DOC, respectively) for the overall target flight plan.  
Figure 7 combines the obtained mitigation potentials for different trajectory-related OIs and different OI application scopes. Obviously, we find the highest mitigation potentialby implementing CLIM as it incorporates four dimensions in trajectory optimization. On average, approximately one-third of the mitigation potentials of CLIM can be achieved with LOSL, though associated with relatively high changes in DOC. The mitigation potentials of FREE and WIND are found to strongly depend on the selected airspace and the implementation scope. We estimate the mitigation potentials to be between the potentials observed for LOSL and CLIM. In contrast to other OIs, a reduction of routing inefficiencies due to the implementation of FREE/WIND is associated with a decrease in operating cost. However, the obtained results have been achieved for the selected winter day of 11 December 2018 only. In comparison to other day-specific case studies, e.g., [45; 75], we see that mitigation potentials for this day are found to be higher, especially in the North Atlantic region, which needs to be considered when extrapolating the results to annual potentials.