## 3 Results: Comparing Different Operational Mitigation Measures in Aviation
### Mitigation Potential from Assessment of Individual OIs
#### 3.1.1 Individual Mitigation Potential of Trajectory-Related OIs  
The individual study on LOSL finds a climate mitigation potential in ATR20 of 16.1% and 11.5% in ATR100 for 11 December 2018 for a North Atlantic flight sample (\(-5.4\%\) in ATR100 for the full sample of considered European long-range flights). The reduction in climate impact can be explained by an overcompensation of rising effects from CO\({}_{2}\) and NO\({}_{x}\) by a reduction in effects from H\({}_{2}\)O and CiC. Besides the significant reduction in climate impact, an increase in fuel consumption and flight time is observed, leading to a higher operating cost of approximately 1.7% on the selected case study day in December [45; 70]. By contrast, the OIs FREE and WIND show a substantial reduction potential in fuel consumption, CO\({}_{2}\) as well as non-CO\({}_{2}\) emissions, and climate impact. These concepts result in an overall reduction potential between 7 and 9% in fuel consumption and CO\({}_{2}\) emissions, between 26 and 31% in NO\({}_{x}\) emissions, and a climate mitigation potential between 20% and 24% in ATR100 in the focused airspace. Reduction in flight time and fuel costs result in a DOC decrease of up to 4.3%. Nevertheless, travel time and air traffic control (ATC) complexity increase with wind-optimized trajectory planning [47]. Moreover, the analysis of CLIM for four transatlantic night flights shows route-individual climate mitigation potentials between 9% and 15% for ATR20 (8-13% in ATR100) associated with fuel penalties between 2% and 6% [48; 71]. An overview of the mitigation potentials is given in Figure 4, and further details on the results are described in Appendix A.1.  
Although all trajectory-related measures are based on an assessment of individual flight missions on 11 December 2018, different assumptions are made for the reference case. Therefore, an additional adjustment and scaling of the results is required before comparing the individual studies' results. Different sizes of the considered scope are illustrated in Figure 4 by covered ASK in the reference case. For instance, the size of the flight plan (large sample of North Atlantic flights for LOSL in comparison to selected flights for CLIM or flights in a defined airspace for FREE and WIND) and the considered aircraft types (wide-body or narrow-body aircraft) explain large differences in covered ASK per reference flight plan, which requires scaling of the individual results to a comparable scope. In this context, it needs to be considered that results for all trajectory-related OIs are only comparable for the investigated winter day and cannot directly be extrapolated to one year. Figure 5 illustrates the regional climate sensitivity as indicated by the merged aCCF for two representative days, one for winter and one for summer 2018, that have been analyzed in the LOSL study [45]. We observe significant differences in ATR100 per fuel burnt. In particular, regions of contrail formation are expected to significantly influence the location of highly climate-sensitive areas. Obviously, the location of areas with high climate impact varies for the displayed days, e.g., when looking at the focused airspace in studies on FREE and WIND. This influences the mitigation potentials of trajectory-related measures in general and the scaling accuracy for the investigated reference airspace in FREE and WIND in particular.