# Preliminary Impact Assessment of the Ad Hoc Separation Minima: A New Separation Mode
## 5 Discussion  
After applying the concept in three different scenarios, the achieved outcomes are compared. Regarding the environment and cost-efficiency KPAs, it should be noted that the best results for LECMZMU and LECMTLU are obtained for lateral \(LOS\) resolved with horizontal maneuvers. For LECMDGU, lateral \(LOS\) resolved with horizontal maneuvers \begin{table}
\begin{tabular}{c c c c c} \hline \hline \begin{tabular}{c} **Scenario** \\ **LECMDGU** \\ \end{tabular} & \begin{tabular}{c} **Capacity** \\ **(No. of** \\ **Aircraft/hour)** \\ \end{tabular} & \begin{tabular}{c} **No. of** \\ **Aircraft/hour** \\ \end{tabular} & \begin{tabular}{c} **Difference** \\ **(\%)** \\ \end{tabular} & \begin{tabular}{c} **Percentage of** \\ **Capacity Increase** \\ **(\%)** \\ \end{tabular} \\ \hline \begin{tabular}{c} **Baseline scenario** \\ **ASMT (no CD\&R)** \\ \end{tabular} & 46.74 & 46 & - & - \\ \hline \
\begin{tabular}{c} **Scenario 1** \\ **ASMT (no CD\&R)** \\ \end{tabular} & 47.17 & 47 & 0.43 & 0.9\% \\ \hline
\begin{tabular}{c} **Scenario 2** \\ **ASMT (CD\&R)** \\ \end{tabular} & 47.63 & 47 & 0.89 & 1.9\% \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Capacity results in LECMDGU. Figure 10: Environment and cost-efficiency results for the LECMDGU sector. provide the highest benefits in flown distance and delay while for fuel and \(CO_{2}\) emissions, the best results are obtained for longitudinal \(LOS\) resolved with level change. However, a comparison of results was made regarding the average resolution values corresponding to the total \(LOS\) (lateral and longitudinal). Therefore, the average values obtained, considering the total \(LOS\) resolved with horizontal and vertical maneuvers, are discussed. * **Capacity:** the results are favorable in all three scenarios, with an increase in the number of aircraft per hour. The most significant improvement is observed in the LECMZMU scenario, where capacity is enhanced by 2.3%. In LECMTLU, the increase is 2%, while in LECMDGU it is 1.9%. These outcomes are obtained considering that the ATCO is aided by the ASMT tool, which, in addition to determining the Ad Hoc separation, incorporates CD&R functionalities. These results underscore the positive impact of the Ad Hoc separation concept on capacity (increase of one aircraft/hour). However, they highlight that the separation minima are not a key factor in capacity computation for an ENR scenario. * **Environment and airspace user cost-efficiency**: positive results are obtained for these KPAs. The values obtained for distance flown, fuel, \(CO_{2}\), and delay reduction, are for each \(LOS\) saved by applying the Ad Hoc separation concept. For the LECMZMU sector, the most favorable outcomes occur when lateral \(LOS\) is resolved with horizontal maneuvers. Considering both lateral and longitudinal \(LOS\) (total \(LOS\)), along with both resolution maneuvers (level change and horizontal vector), there is an average reduction of 1.30 NM/\(LOS\) in distance saved (1.6% of the flown distance in the sector), a delay of 0.09 min/\(LOS\) saved (0.8% of the flight time in the sector), 12 kg fuel/\(LOS\) saved, and 37 kg \(CO_{2}\)/\(LOS\) saved. For the LECMTLU sector, the best results are obtained for lateral \(LOS\) resolved with horizontal maneuvers (vectors), as in LECMZMU, although the benefits are slightly lower. Considering the total \(LOS\) (lateral and longitudinal) and both resolution maneuvers (level change and horizontal vector), there is an average reduction of 1.39 NM/\(LOS\) in distance saved (1.2% of the flown distance in the sector), a delay of 0.12 min/\(LOS\) saved (0.8% of the flight time in the sector), 8.5 kg fuel/\(LOS\) saved, and 27 kg \(CO_{2}\)/\(LOS\) saved. For the LECMPGU sector, the obtained benefits are lower than in LECMZMU and LECMTLU. However, due to the predominance of \(LOS\) resolutions with level changes, the best results are observed for fuel consumption and \(CO_{2}\) metrics.