# Airline Network Planning Considering Climate Impact: Assessing New Operational Improvements
## 3 Results
### ATR Scenario  
In this analysis, we compared ATR with BAU scenarios for all three airlines to show how considering climate impact would affect an airline's network structure. The aggregated implications of the new objective function on the climate and non-climate KPIs are depicted in Figure 4. According to the findings, Easylet and KLM may reduce around 11% of their ATR20 and ATR100 while compromising 10% of their profit. Because there is no long-haul flight in the Easylet case study, the KPIs associated with long-haul flights remain unchanged for this airline. TAP, on the other hand, reduces ATR20 by 36% while losing 20% of its profit. TAP has a relatively higher ATR20 reduction because the long-haul flights are significantly reduced in the new network plan. TAP has fewer long-haul destinations than KLM, resulting in limited alternative long-haul destinations when aiming for ATR20 reduction. As a result, some of the videbodies are assigned to shorter distances, significantly reducing long-haul ATR20 at the cost of increasing short-haul ATR20. In general, long-haul flights are more profitable than shorter ones. Therefore, reducing the number of long-haul flightsmay deteriorate the profit more than tweaking the short-haul routes. Figure 4b depicts this scenario's increase in short-haul flights. Despite a high percentage increase in the ATR20(SH) value, the net ATR20 shows a reduction. The relative changes in the number of both short- and long-haul flights show an increase for KLM. KLM also offers more seats due to the increased number of flights. At the same time, ASK decreases, which is due to the fact that flights are being operated on shorter long-haul routes. RPK is also reduced because shorter long-haul flights are not as profitable as the longer ones. Therefore, there is a shift from flying in longer long-haul routes towards shorter ones. Shorter flights also result in lower utilisation because, on average, an aircraft spends more time in terms of turnaround time and waiting for the next flight rather than flying in a route with a long block hour. KLM serves a similar number of passengers in this scenario, but the portion of connecting passengers is lower than in the BAU scenario which contributes to the lower profit. Transporting connecting passengers is more profitable because of the average higher airfare as well as improving the LF of the outbound flights from the hub airport. In the TAP and Easylet case studies, similar patterns of relative changes in non-climate KPIs occur. The total number of flights and offered seats are increased while the ASK and RPK are decreased. In contrast to KLM, fleet utilisation increases for TAP and Easylet. An increase in fleet utilisation is expected to lead to more profit, but in this study, this was not the case. TAP and Easylet reduce their flights in their highly profitable routes due to the high ATR20 value at the same time. Consequently, the extra profit gained by increasing fleet utilisation compensates for a part of the profit loss from fewer flights on highly profitable routes. Further examination of the TAP and KLM networks reveals a strong relationship between the viability of long-haul flights and the effectiveness of feeding flights. In order to maintain profitable long-haul flights in the network, enough connecting passengers must be transported to the hub at the right time. Long-haul flights are only scheduled if a break-even LF is met. In particular, for TAP, it is difficult to keep the frequency of some long-haul routes, even for some high-yield routes. Although the number of short-haul flights is increased, the required connecting interval at the hub airport is not met. Hence, the majority of extra passengers in the ATR scenario are local passengers who do not contribute to the profitability of the outbound connecting flights. In the case of KLM, the demand is more flexible (due to the availability of a larger number of destinations) so many alternative feeding flights could be scheduled.