# Innovative Integration of Severe Weather Forecasts into an Extended Arrival Manager
## 5 Case Studies
### Synoptic Analysis
In the case of MXP, there were two available days--7 July 2019 and 6 August 2019--without airport closure under disturbed weather conditions and one day--11 May 2019--when adverse weather conditions caused temporal closure of the airport. For BGY, there were two days--11 May 2019 and 7 July 2019--in the dataset where adverse weather did not lead to an airport closure and one day--6 August 2019--when the airport was temporarily closed. As the airports are located adjacent to each other, it is of interest to investigate the datasets in pairs in order to analyze the influence of the changing capacity of one airport on the second one. Therefore, the following pairs of data were considered:  
* On 7 July 2019, both airports operated under adverse weather conditions without closures;
* On 6 August 2019, BGY was temporally closed; however, MXP was open all the time;
* On 11 May 2019, MXP was closed for some period of time due to bad weather conditions, whereas BGY continued operations. Figure 8: European Centre for Medium-Range Weather Forecasts—High Resolution Forecast (ECMWF-HRES) analysis: 500 hPa temperature (\({}^{\circ}\)C), wind (barbs), and geopotential height (dm, contours) on 7 July 2019 (**left panel**) and 6 August 2019 (**right panel**) at 12:00 UTC. The first two datasets recorded on 7 July 2019 contain 322 arrivals at MXP and 144 arrivals at BGY. The travel time of arrivals in the extended TMA and touchdown time are illustrated in Figure 9 in orange for MXP and in blue for BGY. In order to detect peak times while smoothing the influence of outliers, a moving mean value over five neighbor travel times was calculated. These mean values are shown as dark blue and dark orange lines in Figure 9. In the case of MXP, the time until landing in the extended TMA varied between 693 and 2913 s with an average time of 1246 s and five peak periods, the most noticeable of which was between 19:30 UTC and 21:30 UTC (Figure 9). The maximal and the average flown distances in the extended TMA were approximately 302 and 168 km, respectively, whereas the average flown distance at the mentioned peak period was equal to 225 km (i.e., 57 km longer than the average flown distance over the whole day). In the same day, there were two outlier arrivals at BGY in terms of travel time in the extended TMA. Taking them into account, the time until landing varied between 817 and 4836 s, with an average travel time of 1186 s. The detectable peak period is between 16:15 UTC and 17:30 UTC (Figure 9). The maximal and the average flown distances in the extended TMA are approximately 718 and 160 km, respectively. The average flown distance at the peak time amounts to 247 km with the outlier arrival and 194 km without it. Even without the outlier, the average flown distance during the peak period is 34 km longer than the corresponding value over the whole day. Summing up, there are two possible coherent peaks at the considered airports that may have been caused by weather conditions. These peaks are pairwise-marked by the areas bounded by the dotted lines in Figure 9.  
The second pair of datasets collected on 6 August 2019 contains 421 arrivals. It includes 99 more arrivals than the traffic scenario on 7 July 2019 for MXP and 144 arrivals for BGY. The travel time in the extended TMA and the touchdown time of arrivals are shown in Figure 10. The time until landing in MXP's extended TMA was between 715 and 2436 s, with an average travel time of 1161 s. The maximal and the average flown distances in the extended TMA were approximately 352 and 161 km, respectively. In spite of the fact that this scenario is larger than the previous one for MXP, it has lower values for maximal and average travel time and, as a consequence, average travel distance. Figure 9: Visualization of travel time in the extended TMA and touchdown time for historical traffic at MXP (orange color) and at BGY (blue color) on 7 July 2019.