## 2 Components of Vertiport
### Comparison of Topologies  
This section compares the linear, satellite, and pier layouts that we applied for the same area to comply with the FAA's and EASA's new regulations. First, the minimum area required for each layout of the vertiport was determined using the sizes of the TLOF pad and gate. For satellite topology and pier topology, the area was designed to be capable of holding at least two gates per one TLOF pad. According to the FAA's and EASA's new regulations, the standard area required in common for the three deployments is 15,850.56 m\({}^{2}\) and 7384.8 m\({}^{2}\), respectively, and the linear, satellite, and pier layout configurations were determined by applying the previously defined vertiport component sizes. When the linear topology tends to support takeoff and landing in one direction, the transition surface is as shown in Figures 9 and 10. For satellite and pier topologies that support relatively multidirectional takeoff and landing, the preferred approach/departure surface is based on the predominant wind direction. Where a reciprocal approach/departure surface is not possible in the opposite direction, it is recommended to use a minimum 135-degree angle between the two surfaces [14].  
In a linear topology, several TLOF pads are usually arranged in a row, which is efficient for thin and long spaces such as along a seaside or a riverside. This topology has an advantage when TLOF pads are without gates. Each TLOF pad can take the role of a gate and this arrangement is relatively simple. However, it is necessary to secure additional space in the other than takeoff and landing directions when this topology is installed on a single or lower floor. Therefore, it is necessary to secure additional space in accordance with the approach/departure surface and path regulations in reference [9], considering the height of the structures that may interfere with takeoff and landing around the TLOF pad. An example of a linear topology with a TLOF pad is shown in Figures 9 and 10.  
The satellite topology is suitable for a square or circle space, such as SHoP's Architects' Arc' skyport [19], in which one or more TLOF pads are surrounded by several gates. As shown in Figures 11 and 12, the gate is highly utilized because the length of the taxiways is  
Figure 10: Example of linear topology that complies with the EASA’s new regulations.  
Figure 9: Example of linear topology that complies with the FAA’s new regulations.  
constant. However, this method has constraints in taking off and landing in the direction of the gate and in integrating with the existing infrastructure.  
The pier topology has an intermediate rectangular form between a linear topology and a satellite topology. This layout separates the area of the TLOF and the gate to make the takeoff and landing angles at the TLOF pad wider, and a large number of gates can increase the gate utilization. However, since this arrangement shares one taxiway, aircraft turnaround times may be extended and the gate area may be congested. To overcome these problems, a high-level flight air traffic control (ATC) system or two or more taxiways is necessary. A minimum space example of the pier layout providing a multidirectional approach/departure path is shown in Figures 13 and 14. The minimum space was not mentioned in the EASA's new regulation [15], except for the protection area, which is 1.2 times CD.  
Figure 11: Example of satellite topology that complies with the FAA’s new regulations.  
Figure 12: Example of satellite topology that complies with the EASA’s new regulation.