# A Method for Managing ADS-B Data Based on a 4D Airspace-Temporal Grid (GeoSOT-AS)
## 3 A 4D Airspace-Temporal Grid Framework (GeoSOT-AS) for ADS-B Data Organization
### GeoSOT-AS Rules and Methods for Planar Dimensional Profiling  
#### 3.1.1 Planar Dimensional Profiling Method  
Considering the above three practical needs of actual airspace and flight information management, it has been proposed that the profile of the earth's surface plane corresponds to the multi-level Chinese specification of civil aeronautical charting, with a base consideration design which can be compatible with various tasks of airspace data management (Figure 2). The chart correspondence constraints are as follows:  
1. Aeronautical charts, which are those used by aircraft for flight paths or routes and can cover a large area, generally maintain a scale of 1:1,000,000, corresponding to the first level of GeoSOT-AS sectional charts;
2. Regional charts, which are generally enlarged charts of flight paths in areas of intense flight activity and complex airspace, are generally at a scale of 1:500,000, and correspond to the second level of GeoSOT-AS;
3. Terminal area charts (TACs), such as airport plans, parking space, standard approach and departure, instrument approach, fuel discharge area, airport obstacle, and air corridor charts, are at scales of 1:250,000, corresponding to the third level of GeoSOT-AS (Table 1 shows the specific correspondence);
4. Such forms are compatible with all kinds of finer scale maps, including major areas, with 100 km, 1 km level, and 100 m level granularity. Based on the above constraints and correspondences, the following airspace planar dimensional discretization was designed, with the basic discretization architecture shown in Figure 3. The origin of the Earth's surface airspace 2D grid is at the intersection of the equator and the prime meridian. The Earth's surface 2D grid is divided into 11 levels according to the following division method:  
Figure 2: (**a**) 6 \(\times\) 4\({}^{\circ}\) profile structure of the primary grid (1 st level profile); (**b**) The order of the codes represented by the space-filling curves (2 nd and 3 rd level profile); (**c**) Aeronautical maps of the corresponding scale. The 1 st-level grid is divided according to the 1:1 million aeronautical chart, with a cell size of 6\({}^{\circ}\)\(\times\) 4\({}^{\circ}\), and is used as the basic framework for the national airspace management. The 2 nd-level grid is divided according to the 1:500,000 aeronautical chart, with a cell size of 3\({}^{\circ}\)\(\times\) 2\({}^{\circ}\). The 3 rd-level grid is divided into 3 \(\times\) 2 s-level grids according to the equal division of latitude and longitude, corresponding to a 1\({}^{\circ}\)\(\times\) 1\({}^{\circ}\) grid (\(\sim\)111.32 \(\times\) 111.32 km) at the Earth's equator. This corresponds to a 100 km level grid. The 4 th-level grid is divided into 2 \(\times\) 2 according to latitude and longitude equalization, corresponding to a 30\({}^{\prime}\)\(\times\) 30\({}^{\prime}\) grid (\(\sim\)55.66 \(\times\) 55.66 km at the Earth's equator). The 5 th-level grid is divided into 2 \(\times\) 3 grids according to latitude and longitude equalization, corresponding to a 15\({}^{\prime}\)\(\times\) 10\({}^{\prime}\) grid of 1:50,000 aeronautical chart area (\(\sim\)27.83 \(\times\) 18.55 km at the Earth's equator). The 6 th-level grid is divided into 3 \(\times\) 2 grids according to 5\({}^{\prime}\)\(\times\) 5\({}^{\prime}\) latitude and longitude (\(\sim\)9.28 \(\times\) 9.28 km at the Earth's equator). The 7 th-level grid division is divided equally by latitude and longitude into 5 \(\times\) 5 grids corresponding to 1\({}^{\prime}\)\(\times\) 1\({}^{\prime}\) (\(\sim\)1.86 \(\times\) 1.86 km at the Earth's equator). The 8 th-level grid is divided into 2 \(\times\) 2 grids, corresponding to 30\({}^{\prime\prime}\)\(\times\) 30\({}^{\prime\prime}\) grid (\(\sim\)928 \(\times\) 928 m grid at the Earth's equator), according to latitude and longitude equalization.