Dataset Direct Download Service (WFS): SUP_PT2 — Radio Reception Centre Areas and Areas

The attitude of an easement is the spatial field (i.e., the geographical area) within which the easement applies. This spatial field may be defined either in 2D or in 3D in particular in the particular cases of clearance easements at airports, easements for the protection of radio transmission centres.The attitude shall include primary clearance zones, secondary clearance zones, special clearance zones and clearance areas.The maximum distance separating the limit of a radio station and the perimeter of the easement areas may not exceed:- 2 000 metres in the case of a secondary clearance zone;- 400 metres in the case of a primary clearance zone surrounding an aeronautical safety facility or a radio-gonometric centre;- 200 metres in the case of a radio area not exceeding a maximum area of clearance. In practice, the beam shall be assimilated to a band and the attitude shall not exceed 50 m on either side of the axis.The maximum width of a clearance area protecting a radio tracking or navigation station may not exceed the width of the angular area explored by the station, increased, where appropriate, by a safety margin of not more than one degree beyond the two limits of that area.

地役权（easement）的空间适用范围（attitude），指该土地地役权生效的空间场（spatial field，即地理区域）。该空间范围可采用二维或三维定义，针对机场净空地役权（clearance easements）、无线电传输中心（radio transmission centres）保护地役权等特定场景尤为如此。
该空间适用范围应涵盖主要净空区（primary clearance zones）、次要净空区（secondary clearance zones）、特殊净空区（special clearance zones）及净空区域（clearance areas）。
无线电台（radio station）边界与地役权区域周界之间的最大间距不得超过以下限值：
- 次要净空区场景下为2000米；
- 环绕航空安全设施（aeronautical safety facility）或无线电测向中心（radio-gonometric centre）的主要净空区场景下为400米；
- 未超出最大净空面积的无线电区域场景下为200米。
实际应用中，波束可等效为带状区域，且该空间适用范围在轴线两侧均不得超过50米。
保护无线电跟踪站（radio tracking station）或导航站（navigation station）的净空区域，其最大宽度不得超过该站探测的角域宽度；必要时，可在该区域的两个边界外增加不超过1度的安全裕度，以拓宽该区域。