Annular waypoints ?

[el #]

Hi, this question come from playing some mission in FS.
I've noticed, there are waypoints (at least in the FS's GPS map) nicely positioned in circle around the airports on the atolls in the pacific, like Mali or Hanamadu. Is that common for all the atolls ? Is there a specific reason for that ?

[Intruder]

Control zones are often defined as a radius around a VOR or airport. Common ingress/egress points are plotted to help standardize flight plans.