The priority of communication systems is to increase the role of digital networks data between aircraft, ATC and airlines. This triangle connection (Fig. 203) is the main connecting element CNS / ATM. To ensure data exchange between its components can be used one or more digital data network:
- communicate at microwave frequencies (VDL);
- a global network of digital exchange by data on high-frequencies (HFDL);
- satellite communication (SATCOM);
- receiving and transmitting equipment (UAT).

Fig. 203. Triangle of connection