Radio navigation systems serve the flight crew in determining their position during the flight, and to assist them in their landing approach. The radio navigation systems are classified according to their purpose as the airport equipment and en route facilities. Some devices (depending on location) perform both tasks.
The airport radio navigation systems help pilots to guide the aircraft on landing. Depending on the type of approach, a non-directional beacon NDB (Non Direction Beacon), omnidirectional beacon VOR (VHF Omni directional Radio Range) or a precision approach system ILS (Instrument Landing System) is used. The advantage of the ILS system is the guiding of the aircraft in the course axis (Localiser) and the glide axis (Glide path) of the runway and the determination of the distance from the runway threshold DME (Distance Measurement Equipment) and MKR (Marker). Modern ILS devices allow landings even in low or "zero" visibility.
En route radio navigation systems allow the pilot to determine his position during the flight. The facilities are located so as to ensure coverage of radio navigation signals across the airspace of the Czech Republic. They are mostly placed on the important points of airways. Non-directional beacons (NDB), VHF omnidirectional radio beacons (VOR) and distance measuring equipment (DME) are not considered en route facilities.