THE NAVIGATION/COMMUNICATION SET
The Nav/Com is a radio set, in fact, as the name suggests, two radio sets in one. The Communications (Com) part is used to communicate with Air Traffic Control. The navigation (Nav) part is used to tune into the VOR beacons and instrument let down aids. They work in the VHF part of the radio spectrum. The communication part utilizes frequencies between 118.00 Megahertz and 136.975 Megahertz, with 25 Kilohertz spacing, (760 channels).
The navigation part utilizes frequencies between 108.00 Megahertz and 117.95 Megahertz, with 50 Kilohertz spacing, (200 channels).
The range of the VHF radio is limited to line of sight and will depend on how high you are flying. Larger, long range, aircraft are fitted with short wave radio sets for use when communicating from over oceans. These radios are very rarely fitted in light aircraft.