Basically, you need to know:

• Nav frequencies are 108 to 117.975 MHz
• Voice Comms are 118 to 137 MHz

ICAO Annex 10, Volume III - Part II

The AIRBAND is the spectrum of frequencies used for radio communication in aviation. Airband is often used for referring to the VHF spectrum between 108 MHz and 137 MHz, which covers its use for commercial and general aviation, radio-navigational aids, air traffic control and other uses. In common use among aviation professionals, the range of frequencies is sometimes referred to as VHF or Victor. Military aircraft also operate using additional frequencies (225 - 400 MHz) which are not part of the airband.

The lower part of the spectrum, from 108 to 117.975 MHz, is reserved for navigational aids such as VOR beacons and Automatic Terminal Information Service (ATIS), and precision approach systems such as ILS or LAAS. Some types of aviation-related stations, such as NDBs and DMEs, do not operate on these frequencies; in the case of NDBs the longwave frequency spectrum is used. The rest of the airband (118 - 137 MHz) is allocated to voice communications using amplitude modulation.

Channel spacing on the airband has been 25 kHz. However, increasing congestion has led to further subdivision into 8.33 kHz channels in the ICAO European region; all aircraft flying above 19 500 feet (FL195) are required to be capable of handling this reduced spacing. A switch to digital radios has been contemplated, as this would greatly increase capacity by reducing bandwidth. However, this has yet to happen, partly because the mobility of aircraft necessitates complete international cooperation.