Airband

The airband or air band is the band of frequencies used for radio communication in aviation. "Airband" is used to mean the VHF band between 108 MHz and 137 MHz, which covers its use for commercial and general aviation, radionavigational aids, air traffic control and other uses. In common use among aviation professionals, the band 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 band, from 108 to 117.975 MHz, is reserved for navigational aids such as VOR beacons, Automatic Terminal Information Service (ATIS) and Automated Surface Observing System (ASOS) messages, 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 band is used. The rest of the airband 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 are required to be capable of handling this reduced spacingcite web | url = http://www.eurocontrol.int/vhf833/public/subsite_homepage/homepage.html | title = 8.33kHz Programme
accessdate = 2007-12-24 | publisher = Eurocontrol] . 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.

References