Ground communications outlets (GCO) have been installed at some U.S. airports to provide a means for pilots on the ground to communicate with flight service stations and air traffic control (ATC) facilities for the purpose of filing, opening and closing VFR or IFR flight plans; obtaining weather briefings and clearances; and similar communications.
Because GCO units are not part of the official air traffic control radio system, they may not receive regular operational status checks and therefore may experience unreported outages.
However, since they do not provide guaranteed service, they also entail lower costs and can be installed at smaller locations that cannot afford an RCO.
In areas with cellular telephone coverage, the use of a GCO has sometimes been replaced by simply calling the air traffic control facility directly.
GCO availability is noted in the text portion of the airport diagram.