Flight Service Station
A Flight Service Station (FSS) is an air traffic control facility that provides information and services such as flight plan filing and weather information to pilots before, during, and after flights. Unlike air traffic control, (ATC), flight service stations are not responsible for giving instructions or clearances or providing aircraft separation. The people who communicate with pilots from flight service stations are not controllers but are known as flight specialists.
The exact services offered by stations vary by country, however most FSS services include providing pilots with preflight briefings including weather and notices to airmen (NOTAMs); filing, opening, and closing flight plans; monitoring navigational aids (NAVAIDs); collecting and disseminating pilot reports (PIREPs); offering traffic advisories to aircraft on the ground or in flight; relaying instructions or clearances from air traffic control; and providing assistance to pilots and aircraft in an emergency. In addition flight service stations in most countries also operate at mandatory frequency airports to help co-ordinate traffic in the absence of air traffic controllers. Furthermore, they may also take over a control tower frequency at a controlled airport when the tower is closed.
Due to the fact that pilots often need to contact flight service stations en-route, pilots can reach most flight service stations by radio, in flight, or by telephone when on the ground. Flight service stations in most countries consolidate flight services into large regional centers, which in most cases have replaced former local flight service stations with remote communications outlets (RCOs) connected to the main centers.