While not providing specific control, flight service stations (FSS) are the element of the air traffic management system that provides information and other noncontrol communications to aircraft operating in the system. Their principal functions are to accept and close flight plans, brief
pilots about their routes of flight, and to provide important information, in the form of notices to airmen (NOTAMs) before flight and in flight, on such items as severe weather, the status of navigational aids, airport runway closures, and changes in published approach and departure
procedures. A secondary function is to relay traffic control messages between aircraft and the appropriate control facility on the ground.