Flight Plans

Prior to flying in controlled airspace under IFR conditions or in Class A airspace, pilots are required to file a flight plan. IFR (as well as VFR) flight plans provide air traffic center computers with accurate and precise routes required for flight data processing (FDP1). The computer knows every route (published and unpub lished) and NAVAID, most intersections, and all airports, and can only process a flight plan if the proposed routes and fixes connect properly. Center computers also recognize preferred routes and know that forecast or real-time weather may change arrival routes. Centers and TRACONs now have a computer graphic that can show every aircraft on a flight plan in the U.S. as to its flight plan information and present position. Despite their sophistication, center computers do not overlap in coverage or information with other Centers, so that flight requests not honored in one must be repeated in the next.