Preferred Instrument Flight Rules Route

Routes established between busier airports to increase system efficiency and capacity. They normally extend through one or more Air Route Traffic Control Center (ARTCC) areas and are designed to achieve balanced traffic flows among high density terminals. Instrument Flight Rules (IFR) clearances are issued on the basis of these routes except when severe weather avoidance procedures or other factors dictate otherwise. Preferred IFR Routes are listed in the Airport/Facility Directory. If a flight is planned to or from an area having such routes but the departure or arrival point is not listed in the Directory, pilots may use that part of a Preferred IFR Route which is appropriate for the departure or arrival point that is listed. Preferred IFR Routes are correlated with standard instrument departures (SID) and standard terminal arrival routes (STAR) and may be defined by airways, jet routes, direct routes between NAVAID's, Waypoints, NAVAID radials/distance measuring equipment (DME), or any combinations thereof. (FAA4)