Pilot/Controller Glossary PREFERRED IFR ROUTES- Routes established between busier airports to increase system efficiency and capacity. They normally extend through one or more ARTCC areas and are designed to achieve balanced traffic flows among high density terminals. 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 Chart Supplement U.S. If a flight is planned to or from an area having such routes but the departure or arrival point is not listed in the Chart Supplement U.S., 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 DPs and STARs and may be defined by airways, jet routes, direct routes between NAVAIDs, Waypoints, NAVAID radials/ DME, or any combinations thereof. (See CENTER"S AREA.) (See INSTRUMENT DEPARTURE PROCEDURE.) (See PREFERENTIAL ROUTES.) (See STANDARD TERMINAL ARRIVAL.) (Refer to CHART SUPPLEMENT U.S.) (Refer to NOTICES TO AIRMEN PUBLICATION.) PRE-FLIGHT PILOT BRIEFING- (See PILOT BRIEFING.) PREVAILING VISIBILITY- (See VISIBILITY.) PRIMARY RADAR TARGET- An analog or digital target, exclusive of a secondary radar target, presented on a radar display. PRM- (See ILS PRM APPROACH and PRECISION RUNWAY MONITOR SYSTEM.) PROCEDURAL CONTROL [ICAO]" Term used to indicate that information derived from an ATS surveillance system is not required for the provision of air traffic control service. PROCEDURAL SEPARATION [ICAO]" The separation used when providing procedural control. PROCEDURE TURN- The maneuver prescribed when it is necessary to reverse direction to establish an aircraft on the intermediate approach segment or final approach course. The outbound course, direction of turn, distance within which the turn must be completed, and minimum altitude are specified in the procedure. However, unless otherwise restricted, the point at which the turn may be commenced and the type and rate of turn are left to the discretion of the pilot. (See ICAO term PROCEDURE TURN.) PROCEDURE TURN [ICAO]- A maneuver in which a turn is made away from a designated track followed by a turn in the opposite direction to permit the aircraft to intercept and proceed along the reciprocal of the designated track. Note 1: Procedure turns are designated "left" or "right" according to the direction of the initial turn. Note 2: Procedure turns may be designated as being made either in level flight or while descending, according to the circumstances of each individual approach procedure. PROCEDURE TURN INBOUND- That point of a procedure turn maneuver where course reversal has been completed and an aircraft is established inbound on the intermediate approach segment or final approach course. A report of "procedure turn inbound" is normally used by ATC as a position report for separation purposes. (See FINAL APPROACH COURSE.) (See PROCEDURE TURN.) (See SEGMENTS OF AN INSTRUMENT APPROACH PROCEDURE.) PROFILE DESCENT- An uninterrupted descent (except where level flight is required for speed adjustment; e.g., 250 knots at 10,000 feet MSL) from cruising altitude/level to interception of a glideslope or to a minimum altitude specified for the initial or intermediate approach segment of a nonprecision instrument approach. The profile descent normally terminates at the approach gate or where the glideslope or other appropriate minimum altitude is intercepted. PROGRESS REPORT- (See POSITION REPORT.) PROGRESSIVE TAXI- Precise taxi instructions given to a pilot unfamiliar with the airport or issued in stages as the aircraft proceeds along the taxi route. PROHIBITED AREA- (See SPECIAL USE AIRSPACE.) (See ICAO term PROHIBITED AREA.) PROHIBITED AREA [ICAO]- An airspace of defined dimensions, above the land areas or territorial waters of a State, within which the flight of aircraft is prohibited.