PRECISION APPROACH RADAR/PAR (ICAO) - Primary radar equipment used to determine the position of an aircraft during final approach, in terms of lateral and vertical deviations relative to a nominal approach path, and in range relative to touchdown.
NOTE - Precision Approach Radars are designed to enable pilots of aircraft to be given guidance by radio communication during the final stages of the approach to land.
PREFERENTIAL ROUTES - Preferential routes, (PDRs, PARs, and PDARs) are adapted in ARTCC computers to accomplish inter/intra-facility controller coordination and to assure that flight data is posted at the proper control positions. Locations having a need for these specific inbound and outbound routes normally publish such routes in local facility bulletins and their use by pilots minimizes flight plan route amendments. When the workload or traffic situation permits, controllers normally provide radar vectors or assign requested routes to minimize circuitous routing. Preferential routes are usually confined to one ARTCC's area and are referred to by the following names or acronyms:
(1)
PREFERENTIAL DEPARTURE ROUTE/PDR - A specific departure route from an airport or terminal area to an enroute point where there is no further need for flow control. It may be included in a Standard Instrument Departure (SID) or a Preferred IFR Route.
(2)
PREFERENTIAL ARRIVAL ROUTE/PAR - A specific arrival route from an appropriate enroute point to an airport or terminal area. It may be included in a Standard Terminal Arrival Route (STAR) or a Preferred IFR Route. The abbreviation “PAR” is used primarily within the ARTCC and should not be confused with the abbreviation for Precision Approach Radar.
(3)
PREFERENTIAL DEPARTURE AND ARRIVAL ROUTE/PDAR - A route between two terminals which are within or immediately adjacent to one ARTCC’s area. PDARS are not synonymous with Preferred IFR Routes but may be listed as such as they do accomplish essentially the same purpose. (See Preferred IFR Routes, NAS Stage A)
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. If a flight is planned to or from an area having such routes but the departure or arrival point is not listed, 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 SIDs and STARs and may be defined by airways, jet routes, direct routes between navigational aids, waypoints, navigational aid radials/DME, or any combinations thereof. (See Standard Instrument Departure, Standard Terminal Arrival, Preferential Routes, Center Area)
PREVAILING VISIBILITY - (See Visibility)
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