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Aeronautical Information Manual (AIM), page 687

12/10/15 Pilot/Controller Glossary

PRECISION APPROACH RADAR- Radar equip-
ment in some ATC facilities operated by the FAA
and/or the military services at joint-use civil/military
locations and separate military installations to detect
and display azimuth, elevation, and range of aircraft
on the final approach course to a runway. This
equipment may be used to monitor certain nonradar
approaches, but is primarily used to conduct a
precision instrument approach (PAR) wherein the
controller issues guidance instructions to the pilot
based on the aircraft's position in relation to the final
approach course (azimuth), the glidepath (elevation),
and the distance (range) from the touchdown point on
the runway as displayed on the radar scope.
Note: The abbreviation "PAR" is also used to
denote preferential arrival routes in ARTCC
computers.
(See GLIDEPATH.)

(See PAR.)
(See PREFERENTIAL ROUTES.)
(See ICAO term PRECISION APPROACH
RADAR.)
(Refer to AIM.)
PRECISION APPROACH RADAR [ICAO]- Pri-
mary 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.

PRECISION OBSTACLE FREE ZONE (POFZ)-
An 800 foot wide by 200 foot long area centered on
the runway centerline adjacent to the threshold
designed to protect aircraft flying precision
approaches from ground vehicles and other aircraft
when ceiling is less than 250 feet or visibility is less
than 3/4 statute mile (or runway visual range below
4,000 feet.)
PRECISION RUNWAY MONITOR (PRM)
SYSTEM- Provides air traffic controllers
monitoring the NTZ during simultaneous close
parallel PRM approaches with precision, high update
rate secondary surveillance data. The high update rate
surveillance sensor component of the PRM system is
only required for specific runway or approach course
separation. The high resolution color monitoring
display, Final Monitor Aid (FMA) of the PRM


system, or other FMA with the same capability,
presents (NTZ) surveillance track data to controllers
along with detailed maps depicting approaches and
no transgression zone and is required for all
simultaneous close parallel PRM NTZ monitoring
operations.
(Refer to AIM)
PREDICTIVE WIND SHEAR ALERT SYSTEM
(PWS)- A self-contained system used onboard some
aircraft to alert the flight crew to the presence of a
potential wind shear. PWS systems typically monitor
3 miles ahead and 25 degrees left and right of the
aircraft's heading at or below 1200' AGL. Departing
flights may receive a wind shear alert after they start
the takeoff roll and may elect to abort the takeoff.
Aircraft on approach receiving an alert may elect to
go around or perform a wind shear escape maneuver.

PREFERENTIAL ROUTES- Preferential routes
(PDRs, PARs, and PDARs) are adapted in ARTCC
computers to accomplish inter/intrafacility 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:
a. Preferential Departure Route (PDR). A specific
departure route from an airport or terminal area to an
en route point where there is no further need for flow
control. It may be included in an Instrument
Departure Procedure (DP) or a Preferred IFR Route.
b. Preferential Arrival Route (PAR). A specific
arrival route from an appropriate en route point to an
airport or terminal area. It may be included in a
Standard Terminal Arrival (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.
c. 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.)


PCG P-3

Page 687 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

Index   686 -- Page 687 -- 688