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6/17/21 

Pilot/Controller Glossary 

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 on board 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.) 

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 

PCG P