Pilot/Controller Glossary 

9/5/24 

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

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 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)

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 A self

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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. 
PREFERRED IFR ROUTES

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 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., and are also available at 

https://www.fly.faa.gov/rmt/nfdc_preferred_routes_database.jsp

. 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 may be defined by DPs, SIDs, or STARs; NAVAIDs, Waypoints, 

etc.; high or low altitude airways; or any combinations thereof. Because they often share elements with adapted 

routes, pilots’ use of preferred IFR routes can minimize flight plan route amendments. 

(See ADAPTED ROUTES.) 
(See CENTER’S AREA.) 
(See INSTRUMENT APPROACH PROCEDURE.) 
(See INSTRUMENT DEPARTURE PROCEDURE.) 
(See STANDARD TERMINAL ARRIVAL.) 
(Refer to CHART SUPPLEMENT U.S.) 

PRE-FLIGHT PILOT BRIEFING

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(See PILOT BRIEFING.) 

PREVAILING VISIBILITY

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(See VISIBILITY.) 

PRIMARY RADAR TARGET

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 An analog or digital target, exclusive of a secondary radar target, presented on 

a radar display. 
PRM

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(See AREA NAVIGATION (RNAV) GLOBAL POSITIONING SYSTEM (GPS) PRECISION RUNWAY 

MONITORING (PRM) APPROACH.) 

(See PRM APPROACH.) 
(See PRECISION RUNWAY MONITOR SYSTEM.) 

PRM APPROACH

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 An instrument approach procedure titled ILS PRM, RNAV PRM, LDA PRM, or GLS PRM 

conducted to parallel runways separated by less than 4,300 feet and at least 3,000 feet where independent closely 

spaced approaches are permitted.  Use of an enhanced display with alerting, a No Transgression Zone (NTZ), 

secondary monitor frequency, pilot PRM training, and publication of an Attention All Users Page are required 

for all PRM approaches.  Depending on the runway spacing, the approach courses may be parallel or one 

approach course must be offset. PRM procedures are also used to conduct Simultaneous Offset Instrument 

PCG P

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