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Pilot/Controller Glossary

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 a[1]t

[2]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

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References

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