P3I Pre-planned product improvement
PA Public address system
also:   Passenger address system
PACAF Pacific Air Forces (USAF)
PAH PanzerAbwehrHubschrauber (German); anti-tank helicopter
PAPI Precision Approach Path Indicator
PAR Precision approach radar
passenger load factor Seat-kilometres used divided by seat-kilometres available; expressed as percentage
Pax Passenger(s)
payload - Commercial aircraft: revenue generating load
- Military aircraft: total load of armament, cargo and mission equipment
PBW Power-by-wire; uses electrical power to move control surfaces or perform other mechanical tasks
PCN Pavement classification number
PCU Power control unit
PDF Precision direction finder
PDR Preliminary design review
PDU Power distribution unit
PERM Permanently
PF Pilot flying
PFA Popular Flying Association (UK); renamed Light Aircraft Association
PFCS Primary flight control system
also:   Primary flight computer system
PFD Primary flight display; shows all data for aircraft flight path control
PFP Partnership For Peace (NATO)
PGM Precision guided munition
phased array Radar which scans the beam electronically in 1 or 2 axis while the antenna remains stationary
PHI Precision heading indicator
also:   Precision homing indicator
PI Practice interception
PIC Pilot in command
PICUS Pilot in command under supervision
PIREP Pilot report
PLC Public limited company
PMFD Primary multi-function display
PN Part number
pneumatic de-icing Method of shedding ice accretion by pumping in and out a flexible surface coating
PNF Pilot not flying
PNVS Pilot night vision system
POC Proof of concept
point defence Defence of a specific area, city, installation
POL Petroleum, oil, lubricants
port Left side, while looking forward
POS Position
power loading MTOGW of aircraft divided by total thrust or total horsepower at take-off
power train A complete mechanical drive system
PPI Plan position indicator
PPL Private pilot's licence
PPV Pre-production verification
PR Photo-reconnaissance
also:   Public relations
PRELIM Preliminary
PRF Pulse repetition frequency (for radar)
proprotor Large propeller capable of tilting, used for both vertical and forward flight
psi Pounds per square inch (1 psi = 0.069 bar)
PSR Post-strike reconnaissance
PV Private venture
PWR Passive warning receiver
also:   Power
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