the Aviation Dictionary

polyvinyl chloride (PVC) - positive temperature coefficient
polyvinyl chloride (PVC) - 1. A thermoplastic resin
used in the manufacture of transparent tubing for
electrical insulation and fluid lines that are not subject
to any pressure. 2. A popular, low-cost, wire insulating
material.
pontoon - A float attached to the landing gear of a land
airplane to allow it to operate from water.
poor judgment chain - A series of mistakes that can
lead to an accident or incident. Two basic principles
generally associated with the creation of a poor
judgment chain are: (1) one bad decision often leads to
another; and (2) as a string of bad decisions grows, it
reduces the number of sbbsequent alternatives for
continued safe flight. Aeronautical decision making is
intended to break the poor judgment chain before it can
cause an accident or incident.
pop-open nozzle - The afterburner nozzle that pops full
open at idle for the purpose of efficient engine
operation at very low thrust.
lights be displayed in flight during the hours of
darkness.
position report - A report over a known location as
transmitted by an aircraft to ATC.
position symbol - A computer-generated indication
shown on a radar display to indicate the mode of
tracking
positive - Symbol: +. A condition of electrical pressure
caused by a deficiency of electrons.
positive acceleration - An increase in the rate of change
of velocity.
positive angle of
attack - A flight
condition where
the angle " of attack
formed between the relative wind and the chord line of
the airfoil is formed with the relative wind being the
bottom leg in relation to the chord line and the socalled
top surface of the aircraft.
poppet valve - A circular-headed, T-shaped valve. Used
to seal the combustion chamber of a reciprocating positive buoyancy - The tendency of an object, when
engine, and at the proper time, either admit the fuel-air placed in a fluid, to ascend or float because it is lighter
mixture into the cylinder or conduct the burned exhaust than the fluid it displaces.
gases out of the cylinder.
positive control - Control of all air traffic, within
porcelain -A hard, smooth surfaced ceramic material. designated airspace, by air traffic control.
pores - Small holes or openings on the surface of
metals.
porosity - The condition of a material having small
pores or small cavities throughout the material.
porous chrome - A plating of hard chromium on
bearing surfaces. The surface of the plating consists of
tiny ciacks in which lubricant can-adhere to reduce
sliding friction.
porous chrome plating - An electrolytically deposited
coating of chromium on the walls of aircraft engine
cylinders. The surface contains thousands of tiny
cracks that hold oil to provide for cylinder wall
lubrication.
porous salt - The residue normally left on the surface of
a metal that has been attacked by corrosion.
porpoising - Hunting, or oscillating, around the lateral
axis of the aircraft normally caused by an incorrectly
functioning automatic pilot.
port side - The left-hand side of an aircraft or ship as
one faces the nose of the aircraft or bow.
position error - The error in an airspeed indicator
caused by the static source not being exposed to
absolutely still air.
position lights - Lights on an aircraft consisting of a red
light on the left wing, a green light on the right wing,
and a white light on the tail. FARs require that these
Aircraft Technical Book Company
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positive control area - An obsolete term that designated
what is now referred to as Class A Airspace.
positive course guidance (PCG) - A continuous
display of navigational data that enables an aircraft to
be flown along a specific course line, e.g., radar vector,
RNAV, ground-based NAVAID.
positive electrical charge - An electrical condition
caused by a deficiency of electrons.
positive feedback - In electronics, a signal fed from the
output section back into the amplifier to reinforce the
input signal.
positive ion - An atom that has fewer electrons than
orotons.
positive logic - The logic used in binary computers. The
more positive signal is considered to be equal to a one
and the less positive or more negative signal is
considered to be equal to a zero.
positive static stability - The condition of stability of
an aircraft that causes it, when disturbed from a
condition of straight and level flight, to tend to return
to straight and level flight.
positive temperature coefficient - A ratio that shows
an increase in length, resistance, capacitance, etc. with
an increase in temperature.