public relations /pbl.k r.
le..(.)nz/ noun the task of maintaining good relations with the public. Public relations may also involve putting across a point of view or publicising a product. . The arrangements for the VIPs are being handled by the public relations department. Abbreviation PR publish /pbl../ verb to prepare and issue a book, magazine, chart, etc., and sell or distribute it to the public . All known air navigation obstructions in the UK are published in the Air Pilot.
pull out /pυl aυt/ verb to stop a dive in an aircraft and return to level flight
pullout /pυlaυt/ noun a manoeuvre in which an aircraft changes from a dive to level flight
pulse /pls/ noun a single vibration of electric current

pulse modulation /pls
m.djule..(.)n/ noun the use of a series of short pulses, which are modi-fied by an input signal, to carry infor-mation
pump /pmp/ noun a device with rotary or reciprocating action which is used to move fluids along pipes or for compressing fluids . verb to move or compress a fluid by means of a pump .
Fuel is pumped from the tanks to the carburettor.
COMMENT: Most modern aircraft are fitted with hydraulic pumps driven from the engine. Other types of pumps may be found, but these are usually used to power emergency systems. Pumps can be driven directly from the engine gearbox, by an electric motor, or by air.
pure /pjυ./ adjective not mixed with something else . Inner tubes for tyres are made of pure rubber. . Magnesium does not possess sufficient strength in its pure state for structural uses. . pure aluminium aluminium which has not been combined with any other metal to create an aluminium alloy

purple airway /pp(.)l e.we./
noun an area of temporarily controlled airspace, established to provide special protection to Royal flights in fixed-wing aircraft, in which additional rules for air traffic apply at all times and in all weathers
purpose /pp.s/ noun 1. function .
The purpose of the engine is to convert heat energy to mechanical energy. 2. a use . For practical purposes, any straight line drawn on a Lambert’s chart represents a great circle. . gen-

183 pyrotechnic
eral purpose for all-round or general
use push-back /pυ. bk/ noun the proc-ess of pushing a plane out from its parked position using a special vehicle