The Cambridge Aerospace Dictionary Episode 7 pptx

4 Linear or angular difference beween major axis eg of aircraft or engine and axis of drive shaft from gearbox.. on-board aircraft server Integrates flight deck, cabin, maintenance and g

nose ribs Ribs along leading edge extending chordwise

only as far as front spar

nose slice Maximum-rate yaw induced by rudder

nose slots Apertures in low-pressure region of high

velocity around nose for discharge of fluid flow, eg

cooling air

nose tow Standard US Navy method of catapult link for

accelerated carrier takeoff by pulling on nose leg

nose up To rotate in pitch from level flight to climb

nosewheel Wheel(s) of nose gear

no-show Airline passenger who has booked ticket but

fails to check in for flight

Nosig No significant meteorological change (ICAO)

no step Stencilled warning on aircraft: do not put weight

on this area

NOT Naczelna Organizacja Techniczna (Polish

federa-tion of engineering associafedera-tions)

Notal Not to all

Notam, NOTAM Notice to Airmen, identified as notice

or as Airmen Advisory, disseminated by all means to give

information on establishment, conditon or change in any

aeronautical facility, service, procedure or hazard; suffix

D distant [wide dissemination], L local (ICAO)

Notam code Standard code for transmitting Notams; eg

QAUED 3 MC 5813 142359 is interpreted as ‘Met com

operating frequency of 3 MHz will be changed to 5,813

kHz on 14th of this month at 23.59’

Notar No tail rotor, torque reaction supplied by offset

thrust from air blown through slit in tail boom (Hughes,

then McDonnell Douglas, now Boeing)

notch Essentially chordwise or streamwise sawcut or

groove over nose of aerofoil

notch aerial Formed by cutout in skin of vehicle, leaving

aperture matched to wavelength (usually in HF com

band) and covered with dielectric skin to original profile

notched cone nozzle Promising primary nozzle in

ejector-lift system in which primary flow is discharged

through row(s) of fishtail (lozenge-section) nozzles

gener-ating plumes orthogonal to long axis of duct

notched elevators Cut away at trailing edge for rudder

movement

notch effect Shortcoming of early (1960s) all-flying

tailplanes or slab tails in which demands tended to be in

noticeable increments [pilot often reverted to flying on

trimmer]

notch flap Leading-edge flap extended from fuselage

notifiable accident One which cannot legally go

un-reported, where any person suffers injury, third-party

property is damaged or public are in any way put at risk;

variable rules governing scale of damage to aircraft

no-transgression zone Airspace where aircraft under

positive electronic IFR control must not penetrate, esp

region 900+ m/2,000+ ft wide between aircraft making

ILS approaches on to parallel runways

NOTS Naval Ordnance Test Station (USN, China

Lake, Inyokern etc, now NWC)

Notus Notice to users (Arinc)

Nova Networked open versatile architecture

NOV-AB Non-persistent Toxic-B gas bomb (USSR)

Novcam Non-volatile charge-addressed memory

Novoview Range of CGI(2) visual systems, some

textured (Rediffusion)

Novram Non-volatile RAM

Nowcast Report on current weather

no-wind position Geographical position aircraft wouldhave occupied had wind velocity been zero

NOx, NOX Nitrogen/oxygen breathing mixture(normally means supplied in absence of atmosphere)

NOx Shorthand for all oxides of nitrogen resulting fromcombustion of fuel in air

noy, Noy Subjective measure of noisiness in bandwidths

of one-third octave (see noise).

NOZ No operating zone

nozpos Nozzle position[s], ie angle

nozzle 1 In jet-propulsion or reaction-jet control,

aper-ture through which fluid escapes from system toatmosphere and in which as much energy as possible is

converted to kinetic energy (see choked, con/di).

2 Wind-tunnel section immediately upstream of

working section

3 Primary aperture through which fuel is injected into

gas-turbine engine combustion chamber [US usage]

4 Section of fluid flow duct upstream of axial turbine,

in which flow is controlled to enter turbine at favourabledirection, pressure and velocity Form depends onwhether turbine is impulse/reaction or pure impulse

5 Incorrectly, nozzle guide vane.

nozzle blade See nozzle guide vane.

nozzle block See nozzle (2).

nozzle box Assembly of nozzle guide vanes (all, or agroup filling portion of periphery) and surrounding walls

of gas duct

nozzle bucket See nozzle guide vane.

nozzle contraction ratio Ratio of flow cross-section area

at inlet or start of nozzle (esp con/di or rocket) to area atthroat

nozzle diaphragm Nozzle (4) as complete assembly

nozzle efficiency Usually ratio of actual change inkinetic energy across nozzle to ideal value for given inletconditions

nozzle exit area Area of cross-section of flow at exit

nozzle expansion ratio In supersonic nozzle, ratio of exitarea to throat area

nozzle guide vane Radial aerofoils upstream of axial gasturbine, convergent passages between which formnozzle (4) through which gas is directed on to turbinerotor blades Also called turbine stator

nozzle insert Small blocking body fixed inside nozzle (1)

to trim exit area; colloq = mice

nozzle ring Complete 360° assembly of nozzle guidevanes

nozzle throat Region of con/di nozzle having smallestcross-section area

nozzle thrust coefficient Usually defined as actualachieved thrust divided by product of chamber pressureand throat area (rocket)

2 National Packaging Authority (UK).

3 National Pilots’ Association [trade union] (US).

4 Non-precision approach.

NPB 1 Nuclear-powered (or propelled) bomber.

2 Nadge Policy Board.

NPD Need and planning documents.

NPDU Network protocol data unit

NPE Navy preliminary evaluation (USN)

NPG 1 No performance group type aircraft (CAA).

2 Nuclear planning group.

3 Non-unit personnel generator.

NPI Non-precision instrument

NPIAS National Plan of Integrated Airport Systems

(US)

NPL National Physical Laboratory (UK, 1899–)

NPLOs NATO production and logistics organizations

NPL tunnel A closed-jet tunnel, original * = return flow,

standard * = non-return flow

NPO Scientific production union (USSR, R)

NPOESS National, later (2002) changed to New,

polar-orbiting operational environmental satellite system

(NASA, NOAA, USAF)

NPP 1 Research and production enterprise (R).

2 NPOESS preparatory project.

NPPL National Private Pilot’s Licence [proposed, VFR

only] (UK)

NPR 1 No power recovery.

2 Nozzle pressure ratio.

3 Nuclear posture review (US).

4 Noise preferential route.

NPRM Notice of proposed rulemaking (FAA)

NPRS Non-persistent

NPS 1 Non-prior service.

2 Naval Post-graduate School (USN).

3 Nuclear profiled sortie.

NPT Non-proliferation treaty, 1 July 1968

NPTR 1 National Parachute Test Range.

2 No procedure turn required.

NPU Navigation processor unit

NQA National Quality Assurance [certification

authority] (UK)

NQIS Navigation-quality inertial sensor

NQR Nuclear quadrupole resonance

NRC 1 National Research Council.

2 Nuclear reporting cell.

3 Nuclear Regulatory Commission (US, 1974

onwards)

NRCS Normalized radar cross-section

NRD Network routing domain

NRDC 1 National Research Development Corporation

(UK)

2 Natural Resources Defense Council (US).

NRDS Nuclear rocket development station (Jackass

Flats, US)

NRF NATO Response Force (2002–)

NRH No reply heard

NRI Net radio interface

NRL Naval Research Laboratory (USN)

NRMM Navaids remote maintenance and monitoring

NRO National Reconnaissance Office (US)

NROSS, Nross Navy remote ocean sensing system orsatellite (spacecraft, USN)

NROTC Naval Reserve Officer Training Corps (US)

NRP 1 Normal rated power.

2 Narrow programmable receiver.

3 National Route Program, or Plan (US).

4 Non-return point.

NRPA Net return on productive assets

NRPB National Radiological Protection Board

NRR Noise-reduction rating (EPA)

NRRC Nuclear-Risk Reduction Centers (1987)

NRSC National Remote Sensing Centre (in civilenclave at former RAE Farnborough, UK)

ns Maximum sustained normal acceleration

NSA 1 National Security Agency (US).

2 National Standards Association (US).

NSAP Network service access point

NSAR North Sea air-combat manoeuvring mented range

instru-NSAWC Naval Strike and Air Warfare Center (USN)

NSC 1 National Security Council (US).

2 No significant cloud.

3 New Scottish [ATC] Centre, Prestwick.

NSCA National Safety Council of America

NSDA National Space Development Agency (J)

NSDU Network service data unit

NSE Near-synchronous equatorial

NSEU Neutron single-event upset

NSF National Science Foundation (US)

NSFAC Non-Scheduled Flying Advisory Committee(CAA, 1945)

NSG 1 NATO Standardization Group.

2 North-seeking gyrocompass.

NSGr Night close-support group (G, WW2)

NSIA National Security Industrial Association (US)

NSIU Navigation switching interface unit

NSM Non-contact stress measurement

NSMS Non-intrusive stress-monitoring system

NSMV Near-space maneuvering vehicle (USAF)

NSN National [or NATO] stock number[s]

NSNF Non-strategic nuclear forces

NSO Navigation/systems operator

NSOC Naval Satellite Operations Center (Pt Mugu,CA)

NSP 1 Normal sea-level power.

2 Night surveillance payload.

3 National Simulator Program; O adds Office (FAA).

NSPE National Society of Professional Engineers (US)

NSPOL Non-scheduled policy (ECAC)

NSR 1 No scheduled removal.

2 Naval [or NATO] Staff Requirement.

NSRI National Soil Resources Institute (U ofCranfield)

NSRP National Search and Rescue Plan (US).

NSS 1 National seismic station (US).

2 Near-source simulation.

3 Navigaton subsystem.

4 National Security Space (US).

NSSA 1 National Safe Skies Alliance (US).

2 National Space Society of Australia.

NSSC Naval Ship Systems Command (USN)

NSSFC National Severe Storms Forecast Center

(Kansas City)

NSSI National Security Space Integration; O adds

Office (DoD)

NSSL National Severe Storms Laboratory (US)

NST 1 NATO Staff Target.

2 Noise, spikes and transients.

NSTAC National Security Telecommunications

Advisory Council (US)

NSTAP National strategic technology acquisition plan

(UK)

NSTB National satellite testbed

NSTD Non-standard

NSTL 1 National Space Technology Laboratories

(NASA, previously MTF, now SSC (4))

2 National security threat list (US).

NSTO Near single stage to orbit

NSTP National space technology programme (DTI,

UK)

N-strut Interplane or other bracing system having

general shape of N

NSVN NATO secure voice network

NSW 1 Nominal specification weight.

2 No significant weather [TAF or Metar].

NSWC Naval Surface Warfare Center (USN)

NSWP Non-Soviet Warsaw Pact

nT Nanotesla; terrestrial field varies from c 25,000

(magnetic equator) to c 70,000 nT (poles), vertical

compo-nent usually being measured in geophysical prospecting

and ASW

nt Nit (name not usually used)

NTAOCH Notice to AOC holders (CAA)

NTAP Notice to Airmen publication (USGPO)

NTAS Norad tactical Autovon system (USAF)

NTAT Near-term Acme technology

NTB 1 National test bed (US, SDI).

2 Nuclear test ban; T adds Treaty.

NTC 1 National Training Center (US DoD).

2 Numerator time constant.

3 Notice.

NTD National Test Director (ISS)

NTDD Normalized total departure delay

NTDS Naval tactical data, or distribution, system

NTE 1 Not to exceed.

2 Northerly turning error.

NTF 1 No trouble found.

2 NATO task force.

NTFWTC NATO Tactical Fighter and Weapons

Training Centre

NTG Nachrichtentechnische Gesellschaft im VDE (G)

Nth country Next power to possess nuclear weapons

(DoD)

NTI Next [runway] turn indicator

NTIA National Telecommunications and Information

Administration (US)

NTIS National Technical Information Service (US)

NTK Scientific and technical committee (many inUSSR, R)

NTM 1 National technical means, of verification of

MBFR and precise Earth mapping

2 NDT manual.

3 NATO Tiger Meet.

NTMV National technical means of verification

NTNF Royal Norwegian council for scientific andindustrial research

NTO 1 Nitrogen tetroxide.

2 Notice to operators.

3 No technical objection[s].

NTOS No time on station

NTP Normal (ie standard) temperature and pressure

NTPD NTP dry (gas bottle capacities)

NTS 1 Negative-torque signal.

2 Navigation technology satellite (USN).

3 Night targeting system.

NTSB National Transportation Safety Board (US,from 1966)

NTSC National Television Standards Commitee (US)

NTT Non-threat traffic

NTTC National Technology Transfer Center (NASA)

NTU 1 State technical administration (USSR, R).

2 Navigation training unit.

3 New-threat upgrade.

4 Not taken up [civil registration].

NTW Navy theater-wide; /BMD adds ballistic-missiledefense (USN)

N2O4 Nitrogen tetroxide.

NTWS New threat-warning system

nuclear capable Nuclear bomber

nuclear cloud All-inclusive term for volume of hot gas,dust, smoke, and other particulate matter from nuclearbomb and environment carried aloft with fireball (DoD,NATO)

nuclear column Hollow cylinder of water and spraythrown up from underwater nuclear explosion throughwhich hot high-pressure gases escape to atmosphere(DoD, NATO)

nuclear defence Defence against attack by nuclear orradiological weapons

nuclear dud NW which after being triggered fails toprovide any explosion of that portion designed to producenuclear yield (DoD)

nuclear emulsion Thick layer used on photo-type platesfor recording tracks of energetic particles

nuclear energy That liberated by fission; more rarely,that liberated by fusion reaction, and some definitionsinclude radioactive decay

nuclear explosive Material designed to achieve greatestuncontrolled fission or fission + fusion reaction

nuclear/heater propulsion Using nuclear reactor to heatworking fluid for rocket propulsion

nuclear incident Unexpected event short of NWA butresulting in damage to NW or associated facilities or

increase in possibility of explosion or radioactive

conta-mination (DoD)

nuclear radiation All EM and particulate radiations

from nuclear processes

nuclear reactor Device for containing controlled nuclear

fission (rarely, fusion) reaction

nuclear rocket Usually one whose working fluid is

heated in nuclear reactor

nuclear safety line Line drawn (if possible through

prominent topographic features) on map to serve as

refer-ence in describing levels of protective measures, degrees of

damage and limits allowed for effects of friendly NW

nuclear surface burst One in which centre of fireball is

below that height equal to maximum radius

nuclear underground burst One in which centre of

detonation lies below original ground level

nuclear weapon One in which almost all released energy

results from fission, fusion or both; abb NW Original

1945 designs used chain-reaction triggered by critical

mass of uranium with unnaturally high concentration of

isotope U-235 Second form was based on plutonium

Pu-239 Loosely called atomic, or fission, bomb See

hydrogen bomb.

nuclear-weapon(s) accident Unplanned occurrence

resulting in loss of, or serious damage to, nuclear weapons

or components resulting in actual or potential hazard to

life or property (DoD, NATO)

nuclear-weapon degradation Degeneration of NW to

such extent that anticipated yield is reduced

nuclear-weapon employment time Reaction time of NW

nuclear-weapon exercise Exercises involving real NW

but excluding launching or flying operations

nuclear yield Energy released in detonation of NW

measured in terms of mass of TNT required to liberate

same amount: categorized as very low (less than 1 kT), low

(1–10 kT), medium (10–50 kT), high (50-500 kT) and very

high (over 500 kT)

nucleating agent The material released into the

atmos-phere in cloud seeding, such as silver iodide

nucleon Particle of atomic nucleus, eg neutron, proton

nucleonics Science of applications of nucleons and

atomic emissions

nucleus 1 Particle upon which atmospheric water

vapour can condense and/or freeze

2 Positively charged core of atom.

nuclide Member of family of atoms distinguished by

having same nucleus (immediately decaying nuclear states

are excluded)

Nudets Nuclear detonation detection and reporting

system; system for surveillance of friendly target areas and

immediately providing place, ground zero, burst height

and yield of nuclear explosions (DoD, NATO)

Nufas NATO uhf frequency-assignment system

Nugget First-tour aviator (USN)

nugget Obturator (US, colloq.)

NUGP Nominal unit ground pressure

NUI Network-user identification

nuisance malfunction One caused by failure of safety

system, eg auto-disconnect of AFCS, main system being

serviceable throughout

null 1 Orientation of receiver aerial [antenna] (eg ADF)

in which no signal is heard

2 In DLC, angular setting (usually about 7°) about

which spoilers oscillate

3 Location in space where, at any moment,

gravita-tional forces cancel out (eg five centres of libration nearEarth/Moon system)

nullo Flown without human on board equipped target or other RPV], from ‘no live, or local,operator’

[cockpit-null position See null (2).

NUM Nuova unita maggiore, future aircraft carrier(Italy)

Numast National Union of Marine, Aviation andShipping Transport officers (UK)

No 1 engine Port outer: engines numbered acrossaircraft port to starboard

numbers 1 Runway designator.

2 Piano keys, to land on the *.

3 Any numerical data needed for flight, as ‘have *’.

numerator time constant Controls rate at which attitudechanges result in flight-path changes, symbol Tθ2

numerical control Control of system, esp machine tool,

by series of commands expressed in numeric (digital)terms giving locations, directions and speeds, andsecondary information (eg cutter speed) in correctsequence Software usually punched paper or magnetictape

numerical weather prediction Repeatedly refinedmethods in which powerful computers solve equationsand simulate local atmosphere, hence numerical forecast,numerical model

Nunio Network universal input/output [local Ethernet]

NURK Astronautics Society (J)

nurse balloon Fabric gas container used as reservoir or

to maintain constant inflation pressure in aerostat onground

Nusselt number Non-dimensional parameter Nu =qD/λδT where q is quantity of heat, D is typical length, λ

is thermal conductivity and δT is temperature difference

Nut Near-unity probability

nutating feed Microwave feed to tracking radar in whichbeam oscillates in one plane while plane of polarization(and usually aerial [antenna] reflector) remains fixed

nutation 1 Oscillation of axis of rotating body (eg gyro).

2 Irregularities in precession of equinoxes and other

effects and of rotary precession of Earth’s axis in period

of 18.6 years (* period) with maximum displacement of9.21 s (constant of *)

nutator Drive mechanism causing dipole or aerial[antenna] feed horn to gyrate about focus of paraboloidalaerial without changing plane of polarization

nutcracker V/STOL aeroplane whose fuselage hingesnear mid-length to vector main-engine thrust

nut plate, nutplate Nut, esp elastic stop nut, providedwith flat-plate base attached permanently to airframe toprovide anchor into which attachment bolt can be screwedfor securing access panel or other removable item

nut runner Large nut threaded on screwjack so thatwhen either ** or screw is rotated a linear motion results(eg to drive tailplane)

NV 1 Naamloze Vennootschap (Netherlands, Belgium,

company constitution)

2 National Variants, to FAR-25 and similar.

3 Night vision.

4 Non-volatile.

NVCA National Venture Capital Association (US)

NVEO Night-vision electro-optics

NVESD Night Vision Enhanced [or and Electronic]

Sensors Directorate (USA)

NVG Night-vision goggles; T adds training

NVIS 1 Near-vertical incident skywave.

2 Night-vision imaging system.

NVL Netherlands air transport association

NVLP Netherlands Aerospace Writers Association

NVM Non-volatile memory

NVPS Night-vision pilotage [or piloting] system

NVQ National Vocational Qualification (UK)

NVR Netherlands astronautical society

NVRAM Non-volatile RAM

NVS 1 Night-vision system.

2 Noise and vibration suppression [or simulation].

nvt Neutron volts, measure of ionising radiation

NV thrust Nominal vacuum thrust

NVTS Night-vision targeting sight

NVvL Nederelandse Vereniging voor

Luchtvaart-techniek

NW 1 Nuclear weapon, or warfare.

2 Nosewheel.

NWA Nuclear-weapon(s) accident

NWAA North West Aerospace Alliance; 180+

companies (UK)

NWC 1 Naval Weapons Center (China Lake, USN).

2 National War College (US).

NWDC Navy Warfare Development Command

(USN)

NWDS Navigation and weapons-delivery system

NWEF Naval Weapons Evaluation Facility

(Albu-querque, USN)

NWP Numerical weather prediction

NWPRA National Women’s Pylon Racing Association

NWSSG Nuclear weapon system safety group

NWT Natural work team

NWTS Naval Weapon Test Squadron (NAS PointMugu)

NWV New World Vistas (USAF)

NXT Next [K adds track]

ny

–

Yawing moment coefficient due to sideslip

Nycote Nylon lacquer protective coating

nylon Long-chain synthetic polymer amide with rent amide groups distributed along chain (somedefinitions add ‘capable of being drawn into filamentwhose structure is oriented along fibre’) Large family,now often used for 3-D mouldings and many structuralpurposes (formerly TM for Du Pont de Nemours)

recur-nylon letdown Parachute

NYO Not yet operating

Nz 1 Normal load factor, ie along OZ axis.

2 AMSU normal-acceleration ouput.

NZAF New Zealand Aviation Federation Inc

NZAPA NZ Airline Pilots’ Association

NZAT NZ Airport Technologies (trade association, 19members)

NZCA NZ College of Aviation

NZDF NZ Defence Force

NZG Near-zero growth (tyres)

NZGA NZ College of Aviation

NZMAA NZ Model Aeronautical Association

NZMS NZ Meteorological service

NZRA NZ Rotorcraft Association

NZSFA NZ Space Flight Association Ltd

O 1 Opposed configuration (US piston engine

designa-tion)

2 Operating cost over given period.

3 Ground speed ‘on’ (onwards from critical point).

4 Observation aircraft category (US services from

1922)

5 Hang-glider category (FAI).

6 Other meanings include odd, over, oxygen and

OAA Orient Airlines Association

OAAN Organismo Autónomo Aeropuertos Nacionales

(Spain)

OAB Outer air battle

OAC 1 Operations Advisory Committee (UK CAA).

2 Oceanic Area Control [C adds Centre].

3 Austrian aero club.

OACI ICAO (F)

OACS Optically active coding system

OAD Office of Aviation Development [CAA, 1949 on]

OADS Omnidirectonal air-data system (helicopter)

OAE Optimized after erosion (helicopter blade profile)

OAF Optical-alignment facility

OAFS Open apron, free-standing (ie, no air-bridge)

OAFU Observers advanced flying unit

OAG 1 Operational Advisory Group (BATA, USN).

2 Official Airline Guide.

OAIRMS Open-architecture integrated radio

manage-ment system

OALC Ogden Air Logistics Center (Hill AFB, Utah)

OALT Operationally acceptable level of traffic

OAM Office of Aviation Medicine (FAA)

OAMCM Organic airborne mine countermeasures

OAMP Optical airborne measurement platform

OAMS Orbital attitude and manoeuvre system

O&C Operations and checkout

O&D Origin and destination

O&I Operations and integration

O&M Operations & maintenance [CM adds

configura-tion management]

O&O Organizational and operational (RPV)

O&S 1 Operational and support (costs).

2 Operations & Sustainment, of hardware in service

(USAF)

OANS Observers air navigation school

OAO 1 Orbiting astronomical observatory.

2 Out-of-area operations.

OAOI On-and-off instruments

OAP 1 Organizzazione dell’Aviazione Privata e

d’Affari (I)

2 Offset aiming point.

3 On-board attitude processor.

OAPD Online airline product database (IATA)

OAPEC Organization of Arab Petroleum ExportingCountries

OAPP Office of Aviation Policy and Plans (FAA 1)

OAPS Oblique air photograph strip

OAR Office of Aerospace Research (USAF andFAA/DoT)

OARB Orient airlines research bureau

OARF Outdoor Aerodynamic Research Facility(NASA)

OARN Off-airways R-nav

OART Office of Advanced Research & Technology(NASA; now AST)

OAS 1 Offensive avionics system.

2 Offensive air support (air support directly linked to

land operations, US)

3 Omnidirectional airspeed system (helo).

4 Open-access service.

5 Optimal aircraft scheduling.

6 Obstacle assessment surface.

7 Office of Aviation Safety (CAA).

8 On active service.

9 Oceanic Automation System (FAA/USN).

OASC Officer and Aircrew Selection Centre (RAF,Biggin Hill)

OASD Office of the Assistant SecDef (US)

OASF Orbiting astronomical support facility

Oasis 1 Oceanic and atmospheric scientific information

system (NOAA)

2 Operational application of special intelligence system

(AAFCE)

3 Omnidirectional approach-slope indicator system.

4 Operational and supportability implementation

system (USAF/FAA)

5 Organic airborne and surface-influence sweep.

6 Oceanic Area system improvement study.

7 On-board aircraft server and information system.

OASPL Overall sound pressure level

OAST Office of Aeronautics and Space Technology(NASA), more usually AST

Oasys Obstacle-avoidance, or awareness, system

OAT 1 Outside air temperature.

2 Operational acceptance test.

3 Operational air traffic (ie military).

4 Oxide aligned transistor.

5 Operational, or optional, auxiliary terminal (Acars).

6 Operational airfield test set.

7 Orbit and attitude tracking; S adds system.

OAV Organic air vehicle

OAVUK Society for aviation and gliding of Ukraineand Crimea

OBA Outbound boom avoidance (SST).

OBAP Organization of Black Airline Pilots (US)

OBC 1 Optical barrel camera.

2 On-board computer.

OBCO(S) On-board cargo operations (system)

Ob.dL Oberkommando der Luftwaffe (G)

OBDMS On-board data-monitoring systems

OBE 1 Off-board expendables.

2 Overtaken by events.

OBEWS 1 On-board electronic warfare simulation.

2 On-board EW system(s).

OBFM Offensive basic flight manoeuvres

OBI Omni-bearing indicator

Obiggs On-board inert gas generating system

OBIS On-board information system

objective 1 Normally, in optical, EO or IR system, first

lens or lens group to receive incoming radiation

2 Military target for capture or other action by surface

forces; not used for target for aerial attack

oblique Oblique photograph

oblique camera One mounted in aircraft with axis

between vertical and horizontal

oblique photograph One taken by oblique camera;

subdi-vided into high * in which apparent horizon appears and

low * in which it does not

oblique projection Map projection with axis inclined at

oblique angle (say, 20° to 60°) to plane of Equator

oblique-shock inlet Inlet designed for use in supersonic

vehicle and provided with centrebody, wedge or other

projecting portion intended to focus oblique shockwave

on opposite lip

oblique shockwave Inclined shock formed whenever

supersonic flow has to turn through finite angle in

compressive direction

oblique wing Wing arranged to pivot at mid-point as

single unit so that, as one half is swept back, other half is

swept forwards Also called slew wing

OBLMS On-board life-monitoring system

Oboe WW2 precision navaid of SSR type with Cat

station near Dover and Mouse station in Norfolk sending

synchronized pulses which formed continuous note along

correct flightpath over distant target; Mouse operators

also sent signals to tell aircrew when to release bombs or

TIs

Obogs On-board oxygen generation (or generating)

system

OBP 1 On-board processor, or processing [satcom].

2 Omnidirectional ball panel.

3 Operational build plan.

OBPR Office of Biological and Physical Research

(NASA)

OBR Optical beam rider, or riding

OBRC Operating budget review committee

OBRM On-board replacement module

OBS 1 Omni-bearing selector.

2 Observe/observed/observing (ICAO).

3 On-board simulation.

4 Organizational breakdown structure.

5 Optical bypass switch.

6 Observation-balloon system (tethered near major

highway)

obs 1 Obstruction lights.

2 Observe[d], observation.

3 Obstacle.

Obsc, OBSC Obscure/obscured/obscuring (ICAO)

obscuration methods Instrument techniques formeasuring visible smoke (eg from jet engine) such as HSUand PSU where cutoff of calibrated light beam ismeasured over known distance

observation 1 Many military definitions, most agreeing

that * platform is for gathering all possible tactical mation about an enemy

infor-2 Complete set of meteorological readings at one place

and time

observation balloon In bygone wars, tethered ballooncarrying human who reported on fall of shot and onenemy activity

observation balloon system In US, usually tethered atairfield to monitor potentially conflicting road traffic, eg

at runway crossing

observation mirror A horizontal mirror with posed graticule used in the same way as a camera obscura

superim-observed value Measured, not calculated

observer Common title for second crew member in seat military (especially combat) aircraft whose functionsmay include navigation, systems management, electronicwarfare, command guidance of weapons and other tasks;title is traditional and may bear no relation to actualduties

two-OBST, obst Obstruction, obstacle

obstacle clearance height Lowest height above runwaythreshold or aerodrome elevation used to establishcompliance with obstacle clearance criteria in instrumentapproach

obstn Obstruction (FAA)

obstruction Also called obstacle, a real or notional solidbody forming hazard to aircraft on or near runway orflight path For certification purposes has height of 10.7

mm (35 ft) or 15 m (50 ft)

obstruction angle Angle between horizontal and linejoining highest point of object in flightway [ie, approachpath] to nearest point of appropriate runway

obstruction clearance surface Surface in form of plane orflat cone sloping at obstruction angle

obstruction-free zone Free from all fixed obstaclesexcept light frangibly mounted navaids

obstruction light Red light visible 360° on top of objectdangerous to moving aircraft in air or on ground

obstruction marker Object of approved shape or colourmarking obstruction or boundary of hazardous surface

on airfield

Obtex Off-board targeting experiment[s]

obturator Rigid or flexible body tailored to preventingescape of gas under pressure from particular orifice orother leakage path

obturator ring Piston ring of L-section intended to begastight

OBW 1 On-board wheelchair (for disabled pax).

OCA 1 Obstacle clearance altitude [suffix Hfm, height

for finals and straight missed approach; Hps, height for

3 Occupied [telephone line].

4 Operator control console.

Occar Organisme Conjointe de Co-opération en

Matière d’Armément (Int.)

occluded front Warm air mass forced aloft by overtaking

cold front

occlusion 1 Atmospheric region in which cold front has

overtaken slow or stationary warm front and forced warm

air mass upwards

2 Trapping of gas bubbles in solidifying material or by

molecular adhesion on surface, esp removal of gas in

high-vacuum technology by a getter

OCCM Optical counter-countermeasures

occultation Complete disappearance of body, esp

source of illumination such as star or aircraft lights,

behind another object of much larger apparent size

occulting Flashing, but with illuminated periods clearly

predominant

OCD 1 Operational concept demonstration.

2 Oceanic clearance delivery.

3 Office of Civilian Defense (US, 1941).

oceanic airspace Controlled airspace over ocean areas

oceanic clearance Clearance delivery to enter oceanic

airspace

oceanic navigation error report Filed when surveillance

monitor observes aircraft exiting oceanic airspace

seri-ously off track

OCF Occluded frontal passage

OCFNT Occluded front

OCH Obstacle clearance height

OCI 1 Outside of clearance indicator (MLS).

2 Out-of-coverage indicator (navaids).

OCIG Oceanic communications improvement group

OCIP Offensive capability improvement program

OCL 1 Obstacle [or obstruction] clearance limit.

2 Optimum cruising level.

OCLD Occlude

OCLN Occlusion

OCM 1 On-condition maintenance.

2 Optical countermeasures.

OCNL Occasional [Y adds occasionally]

OCNR Office of the Chief of Naval Research (USN)

OCP 1 Onmnidirectional control pattern.

2 Oceanic clearance processor.

OCR 1 Optical-character recognition, or reading.

2 Oceanic control region.

3 On-condition replacement.

4 Office of Commitments and Requirements.

5 Occur.

OCS 1 Optimum-cost speed.

2 Officer Candidate School (US).

3 Oceanic Control System (NZ).

4 Obstacle clearance surface.

5 Operational control segment.

6 Officers Command School (RAF Henlow).

oct Octane (FAA)

octa Unit of visible sky area representing one-eighth of

total area visible to celestial horizon, now okta.

Octagon Trade-name of a range of de-icing fluids,including potassium and sodium acetates, sodiumformate and propylene glycol

octal 1 Standard base for electronic device having eight

connector pins

2 Counting system to base 8.

octane number Standard system for expressingresistance of hydrocarbon or other fuel to detonation inpiston engine, ranging from 0 (equivalent to n-heptane)through 100 (iso-octane) upwards to about 150 Measuresare taken with lean mixture and with rich, latter givinghigher values Also called knock rating (strictly, anti-knock) or performance number, esp when above 100 See

MON, RON.

octane rating See octane number.

octane test Standard test in which sample of fuel is used

to run special variable-compression single-cylinder engineand compared with mixtures of n-heptane and iso-octane,

or (above 100 performance number) with other referencefuels

octant Bubble sextant able to measure angles to 90°

octave Interval between any two frequencies havingratio 1:2

octet Complete set of four pairs of electrons forminglayers 2 and 3 (in all noble gases except He, outer shell)

Octol HE warhead filling, HMX/TNT

Octopus Operational and certified takeoff and landingperformance universal software

Octu Officer Cadet Training Unit (UK)

OCU 1 Operational Conversion Unit (UK).

2 Optical coupler, or control, unit.

3 Operational capabilities upgrade.

4 Operator control unit (IRCM).

oculogyral illusion Apparent movement of fixed objectsseen under high-g

OCV Organisme de Contrôle en Vol (F)

OCXO Oven-compensated crystal oscillator

OD 1 Outside diameter.

2 Ordnance delivery.

3 Olive drab colour.

4 Optical disk.

ODA Overseas Development Administration (UK)

Odads Omnidirectional air-data system

Odals, ODALS Omnidirectional approach lightingsystem

Odapi Omnidirectional approach-path indicator

Odaps Oceanic display and processing [or planning]system

ODC Office of Defense Co-operation (US DoD office

in Germany)

ODF Operational degradation factor

ODFDMU Optical disk flight-data management unit

ODID, Odid Operational display and input ment

develop-Odin Operational data interface

Odis Operational data interface system

ODL Optical, or Oceanic, data-link

ODM 1 Ministry of Overseas Development (UK).

2 Operating data manual.

3 Operational development model.

4 Ordnance deployment manager.

5 Optical driver modem.

6 Original design manufacturer.

ODMS 1 Oil-debris monitoring system.

2 Operational data-management system (ATC).

odometer Digital readout of numerical quantity, esp

distance, as in DME

ODP Office of Defense Plants (US 1945)

ODR 1 Overland downlook radar.

2 Operator difference requirements.

3 Overnight defect rectification.

ODS 1 Oxide-dispersion strengthened.

2 Operational debrief station.

ODT 1 Overland downlook technology.

2 Omnidirectional transmitter or transmission.

3 Office of Defense Transportation (US).

ODTC Office of Defence Trade Controls (US)

ODU Optical display unit

ODVF Society of friends of the air fleet (USSR)

ODW Optimum-drag windmilling

OE 1 Opto-electronic (not necessarily synonymous

with EO)

2 Over-excitation.

OEANC Optical and electronic aiming and navigation

complex

OEB Operations engineering bulletin

OEC Operational emergency clearance

OECD Organization for Economic Co-operation and

Development (19 member countries)

OED 1 Operational evaluation demonstration.

2 Operator-workstation embedded disk.

3 Operational-employment date (UK).

OEI One engine inoperative

OEIM Organisme Egyptien pour l’Industrie Militaire

OELD Organic electroluminescent display

OEM 1 Original equipment manufacturer.

2 Office of Emergency Management (US).

OEO Operational equipment objective

OEP 1 Office of Emergency Preparedness (US).

2 Operational evolution plan (FAA).

OER 1 Operational effectiveness rate.

2 Officer effectiveness report.

oersted Non-SI unit of magnetic field strength, = 79.577

A/m, exact conversion is 1,000/4π

OEST Outline European staff target

OEU 1 Operational Evaluation Unit (RAF).

2 Overhead electronics unit[s].

OEW Operating empty weight [OWE is preferred]

OEX Orbiter experiment; SS adds support system[s]

(NASA)

OF 1 Over-frequency.

2 Objective Force, major long-term program (USA).

3 Ocean Flight [tower system]; DVPS adds data visual

and processing system

O/F Oxidizer (oxidant)-to-fuel ratio

OF 2 Oxygen difluoride rocket propellant

OFA Office Fédéral de l’Air (Switzerland)

OFAB HE fragmentation (bomb, USSR, R)

OFAM Office Fédéral des Aérodromes Militaires(Switzerland)

OFCM Office of the Federal Co-ordinator forMeteorological Services and Supporting Research (USDept of Commerce)

OFCR Overhead flight-crew rest, in normal wide-bodyunused above-ceiling volume

OFDM 1 Operational flight-data monitoring.

2 Orthogonal frequency-division multiplexing.

OFDPS Oceanic flight-data processing system

OFEMA, Ofema Office Français d’Exportation desMatériels Aéronautiques

off-block time When aircraft leaves gate [probablytravelling backwards] or starts to taxi

offboard Released or ejected from the platform [aircraft

or ship], usually as decoy

offboard data Supplied by sensors outside the aircraft

off-design 1 Any operating condition other than that or

those for which equipment was intended

2 Less common definition: at or near stall or buffet

boundary, or in severe turbulence

offensive avionics Those carried in attacking aircraft toassist fulfilment of mission, eg by providing navigation,target sensing and weapon guidance

offensive sweep Low-level flight by fighters over enemyterritory looking for targets of opportunity

office Cockpit or flight deck (colloq.)

off-line 1 Connected to computer but not forming part

of dedicated controlled sytem

2 Computer peripheral not directly communicating

with central processor

3 Not on airline’s route network (eg Western Airlines

has an * office in Washington DC)

4 Computer or EDP (4) installation which stores input

data for processing when commanded

5 No longer supplying power [usually electric] to

offset 1 In major international purchase, eg of quantity

of combat aircraft, agreement in reverse direction inwhich purchasing country is awarded one or morecontracts for products which may or may not beconnected with original hardware This kind of * may be(1) purely window dressing to render costly import lessunpalatable, (2) important commercial deal to benefitoriginal importing country, (3) designed to bolster ailinghome industry, or (4) important vehicle for transfer ofadvanced technology to importer

2 Linear distances, usually small, measured from

base-line to joggled or tapered edge, bevel, flange at angle otherthan 90°, or similar part dimension

3 Precisely defined point on ground in surface attack (see * bombing) or in space in air interception (see * point).

4 Linear or angular difference beween major axis (eg

of aircraft or engine) and axis of drive shaft from gearbox

5 In fir-tree root, distance between teeth measured

parallel to major axis of blade

6 Length of normal common to landing-gear castor

axis and wheel axle [can be zero]

7 Lateral and vertical distances from desired G/S and

runway centreline of (a) an actual landing aircraft, or

(b) ILS beam (locus of peak signal strength)

8 Bearing/distance to runway threshold from point

navaid, eg Tacan

9 See * factor).

10 See next.

offset angle 1 Angle in vertical plane between horizontal

through tug and line joining tug to glider, tow-target or

other towed body

2 Offset (4).

offset attack See offset bombing.

offset bombing Any surface-attack procedure which

employs aiming or reference point other than target

offset distance 1 See offset (2).

2 Distance from desired ground zero or actual ground

zero to point target or centre of area target (DoD,

NATO)

offset factor In parafoil delivery, distance divided by

drop altitude

offset frequency simplex Two stations transmit to each

other on slightly different frequencies

offset frontal Meeting between two DA (3) aircraft and

two hostiles (7–10 miles ahead) on reciprocal, such that no

aircraft will pass between opposing pair

offset hinge Helicopter main-rotor hinge at substantial

radial distance from axis of rotation

offshore procurement Procurement by direct obligation

of MAP funds of materiel outside US territory; may

include common items financed by other appropriations

(DoD) In other words, US taxpayers paid for aircraft

made in Europe, to assist industrial recovery 1951–55

offst Offset track

offtake Route through which power-source physical

output is extracted, notably pipe for hot bleed air or shaft

for rotary power

off the shelf Already fully developed to military or

commercial standards and available from industry for

procurement without change to meet military

require-ment

off-wing With the engine removed from the aircraft [not

necessarily an under-wing installation]

off-wing slide Emergency escape slide well ahead of or

behind wing

OFIS, Ofis Operational Flight Information Service

(ICAO)

OF/NT Operational flight/navigation trainer (USN)

OFO Orbiting frog otolith [programme]

OFP 1 Operational flight programme.

2 Occluded frontal passage.

OFPP Office of Procurement and Policy (DoD)

OFS Operational flying school (RN)

OFSHR Offshore

OFT 1 Operational flight trainer.

2 Operational flight test.

3 Operational flying training.

4 Orbital flight test.

5 Office of Fair Trading (UK).

6 Outer-fix time.

7 Office of Force Transformation (DoD).

OFTS Operational flight and tactics simulator

OFU Overseas Ferry Unit (RAF, WW2)

OFV Outflow valve

OFZ Obstacle-free zone

OG Observation group (USAAC, USAAF)

OGA 1 Outer gimbal angle.

2 Office Général de l’Air (F, export distribution).

OGE 1 Out of ground effect; supported by lifting

rotor(s) in free air with no land surface in proximity

2 Operational ground equipment.

ogee See ogive.

oggin, the The sea (RN colloq.)

ogive 1 Loosely, any shape formed by planar curve

whose radius increases until it becomes straight line

2 Wing plan having approximate form of curve

becoming straight line parallel to longitudinal axis oneach side of centreline; so-called ‘Gothic window’ shape

3 Body of revolution formed by rotation of curve as in

(1) about axis parallel to line on same side of line as curve

4 Any of various other shapes such as conical * (body

formed by rotation of two straight lines formingcone/cylinder), tangent * (circular arc tangent to line) orsecant * (circular arc meeting line at angle)

5 Common definition is ‘surface of revolution

gener-ated when circular arc and line segment are rotgener-ated aboutaxis parallel to line’; this is incorrect since curve need not

be circular arc and shape can be planar and not body ofrevolution

OGO Orbiting geophysical observatory

OGV Outlet guide vane, or straightener vane

OGW Space agency (Austria)

OH 1 Overhaul.

2 Overhead.

O/H Overheat

OHA Operating hazard analysis

OHAR Overhead attendant rest (above ceiling of body centre fuselage)

wide-OHC 1 Operating hours counter.

ohm 1 SI unit of electric resistance, defined as that of

conductor across which potential difference of 1 Vproduces current of 1 A

2 By analogy with (1), mechanical measure of resistance

derived by dividing applied force by velocity; has sions of g/s

dimen-Ohmist, OHMIST Offshore helicopter meteorologicalinformation self-briefing terminal

ohmmeter Usually, compact instrument for giving quickapproximate indication of resistance of circuit to directcurrent

OHS Office of Homeland Security (US, DoD, created2001)

OHU, Ohud Optical head, or overhead, unit of HUD

OHV Overhead valve[s]

OI 1 Operational interruption.

2 Office of Information.

3 On instruments.

4 Operating instruction.

OIA Office of International Aviation (US)

OIB Orbit-insertion burn

OIC 1 Organized immigration crime.

2 Officer in charge.

OICRs Operational intelligence collection ments

require-OID 1 Optical incremental digitiser.

2 Outline installation drawing.

3 Operator input and display; S adds system.

OIDT Operator interactive display terminal

OIG Office of Inspector-General (US, eg NASA)

oil Vague term which could mean crude petroleum,

hydrocarbon-based lubricant or other ‘oil-like’ materials

Even ester-based synthetic lubricants are often marketed

as turbine oils

oil bottle Container of lubricating oil fed by air/gas

pres-sure or even spring-loaded plunger, to short-life engine, eg

of cruise missile

Oil Burner routes Published routes within continental

US along which USAF, USN and USMC conduct

high-speed training missions at low level in VFR and IFR

oil-can Noun and verb, portion of metal skin where

compressive stress imposed in manufacture has resulted in

slight local bulge between rows of rivets or other

attach-ment which, when subjected to pressure difference or

perpendicular force at centre, can suddenly spring

inwards noisily; potential fatigue hazard with thin skin

oil control ring(s) Piston rings whose main purpose is to

prevent loss of lubricating oil from cylinder wall up into

combustion chamber; usually one or two, below main

compression rings

oil cooler Heat exchanger whose purpose is to remove

heat from lubricating-oil circuit; usually cooled by air or

fuel flow

oil coring See coring.

oil dilution Mixing petrol with lubricating oil to reduce

viscosity to facilitate starting large piston engine at very

low temperature

oil drive Hydraulic drive, usually signifying infinitely

variable ratio

oil radiator See oil cooler.

oil ring Scraper ring

OIML Organisation Internationale de la Métrologie

Légale (Int.)

OIN 1 Organisation Internationale de Normalisation

(Int.)

2 Overhaul information notice.

OIP Optimum implementation plan

OIPC Organisation Internationale de Protection Civile

(Int.)

OIRI French for CCIR

OIS 1 Obstacle identification surface.

2 On-board information system.

OIT Operator-information telex

OITS Organización Internacional de

Telecommuni-caciones por Satelites (Int.)

OIU 1 Orientation/introduction unit.

2 Operator interface unit.

OJCS Organization (or Office) of the Joint Chiefs of

Staff (US)

OJT On the job training (DoD)

OKB Experimental construction bureau, where aircraft

are designed and developed (USSR, R)

OKC Over [a named radio station]

OKO Experimental construction section (various,

USSR)

okta Unit of sky area equal to one-eighth of total sky

visible to celestial horizon [previously octa]

OL Operating location

OLAN On-board local area network

OLBR Operational laser-beam recorder

OLC Operational level of capability, marked byachievement of different Phases

OLDI On-line data interchange

OLDP On-line data processing (or processor)

OLED Organic light-emitting diode

OLEEA On-line exhaust emissions analysis

oleo Telescopic strut which absorbs energy of sive loads by allowing hydraulic oil or other fluid to escapeunder pressure through small restrictor orifice, usuallycontrolled by one-way valve to reduce rebound

compres-oleo-pneumatic Absorbing shock by combination of aircompression and forcing liquid through an orifice

OLF Outlying field

OLGS Operational-level ground station [OLTGS addsTactical]

olive Small ellipsoid resembling an olive threaded oncable either to act as bearing surface in tubular guideway,

or in continuous row separated by small spheres located

in recesses in olive ends, to provide two-way push/pullmechanical interconnection (eg in Bloctube system)

Olive Branch route Lo-Level routes for B-52 training incontinental US

OLM 1 On-line, or operational loads, monitoring, or

measurement

2 Off-line mapper.

3 Organizational-level maintenance.

4 Octane lean mixture.

Ologs Open-loop oxygen generating system

OLOS, Olos Out of line of sight

OLP Open-loop phase

OLR Offload route[s]

OLRT On-line, real time

OLS 1 Optical landing system.

2 Operational linescan, or linescan system.

OLTF Open-loop transfer function

OLTS Optical-line termination equipment

8 Out [of use] for maintenance.

OMAG Independent naval aviation group (USSR)

OMAR Optical microwave approach and ranging(UAV all-weather landing)

OMB 1 Office of Management & Budget (US, White

House)

2 Oilless magnetic bearing.

OMC Organic-matrix composite

Omcads Oil movement control and distribution system,manages fuel [not lubricating oil] installation at airportincluding separation of contaminants

OMCFP Optimized MAC computer flight plan

OMCM Operational and maintenance configurationmanagement (software)

OMD On-board maintenance documentation

OME 1 Operating mass empty, usually same as OWE.

2 Operational mission environment.

Omega Accurate long-range radio navaid of VLFhyperbolic type, covering entire Earth from eight groundstations and usable down to SL or underwater

omega (ω) 1 Angular velocity (SI unit is rad/s).

2 Angular frequency.

3 Any generalized frequency, thus ωnis natural

frequency and ωris undamped natural frequency of rth

mode

OMEV Independent naval helicopter squadron,

Bulgaria’s naval air unit, previously OPLEV

OMG Operational manoeuvre group (USSR)

OMI Omnibearing magnetic indicator

OMIS Operations-management information system

OMM 1 Organisation Métérologique Mondiale =

WMO (Int.)

2 Oxygen-mask microphone.

OMMS Oxygen-mask-mounted sight

Omni VOR (colloq.)

omni-axial nozzle Rocket motor nozzle capable of being

vectored to any angle within prescribed limits about pivot

point defined by intersection of axes of symmetry of

propelling system and nozzle

omni-bearing indicator VOR panel instrument

omni-bearing selector, OBS Knob on most VOR/ILS

indicators which is turned to each required VOR bearing,

which appears in a three-digit window display, left/right

needle thereafter showing difference from required

heading

omnidirectional aerial Antenna emitting to all points of

compass (assumed equal signal strength throughout

360°)

omnidirectional ball panel Removable floor panel

containing free-running balls on which cargo containers

are moved

omnidirectional beacon Fixed ground radio station

giving non-directional signals for airborne DF receivers

(obs)

omniflash beacon Airborne flashing (strobe) light visible

equally through 360° in azimuth

omni-range See VOR.

omnivision Uninterrupted view through 360°

OMNTS Over mountains; also OMTNS

OMOS Department of experimental marine aircraft

construction (USSR, defunct)

OMPS Ozone-mapping and profiler sensor, or suite

OMS 1 Crew chief (USAF).

2 Orbital manoeuvring system, or subsystem.

3 Organisation Mondiale de la Santé (Int.).

4 On-board maintenance system.

5 Order, or operating, or operational, management

system

6 On-board monitoring system.

OMT 1 Other military targets.

2 On-board maintenance terminal.

3 Object modelling [US modeling] technique.

4 Optical modular technology.

OMV Orbital manoeuvring vehicle

ON 1 Omega navigation.

2 Octane number.

ONA 1 Office of Noise Abatement (FAA).

2 Operational net assessment.

ONAC Office of Noise Abatement and Control (EPA,

US)

on-block time Parked at gate

on-board aircraft server Integrates flight deck, cabin,

maintenance and ground-based operations into seamless

system, each aircraft being a LAN

on-board cargo operations system

Microprocessor-based system which automatically positions each item forcorrect c.g and best structural integrity

on-board EW simulator Internally [ie, passively] lates external threats as seen by on-board sensors [alllikely wavelengths]

simu-on-board oxygen generation Usually removes nitrogenfrom bleed air by Zeolite molecular sieve

ONC Operational navigation chart[s]

on call Ready for prearranged mission to be requested

on-call target Planned nuclear target to be attacked not

at specific time but on request

on-condition maintenance Performed only when tion of item demands, instead of at scheduled intervals

condi-on-course signal Electronic signal indicating receiver is

on desired course, usually in form of steady note created

by two superimposed coded signals

OND Optical neural device

1½-stage Vehicle configuration, esp ballistic rocket, inwhich single set of propellant tanks feed two or morethrust chambers, one or more of which is jettisoned inflight

one-dimensional flow Flow through duct in which allparameters are, or are assumed to be, constantthroughout any section normal to the direction of flow

one-dot error One scale divison from centre onILS/VOR needle or similar-type instrument, usually equal

to 0.5°

1553B Standard databus highway (US/NATO)

180°-approach Any of several standard approach cedures involving downwind leg and 180° turn; variationsinclude 180° accuracy landing, 180° spot landing, 180°U-turn approach and 180° semicircular approach

pro-180° error Misreading compass by flying reciprocal ofdesired course, formerly avoided by rule ‘red on red’

1-min turn Procedure turn through 360° (rarely, 180°)taking one minute to complete; bank angle is about 30°

one-off Aircraft of which only a single example isconstructed

one-on-one Classical air combat by two opposingaircraft

ONER Oceanic navigation error report

ONERA Office National d’Etudes et de RecherchesAérospatiales (F)

ONFA Opera Nazionale per i Figli degli Aviatori (I)

onglet Leading-edge root fillet

on-line 1 Of computer of EDP (1) system, automatically

receiving and instantly processing information andsending output data to required destination

2 Of EDP (1) peripherals, operating under direct

control of central processor

on-mounted Indicates that SSR aerial [antenna], ECMaerial or similar ancillary device is mounted on, and oscil-lates or rotates with, main radar

ONN Optical neural net

ONR Office of Naval Research (USN)

ONS Omega navigation system

ONSHR Onshore

ONST Outline NATO staff target

on the beam Correctly aligned on ILS glidepath or otherguidance beam Today has come to mean ‘on the righttrack’ in most general sense

on the deck At minimum safe altitude (colloq.)

on the fizzer, on the hooks On a charge, facing ciplinary action (RAF colloq.)

on top 1 Above unbroken cloud, with CAVU

environ-ment

2 Directly above operating sonobuoy or indicated

submarine position

Ontrac II American VLF navaid of rho-rho type

ONVL Over-the-nose vision line, lower limit in side

elevation of pilot’s FOV

on-wing With the engine installed in the aircraft [not

necessarily hung on a wing]

OOA 1 Object-oriented analysis.

2 Out of area.

3 Offshore Operators’ Association (UK).

OOB Order of battle

OOD 1 Object-oriented design, or development.

2 Officer of the day.

OODA Observe[r]-orientation-decision-action; hence

Ooda-loop

OODB Object-oriented data-base; MS adds

manage-ment system

OOF Out of flatness (machined plate)

OOK Department of special constructions (USSR,

obs)

OOOI Out [from gate], off [T-O], on [landed], in [at

gate] (Acars)

OOP Object-oriented programming

OOR Out of region

OORA Object-oriented requirements analysis

OOS 1 Department of special aircraft construction

(USSR, obs)

2 Out of service.

OOSA Office for Outer Space Affairs (UN)

OOTW Operations other than war

OOV Objects of verification

OOW Out of window, simulator depicts external scene

OP 1 Observation post, position or point.

2 Oil pressure.

3 Operating procedure.

op An operational flight, hence ops

OPA 1 Component of GB Sarin, isopropylamine plus

isopropylalcohol

2 Office of Price Administration (US).

3 Opaque (icing).

4 Open planar array.

OPAC Operations of aircraft [ECAC working group]

OPACI, Opaci Opera Pionieri e Anziani dell’Aviazione

Civile Italiana

opacity In optical systems or photographic film,

recip-rocal of transmittance (log O = density d); term

absorbance is now recommended

OPAL, Opal 1 Order processing automated line.

2 Orbiting picosat automated launcher.

opaque plasma One through which EM signals cannot

pass; generally plasma is opaque for EM frequencies

below plasma frequency

opaque rime White icing of porous form caused by rapid

freezing of small droplets

OPAS, Opas 1 Overhead-panel Arinc-629 system.

2 Operational assignment (ICAO).

OPAT Office des Ports Aériens de Tunisie

Opats Object-position and tracking sensor

OPB Oxygen preburner

OPBC Overhead-panel bus controller

OPC 1 Operational control (ICAO).

2 Optical-phase conjugation.

Opcom Operational command

OPCW Organizaton for the Prohibition of ChemicalWeapons

Opdef Operational defect

OPEC, Opec Organisation of Petroleum ExportingCountries

open 1 Aircraft has * cockpit with no canopy.

2 With normal control path disconnected; such failure

interrupts or seriously distorts signal passing along thatchannel

open angle Angle of mating part slightly greater than 90°

or other angle of edge of metal structure such as anglesection; fault condition in sheet metalwork

open architecture Easily added to or modified

open-bladed Not enclosed in a shroud or duct

open-centre system Hydraulic system without anaccumulator

open circuit 1 Electrical, circuit interrupted.

2 Wind tunnel, one having no return path.

Open Class FAI/CIVV categories for competitionsailplanes, in one case with Standard Class span of 15 mand alternatively with span unrestricted but usually 17 to

20 m In each case all refinements such as flaps arepermitted

open cockpit Not provided with a canopy, leaving pant’s head [and possibly upper torso] in slipstream

occu-open-coil armature Ends of each coil connected todifferent bars of commutator

open competition Industrial competition in which allproposals, promises or offers are communicated toall participants

open delta Three-phase transformer comprising twosingle-phase transformers linking three lines

open-ended Spaceflight continued until either allpossible information has been gained, and mission objec-tives met, or spacecraft systems run low or become faulty

open-gore Parachute in which fabric is absent from onegore to assist trajectory control

open-hearth Principal method of high-quality making in many countries, using shallow regenerativefurnace with or without oxygen

steel-open improved site Open-air site for military storagewhose surface has been graded and surfaced with topping

or hard paving

open items 1 Work done on sections of airframe at

loca-tion away from assembly line prior to major join

2 The sections worked on in [1].

3 Parts or procedures inadvertently omitted during

manufacture

open-jaw ticket Generally, airline booking out by oneroute and return by another or over return route todifferent destination

open-jet tunnel Wind tunnel in which working section isopen and has no tunnel walls

open-link ammunition Rounds are held in clips that donot encircle each case, which can be pushed out diagonallyinstead of removed only to rear

Open List List of military aircraft on which nothing wassecret (RAF 1918 – c1960)

open loop Servomechanism or other system comprisingcontrol path only, with no measurement of result or feed-back to give self-correcting action

open production line Inactive, but in a state ready toresume production should further aircraft be required

open propfan Propfan or UDF without a surrounding

shroud

open rate Situation in which fares on particular

air-carrier route are fixed by each operator independently

open rotor Open propfan.

open section Structural member devoid of closed and

thus uninspectable surface

Open Skies Country allows unlimited traffic rights to

foreign carriers, usually reciprocal

open system Using stored food/oxygen and discarding

all body wastes

oper Operate (FAA)

operand EDP (1) quantity entering or arising in

instruc-tion; can assume many forms, from argument to address

code; generally a word on which operation is to be

performed

operating active aircraft Those for which funds are

provided, as distinct from non-operating active aircraft

(DoD)

operating envelope Plot of extreme boundaries of

conditions to which hardware is subject, eg

acceleration/temperature, or (in case of aircraft)

altitude/Mach or V/n gust envelope

operating expenditure Airline’s total costs of generating

ATKs

operating ratio Airline operating revenue divided by

operating expenditure

operating revenue Gross income from an airline’s

air-carrier operations, normally excluding other activities and

any state subsidy

operating speed Traditionally 87.5 per cent of rated rpm

for light piston engine (US, obs.)

operating weight empty Total mass of aircraft ready for

flight, including oil, water, food and bar stocks, passenger

consumable stores, flight and cabin crews and their

baggage and, according to most definitions, empty

baggage containers where appropriate, but excluding fuel

and payload In case of military aircraft, ADI fluid and

drop tanks are excluded but EW pods are included

operation 1 A military action, or carrying out of

mission

2 Operational flight, recorded by individual’s logbook;

if enemy opposition was weak, a completed * might count

as only ½ in assessing individual’s total

operational Ready to accomplish mission

operational agility ‘The ability to adapt and respond

rapidly and precisely with safety and poise to maximise

mission effectiveness’, also defined as ‘airframe agility +

systems agility + weapons agility’

operational aircraft In British usage, one intended and

ready for combat missions, as distinct from transport or

training

operational air traffic Generally, that which cannot

conform to requirements of flights within airways or

controlled airspace

Operational Bulletin Issued when necessary, eg

following difficulty or technical failure, giving advice,

especially to flight crews [but not giving mandatory

instructions]

operational characteristics Those numerically specified

parameters describing system performance; system can be

aircraft, radar, etc

operational command Normally synonymous with

oper-ational control, and covers all functions involving

composion of forces, assignment of tasks, designation ofobjectives and direction of mission; does not include suchmatters as administration, discipline or training

operational control 1 Authority granted a commander

to direct forces to accomplish missions (NATO, etc)

2 Exercise of authority over initiation, continuation,

diversion and termination of a flight (ICAO)

operational control communications Communicationsrequired for operational control (2) between aircraft andoperating agencies

operational control segment That portion of cations link of GPS or Navstar used to transmitcommands

communi-Operational Conversion Unit Turned qualified pilotsand other crew members into crews fit for operations(RAF WW2 and later)

operational development model Almost same as a type, but to evaluate hardware for a new or modifiedmission, eg an AEW/AWACS airship

proto-operational effect rate Usually, flying rate

operational evaluation Test and analysis of system underoperational conditions, with consideration of capabilityoffered, manning and cost, potential enemy accomplish-ments and alternatives, to form basis for decision onquantity production In practice ** is often not accom-plished until long after production decision

operational factors Those exercising constraints onflightplan, notably ATC (1), pilot workload, availableaids, specified refuelling locations, etc

operational flight In the face of the enemy, carryingweapons or cameras or troops or food parcels or towingglider, etc, and underlined in red in logbook US = combatmission

operational flightplan Operator’s plan for safe conduct

of particular flight

operational interchangeability Ability to substitute oneitem for another of different composition or originwithout loss of effectiveness or performance

operational interruption Period during which an item isunserviceable

operational load measurement On-going structural audit

to establish safe fatigue life, esp of fighter or militarytrainer

operational loss or damage Loss or damage to militaryitem caused by reason other than combat

operational manoeuvrability ceiling Maximum height atwhich, for any given weight, aeroplane can sustain speci-fied load factor (vertical acceleration) at onset of buffet

operational meal Special treat for aircrew returned from

an operational mission; key element: a fried egg (RAF,WW2)

operational mission Many definitions, all faulty;suggested: a miltary flight in furtherance of armedconflict Aircraft need not be armed, and need notencounter enemy

operational mode Any of selectable alternative methods

of operation for functioning system, eg controlled, automatic with feedback, automaticopen-loop, semi-automatic and manual

computer-operational net assessment Study of a hostile countryfrom economic, military, political and diplomatic view-points, and potential for fomenting revolution (US)

operational performance categories Categories I to IIIC

defining ILS and blind (automatic) landing installation

performance See Categories (3).

operational phase Period from acceptance by first user to

elimination from inventory

operational readiness Capability of unit or hardware to

perform assigned missions or functions Hence **

inspec-tion

operational readiness platform Ramp where aircraft at

various ready states (including alert states) are parked,

with all required connections (eg telebrief) in place

operational readiness training Consolidated

instruc-tional period wherein qualified personnel for operainstruc-tional

units are given integrated training in operational mode

operational research Generally, analytical study of

problems to provide numerical (some defininitions say

“scientific”) basis for decision-taking; in US often called

operations research

operational test and evaluation Test and analysis of

system under operational conditions, promulgation of

associated doctrines and procedures, and continuing

evaluation against new threats or changed environment or

circumstances

operations Engaged in operational flying

operations manual Usually, definitive handbook for user

of system, as distinct from engineering, repair or design

manuals; for aircraft called flight manual

operative 1 Able to operate; in true fail-* system there is

no loss in performance (though there may be in integrity)

after failure

2 Employee engaged in routine operation of tool or

machine on production work

operator 1 Person, organization or enterprise engaged

in or offering to engage in aircraft operation (ICAO)

2 Licensed air carrier.

3 American term for employee other than foreman or

manager

operator’s local representative Agent located to obtain

meteorological information for operational purposes and

to provide operational information to local met office

Opeval Operational evaluation

OPF Orbiter processing facility

Opfor The opposing force[s] [tactical simulation]

Op.Hr. Operating hours

OPIAR Association of aerospace companies

(Romania)

OPLE Omega position-locating equipment;

synchro-nous satellite providing control beyond LOS

OPLEV See OMEV.

OPM 1 Office of Personnel Management.

2 Operation performance monitor.

3 Operations Policy Manual (JARs).

Opmet Operational meteorological information or

service

OPN Optimised-profile navigation

opn Operation, open, opening

Opos Open purchase order summary

OPOV Oxygen preburner oxidiser valve

opportunity servicing Servicing carried out at any

conve-nient time, within specified flight or operating-time

intervals

opportunity target See target of opportunity.

opposed engine Piston engine having left and right rows

of (usually horizontal) cylinders either exactly or

approx-imately opposite to each other, with crankshaft on line

centre-opposed-piston engine Piston engine, usually of cycle compression-ignition type, in which each cylinderhas central combustion space and two pistons working inopposition and driving crankshafts at oppositeextremities

two-opposition manoeuvres Two aircraft perform in unison,one flying the mirror image of the other’s manoeuvres

OPR 1 Overall engine pressure ratio.

2 Office of Primary Responsibility (DoD).

3 Operate, operation[s], operating, operator,

oper-ational, etc

4 Operational preference.

5 Once per revolution [or o.p.r.].

OPS 1 Operational performance standards.

2 Operations per second [or o.p.s.].

Ops, ops Operations; an individual might complete 25 *and still be on * (RAF WW2)

opsec Operational security

OPSP Operations Panel (ICAO)

Opspecs Operational specifications

optical countermeasures ECM in visible range of EMspectrum

optical display unit The optical element of a HUD, alsocalled optical head unit

optical electronics One meaning is use of optics to focus

IR on sensitive detector in search for electronic emitter

optical fibre Filament drawn from two kinds of glasshaving different refractive indices, in form of core andsheath; light entering at one end is reflected each time itencounters core/sheath boundary until it emerges at otherend

optical guidance Usually, passive guidance based onsensitive photocells which sense presence of target andcause vehicle to home on it

optical gyro Fibre-optic gyro

optical head unit See optical display.

optical instrumentation Use of optical systems scope, theodolite, precision graticules and marking onvehicle) in conjunction with cameras and TV to providestored information of location in three dimensions,velocities and other parameters of hardware orphenomena

(tele-optical landing system Refined form of mirror sight inwhich gyrostabilized light beams indicate to approachingpilot deviation from glidepath (USN, USMC)

optical line of sight LOS through atmosphere, which inprecision measures is not to be regarded as straight

optical linescan Term used for various line-by-line ning at optical wavelengths, including RBV (video)

scan-optically flat panel Window used in visual ing systems through which light passes with near-zerodistortion

sight-optical maser See laser.

optical Mems Mems operating at optical wavelengths

optical pyrometer Instrument giving numerical readout

of temperature of hot surface by measuring incandescent

brightness

optical reference point Index mark on canopy or

else-where providing pilot with sightline guidance in vertical

or near-vertical landing

optical turbulence Fluctuating distortion of light rays

caused by time-varying gradients of refractive index

optimized profile Flight trajectory calculated to

mini-mize energy consumption throughout flight (but for

operational reasons seldom attainable)

optimum angle of attack That giving maximum L/D and

thus highest cruise efficiency

optimum angle of glide That at which glide ratio is a

maximum

optimum coupling Matched radio impedance in which

load equals output of amplifier or transmission line, for

maximum power transfer

optimum height Height of air burst or conventional

explosion producing maximum effect against given target

option 1 Acquisition of particular place in aircraft or

other major equipment item production programme, with

or without deposit and without agreement to purchase

2 Variation in standard of product offering customer

choice, eg avionic fit, long-range tankage, de-icers etc

3 Alternative decisions open to commander engaged in

battle

optional, or optimal, yield management Determining

traffic mix by class code and fare type to maximize

revenue

opto-electronic Combining optical and electronic

subsystems in single device; term appears to be used

synonymously with EO

optronics Technology of systems using wavelengths

from optical to electronic Appendix 4.

optrotheodolite Doubtful designation for precision

position-correlating instrument combining laser and

video camera

OPU Overspeed protection unit

OPV Optionally [or operationally] piloted vehicle; some

of this class are helicopter UAVs

OQAR Optical quick-access recorder

OQPSK Offset quadrature phase-shift keyed, or

keying

OR 1 Operational research.

2 Operational requirement[s] (UK).

3 Operational readiness; also (1985) operationally

Orads Optical ranging and detecting systems (USA)

Oralloy Classified metal alloy, not necessarily based on

U-235, used as preferred primary fissile material in NW,

with or without tritium

Orange Could be friendly or hostile, uncertain

Orange Force Simulated hostile force during exercise

(NATO, IADB)

oranges Weather (RAF, WW2)

Oranges Sour Air-intercept code: weather unsuitablefor mission (DoD)

Oranges Sweet Air-intercept code: weather suitable formission (DoD)

Orasis Optical real-time adaptive spectral identificationsystem

ORB, Orb 1 Operations record book (RAF).

2 Omnidirectional radio beacon.

orbat Order of battle

orbit 1 Closed elliptical or quasi-circular path of body

revolving around source of gravitational attractionbalanced by its own centrifugal force

2 Closed pattern, usually circular or racetrack,

followed repeatedly by aircraft, eg in air-intercept loiter

or when holding

3 To follow an * as in (1) or (2).

orbit[al] decay Decay (1).

orbital elements See orbital parameters.

orbital manoeuvring vehicle Used from Shuttle and laterfrom space station to position and retrieve satellites about1,000 miles distant (NASA)

orbital parameters Basic numerical values describingorbit, such as apogee, perigee, inclination and period

orbital period Time to complete one revolution (relative

to space, ignoring such irrelevancies as rotation ofprimary body); symbol P, whose square is always propor-tional to cube of semi-major axis of orbit (distance fromcentre of primary to apogee)

orbital rendezvous See rendezvous.

orbital transfer vehicle 1 The first * was a reusable tug

shuttling between a planetary or lunar orbiter and higherorbits

2 Part of the planned MSP, a vehicle for orbit transfers

and servicing, potentially reducing spacecraft weight andextending on-orbit life

orbit determination Calculation of orbital parameters ofunknown satellite

orbiter 1 Portion of spaceflight system designed to orbit,

as distinct from booster stages, tanks, etc

2 In particular, bus to inspect planetary body from a

distance, with or without probes

orbit point Geographically or electronically definedlocation above Earth’s surface used as reference instationing orbiting aircraft

ORC Oversight and review committee

Orca Optimized raster chart analyzer [sic].

Orchidée Observatoire radar cohérent heliporté, vestigation des éléments ennemis; name means orchid (F)

d’in-Orcon Fire-resistant insulation batting using RKcarbon fibre

ORD 1 Order.

2 Operational, or operations, Requirement[s]

Document

3 Operational readiness demonstration.

4 Optional retirement date (RAF).

Ordalt Ordnance alteration

order book Real or symbolic book containing list ofcustomers for major equipment item, esp commercialtransport, broken down into firm orders, options, leases,etc, and fading from importance with programme’s matu-rity and second-hand customers

ordinate 1 Vertical axis on graph or other geometric

plot

2 Vertical distances measured from datum, eg from

chord line to upper/lower surfaces of aerofoil

ordnance Explosives, chemicals and pyrotechnics for

use against an enemy, including nuclear, together with

directly associated hardware such as guns, rocket

launchers, etc

ordnance alteration Change [usually last-minute] to load

carried by attack aircraft

ordnance devices Explosive or pyrotechnic parts of

spacecraft, RPV or other [especially non-weapon] system

ordnance work rate Various measures intended to offer

single numerical value of rate of application of ordnance

in particular theatre or against one target

Orel Omnidirectional runway-edge lights/lighting

Orex Orbital re-entry experiment

ORGALIME, Orgalime Organization for liaison

between European electrical and mechanical engineering

industries

organic 1 Originally, living material; today broadened

to cover all compounds of carbon and hydrogen, and

often with other elements

2 Assigned to, and forming essential part of, military

formation

3 In many applications involving heat exchange (eg *

reactor, * Rankine cycle), use of organic (1) fluid, often

mixture of polyphenyls

organic air vehicle Organic(2) aircraft; but the first

meaning is a small UAV controlled by a squad of infantry

(SOF, USA)

organizational-level maintenance Performed on a

squadron or other operator unit, eg on an installed or

backed-off engine

organometallic Compound having metal atom attached

to organic radical

OR gate Logic device which, whenever a voltage (eg a 1)

appears at any input, responds with voltage at output)

ORHE On-ramp handling equipment

ORI Operational readiness inspection

orientation 1 Determination of approximate position or

attitude by external visual reference

2 Turning of instrument or map until datum point or

meridian is aligned with datum point or true meridian on

Earth (ASCC)

3 Direction of fibres in lay-up, prepreg or finished FRC

part

orifice meter Fluid-flow measuring technique where

pressure is measured upstream and downstream of

trans-verse plate with calibrated hole

origin 1 Point 0,0 on cartesian graph.

2 Base from which map projection is drawn.

originator Command by whose authority a message is

sent

ORLA Optimum repair-level analysis

ornithopter Aerodyne intended to fly by means of wings

flapping or oscillating about any axis, but not rotating

Oroca Off-route obstruction-clearance altitude

orographic uplift Large-scale uplift and cooling of air

mass caused by mountains; hence * rain or precipitation

Generally synonymous with mountain-wave turbulence

OROS, Oros Optical read-only storage

ORP 1 Optical reference point.

2 On-request reporting point.

3 Operational readiness platform.

ORS 1 Off-range site.

2 Offensive radar system.

3 Occurrence reporting system.

4 Operational Research Section.

ORT 1 Optical relay tube (TADS).

2 Optical resonance transfer.

3 Operational readiness test.

ORTA Office of Research and Technology Assessment

orthicon Camera tube with secondary emission reduced

or eliminated by using low-velocity electrons to scan sided sensitive mosaic, one side scanned and reverse faceilluminated, resulting in stored charges on mosaic beingremoved by beam and generating output signal

two-orthodrome Great circle, hence orthodromic course

orthogonal Originally meant perpendicular; todayblurred, as shown below

orthogonal aerial Pair of transmitting and receivingaerials [antennas], or single T/R aerial, designed tomeasure difference in polarization between radiatedsignal and echo from target

orthogonal biplane One without stagger

orthogonal scanning Use of combined axial and lateralmagnetic fields to control low-velocity electron beam incamera tubes

orthographic Rectilinear projection of solid objects ontwo-dimensional sheet by use of parallel rays, in contrast

to conical perspective rays; result is six possible views (left,right, front, rear, top, bottom), of which four (front, top,left, right) are normally used (in different relative posi-

tions in Europe and N America, see third-angle projection), each representing appearance of object as seen

from infinitely large distance

orthomorphic Map projection in which meridians andparallels cross at right angles, all angles are correctand distortion of scale is equal in all directions from anypoint; several variations are in use, chief being Lambert’sconformal and Mercator’s

ORTL Optical resonance transfer laser

ORU Orbital replacement unit

OSA 1 Operational support aircraft.

2 Official Secrets Act.

3 Open-systems architecture.

OSACOM Written thus though said as a word,Operational Support Airlift Command (USA)

OSAD Outer-Space Affairs Division (UN, Int.)

OSAF Office of the Secretary of the Air Force (US)

OSAMC Open-systems architecture mission computer

OSBV One-shot bonding verfahren (G)

OSC 1 Overhead stowage compartment(s) for carry-on

baggage

2 Optical sensor converter.

Oscar 1 Open-systems core-, or commercial-, avionics

requirements

2 Orbiting satellite[s] carrying amateur radio.

OSCE Organization for Security and Co-operation

in Europe (Vienna, many Permanent Missions anddelegations)

oscillation Repeated fluctuation of quantity on each side

of mean value

oscillator Device for converting direct current into

alter-nating current to give control or carrier frequency, using

not rotating mechanism but transistor or thermionic

valves

oscillogram Hard-copy (eg photographic) record of

oscilloscope output

oscillograph Sensitive electromechanical device

trans-lating varying electrical quantities into visible trace on

paper or film (generally superseded by oscilloscope)

Oscillogyro Patented (Ferranti) gyro having unique

property of measuring displacements about two axes

oscilloscope Device translating varying electric

quanti-ties into visible traces on screen of CRT or similar display

OSD 1 Office of the Secretary of Defense (US).

2 Out of service date.

3 On-screen display.

OSDBU Office of Small and Disadvantaged Business

Utilization (NASA)

OSDS Oceanic system development support (FAA)

OSE 1 Optical shaft encoder.

2 Office of Systems Engineering (DoT, US).

3 Operations support equipment.

Oseen flow See viscous flow.

OSEM Office of Systems Engineering and

Management (FAA, US)

OSF 1 Optronique secteur frontale, fighter EO sensor

OSIA On-Site Inspection Agency (INF Treaty)

OSIE OSI environment

OSI-RM OSI reference model

OSK Department of special construction (USSR, obs.)

OSM Optical support measures, eg laser threat

warning

osmium Hard, heavy, corrosion-resistant silvery metal,

MPt 3,054°C, densest element (at 20°C = 22.588),

symbol Oss

OSO Orbiting solar observatory [Nos 1–8]

Osoaviakhim Society for the support of defence,

aviation and chemical industries (USSR)

OSP 1 Offshore procurement.

2 Orbital/suborbital program (USAF).

3 Optical surveillance platform.

4 Operational special program (JTIDS).

5 Orbital Space Plane (NASA).

OSPF Open shortest path first.

OSR 1 Optical solar reflector.

2 On-site repair.

3 Order status report.

OSRD Office of Scientific Research and Development

5 Office of Space Sciences (US).

OSSAI Organisation Scientifique et Sportive

d’Aérostation Internationale

OS-SAP Operations and support special-accessprogram

OST 1 Outline staff target (UK).

2 Operational suitability test (DoD).

3 Office of Strategic Trade (US).

4 Outer Space Treaty (1967).

5 Office of the Secretary of Transportation (US).

OSTA Office of Space and Terrestrial Applications(NASA)

OSTD Office of SST Development (DoT, US)

OSTIV Organisation Scientifique et TechniqueInternationale du Vol à Voile (Int., office Delft)

OSTM Ocean-surface topography mission

OSTP Office of Science and Technology Policy (US)

OSU Omega/vlf sensor unit

OSV Ocean station vessel

Oswatitsch inlet Supersonic inlet/diffuser in form ofbody of revolution having pointed conical centrebody

of progressively increasing semi-angle, thus generatingsuccession of inclined shocks at increasingly coarse anglesall focused on peripheral lip

2 Orbital transfer assembly.

3 Over the [or overflight] top attack.

4 Other transaction agreement[s].

OTAA Office of Trade Adjustment Assistance (US)

OTAEF Operational Test & Evaluation Force (but seeOTE, OT&E)

OTAES Optical technology Apollo extension system

OTAN NATO (F)

OT&E Operational test and evaluation

OTAR Over-the-air re-keying

OTAS On top and smooth

OTC 1 Operational training course (USAF).

2 One-stop tour charter.

3 Overseas Telecommunications Commission of

Australia

4 Operational [or official] test centre.

5 Officer in Tactical Command.

OTCIXS Officer in tactical command informationexchange system

OTD 1 Origin to destination.

2 Optimal terminal descent.

3 Optical-transient detector.

OTDA Office of Tracking and Data-Acquisition(NASA)

OTDF Outlet temperature distribution factor

OTE National telecommunications organisation(Greece)

OTE, OT&E Operational test and evaluation [A addsAgency, C adds Command] (USA)

OTER Over-temperature emergency rating

Otevfor Operational test and evaluation for operationalrequirements (USN)

OTFP Operational traffic flow planning

OTH 1 Over the horizon; hence * radar.

2 Other.

OTH-B Over the horizon, backscatter

other ranks Soldiers who are not yet NCOs, army alent of airmen (UK)

OTH-R Over the horizon, radar.

OTH-SW Over the horizon, surface wave

OTH-T, OTHT Over the horizon, target[ting]

OTIS Optronic tracking and identification system

2 On-top position [ie, above submerged submarine].

3 Operation[al] test programme [S adds set].

OTPI On-top position indicator

OTPS Oceanic traffic-planning system (FAA)

OTQ Over-temperature qualification

OTR 1 Operational turn-round.

2 Oceanic transition route.

3 Other.

4 Overberg Test Range (S Africa).

5 Operational Test and Readiness; R adds Review.

OTS 1 Over the shoulder.

2 Orbital test satellite.

3 Out of service.

4 Organized track system[s].

5 Off the shelf.

6 One-man ticketing system, or structure.

OTSI Operating time since inspection

Otto cycle General name for four-stroke spark-ignition

cycle for piston engine

OTU Operational training unit

OTV 1 Orbital transfer vehicle.

2 Obstruction to vision.

OTW 1 On the wing; hence * replacement of engine

module

2 Over the wing; B adds bridge.

OTWD Out-the-window display (simulator)

OU Operations unit

OUBD Outbound

OUE Operational utility evaluation

ounce Imperial mass, 28.3495 g, abb oz

out 1 Radio procedure word: conversation is completed.

outboard 1 In direction from centreline to wingtip.

2 Further from centreline (eg * engine, in relation to

other[s] on same side)

3 Carried outside main structure.

outbound 1 Towards destination; hence VOR * radial.

2 Away from Conus (US military usage).

3 In holding pattern, side opposite to inbound (which

heads towards holding fix)

outbound bearing That of outbound leg of holding

pattern or of VOR radial en route to destination or next

outer Further from aircraft centreline, but see * wing

outer air battle Taking place 100 nm or more from

surface fleet Battle Force, beyond radius of ship-to-air

weapons

outer cover External skin of rigid airship

outer fix Fix in destination terminal area, other thanapproach fix, to which aircraft are normally cleared byATC and from which they are cleared to approach forfinal approach fix (FAA)

outer loop FCS in autopilot mode, human pilot beinginner loop

outer marker ILS marker normally on approach line approximately 4½ nm (8.3 km) from threshold;usually identified by 400 Hz aural dashes and synchro-nized blue panel light

centre-outer panel Left or right wing outboard of centresection

outer wing Apart from obvious meaning: in a turn, thatpointing away from centre of turn, experiencing increasedairspeed

outfall valve Usually synonymous with outflow valve

outflow Violent low-level wind radiating out fromdownburst, or created beneath hovering VTOL aircraft

outflow pattern Isobar pattern above wing at positiveangles of attack

outflow valve That incorporated in isobaric pressure regulator through which air is allowed to escape

cabin-to atmosphere during climb cabin-to isobaric altitude

outgassing Emission of gas from metals and othermaterials in high-vacuum conditions

outlet temperature distribution factor Combustionchamber outlet peak temperature (T) minus outlet mean

T divided by mean combustion chamber T rise

out of alignment In case of propeller or rotor blade,having incorrect sweep (bent forward or back in plane ofrotation)

out-of-control lights Two superimposed red lights 6 ft(2 m) apart hoisted at night on mast of marine aircraftwhose engines have failed and which is not anchored

out of phase Not synchronized; two or more cycles orwavetrains which have same frequencies but pass throughmaxima and minima at different times

out of pitch In case of propeller or rotor blade, havingblade angle different from that of remaining blades

out of step Not synchronized; two or more series ofdigital pulse trains or other discrete phenomena havingessentially same frequency but occurring at differenttimes

out of track In case of propeller or helicopter rotorblade, having incorrect tilt so that particular tip does notlie on tip-path plane

output 1 Total product or yield from system, eg

4 Signal from transducer or other instrumentation.

5 Power developed by engine or other prime mover.

6 Shaft at which power is extracted from shaft-drive

engine

7 Verb, to deliver an * (2), hence outputting.

outriggers 1 Primary structural members carrying tail of

aeroplane with short fuselage, nacelle or boat hull, alsocalled booms

2 Ancillary landing gear near wingtip or at other

loca-tion well outboard from centreline on aircraft with bicycle

or other type of centreline landing gear

outside air temperature 1 Free-air static temperature

(UK)

2 The uncorrected reading of the OAT instrument,

requiring corrections to obtain true static temperature

(US)

outside loop Inverted loop, performed with aircraft

upper surface outwards and thus under negative g

outside roll One started from negative g, esp from

inverted attitude

outside wing That on outer side of spin, having greater

airspeed than inside wing

outsourcing Subcontractor brings in someone else to

help

outspin On outer side of spin, hence * aileron or rudder

outspin yaw Yaw inevitably present in normal spin,

usually function of pitch attitude

outyears Period during which item is in operational

service (USAF, later general use)

OUV Oskar-Ursinus Vereinigung, association of

amateur aircraft constructors (G)

ovalisation Structural distortion such that circular parts

become ovals, esp on pylon-mounted turbofans

oval office The President of the United States; thus *

green = his authority to proceed

OVC Overcast

ovenise To bake electronic device to simulate overload

test condition

over Radio procedure word: ‘My transmission is ended

and I expect a response from you’

overall efficiency In case of aircraft propulsion system,

usually thermal efficiency multiplied by propulsive

(Froude) efficiency

overall length Most definitions for aircraft stipulate in

flying attitude; distance between local perpendiculars

aligned with extremities of basic airframe (but usually

excluding pitot or instrument probes, static wicks etc) See

length.

overall pressure ratio OPR, ratio of total pressure at

delivery to combustion chamber to that at engine inlet [the

latter taken as unity, so OPR 26:1 can be written as 26]; in

a turbofan OPR = FPR × compressor PR

overbalanced Provided with excessive balancing mass,

aerodynamic area or other source of control-surface

moment assisting pilot, so that control surface has little

feel (and in extreme case can move by itself to hard-over

deflection)

overboard bleed From compressor to assist starting, not

used in normal running

overbooking Practice of selling more tickets for a

partic-ular flight than there are seats, to compensate for

(1) no-shows and (2) individual pax or agents making

multiple reservations for one journey

overbuilt Made stronger than necessary, usually to allow

for future development

overburn Operation of rocket or other space propulsion

system for too long a period (0.1s can be significant),s

resulting in incorrect cutoff velocity and/or trajectory

overcast Means 0.9+ cloud cover except IWC = ⅞+

[= 0.875+]

overcontrol To apply more control deflection thannecessary, commonly resulting in succession of excursions

on each side of desired flight condition

overdesigned 1 Stronger than necessary to meet

require-ments

2 More refined than necessary, usually resulting in

lighter structure at expense of high cost and complexity

overexpanded nozzle One in which jet leaves at belowambient pressure

overfin Fin added above high [T-type] horizontal tail

overflight Flight over particular route, esp acrossunfriendly territory

overflight top attack Class of missiles which detonate

shaped charges downwards as they pass over armouredvehicle

overfly To fly over

overhang 1 Spanwise distance from junction of wing and

bracing struts to tip; length of cantilever mainplane

2 Spanwise distance to tip of upper wing of biplane

from point vertically above tip of lower wing

overhaul period Also called TBO, the time betweenconsecutive overhauls For aircraft or engine or otherfunctioning item * is actual operating time in hours Formissile and some other items such as ejection seat it is totalelapsed time

overhead Apart from normal meanings, involving theuse of one or more satellites

overhead approach Landing procedure in which pilotflies downwind over point of touchdown and then makesdescending circular pattern centred on extended landingcentreline; also called 360° landing

overhead camshaft In upright cylinder, above the head;thus, beyond horizontal cylinder, below an invertedcylinder

overhead stick Control column pivoted to cockpit roof

overhead stowage Provision in passenger transport forhand baggage and other rigid or heavy items to be stowed

in latched bins above seats

overhead suspension Docked rigid airship hung fromroof of shed

overhung 1 Cantilevered beyond last point of support,

esp applied to fan, compressor or turbine stages mounted

at extremity of shaft system beyond nearest bearing

2 Projecting beyond tip of fixed surface, adjective

normally applied to aileron or elevator

overlap 1 Percentage of photograph duplicated on next frame of same film (see lap).

2 See overlap zone.

overlap tell Transfer of information to adjacent defence facility of (normally hostile or unidentified) tracks

air-in latter’s region

overlap zone Designated area on each side of boundarybetween adjacent tactical air control or defence regionswherein co-ordination and interaction are required

overlay Upper (exoatmospheric) layer of layereddefence system (SDI)

overload report Filed by ATC controller when workload

could lead to safety being compromised

overload response Procedures designed to enable an

inadequate ATC system to handle traffic at peak periods

(UK)

overload weight 1 Alternate MTO weight authorized

only in unusual circumstances

2 Any takeoff weight exceeding permitted maximum.

overpressure 1 Limiting values reached above and below

normal atmospheric pressure during passage of blast

wave of explosion (nuclear or conventional)

2 Peak positive pressure reached during passage of

boom from supersonic aircraft

override Facility for bypassing or overcoming normal

limit on command action to obtain exceptional response,

usually in emergency (eg * boost)

override boost Emergency higher boost pressure

avail-able in exceptional circumstances such as overload

takeoff or in combat

overrun 1 To fail to stop within available landing

distance

2 Control facility causing camera to continue operating

for preset number of frames or seconds after cutoff of

control

overrun area Paved area beyond end of runway which

for any reason is not in use; usually marked with

herring-bone pattern

overrun barrier Layer of material beyond end of runway

provided to arrest overrunning aircraft with minimal

damage; PFA is preferred to gravel

overrunning clutch One allowing driven member (eg

heli-copter rotor) to run ahead of drive system

overseer Common term for software used in managerial

role in large system

overshoe Externally attached de-icer of

pulsating-rubber mechanical type; also called boot

overshoot 1 To abandon landing and make fresh

approach; in US called missed approach or go-around

2 To land too far across available landing area and

make uncontrolled excursion into region beyond

3 To exceed desired IAS, altitude or other flight

condition

4 To pass through enemy aircraft’s future flight path in

plane of symmetry

overshoot area Designated area of semi-prepared

ground available to overshooting (2) aircraft (usually GA

only) from which they may taxi relatively undamaged

overspeed condition Normally applied to rotating

machinery, and permissible for brief specified period and

within specified limit An exceptional and usually

unde-sired condition, and in no way synonymous (as claimed in

one source) with takeoff rpm

overstow position Inoperative position of target-type

reverser with geometry which precludes inadvertent

oper-ation in flight

overstress Application of load which could cause

struc-tural failure [particularly positive or negative pitch input

which could break wing]

oversweep Ultra-acute setting of VG pivoted wings [eg,

to make carrier-based F-14 aircraft more compact when

parked]

overswing Undesired azimuth excursion by aircraft with

long, heavy body during fast turn while taxiing, esp on

over-the-shoulder delivery See toss bombing.

over the top On top (1).

over the weather At pressurized cruising levels; basicmeaning is free from turbulence except CAT, but cloudmay still be present and cu-nims must be avoided

over the wing Aeroplane configuration in whichturbofan is located above wing to give USB powered liftbut without surface scrubbing losses

overturn boundary Limiting sea state for safe operation

of float or pontoon-mounted helicopter

overturn pylon Strong structure to protect occupants ofsmall aircraft in overturn on ground

overwater Particular provisions apply to commercialtransports for use on sea crossings where power-off glide

to land is not possible Adjective also applied to range versions, irrespective of actual intended routes

OVS Overhead video system

OVTR Optical videotape recorder

OW Oblique (slew) wing

OWB Over-the-wing bridge (passenger loading)

OWE Operating weight empty

OWF Optimum working frequency

OWL 1 On-wing life (main engine).

2 Obstacle-warning ladar.

3 Over water and land.

4 On-target weapon, long-range.

OWLD Obstacle warning, location and detection

OWM One-way mission

OWRM Other war reserve materiel (US)

OWS 1 Orbital workshop.

2 Obstacle warning system (helo).

3 Optical weapon sight.

OWSF Oblique-wing single fuselage

OWTF Oblique-wing twin fuselage

OWWS Operational windshear warning system

OX, Ox 1 Longitudinal axis about which aircraft rolls.

2 Oxygen: OX1 HP gaseous, OX2 LP gaseous, OX3 HP

replacement bottles, OX4 LP bottles, no code for liquid

oxidant Chemical carried as rocket propellant forcombination with fuel; examples are lox, nitrogentetroxide, nitric acid and mixtures of fluorine and oxygen(flox)

oxidation 1 Removal of electron from atom or atomic

group

2 Combination with oxygen, as in burning or rusting.

oxidiser Oxidant (N American usage)

oxidising flame In gas welding or cutting, one havingexcess oxygen

oximeter Instrument giving numerical readout of bloodoxygen concentration

OXRB Oxygen replacement bottles available

oxy Oxygen.

oxygen O2, odourless gas, vital to life, density 1.43 gl–1

;liquid [lox] density 1.1, MPt –218°C, BPt –183°C For

aircraft breathing purposes, Grade A mandatory, 99.5%

pure, many other requirements including water

0.005 mg/l In US OX1/2/3/4 are respectively HP gas, LP

gas, HP replacement bottle and LP replacement bottle

oxygen bottle Container for gaseous oxygen under

pressure

oxygen converter Liquid oxygen converter (ie boiler)

supplying gox to breathing system

oxygen mask Face mask for supplying gaseous oxygen

to wearer, usually on demand, and separating exhaled

breath

oxygen microphone Microphone fitted to oxygen mask

(probably arch.)

OY Option Year

OY, Oy Lateral axis about which aircraft pitches

OYM Optional yield management

OZ, Oz Vertical axis about which aircraft yaws

ozone layer See ozonosphere.

ozonosphere Layer of upper atmosphere, roughly at20–40 km altitude, where ozone concentration is muchhigher than at SL and ozone plays major role in estab-lishing radiation balance

P 1 Generalized symbol for force.

2 Power, esp bhp of shaft engine or peak power of

transmitted signal

3 Aircraft category, pursuit (USA, USAS, USAAC,

USAAF, 1925–47, USN 1923), and patrol (USN from

8 Pressure; normally p but gas-turbine pressures

normally written P1, P2etc

9 Pulsed, or pulse (eg with suffix numeral P1, P2 etc).

10 Pilot, with numerical suffix 1, 2, 3 etc to show

hier-archical ranking of pilots in same crew

11 Prefix, plus (wind component).

12 Production cost.

13 Ratio of full-scale length to model length, esp in

radio aerials and related fields

20 Aerospace craft (FAI category).

21 Primary, primary frequency, or winding.

22 Precision (DME, GPS, MLS).

23 Packet (TDM mode).

24 Paved surface.

25 Prefix peta = 1015, thousand million million

26 Airport with instrument-approach procedure.

27 Number of persons on board.

5 Pound mass (ambiguous, eg psi, see next).

6 Per (ambiguous, eg lb psi).

7 Parts (eg ppm, parts per million).

8 Port (ie, left).

2 Specific weight (air-breathing jet engine).

3 Average rocket-motor chamber pressure.

4 Generalized symbol for averaged pressures.

P 0 Total static pressure head; stagnation pressure

P 1 1 Compressor inlet total pressure.

2 First pilot, captain of aircraft.

P 12 , P ½ Fan inlet pressure

P 2 1 Compressor delivery pressure (single-spool) or fan

P4 Runway has 4 PAPIs

P.4, P.6 Standard magnetic compasses (UK, 1930–50)

P-alt Pressure altitude

P-band Frequency band, 225–390 MHz (Appendix 2)

P-channel Packet-mode channel, in two forms, Pd and Psmc.

P-charge Projectile-charge warhead (SAM)

P-clamp For ordinary electric/electronic cables

P-clip For convoluted conduit with raised rib to preventlateral movement

P-code Precise or protected navigation code, billions ofpseudo-random numbers on 10.23 MHz repeating each

267 days, each 168-h (one week) segment unique to ticular GPS satellite

par-P-display Radar display of PPI type

P-factor 1 Asymmetric propeller loading.

2 Effect on propeller aircraft of spiral slipstream[s].

P-lead Primary (switch) cable of magneto

P-line Electric cross-country power line

P-time Proposed departure time

p-type semiconductor One in which majority of carriers are holes (electron absences)

charge-PA 1 Public, or passenger, address.

7 Pilot’s associate, or assistant.

8 Porte avions, aircraft carrier (F).

9 Pressure altitude.

10 Pursuit, aircooled (USA 1919–24).

11 Power[ed] approach [esp to carrier].

P/A Payload/altitude curve (sounding rocket)

Pa 1 Pascal, SI unit of pressure.

2 Polar Atlantic.

Pa Action-time average chamber pressure; sometimesabb Pc

P

pa, p.a. Power amplifier.

PAA 1 Partial air alert.

2 Primary aircraft authorization, or authorized.

3 Passenger-address amplifier.

4 Phased-array antenna.

PAAMS Principal anti-air missile system

PA&E Program analysis and evaluation (DoD)

PABST Primary adhesively bonded structure

tech-nology

PABX Private automatic branch exchange

PAC 1 Parachute and cable (rocket-launched ‘SAM’,

WW2)

2 Public Accounts Committee (UK, House of

Commons)

3 Programmable armament control.

4 Photometrical airfield calibration.

5 Path attenuation compensation.

6 Pacific Region (ICAO).

7 Penetration-aid[s] carrier.

8 Precision attitude control.

9 Public-address control.

10 Poste aérienne de commande (F).

11 Presidential Advisory Committee (US).

12 Pulley and cable [flight control].

PACA 1 Precision attitude control augmentation;

/IAGSS adds improved air/ground sight system

2 Programmed adaptive clutter attenuator.

PACAF, Pacaf Pacific Air Forces (USAF)

PACCS Post-attack command and control system

Pacer Portable aircraft condition evaluation recorder

PA/CI Passenger address and cabin [or

communi-cations] interphone [S adds system]

pacing item Task whose time for accomplishment

deter-mines overall time for programme; any major item on

critical path

PACIS Pilot aid and close-in surveillance

pack 1 Bag in which parachute is packed.

2 Complete system in demountable package which may

be attached inside or outside aircraft, eg for multi-sensor

reconnaissance, rocket thrust-boost, gun and

ammu-nition, or air-conditioning

3 In particular, ECS air-conditioning unit comprising

bootstrap ACM(1) plus air/air heat exchanger

package 1 See pack (1).

2 Complete offer of international contract covering

either collaborative development or manufacture of

aircraft complete with associated offsets, loans, training

and other attractions, and with agreed share to each

partner of overall effort and/or cost

3 Complete offer of international contract covering sale

of aircraft with associated offers of offsets, training,

service support, construction of support facilities, etc

4 Assembly of attack aircraft, tankers, EW jammers,

etc, to carry out a mission

package aircraft Subject of package (2, 3) deal

packaged 1 Of petroleum products – eg POL, jet fuel –

contained in drums having capacity not greater than 55

US gal (208.2 l)

2 Of electric generating plant, nuclear reactor, etc,

mounted on skids and transportable thereon as operative

unit

packaged propellant Rocket motor fed by liquid

propel-lant(s) sealed in container forming single unit with thrust

chamber

package gun One mounted in fairing outside aircraftfuselage, usually fixed

package programme Timetable for package (2, 3)

packet 1 Single pulse of radar, digitized signal or other

coded EM emission

2 Prepacked quantity of chaff, either pre-cut or as

roving, for loading into dispenser

3 Discrete parcel of data sent through multiple network

channels and reassembled at point of delivery

packet mode TDM mode for signalling, control and

data com See Pd and Psmc (GPS).

pack hardening Nitriding by heating inside loose pack ofcarbonaceous material

PACS 1 Passive attitude control system, eg gravity

gradient

2 Pitch-augmentation control system.

PACT 1 Portable automatic calibration tracker.

2 Precision aircraft control technology (CCV).

Pactec Partners in aviation and communications nology, non-profit humanitarian organization working indeveloping countries

tech-Pacts Parliamentary Advisory Council for TransportSecurity (UK, 2002)

PAD 1 Picture assembly device.

2 Point air defence; T adds trainer.

3 Persistent area-denial, or dominance.

4 Precision aerial delivery (USAF).

5 Packet assembler/disassembler.

6 Primary Awacs display.

7 Pad-abort demonstrator, or demonstration.

PADA Phased-array downlink antenna

pad 1 Platform for launch of vehicle, usually of ballistic

or unmanned nature (colloq and becoming arch.)

2 Platform for operation of helicopter, esp on surface

vessel

3 Attachment face on engine or other energy source for

accessory, usually with central shaft drive

4 Network of resistances or impedances to couple to

transmission lines effectively

pad abort Abort before launch from pad (1)

padder See padding capacitor.

padding capacitor In series with superhet lator tuning capacitor to match exactly to frequency

local-oscil-paddle In a rate gyro, damping drag surfaces whichgenerate angular difference proportional to first-orderrate term

paddle blade Propeller blade having unusually widechord maintained to tip

paddleplane See cyclogiro.

paddle switch Ambiguously used to denote electricalswitches operated by dynamic air pressure, dynamic waterpressure in ditching and various other activation sources

PADIS, Padis Procedures for analysing the design ofinteractive solutions (fire-control software)

Padlocked “I have my vision fixed on bogies/banditsand will not look away”

PADM Persistant area-dominance munition

pad output Power rating of shaft at each pad (3) location

on engine, APU or MEPU

PADR Product-assurance design review

PADS, Pads 1 Passive advanced sonobuoy.

2 Position and azimuth determining system.

3 Precision automatic dependent surveillance.

PADUS Principal Assistant Deputy Under-Secretary

(US)

PAF 1 Parabolic aircraft flight.

2 Police de l’Air et des Frontières (F).

3 Potassium acetate fluid (de-icer).

PAFAM, Pafam Performance and failure assessment

monitor (independent flight guidance with flight-deck

displays during autolanding)

PAFU Pilots’ advanced flying unit

PAG 1 Programmable automatic gauge, for NC

dimen-sional checking

2 Portable arrester gear.

Pageos Passive GEOS [Geodynamic experimental

ocean satellite(s)]

PAH 1 Anti-tank helicopter (G).

2 Polycyclic aromatic hydrocarbon.

3 Production approval holder (FAA).

PAI Parachute Association of Ireland Ltd

Paid, PAID Parked-aircraft intrusion detector

paint To create blip on radar display, esp one giving

position of aircraft or other object

paintless aircraft Instead of usual finishes, covered with

protective film of appliqué materials, saving weight, cost

and support requirements

paint-on bag Flexible vacuum bag formed in place to

cover layup of composite material fabrication and seal

tool in prototype moulding of large parts

paint-stripe loading Vertical stripes inside cargo aircraft

to assist loaders in achieving correct load distribution,

esp with regard to c.g

PAIR, Pair Precision-approach interferometer radar

pair Section of two fighters operating together

paired channels Selecting Vortac or ILS frequency

auto-matically also selects a DME

PaK Anti-armour cannon (G)

PAK-FA Future air complex for tactical aviation,

loosely = next-generation fighter (R)

PAL 1 Passive augmenting (or augmentation) lens, eg

Luneberg

2 Standard German TV/video system; from phase

alter-nation line

3 Permissive action link.

4 Portable airfield lighting; S adds set.

5 Programmable array logic.

6 Propulseur d’appoint liquide (F).

7 Preprocessor assignment logic.

PALC Point Arguello Launch Complex

Palea Philippine Airlines Employees Association

PALF Partly aloft (precipitation not reaching ground)

palisade Large hinged flight-deck barrier (RN carriers

1919–32)

palladium Pd, silvery malleable metal, density 12.0, MPt

1,552°C

pallet 1 Standard platform for air freight, eg (Imperial

measures are still used) 88 in × 125 in, 88 in × 108 in and

96 in × 125 in

2 Flat base, not necessarily of above dimensions, for

combining stores or carrying single item to form unit load,

in some cases retained as temporary or permanent base in

operation

3 Standard-dimension base on which can be assembled

experiments, ancillaries and other payloads, eg for

Spacelab

4 Standard-dimension base carrying work-pieces in

mechanized and automated manufacturing

5 Configured (shape-matching) payload carrier for

attachment close against airframe exterior, eg fuel *(FAST Pack)

pallette Subsystems

palletized bladder Flexible container for liquid mounted

on pallet (1) for airfreighting

palletrolley Pallet (2) with wheels for ground transport,

eg for Sea Skua missile

Palmachim On coast south of Tel Aviv, base for flight, IRBM, ABM (Israel)

space-Palmer scan Radar scanning technique in which conicalscan is superimposed on some other, eg Palmer-sector(beam oscillates to and fro over azimuth sector whilecontinuously making small-angle conical scan), Palmer-raster, Palmer-circular etc

palm tree Upward bomb burst (formation aerobatics)

Palnut Thin nut, usually pressed steel, screwed tightlyabove ordinary nut to prevent loosening of latter

PALS, Pals 1 Precision approach and landing system.

2 Portable airfield light set (USAF).

3 Positioning and locating system.

palsar Phased-array L-band SAR

PAM, p.a.m. 1 Pulse-amplitude modulation; also,

confusingly, phase-amplitude modulation

2 Payload assist module.

3 Picture assembly multiplexer.

4 Plasma-arc machining.

5 Precision attack missile.

6 Peripheral adapter module.

7 Portable automated mesonets (weather).

PAMA Professional Aviation Maintenance (formerlyMechanics) Association (US)

PAMC Provisional acceptable means of compliance(ICAO)

Pamela Process abstraction method for embedded largeapplications

Pamir 1 Passive airborne modular IR.

2 Phased-array multifunction imaging radar.

PAMR Public-access mobile radio

PAMS Point anti-missile system

PAN 1 Polyacrilonitrile, precursor of carbon fibre in

most processes

2 Originating station has urgent message to transmit

concerning safety of vehicle or occupant(s) (DoD); seePan

3 Porte avions nucléaires (F).

Pan Radio code indicating uncertainty or alert, generalbroadcast to widest area but not yet at level of Mayday

pan 1 Base of seat tailored to pilot with seat-type pack.

2 Paved dispersal point for single aircraft.

3 Carrier for air-drop parachuted load.

pancake 1 Vague term supposedly indicating landing at

abnormally low forward speed and high sink rate (arch.)

2 Air-intercept code: “I wish to land”, usually followed

by word giving reason, eg * fuel (DoD)

3 Verb, to land (arch.).

4 Flat-topped fuselage regarded as a lifting surface.

pancam Panoramic camera (planetary lander)

P&A Priorities and allocations

Panda Personnel and administration

P&ES Personnel and equipment supply

P&F Particles and fields

P&I Paint and interior.

P&O Plant and operations

P&P 1 Plans and programs (DoD).

2 Payments and progress (NATO).

P&SS Provost and Security Service (RAF)

P&T Priorities and traffic

P&TC Personnel and Training Command (RAF)

panel 1 Single piece of aircraft skin, eg fuselage *.

2 Major section of wing as finished component, eg

outer *

3 Essentially planar base carrying instruments.

4 Complete portion of stressed-skin structure,

sand-wich or, rarely, other constructional form, used for fatigue

or static test purposes; not necessarily portion of actual

aircraft

5 Subdivision of parachute canopy, either complete

gore or portion thereof

6 Body of experts, eg examining *.

7 Marking panel.

panel code Standard code for visual ground/air

com-munication (IADB)

panel elements Items mounted on panel (3) such as

instruments, switches and displays

panel fill factor The percentage of the complete

instru-ment panel facing the pilot that is occupied by

multifunction displays

panelled Equipped with instruments and avionics, thus

well * (colloq.)

panhandle Aircraft dispersal of frying-pan shape

pan-handle Ejection-seat firing handle on seat pan

pan-head screw One having thin, large head with slightly

convex upper surface

panic button Gives emergency recovery to unaccelerated

horizontal flight with wings level (USAF)

PANNI Psychological assessment of noise and number

index [see noise]

pannier Small 1-, 2- or 4-tube rocket launcher added to

CBLS or other stores carrier

panoramic camera One which by means of system of

oscillating or rotating optics or mirrors scans wide strip of

terrain usually from horizon to horizon Mounted

verti-cally or obliquely to scan across or along line of flight

PANS, Pans Procedures for Air-Navigation Services;

/OPS adds aircraft operations, /RAC adds radio com

procedures

PANS-ABS PANS abbreviations and codes

Pantera Precision attack navigation and targeting with

extended range acquisition

panting In/out springy movement of thin skin under

compressive stress; generally similar to oil-can effect

pantobase Landing gear designed for land, water, snow

and possibly other surfaces

pantry Aircraft kitchen without provision for heating

prepacked meals

pants Fixed fairing over landing gear leg and, esp.,

wheels; generally similar to spats but chiefly US usage

pants duct Large-diameter Y-piece forming junction or

bifurcation in duct system

PANYNJ Port Authority of New York and New Jersey

PAO Poly-alpha olefin

PAP 1 Precision approach path.

2 Plug and play (transport a/c fuselage).

3 Paintless aircraft programme.

4 Propulsion [or propulseur] d’appoint à poudre

[ = solid booster rocket]

5 Pierced, or perforated, aluminium plank[ing].

Papa Parallax aircraft-parking aid

paperless Totally on computer; thus * cockpit, in whichall paper is replaced by EFB

paper returns Written lists of [military] aircraft at ness, serviceable, unserviceable and written off, possiblyadjusted for political reasons

readi-PAPI, Papi Precision approach path indicator

PAPM, p.a.p.m. Pulse amplitude and phase tion; narrows signal bandwidth to quadruple carryingcapacity per channel

modifica-Paprica Passenger relief in co-operation with airlines

PAPS, Paps 1 Periodic armaments planning system

(NATO)

2 Phased armaments programme systems.

3 Precision-airdrop planning software (USAF).

PAR 1 Precision approach radar.

2 Progressive aircraft rework (USAF, USN).

3 Phased-array radar, ie electronically steered instead

of mechanically scanned

4 Perimeter-acquisition radar (ABM).

5 Pulse-acquisition radar (SAM).

6 Program(me) appraisal and review.

7 Preferential, or preferred, arrival route.

8 Power analyser and recorder.

9 Parachute/airbag recovery.

10 Parallel.

11 Physiological ageing rating.

12 Performance and reliability.

13 Private pilot, airplane, recreational.

Par Precision aircraft reference (Lear-Siegler twin-gyroplatform)

parabola Conic section made by cutting right circularcone parallel to any of its elements; locus of point whichmoves so that distance from line (directrix) equalsdistance from point (focus), so eccentricity = 1

parabolic aerial One whose reflecting surface formsportion of parabola, thus converting plane waves intospherical waves or vice versa, and either emitting pencilbeam from point feeder or focusing incoming radiation tosingle-point receiver Also called parabolicantenna/mirror/reflector

parabolic trajectory As eccentricity is unity it representsleast eccentricity for escape from attracting body

paraboloid Shape in 3-D formed by rotating parabolaabout major axis

parabrake Braking parachute

Parac PAR(4) attack characterization, system ling-wave tube

travel-parachute 1 Any device comprising flexible drag or

drag + lift surface from which load is suspended by shroudlines Originally canopy was umbrella-shaped but todaymay be of Rogallo or other semi-winged types offeringprecision control of landing within large area Distinctionbetween * and hang glider is blurred, but chief featuresdistinguishing * are rapid deployment from packed condi-tion and suspension of load well below canopy

2 Verb, to use (1).

3 Verb, to deploy an aerodynamic-drag system (UAV).

parachute deployment height Height AGL at whichcanopy is fully deployed

parachute flare Illuminating flare equipped with

para-chute to prolong descent

parachute gore See gore.

parachute harness That to which personal parachute is

attached

parachute pack Bag containing packed parachute

parachute tower 1 Tower or mast from which parachute

descents are made for sport or instruction

2 High-ceiling part of parachute section of airbase

wherein parachutes are hung to dry after use

parachute tray Rigid base to pack of parachute used in

heavy dropping

parachute vent Aperture in top of canopy or left by

blank gore(s) to ensure stable descent

para-circular Near-circular orbit (intended to be

circular)

paradrag drop Ultra-low airdrop of cargo using drag of

arrester parachute to extract and halt payload (NATO)

paradrop Delivery by parachute (from height

signifi-cantly greater than paradrag drop) of personnel or cargo

from aircraft (NATO)

paraffin Kerosene.

parafoil Parachute able to fly as aerodyne (L/D about 3)

and stall, but with canopy instantly deployed from packed

condition and attached by normal harness

parafoveal vision Used at night to see extremely dim

sources; eye is oriented so that what light there is falls on

area of retina populated mainly with rods, not in central

(foveal) region but surrounding it

paraglider 1 Inflatable hypersonic spacecraft having

form of metallised-fabric kite of paper-dart shape

2 Also formerly applied to various flexible-wing gliders,

towed kites and parafoils but today no longer used; each

device must be either a kite, hang glider, parachute or

parafoil

Paralkatone Protective sealant film sprayed on

aluminium alloy aircraft, usually after completion or

during erection

parallax aircraft parking aid Built into airport gate,

gives precise optical guidance for each type of aircraft

parallax error Caused by viewing bi-planar display [eg

dial instrument] obliquely

parallel 1 Great circles parallel to Equator (* of

latitude)

2 Circle on celstial sphere parallel to celestial equator

(* of declination)

3 Connected so that current flow, signal, etc divides and

passes through all components simultaneously, thereafter

recombining

4 Software connection so that each signal has its own

wire; hence a 16-bit wire has 16 conductor paths

parallel actuators Two or more in parallel to drive single

load; usually physically separated and tied by load in force

or torque-summing fashion (thus providing rip-stop

design)

parallel aerofoil Having constant section from tip to tip;

two-dimensional

parallel burning Solid grain which ignites at centre over

whole length and burns purely radially outwards to case

parallel double-wedge Aerofoil whose section is that of

flat hexagon with sharp wedges at leading and trailing

edges and parallel upper and lower surfaces; poor at

subsonic speeds but acceptable supersonic shape, esp for

missiles

parallel-heading square Training manoeuvre in whichhelicopter is flown at low level around a square, each ofthe four legs being flown with helicopter aligned with thatside of square

parallel ILS Serving parallel runways, with minimumlateral separation of 1,500 m, 5,000 ft

parallel-line design Aircraft whose wing LE/TE, tipsand sharp edges are all parallel This concentrates radarsignature into very narrow beams, easily missed byenemy B-2 is example

parallel offset Airway R-Nav route running alongsidedesignated airway

parallel of origin Parallel of latitude used as an origin (2)

parallel redundancy Addition of channels in parallel (3)mode purely to increase redundancy (1)

parallel resonant circuit Tuned circuit with inductiveand capacitive elements in parallel (3)

parallel runways Runways at same airport on samealignment and with sufficient lateral separation to permitsimultaneous use, including parallel ILS approaches.Designators have suffix L or R [left or right] thus 28L issouth of 28R

parallel servo One located in control system so thatservo output drives in parallel with major input; usuallyarranged to drive both cockpit controls and flight-controlsystem and thus performing as alternative to pilot

parallel warfare Use of a sensor network and EBO torender an enemy helpless (USAF)

parallel yaw damper One connected direct intopilot/rudder control loop and, in some cases, resulting inmovement of cockpit pedals Normally superseded byseries damper

paramagnetic Possessing magnetic permeability above 1and permanent magnetic moment; atoms tend to align indirection of external field giving resultant magneticmoment and tend to move to strongest part of field

Paramatta Code for RAF WW2 blind target-marking

by PFF using precision-aimed TIs of sophisticated typesrepeated at intervals; usual form with electronic aidscalled Musical *

parameter Basic definable characteristic or quality, esp.one that can be expressed numerically; specialized mean-ings in maths, EDP (1) and statistics

parametric amplifier Reactance amplifier dependent ontime-varying reactance (fed by signal and a pump source)forming part of tuned circuit; variable-capacitanceusually Varactor or crystal diode Also called Mavar(mixed amplification by variable reactance)

parametric study Study based on numerical values ofsystem variables

parametric take-off number Product of (landing wingloading × 1.11) ×(MTOW ÷ [total installed thrust × CL2])

paramotor Engine/propeller and seat unit for ment to hang glider or parafoil

attach-paramp See parametric amplifier.

pararescue team Trained personnel who reach site ofincident by parachute and render aid

parasheet Parachute in form of regular polygon withrigging lines attached to apices; subdivided into gathered

* (periphery constrained by hem cord) and ungathered *

parasite Aircraft, invariably aeroplane, which forportion of flight relies on another for propulsion andpossibly also for lift Can ride on back of parent, or beattached elsewhere externally or internally, or be towed

parasite drag Sum of all drag components from all

non-lifting parts of body, usually defined as total drag minus

induced drag Not normally used (see profile drag).

parasitic element Resonant element of directional aerial

excited to produce directional pattern; eg reflector added

to Yagi aerial

parasitic material RAM added [usually by adhesive] to

exterior skin to reduce RCS

parasitic oscillation Generated by stray inductances and

capacitances and eliminated by parasitic stopper

parasiting Technique of using parasite

paraski Sport combining downhill ski with lifting

surface such as parachute, parafoil or hang glider;

compe-titions test landing precision

parasol wing One from which rest of aircraft is

suspended by ties.; hence, parasol monoplane

paravane 1 Hydrodynamic body towed (e.g., by

heli-copter) on end of minesweeping cable

2 Aerodynamic body towed on end of cable from

aircraft to keep line taut and steady, eg in mid-air

recovery

para-visual director Attention-getting non-quantitative

flight instrument giving bold linear indication of

excur-sions in pitch or azimuth, generated by rotation of striped

‘barber pole’ display; usually mounted on flight-deck

coaming; indicator in GRDS is AMLCD (Smiths

Industries)

parawing Variation of basic Rogallo flexible wing

developed at NASA Langley for payload recovery and

marketed by Northrop; not current term in hang gliding

PARC Particle-Astronomy Research Council (UK)

parcel Any small volume of gas, esp of atmosphere

Parcs Perimeter acquisition radar characterization

system

PARD Pilotless Aircraft Research Division (NACA,

from 1946)

Pardop Passive ranging Doppler

parent 1 Main aircraft in composite or carrier of

parasite

2 Aircraft carrying one or more RPVs over which it

exercises control following release

parent body Primary around which satellite orbits

PARES Passive-radar ESM system

parity 1 Symmetric property of wave function or other

phenomenon; value is 1 if function is unchanged by

inversion of its co-ordinate system

2 Precise keying of two or more sets of data [eg EDP (1)

software, tapes, reconnaissance pictures or wire

record-ings] so that they run to common time-base System

parities are assigned individual tracks in such devices as

reconnaissance signal recorders

park To establish synchronous satellite at its operating

position, where it is parked

parked Aircraft, esp commercial transport, not in

active use over extended period

Parkerizing Anti-corrosion treatment in which metal

part is boiled in solution of phosphoric acid and

manganese dioxide and then dipped in oil

Parker-Kalon, PK Patented family of self-tapping

screws for sheet

parking brake That applied continuously after aircraft is

parked, to prevent subsequent rolling; also (US) called

PARL Parallel

Parm, PARM 1 Persistent anti-radiation missile.

2 Precision approach runway monitor, = PRM (2).

Parmod Progressive aircraft rework modification(USAF, USN)

parrot Code for IFF transponder (DoD)

PARS, Pars 1 Programmed airline reservation system.

2 Primary attitude-reference system.

parsec Unit of length on cosmological scale equal todistance at which object has heliocentric parallax of 1"(one second of arc) = 206,265 times semi-major axis ofEarth’s orbit = 3.26 light-years = 3.0857 × 1016m, abb pc.Multiples are kpc, kilo-* and Mpc, mega-*

Parsecs Program for astronomical research and tific effects concerning space

scien-Part Chapter in rules governing civil aviation; e.g * 91governs business aviation and * 121 scheduled air carriers(FAA)

part-charter Particular flight, scheduled according totimetable

partial-admission turbine One in which working fluidenters around only part of periphery

partial pressure That exerted by each gas in gaseousmixture; Dalton’s law states value is same as if that gasoccupied whole volume occupied by mixture at sametemperature

partial-pressure suit Skintight suit covering body excepthead, hands and feet and inflatable (usually by stitched-intubing) to press on wearer and oppose internal pressures

partial priority Unusual status accorded special traffic(SST was intended) by ATC services in special circum-stances short of emergency

partial shielding 1 Protection against micrometeorites

incident from one direction only

2 Radiation shielding of crew of nuclear-propelled

aircraft whilst leaving radiation free to escape in otherdirections

particle separator Device for cleaning solid (andpossibly liquid) particles from air entering engine or otherdevice, typically by centrifuging effect in vortex

particle static Radio-communication static thought to

be due to accumulation or shedding of particulate matter

in flight (not defined and suggested arch.)

parting out Procedure for dismantling aircraft to yieldcertifiable parts

Part-Publication Category of military aircraft whosecharacteristics could be openly published except for suchitems as performance, fuel capacity and other sensitivedetails (UK)

part-span shroud Snubber [clapper] near mid-length offan [rarely, compressor] blade; abuts on neighbours todamp out flutter or other vibration

part surface Surface being cut in GPP

part-throttle reheat Augmentation of engine by burner brought in at less than maximum cold thrust,giving smoothly increased thrust and avoiding suddenaugmentation by selecting afterburner at maximum rpm

Afterburner stays lit as throttle is closed, extinguished

only at low fuel flow at low thrust level

Parylene Conformal (vapour-deposited) barrier coating

used to protect precision parts, especially electronics,

from hostile environments (Union Carbide)

PAS 1 Performance advisory system (Simmonds

subsystem offering minimum fuel and maximum

pro-pulsive efficiency)

2 Public-, or passenger-, address system.

3 Power available, shaft (UK, CAA = spindle).

4 Polyarylene sulphide.

5 Projector approach sight.

6 Paralkatone adhesive sealant [I adds inhibiting, TP

temperature protection]

7 Police Air Support (UK).

8 Prime and suppliers.

9 Perch and stare (UAV).

10 Primary alerting system.

11 Pulse-analysis system.

12 Pseudo aircraft system.

13 Precision-attack system[s].

PAS-2 A pioneer PAS (4) processed at relatively low

temperatures for advanced airframes (Phillips

Petroleum)

Pasar Podded advanced synthetic-aperture radar; S

adds system

PASC Pacific Area Standards Congress

Pascal Software language, becoming disused

pascal SI unit of pressure, Pa, = N/m2= 0.02088 lb/ft2,

0.000145038 lb/in2

As it is such a small unit kPa or MPa

are more common

Pascal’s law In fluid at rest, all pressures acting on given

point are equal in magnitude in each direction (neglects

acceleration due to gravity)

PASI Pre-application statement of intent

Paspo Precision-attack systems program office

Pass, PASS 1 Parked-aircraft security system.

2 Passive and active sensor subsystem.

3 Passive aircraft surveillance system.

4 Primary avionics subsystem.

5 Pylon-accommodated self-protection suite, or

system

6 Personnel-access security system.

7 Professional Airways Systems Specialists (US trade

union)

pass 1 Single run by aircraft past point on ground or

other object such as aircraft in flight on same heading at

markedly lower speed

2 Short tactical run or dive by aircraft at target; single

sweep through or within firing range of enemy air

forma-tion (DoD, IADB)

3 Single orbit by satellite, starting at point Equator is

crossed northbound

4 Single passage by satellite overhead.

5 Single period of time during which satellite is within

radio contact of control or data-acquisition station

passenger In addition to basic meaning of humans

carried in vehicle other than vehicle’s crew, normal

meaning in air-carrier terminology is FPP (fare-paying *),

normally, excluding company employees on cheap rate

Latter, however, are normally included in traffic statistics

passenger boarding bridge Passenger loading bridge

passenger breathing equipment 1 Drop-down oxygen

mask

2 Smoke hood.

passenger loading bridge Covered walkway linking

terminal and parked aircraft; see bridge.

passenger profile Distribution of pax at one airportthrough 24-h period

passenger service charge Fee levied by airport authority

on each departure passenger to help cover its costs

passenger service unit Originally comprised overheadpunkah outlet, now adds light(s), call button and possiblyother interfaces

passivating Coating, esp metal surface, with inert film

to prevent electrochemical corrosion

passive 1 Receiving but not emitting.

2 System, eg PFCS, which can only fail open.

passive air defence Includes such activities as cover andconcealment, camouflage, deception, dispersion and shel-ters

passive countermeasures Detection and analysis of

hostile emissions (see ESM).

passive guidance Use of received signals from whateversource in order to navigate

passive homing Tending to fly towards source of sion from target, usually IR

emis-passive jamming Use of chaff and confusion reflectors

passive landing gear One utilizing optimised adaptive damping devices

self-passive missile One equippped with guidance able tohome on emissions generated by the target

passive mode Use of airborne radar in receive-onlymode, eg AWACS

passive munition 1 Delivered safe and then triggered

either by timing system or radio signal

2 Inert until disturbed, eg mine.

passive paralleling Simplest and most common type ofredundancy wherein two parallel functional devices areutilized such that, if one fails, second is still available.Limited to simple elements of control system which canonly fail passive, such as springs and linkages Whenfailure of one element occurs, there is an acceptablechange in performance or capability

passive pilot One who, on long-haul, is relaxing ortaking a nap

passive radar Misnomer; normally interpreted aspassive mode

passive ranging Trajectory-measuring systems that donot rquire a transmitter or transponder in vehicle, egPardop See next

passive ranging subsystem Doppler plus phase rate ofchange to give direction and range

passive sonar Listens for emissions from submarine

passive thermal control Changing attitude of spacecraft

to even-out incident solar flux, esp by roll through 180°;so-called barbecue manoeuvre

pass off To test and clear production item

PAT 1 Process action team (AFLC).

2 Pilot access, or applications, terminal.

3 Private pilot, airplane, recreational, transition.

PATA Polish air-traffic agency

PATC Professional, administrative, technical andclerical

Patca Plurilateral agreement on trade in civil aircraft

Patch Precision approach to coupled hover

patch 1 Strong fabric attachment cemented to aerostat envelope (see eta *, channel *, split *, rigging *).

2 Embroidered or printed badge worn on working

(especially flying) clothing

3 Area of ground illuminated by airborne radar.

PATCO, Patco Professional Air Traffic Controllers

Organization (US, lost status 1981)

Patec Portable automatic test equipment calibrator

path 1 Track of aircraft under control of TMA.

2 Projection on Earth’s surface of satellite orbital plane;

same as track

3 Loosely, aircraft trajectory in 3-D.

Pathfinder 1 Software with immense capacity to extract

intelligence from vast amounts of data

2 Passive thermal Flir for navigation, detection and

enhanced resolution

pathfinder aircraft One with special crew plus

drop-zone/landing-zone marking teams, markers and/or

electronic navaids to prepare DZ/LZ for main force

(NATO)

pathfinder drop-zone control Communication and

oper-ation centre from which pathfinders exercise guidance

(DoD, LADB)

Pathfinder Force Elite sub-force within RAF Bomber

Command 1943–45 charged with marking targets for

main-force attack, abb PFF Pathfinder Association

supports needy survivors

pathfinders Four meanings, all defined as plural:

1 Experienced aircrew who lead formation to DZ, RP

or target

2 Teams dropped or air-landed at objective to operate

navaids

3 Radar or other navaid used to facilitate homing on

objective, esp in bad visibility

4 Teams air-delivered into enemy territory to determine

best approach/withdrawal lanes, LZs and sites for

heli-borne forces (all DoD, LADB)

path-stretching Deliberately routeing incoming traffic

over longer path (1) to achieve correct spacing on

approach

Patio Platform for ATM (7) tools integration up to

pre-operation (Euret)

PATN See Pro-ATN.

Patrick AFB USAF base at Cape Canaveral supporting

AMR

Patriot 1 Provide appropriate tools required to

inter-cept and obstruct terrorism (US)

2 Phased-array tracking to intercept of target.

patrol aircraft 1 Generally accepted term for aircraft

engaged in offshore duties such as search/rescue,

customs/immigration and enforcement of marine laws

2 US designation for large ocean combat aircraft

engaged in ASW, maritime reconnaissance and mining

PATS, Pats 1 Precision automated tracking station.

2 Prototype automatic target screener.

3 Primary aircraft training system.

4 Precision-attack targeting system.

patter Flying instructor’s well-rehearsed flow of verbal

instructions and comments

pattern 1 Replica of part used in constructing casting

mould

2 Radiation of transmitting aerial as plotted on

diagram of field strength for each bearing

3 Circuit (1) (US).

4 Shape traced out on ground by track of aircraft, esp.

in circuit, making procedure turns, in holding stack orother circumstance demanding accurate geometry

5 Authorized flightpath (1) to point of touch-down.

pattern aircraft One supplied to participant in duction programme, eg licensee or co-producer, to serve

pro-as mpro-aster to instruct engineers and solve arguments, andpossibly facilitate local change orders

pattern bombing Systematic covering of target area withcarpet of bombs uniformly distributed according to plan

pattern generator Signal generator whose outputprovides TV-type pattern for testing TV, video, EO orvisual-display systems

PATTS Programmed auto trim/test system

PAT3 Parallel advanced tactical targeting technology

PATU Pan-African Telecommunications Union

Patuxent River US Naval Air Test Center

PATWAS, Patwas Pilots’ automatic telephone weatheranswering service (FSS, US)

PAU Passenger-address unit

PAUC Program-acquisition unit cost

PAV 1 Power assurance valve (CAA).

2 Prototype air vehicle.

Pave With this prefix the USAF designated numeroustactical electronic systems

pavement Airfield paved area, including runways, ways, aprons and possibly dispersals

taxi-pavement condition index A subjective scale based onheave, cracking and surface spalling

Pavg Average power of pulsed-radar signal

PAW Plasma-arc welding

PAWES Performance assessment and workload uation system

eval-Paws 1 Phased-array warning system.

2 Passive airborne, or all-threat, warning system.

3 Portable analyst, or ASAS, workstation.

4 Passive approach warning sensor.

pax Passenger[s]

Pax River See Patuxent River.

Paxsim Models passenger flow through all public areas

of terminal, assisting design

payback Aircraft added to procurement contract toreplace one diverted, eg to another customer

payload 1 That part of useful load from which revenue

is derived (BSI) See Maximum *.

2 Load expressed in short tons, US gal or number of

passengers vehicle is designed to transport under specifiedconditions (DoD etc)

3 In missile, warhead section (DoD), plus container and

activating devices (NATO); both definitions need ing in light of MIRV and similar techniques

modify-4 For spaceflight, not yet defined; * for Saturn V launch

vehicle was complete Apollo spacecraft, whose LM ascentstage had its own * in terms of two crew plus lunar rock

5 For ECM, all discrete devices released or ejected, eg

chaff, flares and jammers in prepackaged * form

6 Maximum load that can be positioned on upper

base-plate (simulator)

payload integration Matching payload (4) to spacecraft,including power supply, environmental system and soft-ware

payload of opportunity One put aboard space launcherbecause mass/volume is available

payload/range Fundamental measure of capability oftransport aircraft usually presented as graphical plot

of payload (1) against range with specified operating

con-ditions and reserves

payload specialist Engineer skilled in designing and

inte-grating payloads (4), esp those of academic-research or

commercial nature

PB 1 Payload bay.

2 Passenger bridge.

3 Aircraft category, patrol bomber (USN, 1935–62);

pursuit, biplace (USAAC 1935–41)

2 Gas-turbine combustion-chamber pressure.

3 Polar modified air.

PBA 1 Pitch bias actuator.

2 Plastic blasting media.

3 Predictive battlespace awareness.

PBAA Polybutadiene acrylic acid (solid rocket

PBB Passenger boarding bridge, see bridge.

PBC Practice bomb carrier

PBCPI Permanent bar-code parts identification

PBCT Proposed boundary crossing time

PBD Program budget decision, or document (US

DoD)

PB/D Place, bearing and distance (waypoint)

PBDI Position, bearing and distance indicator

PBE 1 Protective, or passenger, breathing equipment

[smokehood]

2 Protein-based electronics.

PBF 1 Personnel (occasionally pilot) briefing facility.

2 Polymer-based film [appliqué].

PBG Private pilot, free balloon, gas

PBH Private pilot, free balloon, hot air

PBI 1 Polybenzinidazole, fire-blocking chemical

in-corporated into felts and other fabrics (Celanese)

2 Push-button indicator.

PBID Post-burn-in data

PBIL Predicted, or projected, bomb-impact line

PBJ Partial-band jammer

PBL 1 Probable.

2 Performance-based logistics.

PBM Pulse-bias modulation

PBO Performance-based organization

PbO Lead oxide

PBP&E Professional books, papers and equipment

PBPS Post-boost propulsion system

PBS 1 Prefabricated bituminous surface.

PBX 1 Atmospheric pressure (USSR, R).

2 Family of special explosives used to trigger NW

devices; PBX-9505 is related to, and used with, Cyclotrol;PBX-9404 is still in general use; PBX-9502 is IHE

3 Private branch exchange.

PC 1 Production, or positive, control.

Pc 1 Chamber pressure (any rocket).

2 Polar continental, or Canadian, air mass.

3 Cumulative probability of detection (radar).

Pc Burn-time or action-time average chamber pressure

pc Parsec[s]

PC1, PC2 etc Powered flight-control systems

PCA 1 Polar-cap absorption.

2 Positive-controlled airspace, or area.

3 Physical configuration audit (software).

4 Photovoltaic concentrator array.

5 Pre-conditioned air.

6 Propulsion-controlled airplane (no aerodynamic

controls)

7 Presidency of Civil Aviation (Saudi Arabia).

PCAS Pitch-control augmentation system

PCASP Passive-cavity aerosol spectrometer probe

PCATD Personal-computer aviation-training device[s]

PCB 1 Printed-circuit board.

2 Plenum-chamber burning.

3 Polychlorinated biphenyl(s).

4 Pilot control bay (UAV-GCS).

5 Publications Clearance Branch (UK MoD).

PCBW Provisional combat bomb wing (USAAF)

PCC 1 Parts-consumption cost.

2 Pin-cushion correction.

3 Portland-cement concrete.

4 Pilot/control[ler] communication[s].

5 Prague Capabilities Commitment (NATO).

PCCB Program-configuration control board

PCD Proceed

PCDN Process-change design notice

PCDU Portable [electric] cable diagnostic unit

PCE 1 Phase control electronics.

2 Professional continuing education (USAF).

PCF 1 Pulse-compression filter.

2 Passenger-cum-freight (CAA).

3 Protein crystallization facility.

4 Pounds per cubic foot [not recommended].

5 Photonic crystal fibre.

PCFTD Personal-computer flight-training device

PCG Projectile common guidance

PC(G) Missile-armed patrol craft

PCI 1 Pavement-condition index, scale based on heave,

cracking, etc

2 Protocol control information.

3 Pattern of cockpit indications [failure method].

4 Physical-configuration inspection.

5 Pounds per cubic inch [not recommended].

pciBIRD A 6-DOF magnetic tracker with processor

card

PCID Preliminary change in design

PCIDM Personal-control improved data modem

PCIG Personal-computer image generator

PCIP Precipitation

PCIPB President’s Critical-Infrastructure Protection

Board (US)

PCL 1 Power control lever [not flight controls].

2 Pilot-controlled [cabin] lighting.

3 Passive coherent location.

PCLL Persistent cell [storm stays in same place]

PCM 1 Pulse-code modulation, or modulated.

2 Pyrotechnic countermeasures.

3 Phase-control module.

4 Post-crash management.

5 Parametric cost modelling.

6 Prearranged contact mode.

PCN 1 Pavement Classification Number; part of

proposed ICAO standard ACN-PCN system for relating

aircraft footprints to pavement strengths

2 Personal communications network.

PCO 1 Photochemical oxidant, = smog.

2 Procuring (or procurement) contracting officer

(DoD)

PCOA Phase-control-only array

PCP 1 Platoon command post (SAM).

2 Program change proposal.

PCPN Precipitation amount

PCRT Projection CRT

PCS 1 Performance command system.

2 Portable, or piloting, control station (RPV).

3 Permanent change of station (military).

4 Pitch (or powerplant) control system.

5 Power conditioning system.

PCSB Pulse-coded scanning beam

PCSC Precision-cast single-crystal

PCSV Pilot-to-controller service

PCT 1 Power control test.

2 Portable common tool [software; E adds

environ-ment, I interface]

PCU 1 Powered-control unit (flight controls).

2 Pilot’s, or passenger, or parachute, or portable, or

propeller, or power (engine), control unit

3 Pod conditioning unit.

4 Pitch-change unit (helo).

PCV Pneumatic control valve

5 Project definition (abb results in confusion with [4]).

6 Period (full stop) in message.

PDA, p.d.a. 1 Post-deflection modulation.

2 Photon detector assembly (space telescope).

3 Problem-detection audit.

4 Personal digital assistant.

5 Premature-descent alert.

PDADS Passenger digital-activated display system

PDAF Probabilistic data association filtering

PDAM Precision direct-attack munition

PDAR Preferential departure and arrival route

PDAT Portable data access terminal

PDB 1 Precision digital barometer.

2 Performance data-base.

PDBS Pilot data, or direct, broadcast system

PDC 1 Performance data computer.

2 Public dividend capital.

3 Personnel despatch centre.

4 Programme development card; /PMM adds

per-formance-monitor module

5 Power distribution centre.

6 Pre-departure clearance.

7 Pressure-drop control.

PDCG Pressure-drop control governor

PDCO Pressure-drop control orifice

PDCS Performance-data computer system Siegler/Boeing)

(Lear-PDCU Panel data concentration unit

PDCV Pressure-drop control valve

PDD 1 Post-delivery development.

2 Package design document.

PDDI Product definition data interface

PDE Pulse detonator engine

PDES 1 Pulse-Doppler elevation scan; PDNES plus

electronic scanning in vertical plane to give target height

2 Product-data exchange specification.

PDEW [Passengers] per day each way, measure of totalflow

PDF 1 Precision direction finding.

2 Primary display function.

3 Portable document file [F adds format].

PDFN Phase-distortion at first null

PDG 1 Precision-drop glider.

2 Président directeur-général (F).

3 Programmable display generator.

PDI 1 Powered descent insertion.

2 Primary direction indicator.

PDID Pulse-doppler identification

PDL Program design [or description] language

PDM 1 Pulse-duration modulation.

2 Primary development model.

3 Programmed depot maintenance.

4 Presidential decision memorandum.

5 Product-data management.

6 Pilot decision-making.

P-DME Precision DME

PDMF Programmable digital matched filter(s)

PDMM Pulse-Doppler map matching

PDMS Point-defense missile system

PDN 1 Public data network.

2 Pulse-Doppler navigation.

PDNES Pulse-Doppler non-elevation scan;

surveil-lance down to surface, without indication of target height

PDO Pendulum dynamic observer

PDOP 1 Phase degradation of performance.

2 Position dilution of precision (GPS).

PDOS Powered-door operating [or opening] system

PDP 1 Program(me) decision package.

2 Plasma, or performance, display panel.

3 Portable data processor [S adds system].

4 Project definition phase.

5 Primary defect rate.

6 Preferential departure route.

7 Programmable digital radio.

8 Pressure-drop regulator.

9 Program-development review.

PDRC Pressure-drop ratio control

PDRJ Pulse-Doppler radar jammer

PDRR Product/program project definition and risk

reduction

PDS 1 Passive detection system.

2 Prestocked dispersal site.

3 Pulse-Doppler search mode.

4 Passenger distribution system.

5 Post-design service(s), or support.

6 Primary display system.

7 Project definition study.

8 Portable data store.

PDSTT Pulse-Doppler single-target track mode

PDT 1 Pyrotechnic door [or deployment] thruster.

2 Pacific Daylight Time.

3 Pliable display technology.

PDU 1 Pilot[’s] display unit.

2 Power drive, or distribution, unit.

3 Pneumatic drive unit.

4 Protocol data unit.

PDV 1 Pressurizing and dump valve.

2 Parafoil-delivered, or -deployed, vehicle, for MOP(5).

PDVOR Precision DVOR

PDW 1 Pulse-detonation wave [rocket].

2 Priority delayed weather.

PDWC Post-departure weather change

PDZC Pathfinder drop-zone control

PE 1 Procurement Executive (UK, MoD).

2 Position error, also p.e.

3 Pilot error.

4 Piston engine.

5 Program, or processing, element (DoD).

6 Professional engineer (US).

7 Permanent echo.

8 Ice pellets.

9 Pre-emptive.

10 Precision engagement.

P E Pressure in core-engine jetpipe

Pe See Péclet number.

Pe Total installed power of shaft-drive engine[s]

PEAD PE(10) assessment definition

peak 1 In production programme, time or rate of

peak suction Lowest pressure on upper surface of wing

or on 2-D aerofoil profile; rarely, lowest pressure on otherconvex surface of aerodynamic body

peak/trough ratio Peak (usually summer) traffic ratedivided by lowest (usually winter) traffic rate

peaky Aerofoil section (profile) of traditional typecausing large acceleration of flow over leading edge andhence very low pressure (large peak suction) over narrowstrip at 8–15% chord; opposite to supercritical or roof-top

PEAT Procedural event analysis tool

PEC 1 Personal equipment connector.

2 Pressure, or position, error correction.

3 Pulsed eddy current.

PECHS Percussion/electric conversion hardwaresystem [ammunition]

pecked line Broken or dashed line in graphics orartwork

pecking Touching ground with propeller tips, esp ontakeoff

Péclet number Pe = where V is fluid flow velocity,

l a length and λ thermal conductivity; applies in heattransfer at low airspeeds

PECM Passive electronic countermeasures

PECP Primary entry control point, to hostile airspace

PECT Peer entity contact table

Pectenometers Class of aerodynes weighing c6.5g, 0.23

oz, which fly like, e.g., butterflies, by clapping aerofoilstogether, ejecting air rearwards On separation, air issucked in from the front (NRL)

PED 1 Program(mme) element description.

heli-pedestal 1 Raised box between pilots on flight deck

carrying numerous control and system interfaces

2 Pillar supporting aircraft on ski (and, it is suggested,

float)

Pedoba Portable electronic device[s] on board aircraft

PEDS Portal explosive detection system

PEE Photoelectron emission

PEEK Polyetheretherketone

peel off To roll away from straight-and-level flight, esp.from a formation, and dive away; normally manoeuvreperformed in sequence by all aircraft of formation

peen 1 To cold-work metal surface by repeated light

blows of ball-pane hammer [peen forming] or ment with hard balls [shot peening]

bombard-2 To deform metal part by series of hammer blows, eg

to set rivet or burr end of bolt to prevent loss of nut

PEG Polyethylene glycol

Pegasys Precision and extended-glide airdrop system(USA)

PEI 1 Polyetherimide, important family of resins.

2 Professional engineering institutions.

Vl–––

λ

PEL 1 Personnel licensing.

2 Precision elastic-limit.

PELS Personal equipment life-support system, a

smokehood, with decompression protection

PELSS Precision emitter location strike system

Peltier effect Generation of current by making circuit

containing two different metals and keeping two junctions

at different temperatures; some definitions refer to

gener-ation or absorption of heat at junctions upon passage of

current

PELTP Personnel Licensing and Training Panel

(ICAO)

PEM 1 Parametric estimation model.

2 Program element monitor (DoD).

3 Plastic-encapsulated microcircuit, hence plural Pems.

PEMB Procurement Executive Management Board

(UK)

PEN Photonic exchange network

penaids See penetration aids.

penalty Deficiency in one aspect of aircraft design or

performance in return for improvement in another; eg

adding thermocouple in jetpipe to indicate temperature

assists pilot but creates drag in jet reflected in reduced

cruising speed, range or both

pencil beam Narrow, strongly directional beam with

minimal sidelobes

pendant 1 Arrester wire (deck cable).

2 Flag indicating centre of arrester wire.

pendulum damper Crankshaft counterweight vibration

damper in form of pivoted mass

pendulum stability That inherent in large vertical

distance between high centre of wing lift and low c.g

pendulum valves Gravity-operated flaps covering ports

in housing of air-operated gyro which sense tilt and

control airflow to cause restoring (erecting) precessive

force

penetrant dye Method of detecting cracks and pores by

washing part with coloured liquid and then with white

developer

Penetrate Passive enhanced navigation with

terrain-referenced avionics: radar altimeter and INS plus 3D

terrain model in database (Ferranti)

penetration 1 Flight into hostile, esp defended,

airspace

2 Ability of sailplane to keep going by trading kinetic

energy for distance with minimal loss of height or speed

while heading for next thermal

3 Flight deep into cloud, esp one with large vertical

extent and severe turbulence

4 Flight into eye of tropical revolving storm.

5 Success in previously unattacked market.

6 Progress into flight manoeuvre, esp one posing

potential problem or danger, hence stall-*

7 Portion of high-altitude instrument approach which

prescribes descent to start of approach (DoD)

penetration aids Devices and systems assisting vehicle to

accomplish penetration (1), eg jammers, chaff, flares,

decoys and warning systems, low (lo) flight level, reduced

RCS and improved vehicle hardness

penetration area That within which enemy defences are

to be neutralized to degree assisting succeeding aircraft to

penetrator 1 Tool, usually powered, for quickly cutting

apertures in side of aircraft for speedy rescue ofoccupants

2 Aircraft designed for penetration (1).

3 High-density projectile designed to pierce armour by

kinetic energy

penetrometer Measures ability of airfield surface tosupport static or moving aircraft

penguin Officer devoid of brevet (RAF)

pennant Mooring and haul-down wire for captiveballoon

penny-farthing Helicopter of normal configuration(colloq.)

Pensky Martin Standard apparatus for determination

of flashpoint; used in two forms, closed or open

penthouse roof Top of cylinder combustion space havingsloping sides

pentode Thermionic valve having three grids

PEO Program Executive Officer, or Office (US)

PEP, p.e.p. 1 Peak envelope power.

2 Pre-engine production.

3 Productivity enhancement programme.

4 Pulse envelope programming.

5 Predesignated ejection point.

PEPS, Peps 1 Positive-expulsion propellant system.

2 Pintle escape propulsion system.

PER Performance

PERA Production Engineering Research Association(Melton Mowbray, UK)

perceived noise level See noise.

perch position In pattern (3) with touchdown point 45°behind

percussion cap Detonator/igniter for ammunition vated by sudden deformation

acti-percussion gun Device for cheaply making loud bangs toscare birds

perfect fluid Usually implies inviscid and ible, as well as homogeneous

incompress-perfect gas One exactly obeying Joule and Boyle laws sothat PV = nRT; also obeys Charles, Gay-Lussac andseveral other laws

perforated Pierced by holes, in case of aerodynamicsurface typically removing 25–30% of projected area;perforation of flap or airbrake can reduce actuationpower requirement and increase drag of surface, esp.when at large angle to airflow, but destroys value of flap

as lifting surface and thus confined to divebrakes andairbrakes

performance 1 From operational viewpoint, ability of

system to perform, esp expressed in numerical values

2 From flight-safety viewpoint, ability of aircraft to

perform required functions and manoeuvres, esp indegraded condition and under adverse circumstances,again expressed numerically Subdivided into threecategories: 1, measured *, that actually recorded forparticular aircraft at particular time; 2, gross *, factoredfrom measured to allow for poorest aircraft in fleet,

guaranteed-minimum instead of average thrust

propul-sion and possibly other degrading factors; and 3, net *,

factored from gross to allow for further possible

tempo-rary variations (airframe damage or icing or certain

non-critical fault conditions) and minimum standard of

pilot skill and experience

3 Narrow interpretation of numerical values of aircraft

flight limits such as speeds, altitudes and payload/ranges

performance-command system Microprocessor-based

crew advisory system in commercial transports which

optimises performance and saves fuel

performance factors Those deriving from aircraft

performance which affect airline traffic achieved, as

distinct from commercial and operational factors

performance groups UK aeroplane categories: those

whose first C of A was issued before 1951 are NPG (no

performance group); those built since 1951 are Group A,

large multi-engined; B, spare; C, light multi-engined;

D, single-engined; X, foreign multi-engined imported

before particular dates

performance index Non-dimensional comparator for

radars, derived from xmtr peak power, prf, beam width,

pulse width, antenna gain and receiver noise

performance limiting conditions Those demanding flight

to near boundaries of flight performance or point at which

auto-ignition, stick-shaker or other subsystem is

performance reduction Historically, calculations to

reduce measured aircraft performance to standard values

at a chosen weight and in particular atmospheric pressure

and temperature

performance-type glider Sailplane, esp competition

sailplane

periapsis Pericentre of orbit

pericentre Point on orbit closest to primary

pericynthian Point in spacecraft trajectory closest to

Moon

perifocus See pericentre.

perigee Pericentre of Earth orbit

perihelion Pericentre of solar orbit

perilune Pericentre of lunar orbit

perimeter 1 Periphery of airfield flying area.

2 Boundary of defended area.

perimeter track Taxi track linking ends of runways,

revetments or dispersals and main hangar/apron area

period 1 Time interval between successive passages

through particular point in same direction of SHM or

other wave motion = or

2 Time interval between successive passages through

particular bounding plane in same direction of satellite,

usually time between successive northbound transits of

Equator (orbital *); see sidereal *, synodic *.

periodic inspection Inspection, with or without

tear-down, according to published schedule of time intervals

irrespective of performance (1) of device

periodic reservation Several aircraft book slots on same

Satcom T-channel

period of performance Timeframe in which work is done

peripheral hem Leading edge of parachute canopy

1––

ft1

permanent echo Terrestrial features as seen on radar atfixed site

permanent magnet One which retains its magnetism inabsence of strong demagnetizing field

Permaswage Patented fluid-tight method of connectingpipes

permatron Gas tube similar to thyratron with field control

magnetic-PERME, Perme Propellants, Explosives and RocketMotor Establishment (Westcott, Waltham Abbey, UK)

permeability 1 In magnet, ratio B/H where B is magnetic

flux induction and H is magnetizing force, symbol µ, this

is divided into absolute and relative or specific *, µr,except in emu system, where * of free space is defined asunity; measured in henry/metre

2 In aerostat, measure of rate at which gas at STP can

pass through fabric, usually expressed in litres per 24 h

3 In amphibian, ratio of volume of landing-gear

compartments that can be occupied by water to wholebuoyant volume

permeability tuning Radio tuning by varying ability of inductor core, usually with translating bar offerrite

perme-Perminvar Family of low-hysteresis alloys of Fe/Ni/Co

permissive action link Highly secure, jam-proof datalinks (various categories) which enable bomber crew totrigger weapon live from cockpit when bomber is at safedistance (hi-alt laydown only)

permittivity Dielectric constant: relative * is ratio ofelectric flux density in medium to that which same forcewould produce in vacuum, symbol ⑀r, unit farads permetre; absolute * ⑀ois in vacuum, often called free space

(see Coulomb law).

Permit to fly Issued to categories, such as homebuilts,warbirds, classic GA aircraft and micros, that do notqualify for a C of A but may be flown with restrictions.(UK CAA)

Permly Permanently (FAA)

PERP Peak effective radiated power

perpendicular-heading square Training manoeuvre inwhich helicopter is flown around square, crabbing at 90°sideways along each of the four sides

persistent area-denial Use of loitering robotic systems[ie, UAVs] to provide non-stop surveillance/attack overbattlefield for period of days to months

personal equipment connector Quick-make/break channel coupling for aircrew oxygen, R/T, intercom,g-suit and EC Not necessarily synonymous with AEA

multi-personnel locator beacon Miniature transmitter sendingcoded signal and worn on flying clothing

personnel reaction time Time from nuclear warning to alldefensive measures taken

Perspex Family of methyl methacrylate plasticsimportant as aircraft transparent material (ICI)

Pert, PERT Programme Evaluation and ReviewTechnique; critical path method

PES 1 Passenger entertainment system, audio plus film.