Glossary - Letter C

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C |symbol|  1. Celsius  2. centigrade


CAA |abbreviation| Civil Aviation Authority


cabin |noun| a passenger compartment in an aircraft / Air enters at the front of the cabin and leaves at the rear. /


cabin altitude |noun| the atmospheric pressure in the cabin. Air pressure is artificially maintained at approximately 6,000-8,000 feet inside the cabin. Flying for prolonged periods above 10,000 feet may cause hypoxia, altitude sickness, decompression sickness and acute earache and intestinal pain. Oxygen masks are deployed automatically if cabin altitude reaches 14,000 feet.


cabin attendant |noun| member of the flight crew who looks after passengers, serves food, etc. / If you need something, press the call button and a cabin attendant will respond within a few minutes. / Also called: flight attendant


cabin compressor and blower system |noun| part of the air conditioning system for the cabin


cabin crew |noun| airline staff who are in direct contact with the passengers and whose in-flight responsibilities include: ensuring correct seating arrangements, serving food and attending to the general well-being of passengers, etc.


cabin depressurization |noun| loss of cabin pressurization and an increase in cabin altitude; the cabin altitude, normally maintained at between 6,000 and 8,600 feet, increases and at 14,000 feet cabin altitude the passenger oxygen masks are automatically deployed in the cabin. Cabin depressurization is a perfectly manageable failure, but will result in the passenger oxygen masks dropping, an unscheduled descent, poor communication as the crew will be wearing their oxygen masks and possibly injuries (concussion, broken ribs, bruises, cuts) among the passengers and cabin crew who did not have their seat belts fastened.


cabin environment |noun| the conditions inside the aircraft cabin, including the temperature, the space, the color scheme, the seating arrangements, etc.


cabin pressure |noun| the pressure of air inside the cabin which allows people to breathe normally at high altitudes


cabin pressurization |noun| the maintenance of an acceptable atmospheric pressure in an aircraft while flying at high altitude / At 35,000 ft (feet) passengers can breathe freely because of cabin pressurization. /


cable |noun|  1. thick metal wire - control cables > thick metal wire linking the pilot’s cockpit controls to control surfaces such as the elevators and ailerons   2. a thick metal wire used for electrical connections / Earth return is by cable to the negative pole of the battery. /


cabotage |noun| the right of a country to operate internal air traffic with its own airlines and not those of other countries


calculate |verb| to find out an answer to a problem by working with numbers / The total flight fuel can be calculated by multiplying the time of the flight by kilograms of fuel per hour. /


calculation |noun| an act of finding out an answer to a problem by working with numbers


calculation of fuel required |noun| an arithmetic estimation of fuel needed by using time, distance and fuel-consumption factors


calculator |noun| an electronic machine for making calculations / Students are not allowed to use calculators in the examination. /


calibrate |verb| to adjust the scale or graduations on a measuring instrument or gauge / The international standard atmosphere is used to calibrate pressure altimeters. /


calibrated airspeed |noun| indicated airspeed corrected for instrumentation and installation errors. Abbreviation: CAS


calibration |noun| the adjusting of the scale or graduations on a measuring instrument or gauge / The international standard atmosphere is used for the calibration of instruments. /


call button |noun| a button, often on the arm of a passenger seat, which can be pushed when you need help from an attendant


call-out |noun| a spoken data read-out by a crew member or an automatic synthetic voice / The First Officer made airspeed call-outs during an approach. /


call-sign |noun| a series of words and/or letters and/or numbers used to identify an aircraft or station / The aircraft’s call-sign is ‘College 23’. VOR stations transmit a two or three letter aural Morse call-sign. /


calorie |noun| the amount of heat required to raise the temperature of 1 gram of water by 1°C, equal to 4.186 joules / After 2 calories have been released the temperature will have risen 2 degrees i.e. to 0°C, and so the freezing process ceases temporarily. / Abbreviation: cal


calorific |adjective| referring to calories - calorific value > the heat produced by the complete burning of a given amount of fuel / The calorific value of a fuel is an expression of the heat or energy content released during combustion. /


cam |noun| an oval or egg-shaped wheel which, when rotating, converts circular motion into reciprocating motion / In a piston engine, the shape of each cam is designed to give the correct amount of opening to the valve. /


CAMFAX |noun| the civil aviation meteorological facsimile network


cam plate |noun| a rotating or non-rotating plate with cams on it / The fuel pump consists of a rotor assembly fitted with several plungers, the ends of which bear onto a non-rotating cam plate. /


camshaft |noun| a rotating shaft carrying cams, which opens and closes valves in a piston engine / As the camshaft rotates, the cam will transmit a lifting force. /


canard |noun| a projection similar to a small wing fitted close to the nose of an aircraft and designed to increase its horizontal stability


candela |noun| the SI unit of brightness of a light / The red and green wing tip navigation lights must be at least 5 candela. / (NOTE: It is usually written cd with figures.)


candle power |noun| a unit to measure the brightness of a light / Estimation of visibility is achieved by noting the distances at which lights of a known candle power can be observed. /


canopy |noun|  1. a transparent cover, typically on some fighters, light aircraft and gliders, designed to slide backwards and forwards or hinge upwards to allow pilots to enter or leave an aircraft  2. a covering to protect people in a life raft / The canopy should be erected to provide protection from the weather. /


cantilever |noun| a beam fixed and supported at one end only / The wings are of cantilever design. /


cap |noun| a top or lid / the exhaust valve cap /


CAP |abbreviation| Civil Aviation Publication


capability |noun| the capacity or ability to do something - the flare has a day and night capability > the flare is effective in daylight and in the dark


capable |adjective| competent, having an ability / Aircraft used in aerobatics must be capable of withstanding the extra loads imposed on the airframe by the maneuvers. In most modern multi-engine jet transport aircraft, each fuel tank is capable of feeding any engine. / - a capable person > a person who works well


capacitance |noun| the ability of a system of conductors and insulators to store an electrical charge when there is a positive discharge between the conductors / If the supply frequency is low, the voltage has more time to build up a larger charge, or capacitance. / (NOTE: Capacitance is measured in farads and can either be a fixed amount or variable amount.)


capacitive |adjective| referring to the ability of a system of conductors and insulators to store an electrical charge / Over-speed is usually a fault in the constant speed drive unit which causes the generator to over-speed and damage the capacitive loads on the aircraft. /


capacitor |noun| a system of conductors and insulators which store electrical charge (NOTE: A capacitor is used in a circuit to store energy for a short while.)


capacity |noun|  1. the ability to do something easily / Energy is the capacity for performing work. /  2. the amount of something which a container can hold / Each cylinder has a capacity of 0.5 liters. / - battery capacity > the amount of electrical energy a battery can store and deliver expressed in ampere hours  3. the ability of an ATC system, in a given area, to provide a normal service, expressed in numbers of aircraft


capillary |noun| a very fine or narrow tube


capillary action, capillary flow |noun| the action by which a liquid rises up a narrow tube


capsule |noun| a small closed container


captain |noun| the person in charge of an aircraft / The captain asked all passengers to remain seated until the aircraft had come to a stop. /


Captain probe heat |noun| a system of electrical resistances inside the angle of attack sensor, pitot probe, static port etc. which supply the captain’s instruments with attitude, airspeed and altitude data. The heating prevents the probes from being obstructed or seized up by ice.


captive |adjective| not free to move


captive balloon |noun| a balloon which, when in flight, is attached to the ground by a long cable


capture |verb| to intercept the glide path / When an aircraft captures a glide path, the ILS system on board detects the localizer and glide slope ground transmitter signals and the aircraft’s descent to the runway is automatically controlled under the crew’s supervision. /


carbon |noun| 1. a non-metallic element, which is a component of living matter and organic chemical compounds and is found in various forms, e.g. as diamonds or charcoal  2. a black material with good electrical properties


carbon brush |noun| a small, replaceable, carbon block found in electric motors, generators and alternators, which provides the passage of electric current


carbon deposits |plural noun| residues of burnt oil deposited in the combustion chamber, etc., in the course of the combustion process / Carbon deposits on a spark-plug electrode may cause misfiring. /


carbon dioxide |noun| a colorless, odorless, non-toxic gas found in the atmosphere, and also used in fire extinguishers and fizzy drinks / Carbon dioxide can be solidified at low temperature to produce dry ice. / Symbol: CO2


carbon fiber |noun| a thin, light and very strong strand of pure carbon which can be combined with other materials to make them stronger


carbon monoxide |noun| a colorless but poisonous gas from incomplete combustion found in the exhausts of spark ignition engines. Symbol: CO


carburation |noun| the process of mixing fuel with air in a carburetor / Carburation must ensure that rapid and complete burning will take place within the cylinder. /


carburetor |noun| a device for mixing air with fuel in the right quantities before combustion / Most carburetors are installed so that they are in a warm position. /


carburetor heat |noun| a system for keeping the carburetor and associated components free of ice


carburetor icing |noun| a process by which, under particular conditions, ice forms in the venturi tube of the carburetor


cardioid |adjective| shaped like a heart / The cardioid polar diagram of the magnetic field around a bar-magnet. /


cargo |noun| see > freight


cargo terminal |noun| building used for storage and handling of containers, pallets etc. See also: freight terminal.


carousel |noun| a rotating platform from where arriving passengers can pick up their baggage / Baggage from flight AC123 is on carousel No 4. /


carriage |noun| the act of carrying / Regulations require the carriage of life-rafts when flying over water. /


carrier |noun|  1. a person or organization that carries people or goods from one place to another / Individual carriers assign codes to aircraft. /  2. a frame or bag in which objects can be carried


carrier wave |noun| a radio signal that is transmitted continuously at a constant amplitude and frequency / Amplitude modulation has only one pair of usable sidebands each at about one sixth of the signal strength of the carrier. /


carry |verb| to take somebody or something from one place to another / The aircraft was carrying 120 passengers. / (NOTE: carrying – carried)


carry out |verb| to do, especially a standard procedure / The First Officer is carrying out an external inspection. /


cartridge |noun| a removable unit for an air filter / Cabin air filters normally consist of a casing, housing a replaceable filter cartridge. /


CAS |abbreviation|  1. calibrated airspeed  2. controlled airspace


case |noun|  1. an outer covering, housing or jacket / Cooling air is directed through passages in the engine case to control engine case temperature. /  2. an example, situation or circumstance / In some special cases, e.g. for landing and take-off, wind directions are measured from magnetic north. /


casing |noun| a cover that encloses a piece of equipment, etc. / Annular and outer air casing form a tunnel around the spine of the engine. /


CAT |abbreviation| clear air turbulence


CAT III conditions |noun| conditions when visibility is very poor and aircraft require ILS automation for take-off and landing operations / When shooting a CAT II or III approach the PF must make call-out of ‘CAT 3 dual (or single)’ or ‘CAT 2’ based on FMA information. /


CAT IIIC |noun| Category three C / The crew, aircraft and aerodrome are qualified and equipped to land in conditions with theoretically 0 feet vertical Decision Height and 0 feet longitudinal visibility. /


catastrophe |noun| a very bad event or accident, a disaster  / Although the family were not at home when it happened, the crash which destroyed their house was a catastrophe for them. /


catastrophic |adjective| terrible, disastrous / In a catastrophic accident where many persons may be disabled, those who show signs of life should be rescued first. /


categorize |verb| to put into groups, classes or categories / Aircraft can be categorized by weight, number of engines, role, etc. /


category |noun| an official class or group / Load factors vary depending on the category of aircraft. /


catering truck |noun| elevator truck for delivering meal trays, drinks, newspapers etc.


cathode |noun| a negative electrode or terminal / The cathode is a metal cylinder fitted with an internal heater. /


cathode ray tube |noun| a high-vacuum tube in which cathode rays produce an image on a screen such as a TV screen / Electronic indicating systems show engine indications, systems monitoring and crew alerting functions on one or more cathode ray tubes or liquid crystal displays mounted in the instrument panel. / Abbreviation: CRT


cause |noun| something that makes something else happen, a reason / If the ammeter shows a high state of charge after start up, it is quite normal and no cause for alarm. / - |verb| to make something happen / Air in the fuel line can cause an engine to flame-out or stop. /


caution |noun|  1. advice or a warning to be careful / If a problem occurs in the spoiler system, a master caution light illuminates. /  2. care / Proceed with caution. /


cavitation |noun| the formation of vapor-filled cavities or holes in liquids and gases, caused by low pressure or high speed / Most reservoirs are pressurized to provide a positive fluid pressure at the pump inlet and thus prevent cavitation and the formation of bubbles. /


cavity |noun| a hole / De-icing fluid flows into the cavity in the distributor panels before passing through the porous steel outer skin. /


CAVOK |abbreviation| Ceiling and Visibility OK, pronounced ‘CAV-O-KAY’ / TAF SCAR 142230Z 1500/1524 25005KT CAVOK TN18 /


CB |abbreviation| cumulonimbus cloud formation


cc |abbreviation| cubic centimeters


cd |symbol| candela


CDI |abbreviation| course deviation indicator


cease |verb| to stop / If fuel, oxygen or heat is removed from the fire triangle, combustion will cease. /


ceiling |noun|  1. the highest point  2. the greatest pressure height that can be reached / The aircraft has a ceiling of 50,000 ft. /


celestial |adjective| referring to the sky - celestial navigation > navigation by using the stars in the sky


cell |noun|  1. a system of positive and negative plates for storage of electricity that form a battery / A battery is a device which converts chemical energy into electrical energy and is made up of a number of cells. /  2. the central part of a thunder cloud / The life cycle of the thunderstorm cell ends when the downdrafts have spread throughout the cloud. /


Celsius |noun| a scale for measuring temperature in which water freezes at 0° and boils at 100°. |symbol| C


center |noun|,|verb| US same as centre


center line |noun| US same as centre line


center pedestal |noun| a large standing panel between the two pilots which contains the thrust / throttle levers, radio and navigation control panels / The RMP is located on the center pedestal. /


centimeter |noun| a measure of length that is equal to one hundredth of a meter


central |adjective| located in the center or in the middle / The control knob is moved from the central position. /


Central Flow Management Unit (Brussels) |noun| a central agency in Brussels that is responsible for air traffic management throughout the area controlled by the ECAC


centralize |verb| to put into the center or into the middle position / The operating jack centralizes the control surface after the turn. /


Central Standard Time |noun| the time zone of the east-central part of the USA and Canada, 6 hours behind GMT


center |noun|  1. the middle / The plane of the great circle passes through the center of a sphere. / - center of a circle > mid-point of a circle, point in the middle of a circle  2. a main building or office / Area Forecasting Center / - |verb| to move to a central position / Center the control column. / (NOTE: centered – centering ; the US English is centered – centering.)


center fix |noun| same as self-positioning


centre line |noun| a painted or imaginary line running along the center of the runway


center of gravity |noun| the point at which a body can be balanced / Distribution of the tanks and the fuel in the tanks is vital in maintaining the aircraft center of gravity and trim. / Abbreviation: CG (NOTE: If the center of gravity is outside the limits, the aircraft may be difficult or impossible to control.)


centrifugal |adjective| moving away from the center / The blades must be strong enough to carry the centrifugal loads due to rotation at high speed. /


centrifugal force |noun| outward force caused by turning motion


centrifuge |noun| a device which uses centrifugal force to separate or remove liquids - |verb| to separate liquids by using centrifugal force / The rotating vanes of the breather centrifuge the oil from the mist. /


centripetal |adjective| moving towards the center


centripetal force |noun| inward, center-seeking force working in opposition to centrifugal force / The magnitude of the centripetal force varies with the square of the wind speed. In a turn, lift provides the centripetal force. /


certain |adjective|  1. particular, some / in certain areas, at certain times, under certain circumstances /  2. sure / There are certain to be horizontal differences in the mean temperature of a layer. / - to make certain > to make sure / Make certain that the parking brake is on before doing engine run-up checks. /


certificate |noun| an official document which states that particular facts are true - |verb| to award or give a certificate - aircraft which are certificated for flight > aircraft which have the necessary paperwork to be authorized to fly


certificate of airworthiness |noun| a document issued by an aviation authority stating that an aircraft meets specific safety and performance requirements that allow it to be used in service / An authorized person may require production of the Certificate of Airworthiness. / Abbreviation: C of A


certification |noun| the process of giving certificates /The inferential method of ice detection is used on flight trials for certification of aircraft./


certify |verb| to authorize or permit the use of something / The aircraft is certified for aerobatic flight. /


CFI |abbreviation| chief flying instructor


CFIT |abbreviation| Controlled Flight Into Terrain / CFIT happens when an aircraft, which is airworthy and under the control of the flight crew, is flown unintentionally into terrain, obstacles or water, usually without the crew being aware. /


CFMU |abbreviation| Central Flow Management Unit


CFRP |abbreviation| carbon fiber reinforced plastic


chalk |noun| a soft white limestone rock that may be used in powder form or as a shaped stick for writing with / Oil, which is trapped in the defects, is absorbed by the chalk thus indicating their positions. /


challenge-response call |noun| a pilot-to-pilot exchange which consists of a request for confirmation and a response; in this way, each action and condition is double-checked: ‘Climb’ – ‘Climb set’; ’80 knots’ –  ‘Checked’


chamber |noun| a small enclosed compartment


chandelle |noun| a steep climbing turn in which an aircraft almost stalls as it uses momentum to increase its rate of climb


channel |noun| a special frequency band for the transmission of radio signals / The system operates on VHF communications between 118 and 135.95 MHz giving 360 channels at 50 kHz spacing. /


character |noun|  1. a quality or set of qualities which make something different and separate from something else / The circulation of the atmosphere is zonal in character. /  2. an individual letter, number or symbol used in printing and writing


characterize |verb| - to be characterized by > to have qualities or features which make it different and separate from other things / The stratosphere is characterized by a temperature structure which is steady or increases with height. /


characteristic |adjective| typical of a class or group of things - a characteristic feature > a normal feature of the thing in question - |noun| a feature or quality making something different or separate from something else / Air masses have distinct characteristics which can be used to separate them on a chart. / - handling characteristics > features of an aircraft that make it different from other aircraft when handling it - summer characteristics > climatic conditions which are typical of summertime


charge |noun|  1. an amount of electricity / Friction causes a charge of static electricity. The battery was so old, it would not take a charge. / - a high level of charge > a high amount of electricity  2. money demanded or paid for the providing of a service - overnight parking is free of charge > it costs nothing to park overnight - |verb|  1. to pass electrical current through something and thereby make it electrically active / An installed battery becomes fully charged by the aircraft generator. / - charged particles > atmospheric particles which have either a positive or negative electrical charge  2. to take money for a service / We do not charge for overnight parking. /


charger |noun| - battery charger > device for putting an electrical charge into a battery.


chart |noun| a map for navigational purposes - significant weather chart > a weather chart with important weather information marked on it


chase plane |noun| an aircraft whose role is to escort another aircraft or to photograph it


check |noun| an examination to make certain that something is as it should be / A check was made on the undercarriage and airframe after the pilot reported a heavy landing. / - |verb| to examine something in order to find out if it is correct / It is the pilot’s responsibility to check that the aircraft is airworthy. /


check in |verb| to register by giving in your ticket, showing your passport and giving your baggage at an airline desk before a flight / Passengers should check in two hours before departure. /


check-in |noun| an airline desk where passengers register before a flight / The check-in is on the first floor. / - check-in time > time at which passengers should check in


check-in counter, check-in desk |noun| counter where passengers check in


checklist |noun| a list of items, often in booklet form, to be checked in a given sequence / Before every flight, the pilot should perform pre-flight checks using a checklist. /


chemical |adjective| referring to chemistry / a chemical reaction / - |noun| a substance used in or made by a chemical process


chemistry |noun|  1. the science of chemical substances and their reactions  2. the nature of something / The basic chemistry of fire can be illustrated by the three sides of a triangle representing fuel, oxygen and heat. /


chief |adjective| most important, main - the chief factors > the most important factors


chief flying instructor |noun| the senior rank of flying instructor. Abbreviation: CFI


chock |noun| a wood, rubber or metal device placed in front of the wheels of a parked aircraft to prevent it from moving / The accident happened because the chocks had been removed before the engine was started. /


choke |noun| a valve in a carburetor, which controls the amount of air combining with fuel - |verb|  1. to block a tube, etc., making a liquid unable to move - a choked nozzle > a blocked or partly-blocked nozzle  2. to stop breathing because you have inhaled water or smoke


choke tube |noun| same as  venturi / Increase in rpm increases the speed of air passing through the choke tube or venturi. /


chopper |noun| same as helicopter - |verb| to transport something or somebody by helicopter, or to travel by helicopter


chord |noun| the shortest distance between the leading and trailing edges of an airfoil


chute |noun| same as parachute


circle |noun| a line forming a round shape, or a round shape formed by objects or people / They stood in a circle on the tarmac. / - great circle direction > an imaginary circle on the surface of the Earth which lies in a plane passing through the center of the Earth


circuit |noun| 1. a complete route around which an electrical current can flow  2. the pattern of take-off, climb-out, turn onto crosswind leg, turn onto downwind leg, turn onto base leg, turn onto final approach and landing / When carrying out practice landings at an aerodrome, the pilot should keep a sharp lookout for other aircraft in the circuit. /


circuit board |noun| an insulating board which holds components connected into an electrical circuit


circuit-breaker |noun| a small protective device in the circuit which blows or breaks before a dangerous overload of current arises


circuitry |noun| a system of electrical circuits / In an anti-skid braking system, circuitry is employed which can detect individual wheel deceleration. /


circular |adjective| shaped like a circle / Anodes are circular plates with center holes. / - semi-circular > shaped like a half-circle - |noun| a document distributed to a large number of people / an aeronautical information circular /


circular slide rule |noun| a calculating device on which all manner of conversions and complex calculations can be made to assist in flight planning


circulate |verb| to move round in such a way as to arrive at the point of departure / Water circulates via the radiator and pump through to the engine block itself. /


circulation |noun| the act of moving round in such a way as to arrive at the point of departure / The general circulation is indicated by the arrows. / - cyclonic circulation > the circulation of air which, if viewed from above, is anticlockwise in the northern hemisphere and clockwise in the southern hemisphere


circulatory |adjective| moving around a circuit


circumference |noun| the distance around the edge of a circle / The angle subtended by an arc equal to one 360th part of the circumference of a circle is called one degree. /


circumstance |noun| a condition which affects something in a given situation - in some circumstances, under certain circumstances > in some particular situations


cirro- |prefix| high altitude, i.e. above 20,000 feet


cirro-cumulus |noun| a layer of broken cloud at about 20,000 feet


cirro-stratus |noun| a layer cloud at about 20,000 feet


cirrus |noun| a high cloud in a mass of separate clouds which are formed of ice crystals


Citation |noun| an American twin engine business jet


Civil Aviation Authority |noun| the organization which licenses operators, aircraft and employees for non-military, especially commercial aviation. Abbreviation: CAA


Civil Aviation Publication |noun| a book, etc., published by the Civil Aviation Authority, each publication having its own reference number / The procedure for obtaining a bearing can be found in CAP 413. / Abbreviation: CAP


clad |verb| to protect by covering / Alloys can be protected from corrosion by cladding the exposed surface with a thin layer of aluminum. /


clamshell door |noun| the hinged part of a thrust reverser / Clamshell doors are hydraulically or pneumatically opened, and direct the exhaust gases forwards to produce reverse thrust. /


classification |noun| the act of putting things into groups or classes because they possess particular common features / Classification of aircraft consists of a multi-level diagram with each category divided into sub-categories. A full classification of layer cloud is given in the table. /


classify |verb| to group items so that those with similar characteristics are in the same group / Precipitation is classified as light, moderate or heavy according to its rate of fall. The weather associated with visibility reductions by particles suspended in the atmosphere is classified either as fog, mist, haze, or smoke. /


clean speed |noun| the aircraft airspeed with flaps, slats and landing gear retracted


clear |adjective|  1. referring to conditions in which it is easy to see, e.g. with no cloud or fog - a clear sky > a sky with no cloud - a clear winter night > a night with no fog, mist or other conditions which might impair visibility  2. possible to easily see through  3. with nothing blocking the way - clear runway, the runway is clear > nothing is on the runway - keep the exits clear > do not put anything and do not stand in front of the exits  4. away from  5. easy to hear - clear of cloud > either above or below cloud - keep clear (of) > keep away (from)  6. easy to understand / The explanation is very clear. /  7. understood  8. understood - is it clear? > do you understand? - |verb|  1. to remove a blockage or some other unwanted effect which prevents a system from working correctly / A heater element is fitted to clear the detector of ice. /  2. to disappear / In winter frost and fog are slow to clear. /  3. to make sure that it is all right to do something - clear it with the CFI > make sure that the CFI agrees with the request  4. to officially ask people to quickly leave a given area or place - to clear the building > to quickly leave the building ‘…the principles of weight and balance should have been learned by all pilots during their initial training, but it is clear that, afterwards, some forget’


clear air turbulence |noun| turbulence encountered in air where no cloud is present (NOTE: CAT is often associated with the jet stream.)


clearance |noun|  1. a space made to allow for the movement of hardware relative to other hardware  2. official permission / Obtain clearance for IFR flight. /  3. the disappearance of something unwanted, often rain, fog or snow / Low temperatures caused a delay in the clearance of fog. /


clearance limit |noun| the point to which an aircraft is allowed to proceed when granted an air traffic control clearance


clear ice |noun| ice which is glass-like rather than white


clear pass |noun| an exam result which is in no doubt


clear to land |noun| air traffic control permission to land


climate |noun| weather conditions particular to a given area / Mediterranean climate / - temperate climate > a type of climate which is neither very hot in summer nor very cold in winter.


climatic |adjective| referring to climate or weather conditions particular to a given area / The aircraft forward speed and altitude as well as climatic conditions will influence the value of thrust. /


climatic zone |noun| one of the eight areas of the Earth which have distinct climates (NOTE: The climatic zones are: the two polar regions (Arctic and Antarctic); the boreal zone in the northern hemisphere, south of the Arctic; two temperate zones, one in the northern hemisphere and one in the southern hemisphere; two subtropical zones, including the deserts; and the equatorial zone which has a damp tropical climate.)


climatology |noun| the science of the study of climate / Although pilots do not need to be experts in climatology, they should have a good understanding of the factors which produce changes in the weather. /


climb |noun| the act of increasing altitude by use of power / Fine pitch enables full engine speed to be used during take-off and climb. / Opposite: descent - |verb| to increase altitude by use of power / After take-off, the aircraft climbed to 5,000 ft. / Opposite: descend


climb-out |noun| a flight after take-off from 35 feet to 1,500 feet during which undercarriage and flaps are retracted /Turn right after climb-out./


clockwise |adjective|,|adverb| describing a circular movement in the same direction as the hands of a clock / The relative bearing indicated is measured clockwise from the nose of the aircraft. / Opposite: anticlockwise


clog |verb| to prevent movement of fluid through a pipe, etc., because of a build-up of solid matter / Most filters allow unfiltered fluid to pass to the system when the filter becomes clogged. /


close |verb| to shut / Close the door. /


closure |noun| the act of closing or shutting / The voltage regulator is turned on by the closure of the generator control relay. /


cloud |noun| a mass of water vapor or ice particles in the sky that can produce rain (NOTE: The most important types of cloud are the following: alto-cumulus , cloud formed at about 12,000 feet as a layer of rounded mass with a level base; alto-stratus, cloud formed as a continuous layer between 6,000 and 20,000 feet usually allowing the sun or moon to be seen from the surface;  cirro-cumulus, a layer of broken cloud at about 20,000 feet; cirro-stratus , layer cloud at about 20,000 feet;  cirrus , cloud made of ice crystals at 25,000 – 40,000 feet appearing as hair-like formations; cumulonimbus, cloud formed as a towering mass and often associated with thunderstorms; cumulus, cloud formed in rounded masses with a flat base at low altitude, resulting from up currents of air;  nimbo-stratus, thick dark layer cloud at low altitude from which rain or snow often falls (nimbus = rain cloud);  strato-cirrus , cloud similar to cirro-stratus but more compact;  strato-cumulus , a layer of connected small clouds at low altitude.)


cloud base |noun| the bottom part of a layer of cloud / In general, the lower the cloud base, the less heat is lost by the earth. /


cloud ceiling |noun| the height above the ground or water of the base of the lowest layer of cloud


cloud group |noun| a collection of different cloud types which have similarities, e.g. stratus clouds


cm |abbreviation| centimeter


co- |prefix| together - co-axial > having the same axis - co-located > having the same location


coalesce |verb| to join together to form a large mass or number / The moisture in the air coalesces into large water droplets. /


coalescence |noun| the act of joining together to form a larger mass or number / Coalescence of water vapor in the atmosphere forms larger droplets of water. /


coast |noun| an area where the land meets the sea / Valentia is situated on the coast of south west Ireland. /


coastal |adjective| referring to the coast - coastal area > an area near a coast / Land and sea breezes occur in coastal areas. /


coastal refraction |noun| change in direction of waves when a signal crosses a coastline from sea to land


coastline |noun| the outline of a coast seen from a distance or on a map / It is normally easy to identify a coastline or island. /


coat |noun| a thin covering of a substance such as paint / The coats of paint on a large aircraft significantly increase its weight. / - |verb| to cover with a thin layer of a substance such as paint / Metals are coated for protection against corrosion. /


coating |noun|  1. a thin layer of a substance / There are two coatings on the inside of CRT screens. /  2. the act of covering with a thin layer of a substance


cock |noun| a manually controlled valve or tap to control the flow of a liquid / It is necessary to have a master cock for each engine. /


cockpit |noun| the forward area in an aircraft from where the aircraft is controlled by the pilot / In the case of an in-flight oil loss, a warning indicator will light in the cockpit. / ‘…in the cockpit of the future there will be two animals, a pilot and a dog. The pilot will be there to feed the dog, and the dog will be there to bite the pilot if he tries to touch anything’ [NYT News Service]


cockpit voice recorder |noun| an automatic recycling recorder storing all crew radio and intercom traffic, including crew speech and background noise / The crew can only erase the CVR recording after engine shut-down. /


code |noun|  1. a system of numbers, letters or symbols used to represent language which has to be learned and decoded in order for the receiver to understand the meaning  2. a series of pulses by which an aircraft transponder replies to a signal from the ground


code-share |noun| - code-share deal > an agreement between airlines regarding connecting flights / The two airlines have entered into a code-share deal for flights between Dubai and Bangkok. /


code-share partner |noun| an airline which has an agreement with another airline regarding connecting flights


code-sharing |noun|  1. a procedure which allows travelers to use connecting flights between one airline and another partner airline for worldwide destinations  2. an arrangement by which two airlines sell seats on the same flight using their own flight numbers


coefficient |noun| a mathematical quantity placed before and multiplying another


C of A |abbreviation| certificate of airworthiness


C of G |abbreviation| center of gravity


coil |noun| a device consisting of coiled wire for converting low voltage to high voltage / A voltage coil is connected across the generator. /


coiled wire |noun| a length of wire twisted round and round / A coiled wire connects the terminal to earth. /


coincide |verb| to happen at the same time and/or in the same place / When the aircraft heading is directly into wind or down wind, track and heading coincide. /


coincident |adjective| happening at the same place or at the same time / The Earth’s true north and magnetic north poles are not coincident. /


col |noun| an area of slack pressure gradient between two centers of high or low pressure / The persistence and movement of cols are governed by the movement of the adjacent pressure systems. /


cold front |noun| an advancing mass of cold air, moving under and lifting warmer air / A cold front brought rainy, windy conditions to the country. /


collapse |noun| a sudden and complete fall - the collapse of a company > the end of the existence of the company - |verb|  1. to fall suddenly and completely / The magnetic field will reach a maximum in one direction, collapse to zero and reach a maximum in the opposite direction. / 2. to fold or to close suddenly and unintentionally - the undercarriage collapsed (of an apparatus) > the undercarriage could not support the aircraft and broke or retracted on its own  3. to faint - the passenger collapsed > the passenger fell and became semi- or fully unconscious because of some medical problem ‘…as the aircraft slid off the runway, the left landing gear collapsed’


collect |verb|  1. to gather over a period of time / Any given object will usually collect ice more quickly at high speed. /  2. to take something or to pick something up from a place


collection |noun|  1. a number of things brought together / a collection of vintage aircraft /  2. an act of being collected by somebody / The documents are in the office awaiting collection. /


collide |verb| to bump or to crash into something / The aircraft left the runway and collided with a fire truck. /


collision |noun| a crash between two objects, two vehicles, etc. / If there is a risk of collision, alter course to the right. / - collision avoidance > the prevention of collisions by taking measures beforehand to ensure that they do not happen


column |noun|  1. a body of fluid or solid with a tall, narrow shape / Torricelli first demonstrated that the atmosphere has weight by showing that it can support a column of liquid. /  2. a vertical section of a table in a document


combat |verb| to fight against / Fire extinguishers are provided to combat fire. /


combat aircraft |noun| aircraft designed for warfare


combination |noun| two or more things brought together to form one / The combination of wind direction and wind speed is called velocity. /


combine |verb| to bring two or more things together to make one / The stabilizing channels for ailerons and elevators are combined. Thrust and lift combine to overcome drag and gravity. /


combustible |adjective| burning or igniting easily - combustible materials > materials which will catch fire easily, e.g. wood, paper, etc.


combustion |noun| burning, especially that which takes place in an engine / The heat generated by combustion is considerable. /


combustion chamber |noun| the part of the cylinder in a piston engine where the ignition of the fuel/air mixture takes place


combustor |noun| the part of a jet or gas-turbine engine that burns fuel to produce power. It consists of the fuel injection system, the igniter, and the combustion chamber.


command |noun| an order - the command to evacuate > the order to leave the aircraft in an emergency - in command > having responsibility for and authority over - |verb| to order something to be done / The captain commanded the evacuation of the aircraft. /


commander |noun| a pilot in control of, and responsible for, the aircraft and its contents during flight time - the commander of an aircraft > the member of the flight crew specified by the operator as being the commander


commence |verb| to start to do something - commence the evacuation > start getting people out of the aircraft


commercial |adjective| referring to a business activity - commercial aviation > flying as a business enterprise


commercial aircraft |noun| aircraft used to carry cargo or passengers for payment


Commercial Pilot’s License |noun| the license that a person requires to be pilot-in-command of public transport aircraft certified for single-pilot operations. Abbreviation: CPL


common sense |noun| ordinary good sense / You should use your common sense as well as follow the rules if a passenger feels unwell. /


comms |abbreviation| communications


communicate |verb| to make contact with somebody in order to pass information / The cabin attendants should communicate with the captain. /


communication |noun| the act of passing information to somebody usually, but not always, by using language / Two methods of communication are available to crew members – language and hand signals. /


communication link |noun| a telephone or radio connection, as between the ground crew and flight deck while an aircraft is preparing for departure


communications |plural noun| a system of passing information / VHF communications are allocated the frequency bracket 118–137 MHz. / Abbreviation: comms


commutator |noun| a device containing metal bars connected to the coils of a generator to produce electrical current / As the power output required is DC not AC, a commutator is fixed at one end of the armature. /


compact |adjective| small, close together, or not taking much space / The annular system, as used on modern aircraft, provides a compact system, and, for the same output and mass flow, a shorter system. / - |verb|  1. to make smaller or more dense by pressing  2. to compress, by driving over with heavy machinery / When taxiing on grass, aircraft wheels compact the earth as the aircraft moves over it. /


compaction |noun| the act of pressing things together to form one, or of compressing something to make it hard / The speed of impact when the aircraft passes through a snowstorm causes compaction of snowflakes into a solid mass on leading edges and air-intakes. /


comparable |adjective| possible to compare equally with something else / Titanium is non-magnetic and has an electrical resistance comparable to that of stainless steel. /


comparator |noun| a device to compare two things / The autopilot comparator monitors the operation of the elevator and aileron channels. /


compare |verb| to find the similarities and dissimilarities between two or more things / When the chart is properly orientated, it is easier to compare the distance between landmarks on the ground with their corresponding distances on the chart. An aneroid barometer is small compared with a mercury barometer. /


comparison |noun| a statement expressing the differences and similarities between two or more things / A table showing a comparison of fixed points on various temperature scales is given on page three. /


compartment |noun| a small space or area in a structure for a particular purpose - crew compartment > the area reserved for crew


compass |noun| an instrument usually with a magnetic needle which always points to the magnetic north


compass bearing |noun| a direction or position relative to a fixed point measured in degrees on a compass


compatibility |noun| the ability of a component to operate successfully with other components / Problems of compatibility caused the computerized system to malfunction. /


compatible |adjective| referring to a component or system which can be used with a different component or system without causing any problems / Computer software designed for one particular system may not be compatible with other systems. /


compensate |verb| 1. to make up for the loss of something / The floor covering may be designed to compensate for temperature, pressurization and bending loads. The fall in air temperature increases the air density and so compensates to some extent for the loss of the thrust due to atmospheric pressure. /  2. to give money to a person or organization to make up for a physical or financial loss / The money offered by the company did not compensate for the injuries she received in the accident. /


compensation |noun| money paid to an individual or organization to replace or make up for physical or financial loss / The company paid out $2 million in compensation to the families of those who lost their lives in the tragedy. /


compilation |noun| the putting together of suitable information / The manual is a compilation of materials used by each of the instructors. /


compile |verb| to put together a number of pieces of information / Aviation routine weather reports are compiled half-hourly or hourly at fixed times. /


complement |verb| to fit in with and improve the performance of something / Ultra-sonic detection is used to complement other methods of flaw detection. /


complementary |adjective| the fact of fitting in with and improving the performance of something / SSR is complementary to the primary radars used by ATC. /


complete |adjective|  1. containing all the parts it should contain / The center section can be constructed either as a complete unit or as two separate units. /  2. absolute and total - |verb|  1. to finish or make whole / The number of revolutions for the crankshaft to complete a full cycle is always two. / - complete the work > to continue until the work is finished  2. to fill in information - complete the flight plan > to fill in the required information in the flight plan


completion |noun| the satisfactory finishing of a task / It is important to carry out an inspection of an aircraft after completion of deicing operations. /


complex |adjective| complicated and therefore possibly difficult to understand / Of all the pre-departure activities, route planning is one of the most complex. / - |noun|  1. a whole made up of many different parts - a cumulonimbus cloud complex > a collection of cumulonimbus clouds forming a system  2. a building made up of many different parts - the terminal three complex > the main building and associated buildings which together make up terminal three


complexity |noun| the condition of being complex, or a complication / Up-to-date design does not necessarily mean structural complexity. /


compliance |noun| being in agreement or in accordance with / Each operator shall demonstrate compliance with the requirements. /


complicate |verb| to make more difficult / Map reading is often complicated by seasonal variations. /


complicated |adjective| not easy to understand


complication |noun| a difficulty or problem / The complication with the Mercator’s projection is that great circle directions must be converted to rhumb line directions by the application of conversion angle before they can be plotted. /


comply |verb| to be or do what is required by an instruction or law / Equipment and furnishings of modern jet transports must comply with safety regulations. Passengers must comply with the no-smoking signs. / (NOTE: complying – complied)


component |noun|  1. a part of an aircraft, aircraft system or piece of equipment / The undercarriage is made up of a number of different components. /  2. one part of a force such as wind which consists of a number of different parts  3. a substance which forms part of a compound


compose |verb| to make something from a number of parts /The atmosphere is composed of a mixture of gases./


composite |adjective| referring to something made up of a number of different parts / The flight crew route flight plan is a composite document which serves as a navigation log. / - |noun| a lightweight but very strong man-made material used in aircraft manufacturing / To make a composite it is necessary to combine the reinforcing glass fibers with special glue or resin. / (NOTE: Composites are used in the construction of many modern aircraft, from gliders to aircraft such as the Airbus A320, because they are strong and lighter than metals.)


composition |noun| the make-up or structure of something - composition of the atmosphere > the combination of gases which make up the atmosphere


compound |adjective| referring to something made up of two or more parts or substances - |noun| a substance made up of two or more components /A chemical compound has qualities that are different from those of the substances from which it is made. Advances in sealing compounds have now made fuel tanks less liable to leaks./


compound wound generator |noun| a generator which consists of a number of windings


compress |verb| to put under pressure thereby reducing volume / Pressure is created when a fluid is compressed. /


compressibility |noun| the natural ability of a substance to change volume when under varying pressures / In systems using very high pressure, the compressibility of the liquid becomes important. /


compressible |adjective| referring to something that can be compressed / Air is compressible, but water is not. /


compression |noun| an act or instance of putting pressure on something


compression stroke |noun| the stage of an internal combustion cycle when the fuel/air mixture comes under pressure from the upward-moving piston


compressive |adjective| referring to forces caused by pressure on a surface / A strut is designed to withstand compressive loads. /


compressive load |noun| a load caused by forces acting in opposite directions towards each other


compressive stress |noun| the resistance of a body to crushing by two forces acting towards each other along the same straight line


compressor |noun| a device such as a pump to compress air, in order to increase pressure / A shaft connects the turbine to the compressor. /


comprise |verb| to be made of


concentrate |verb|  1. to collect in a particular place rather than spread around / Most of the mass of air is concentrated at the lowest levels of the atmosphere. / 2. to give attention and thought to something in particular / This chapter concentrates on charts. / - to concentrate hard > to give all one’s thought and attention to something


concentration |noun| 1. the fact of being collected in a particular place rather than spread around / The maximum concentration of ozone is between 20 and 25 km above the Earth’s surface. /  2. the act of giving attention and thought to something / In the early stages of training, instrument flying requires great concentration on the part of the student pilot. /


concentric |adjective| having the same center - concentric circles > circles of different diameters but with the same center point


concept |noun| an idea or abstract principle / The concept of open skies is not one with which everybody agrees. / - a complicated concept > an idea or series of ideas or principles which are difficult to understand


concern |noun|  1. serious interest - a matter for concern > something which must be taken very seriously  2. responsibility / Attention to the welfare of passengers is the concern of the cabin crew. Safety is everybody’s concern. / - this is no concern of ours > this is nothing to do with us - |verb|  1. to cause somebody to feel worried - this report concerns me enormously > I am not at all happy about this report  2. to be about or to be the subject of / If there is serious vibration, the crew should shut down the engine concerned. / - this report concerns me > this report is about me  3. to be of interest and relevance to - the regulations concern all employees > the regulations apply to all employees ‘…the correct storage and handling of cargo and especially dangerous goods is an area which is of considerable concern to the Federation’


concise |adjective| short, efficient, not wasteful, not containing unnecessary information / Being concise is essential in radio communications, because pilots and ATCOs often have to communicate information fast. /


concrete |noun| a substance made of cement, sand and water used in the construction of buildings, roads, etc. / Rock, sand and concrete reflect only 10–20% of radiation. /


concussion |noun| blow to the head / One of the passengers was in the aisle when we encountered the turbulence and is suffering from concussion. /


condensation |noun| the process by which vapor changes into liquid / If the air becomes saturated, further cooling results in condensation. / Opposite: evaporation


condensation trail |noun| same as vapor trail


condense |verb|  1. to change from vapor to liquid form / The most common type of hygrometer is one in which a surface in contact with the atmosphere is cooled until moisture begins to condense on the surface. / Opposite: evaporate  2. to remove unnecessary parts from a text to make it shorter / The synoptic code condenses information without loss of sense. /


condenser |noun| an electrical capacitor / The condenser prevents spark plugs from arcing. /


condition |noun|  1. the present state of something - although the aircraft is old, it is in good condition > the aircraft is old but well cared for  2. the state of the surrounding atmosphere / In a high relative humidity condition, the evaporation rate is low. / - abnormal weather conditions > unusual or unfavorable weather - adverse weather conditions > bad weather  3. circumstances  4. something on which another thing depends - on condition that > only if - the flight will depart on condition that the weather improves > the flight will depart only if the weather improves


conditional clearance |noun| when a clearance is given by a controller conditional upon another traffic movement (departure or arrival) occurring first. For example: ‘Cathay Pacific 396, behind Boeing 777 on short final, line up behind.’


conducive |adjective| favorable, which allows something to happen more easily / Atmospheric conditions conducive to the formation of ice are detected and these operate a warning system. / ‘…when refueling, ensure the aircraft is properly earthed. The very low humidity on a crisp, cold day can be conducive to a build-up of static electricity’


conduct |noun|  1. a manner or way of doing something / The captain is responsible for the safe conduct of the flight. /  2. behavior / The investigation found that the flight attendant’s conduct was unacceptable. / - |verb|  1. to organize and do something; to carry out / Crew will conduct area checks. Security conducted a search of the building. /  2. to allow something such as electricity, heat etc. to pass through / Water conducts electricity. /


conduction |noun| the process by which heat or electricity passes through a substance / Heat is transferred to the layer of air next to the Earth’s surface by conduction. /


conductive |adjective| referring to the ability of a substance to allow heat or electricity to pass through / Steel is a conductive material. Land masses are less conductive than water. /


conductivity |noun| the ability of a material to allow heat or electricity to pass through / Because of the poor conductivity of air, heat is transferred from the Earth’s surface upwards by convection. /


conductor |noun| a substance through which heat or electricity can pass / Water and steel are good conductors. /


cone |noun| a solid body with a base in the shape of a circle, and with sides which narrow to a point, or any object which has that shape


configuration |noun| the pattern or way in which things are arranged - configuration of an aircraft’s fuel tank system > the way in which the tanks are laid out


confine |verb|  1. to limit to a particular area / Cooling is confined to the air in contact with the ground. The damage was confined to a small area. /  2. to limit to a given subject - the report confines itself to the incident of 3rd January > the report deliberately does not mention anything other than the incident of the 3rd January


confined |adjective| limited, small - a confined space > a small defined space which does not allow free movement


confirm |verb| to agree that something is correct, or to repeat it to remove any uncertainty / The attitude indicator shows that the aircraft is in a nose down attitude and the increasing airspeed confirms that the aircraft is not in level flight. Can you confirm that the instructor was flying the aircraft at the time of the collision? VHF and/or UHF radio aids confirm ADF bearings. / (NOTE: Cross-checking of certain flight instruments is used to confirm readings from other instruments, e.g. the airspeed indicator and vertical speed indicator confirm pitch information from the attitude indicator.)


conflicting traffic |noun| traffic at or near the same flight level heading towards each other


conform |verb| to correspond to required standards / Fuels must conform to strict requirements. / - to conform to regulations > to do what is required by rules and regulations


conformal |adjective| representing angles, bearings, etc., correctly / Lambert’s conformal projection /


confusion |noun| the state of being unsure in one’s mind, of being confused: runway confusion is a well-documented error


congestion |noun| a situation where there are too many people or vehicles in a confined space for them to be able to move freely / When leaving the aircraft in an emergency, to avoid congestion, passengers should be directed to move away from exits quickly. /


conic |adjective| based on the shape of a cone - conic projection > the standard two-dimensional representation of the earth


conical |adjective| shaped like a cone / The nose of Concorde has a conical shape. /


conjunction |noun| - in conjunction with > working or operating together with / Built-up areas, used in conjunction with other features such as rivers, railways and coastlines which are near them, are more easily identified. /


connect |verb| to join / Batteries are sometimes connected in series. A cockpit lever is connected to a needle valve in the float chamber. /


connecting flight |noun| a second aircraft which a passenger should arrive on time to catch, and which will take him or her to the final destination / Instead of flying direct to London, take the flight to Amsterdam and then take a connecting flight to London Heathrow. /


connecting rod |noun| an engine part that connects the piston to the crankshaft


connection |noun|  1. the point at which things are joined / There is an electrical connection to the battery. /  2. a link or feature that makes things interdependent / There is a connection between temperature change and altitude. /  3. the process of catching a second aircraft to arrive at a final destination / Follow the ‘Flight Connection’ signs. /


connector |noun| a device which connects two or more things / A connector is used to connect two lengths of wire together. Standard connectors consist of a metal coupling with a rubber sandwich joint. /


consecutive |adjective| following one another without a break / 4, 5 and 6 are three consecutive numbers. / - a period of 28 consecutive days > 28 days following immediately one after the other


consequence |noun| the result of an action / The accident was a consequence of the pilot’s actions. / - as a consequence > as a result


consequent |adjective| resulting / As temperature rises, there will be a consequent increase in the volume of the gas. /


consequently |adverb| therefore, as a result / She was late, consequently she missed the start of the examination. /


conserve |verb| to avoid using unnecessarily / Release the brakes when necessary and conserve main system pressure. / - to conserve energy > to use only as much energy as you really need - to conserve fuel > to use as little fuel as possible


consider |verb| to think carefully about something / If the aircraft is low on fuel, the commander should consider diverting to the nearest suitable airport. /


considerable |adjective| a lot of, quite large / The required range of trim change is considerable. / (NOTE: Considerable does not mean that something should be thought about, as the meaning for the verb consider might suggest.) - a considerable amount of fuel > a lot of fuel, a large amount of fuel - a considerable distance > a long distance - considerable force > a lot of force


consideration |noun| 1. something important to remember and to think carefully about - to take into consideration > to remember to include when thinking about something, solving a problem or making a calculation  2. thoughtfulness, respect - to show consideration for other people and property > to show respect for what belongs to other people


consist |verb| - to consist of > to be made up of / Layer cloud names consist of a prefix, according to height of base, and a suffix according to shape. / - to consist in > to mean, to be


consistent |adjective| always reacting or behaving in the same way / Human hair responds in a consistent manner to changes in the relative humidity. / - consistent performance > performance which maintains a particular standard


consolidate |verb| to make more solid or strong - revision of the subject helps to consolidate it > revision of the subject helps to set it more firmly in the memory


consolidation |noun|  1. a process by which something is made more solid or strong  2. the grouping of goods together for shipment


constant |adjective| unchanging - the temperature of the gas remains constant > the temperature of the gas stays the same - constant pressure > pressure which stays the same


constant speed drive unit |noun| a device fitted to aircraft with constant speed propellers. Abbreviation: CSDU


constant speed propeller |noun| a propeller with a control system which automatically adjusts pitch to maintain selected rpm


constant speed unit |noun| a device that automatically keeps a propeller at a speed set by the pilot. Abbreviation: CSU


constituent |noun| any one of the various parts that make up a whole / Water, whether in the form of vapor, liquid or ice, is a very important constituent of the atmosphere. /


constitute |verb| to make up, to form / Oxygen and nitrogen together constitute most of the atmosphere. /


constrain |verb|  1. to prevent somebody from being completely free or from doing something they want to do / The airline was constrained in its purchase of new aircraft by lack of financial resources. /  2. to force somebody to do something / Lack of financial resources constrained the airline to cancel the purchase of new aircraft. /


constraint |noun| something that reduces freedom of action / The number of landings per 24-hour period is subject to constraint. /


constrict |verb| to make something narrower, especially to make the flow of gas or liquid more difficult by narrowing the passage through which it flows / In the carburetor venturi, the flow of air is constricted. /


constriction |noun| the act of constricting, or a place where something is particularly narrow / A thermometer has a constriction in the base of the tube between the bulb and the beginning of the scale. /


construct |verb|  1. to put together / The table on page 4 can be used to construct the low level forecast for the route. /  2. to build - to construct an aircraft > to manufacture or build an aircraft / Wings are constructed of light alloy pressed ribs and an outer skin. /


construction |noun|  1. the act of putting things together, or the way in which something is put together / The basic construction of the lead-acid cell consists of a positive electrode and negative electrode. /  2. a building / The construction of the home-built aircraft took two years. /


consume |verb|  1. to use up in a given time / Drag must be overcome with thrust, which requires engines, which in turn consume fuel. /  2. to eat


consumption |noun|  1. the amount used up in a given time / Fuel consumption is higher in bigger, more powerful engines. /  2. the process of using up fuel or other resources  3. the amount eaten  4. the act of eating


contact |noun|  1. touch - in contact with > touching / The air in contact with the Earth’s surface cools. /  2. - to be in contact with > to communicate with e.g. by telephone or radio - to be in visual contact > to see - to make contact > to communicate - to lose contact > to stop communicating / ATC lost contact with the aircraft. /  3. a person who can be contacted in order to get something done - I have a contact in Madrid who can help > I know somebody in Madrid who can help  4. an electrical connection / Dirty contacts were the cause of the problem. / - |verb| to get in touch with somebody e.g. by radio or telephone / The captain couldn’t contact ATC. /


contact breaker |noun| a mechanically operated switch which is timed to break the primary circuit when maximum current is flowing


contact flight |noun| a method of navigation for aircraft in which the pilot or crew use no navigational aids, but find their way by observing visible features of the ground


contact number |noun| a telephone number where information can be obtained


contain |verb| to hold, to have inside / Most clouds contain some super-cooled water droplets. The booklet contains details of the airline’s flight schedule. /


container |noun| a box, bottle, etc., which holds something else / A smouldering fire in a waste container could become very active due to pressure changes during ascent. /


contaminate |verb| to make something impure, harmful or dangerous / If contaminated air enters the cabin, the dump valve can be opened. /


contaminated fuel |noun| fuel which contains an unwanted substance, such as water, and is therefore dangerous to use


contamination |noun| a process by which a liquid, gas or object is made unusable because impurities or foreign matter are allowed into or onto it - contamination of air > air pollution - fuel contamination > a situation in which fuel becomes unusable because an unwanted substance such as water gets into it - nuclear contamination > damage done to an object, person or substance because of contact with nuclear radiation


content |noun| the amount of a substance that is contained within something, often expressed as a percentage / The stratosphere is a layer in which the water vapor content is low. / - the moisture content of the atmosphere > the amount of water vapor in the air


continent |noun| one of the seven great land masses of the Earth


continental |adjective| referring to a continent


continental climate |noun| the type of climate found in areas where there is no effect from the sea


contingency |noun| something which might happen in the future and therefore must be planned for


contingency plan |noun| a plan B; a pre-prepared plan to be implemented in case events do not take place as initially planned / We need a contingency plan in case we have to divert. /


contingency reserve fuel |noun| fuel which would only be used in an unusual situation such as a diversion


continuity |noun| continuing - continuity of precipitation > continuing rain, snow or hail


contour |noun| the shape of something


contour chart |noun| chart which shows areas of high and low ground


contour gradient |noun| steepness of change in elevation


contour line |noun| a line on a map or chart joining points of equal elevation


contract |verb| to become smaller in volume / Liquids will expand or contract as a result of temperature changes. / Opposite: expand


contraction |noun| the decrease in volume of a substance brought about by cooling / Due to contraction, the length of a mercury column shortens. / Opposite: expansion


contradictory |adjective| showing different information / The Captain and First Officer airspeed displays were contradictory. /


contrail |noun| same as vapor trail


contrast |noun|  1. the amount of light and dark in something seen / Contrast and color enable a pilot to identify ground features. /  2. the difference between two things / There is an enormous contrast between the performance of the two aircraft. / - in contrast to > when compared with / Air at altitude is cold in contrast to air at the surface. /


contribute |verb| to give or provide as part of the whole / Exhaust gases contribute to engine power. / - although the weather was bad, pilot error contributed to the accident > pilot error was partly responsible for the accident


contributing factor |noun| one of several factors that lead to an event / A lack of English language proficiency was a contributing factor in several high-profile accidents. /


contribution |noun|  1. the part that something plays in making or causing something / The differences in the effect of solar radiation on land and sea make the biggest contribution to weather and climate. /  2. the act of contributing or something, especially money, that is given or provided


contributor |noun| a person or thing that contributes to something / There are other factors which cause the division of the lower atmosphere into two layers but the ozone effect is a major contributor. /


control |noun|  1. the authority or ability to direct somebody or something 2. - crowd control > the management of the movements of large numbers of people  3. checking or examining - |verb| to direct, to manage or to make a machine, system, procedure, etc., work in the correct way / The purpose of the centrifugal switch is to control the starting and ignition circuits. / (NOTE : The word  control in English is used in a different way to similar words in other languages. In English, the verb check is more often used to mean ‘look at and verify’ while control is used in the sense of ‘to make something work in a particular way’:  the yoke and rudder pedals are used to control the movement of the aircraft. Note also: controlling – controlled.)


control area |noun| the airspace above a particular area on the ground, which is controlled by a particular authority. Abbreviation: CTA


control column |noun| the main hand control used by the pilot to control the aircraft in roll and pitch


control tower |noun| a tall ATC building with overall visibility of the airport


controlled airspace |noun| airspace which is governed by rules and regulations which pilots must comply with. Abbreviation: CAS


controller |noun|  1. a device which ensures that something operates in the correct way  2. a person who manages systems to ensure the smooth operation of procedures


controls |plural noun| manual or automatic devices that are used to control a machine, a system, etc., or to make a machine, a system, etc., work in a correct way - the pilot at the controls of the aircraft > the pilot who is operating the flying controls


control surfaces |plural noun| moveable airfoils, usually on the wings and tailplane, which can be operated from the cockpit by the pilot, thus changing aircraft attitude


control tower |noun| a tall building on an airfield from which air traffic controllers organize incoming and outgoing aircraft by speaking to their pilots by radio


control zone |noun| a designated ATC area. Abbreviation: CTR


convection |noun| the process by which hot air rises and cool air descends / Heat is transferred from the Earth’s surface upwards largely by convection. /


convective |adjective| referring to convection, or something which is affected by the vertical circulation of air - convective movement > movement caused by warm air rising and cool air descending


convective clouds |plural noun| clouds formed as a result of warm moist air rising and condensing at altitude


convenience |noun|  1. personal comfort and benefit / Reading lights are provided for passengers’ convenience. / - at your convenience > when it is least troublesome for you  2. ease of understanding / For convenience we will assume that the Earth is round. /  3. usefulness, or easiness to use


convenient |adjective|  1. useful / The circular slide rule has a convenient scale for converting weights and volumes. /  2. suitable and unlikely to cause problems / We must arrange a convenient time and place for the meeting. /


convention |noun|  1. an idea which because of long usage has become normal and accepted / By convention, wind direction is the direction from which the wind blows. /  2. a meeting involving large numbers of people and long discussions in order to arrive at an agreed course of action often outlined in a public statement / the Tokyo Convention /


conventional |adjective| usual or familiar to most people / Every pilot must know the conventional symbols used for depicting the various ground features on charts. /


converge |verb| to come together at a particular point / Meridians converge towards the poles. / - aircraft on converging courses > aircraft on courses which may eventually be too close to each other if no corrective action is taken. Opposite: diverge


convergence |noun| the fact of coming together at a particular point / The inter-tropical convergence zone is the zone in which the trade winds from the two hemispheres approach each other. There is convergence of meridians of longitude at the north and south poles. / Opposite: divergence


converse |noun| the opposite / The converse of port is starboard. / - warm air rises – the converse is also true > in other words, cool air descends


conversion |noun|  1. a change to a different system or set of rules / The conversion of km into nm is not difficult. /  2. - conversion course > flying training which enables and qualifies a pilot to fly a different aircraft type


convert |verb| to change to a different system or set of rules / How do you convert degrees C into degrees F? /


converter |noun| a device which alters the form of something / A backup converter converts the alternating current power into direct current. /


convertible |adjective| possible to change easily, e.g. to fit in with a new system or set of standards / The statute mile, unlike the nautical mile, is not readily convertible into terms of angular measurements. /


convey |verb| to carry or move from one place to another / A large number of tubes convey the cooling medium through the matrix. Buses are used to convey passengers from the aircraft to the terminal building. / - to convey information > to pass information from one person to another, or from one place to another


conveyor belt loader |noun| rotating rubber belt for loading bulk cargo


cool |adjective| a little cold - cool weather > weather which is not hot, warm nor very cold - |verb| to become or cause to become less hot / The airflow is used to cool the oil. /


coolant |noun| a substance, usually liquid, used to cool something such as an engine / The coolant is sprayed into the combustion chamber inlet. /


cooler |noun| a device for cooling / A self-contained system, consisting of an oil tank, pump, filter, cooler, and oil jets, lubricates the auxiliary power unit. /


cooling |noun| the action of making something cool / the cooling of the oil by the airflow / - |adjective| reducing the temperature of something - cooling medium > a substance which reduces the temperature of another substance or material


coordinate |verb|  1. to bring together the various parts of a procedure or plan to ensure that the operation works correctly / It is the task of air traffic controllers to coordinate the movement of traffic in and out of a terminal. /  2. to make different parts of the body work well together / During a hover, helicopter pilots must be able to coordinate movements of both hands and feet. /


coordinated flight |noun| flight, especially during turns, in which the horizontal and vertical forces acting on the aircraft are in balance / In coordinated flight, the ball in the turn coordinator will be in the center. / (NOTE: The ball in the balance indicator of the turn coordinator shows the pilot if the aircraft is in coordinated flight or if it is slipping or skidding. When the ball moves to the left the pilot should apply left rudder pedal pressure, if the ball moves to the right, the pilot should apply right rudder pedal pressure.)


Coordinated Universal Time |noun| time used in aviation based on the 24-hour clock format. GMT


coordinates |plural noun| values used to locate a point on a graph or a map / The airfield can be seen on the map at coordinates B:12. /


coordination |noun|  1. the process of bringing together the various parts of a procedure or plan to ensure that it works correctly / A rescue coordination center is set up to control the emergency. /  2. the ability to use different parts of the body together well / A pilot must have good hand/eye coordination. /


cope |verb| to manage to do something, often with some difficulty / In heavy rainstorms, the windscreen wipers may not be able to cope. The aircraft structure must be able to cope with increased loads caused by turning movement. /


copilot, co-pilot |noun| a licensed pilot who is second in command to the captain of an aircraft / The copilot landed the aircraft. /


copter |noun| same as helicopter (informal)


cord |noun| a strong thread, usually of nylon / Tires are of pure rubber and are either cord-strengthened or reinforced. / (NOTE: Cord is used to reinforce tires.)


core |noun| the central part, the heart of something / The primary windings consist of heavy gauge wire mounted on a soft iron core. / - the core of a problem > the central, most fundamental part of a problem


Coriolis force |noun| force which accelerates the movement of a rotating mass perpendicular to its motion and towards the axis of rotation / The Coriolis force explains why wind patterns are clockwise in the northern hemisphere and anti-clockwise in the southern hemisphere. / (NOTE: The Coriolis force acts at a right angle to wind direction and is directly proportional to wind speed. It is named after G. G. Coriolis, a French engineer who died in 1843.)


correct |adjective| right - correct tire pressure > the pressure at which the tires should be maintained - |verb|  1. to adjust in order to make right / A servo-motor fitted in the elevator trim system will automatically correct for loads. Calibrated airspeed or rectified airspeed is indicated airspeed corrected for instrumentation and installation error. /  2. to mark answers right or wrong, as in an examination / The instructor has corrected the students’ examination papers. /


correction |noun|  1. an adjustment or change made to something to make it correct  2. the use of a mathematical formula for adjusting a known inaccuracy of calculation / In applying this correction the reading is converted to that which would occur at mean sea level. /  3. an alteration on, e.g. a test answer, which provides the right answer in place of the wrong answer given / I made several corrections to the text. /


corrective |adjective| referring to something designed to correct


corrective action |noun| action taken to put a situation right / If the pilot realizes that the plane is too high on the approach, he or she should take corrective action immediately. /


correlate |verb| to measure something against something else in order to form a relationship between the two / Power is measured not by the amount of work done, but by units of accomplishment correlated with time. /


correlation |noun| a measurable and predictable relationship / At a given speed, there is a correlation between time and distance. /


correspond |verb|  1. to fit with or have a direct relationship with / Movements of the control surfaces correspond to movements of the pilots flying controls. /  2. to be similar to / In the interests of passenger comfort, the ideal cabin conditions to maintain would be those corresponding to sea level. /


corridor |noun| same as air corridor


corrode |verb|  1. to destroy by a slow chemical process such as rust / The sulfur and water content of turbine fuels tend to corrode the components of the fuel and combustion systems. /  2. to be destroyed by a slow chemical process such a rust / Aluminum will not corrode easily. /


corrosion |noun| the destruction of a material by chemical processes / Aluminum has a high resistance to corrosion. /


corrosion protection |noun| action and/or measures taken to prevent corrosion such as rust


corrosive |adjective| causing corrosion /Sulfuric acid is very corrosive./


cosine |noun| a trigonometric function defined as the length of the side adjacent to an angle in a right-angled triangle divided by the length of the hypotenuse. / Abbreviation: cos


counter |verb| to act against something so as to remove or reduce its effect / For level flight, lift must counter the force of gravity. Some people find that swallowing hard counters the effects of changes in pressure. /


counter- |prefix| against


counterclockwise |adjective|,|adverb| US same as anticlockwise


counter-rotating propellers |plural noun| propellers which turn in opposite directions (NOTE : They are also called contra-rotating propellers.)


couple |noun| two of something - a couple of minutes > two or three minutes - |verb|  1. to connect or to join, often mechanically / The auxiliary power unit is a self-contained unit which normally consists of a small gas turbine engine which is coupled to a gearbox. /  2. to combine / Pilot error, coupled with poor weather conditions, resulted in an accident. /


coupling |noun| a joining or connecting component / When not in use, the coupling is sealed by a dust cap. /


course |noun|  1. an imaginary line across the surface of the Earth which must be followed in order to arrive at the destination - to alter course > to change direction or to follow a different route  2. a formal period of study  3. continuing time - in the course of the briefing > during the briefing


course correction |noun| same as heading correction


course deviation indicator |noun| a needle in an omni-bearing indicator which indicates if an aircraft is on a selected course. Abbreviation: CDI


cover |verb|  1. to include e.g. the complete extent of a period of time or the whole of a particular area / The restriction covers the period from 4th-8th July. / - the area covered by the forecast > the area which the forecast deals with  2. to deal with a subject, as in a text / The subject of central warning systems is covered in the systems book. /  3. to be completely over something so as to hide what is underneath / The area is covered in snow. / - |noun| something which goes over something else completely - cloud cover > the amount of cloud - snow cover > a situation in which there is a layer of snow on top of the earth so that the earth cannot be seen


coverage |noun| 1. the amount of space or time given to a subject, an event, etc. / More complete coverage of the one-in-sixty rule is given in the plotting section of these notes. / 2. the area within which a radar unit can detect objects / glide path coverage, localiser coverage /


cowl |noun| a covering usually made up of hinged or removable panels - cowl flap > a removable or hinged panel of a cowl / Further cooling can be obtained by the use of controllable cowl flaps which regulate the amount of air flowing across the cylinders. /


cowling |noun| a covering usually made up of hinged or removable panels / Access to the engine compartment is normally via hinged cowling panels. /


CPL |abbreviation| Commercial Pilot’s License


crab |noun| a maneuver in which an aircraft is steered slightly into a crosswind to compensate for flying slightly off course - |verb| to steer an aircraft slightly into a crosswind to compensate for flying slightly off course


craft |noun|  1. a boat, etc., for carrying people or goods on water  2. an aircraft or spacecraft for carrying people or goods in the air or in space / An airship is classified as a lighter-than-air craft. /


crankcase |noun| the part of the engine that houses the crankshaft and also usually the oil pump / Oil passages in the crankcase allow lubricating oil to pass through. /


crankshaft |noun| the part of a piston engine connecting the pistons, via the connecting rods, to the flywheel and gearbox /Rpm is the number of revolutions per minute that the engine crankshaft is making./


crash |noun| an accident that causes damage - |verb| to have an accident or collision that causes damage / The aircraft crashed into the sea. /


crash-dive |verb| to move downwards quickly through the air front first and crash, or cause an aircraft to do this


crash-land |verb| to land heavily without using the undercarriage, so that the aircraft is damaged / The aircraft crash-landed short of the runway. /


crash-landing |noun| an act of landing an aircraft heavily, sometimes without the undercarriage / The crash-landing did not damage the aircraft as much as the pilot expected. /


create |verb| to make, to produce / The velocity and pressure of the exhaust gas create the thrust in the turbojet engine. /


creep |noun|  1. a process of weakening and slow damage to something / Creep is a particular feature of components which are subjected to operation at high temperatures. /  2. a slight movement of a tire on a wheel caused by landing / Aligned white marks on the wheel and tire indicate that there is no creep. /


crest |noun| the top of a mountain or wave / Wind speeds increase with height, the speed of the wind at the crest of a mountain or wave being the greatest. /


crew |noun| two or more people who have responsibility for flight operations


crew minibus |noun| small bus to take crew to and from aircraft / We are still waiting for the crew minibus to pick us up. /


crew resource management |noun| a branch of human factors which analyses the ways in which team work and good communication can reduce the effects of human error. Abbreviation: CRM / CRM training has become part of mainstream pilot training. /


criteria - criterion


criterion |noun| a standard by which you define, decide or judge something (NOTE: The plural form is criteria.) - the criterion for promotion is seniority > senior staff will be promoted first


critical |adjective|  1. extremely important, essential / Temperature and oil pressure are critical to any type of system. /  2. at which an important change occurs / As the angle of attack is increased, it reaches the critical point when the airflow over the upper surface of the wing begins to break down. /


CRM |abbreviation| crew resource management


cross |verb|  1. to get from one side of an area to another - to cross the Atlantic > to go from one side of the Atlantic to the other  2. to go across each other at an angle / Meridians intersect at the poles and cross the equator at right angles. /


cross-check |noun| verification, making certain - |verb| to verify or make certain / Cross-check doors closed and locked and escape slides armed. / (NOTE: This word is often used in brief messages from one crew member to another, as from the pilot to cabin staff, to confirm that an action has been carried out.)


cross-country |noun| a flight during which the student pilot must demonstrate navigation skills / the qualifying cross-country flight for the PPL /


cross-pointer indicator |noun| a display with crossing horizontal and vertical bars to indicate aircraft position in relation to the glide slope


cross-section |noun| a view of an object seen as if cut through / The diagram is a cross-section of a turbojet engine. /


crosswind |noun| a surface wind which blows at an angle to the landing or take-off heading / On some aircraft, crosswind take-offs should be made with full aileron deflection in the direction from which the wind is blowing. / (NOTE: A crosswind landing is one of the most difficult exercises for a student pilot. The final approach is usually made with the aircraft yawed into wind, while tracking the extended runway center line. Just before touchdown, the pilot aligns the aircraft with the direction of flight using the rudder pedals. Correct timing for the alignment and accurate airspeed are required to achieve positive contact with the runway surface otherwise the aircraft may depart the runway to one side.)


crosswind component |noun| that part of the wind force acting at an angle to the direction of flight


crosswind leg |noun| part of the airfield traffic circuit flown at approximately 90° to the direction of take off and climb out, followed by the downwind leg


CRT |abbreviation| cathode ray tube


cruise |noun| the main part of the flight between top of climb after take-off and descent for landing - |verb| to fly the main part of the flight between top of climb after take-off and descent for landing / We are cruising at 500 kt. Cruising speed, cruising power and cruising altitude are selected to give maximum engine efficiency and prolong engine life. /


cruising altitude, cruising level |noun| the altitude at which most of a flight is flown en route to a destination, from top of climb to top of descent / Our cruising altitude will be 35,000 feet. /


cruising power |noun| engine power used to give required speed from top of climb to top of descent usually giving fuel economy and long engine life / Cruising power is about 2,300 rpm. /


cruising speed, cruise speed |noun| the speed selected from top of climb to top of descent, usually giving fuel economy and long engine life / The cruising speed is 110 knots. /


cruising weight |noun| the weight of an aircraft in flight, consisting of its weight when empty, the weight of its payload, and the weight of the fuel that it has left


crush |verb| to damage by pressure / Excessive load on the beam may crush the core. /


crystal |noun| a regular geometric shape formed by minerals, or as water freezes


CSDU |abbreviation| constant speed drive unit


CSU |abbreviation| constant speed unit


CTA |abbreviation| control area


CTOT |abbreviation| calculated take-off time


CTR |abbreviation| control zone


cubic |adjective| measured in volume, by multiplying length, depth and width - cubic centimeters (cc) > the usual unit used to measure the capacity of an internal-combustion engine / The engine has a capacity of 2,000cc. / Abbreviation: cc - cubic foot, cubic inch, cubic meter, cubic yard > the volume of a cube whose edge measures one foot, inch, meter or yard, respectively


cumuliform |adjective| which develop vertically / cumuliform clouds such as cumulonimbus /


cumulonimbus |noun| a dark, low cumulus – type of cloud associated with thunderstorms / A cumulonimbus has a characteristic anvil shape. / Abbreviation: CB


cumulus |noun| big, fluffy, white or grey cloud heaped or piled up, which develops at low altitude / Cumulus clouds may develop because of thermal activity resulting from the warming of the surface. Grey cumulus often develop into cumulonimbus. /  


cumulus cloud |noun| clouds which form only in an unstable atmosphere and, as the name suggests, often build vertically for great distances. Also called: heap cloud


current |adjective| present, actual, happening at the moment - current weather conditions > present weather conditions - current position > the position now - |noun|  1. an electrical supply / alternating current, direct current /  2. flow


current Information K |noun| ATIS Information Kilo in a series of updates (…India, Juliet, Kilo…) so that pilots can check easily that they have the most recent meteorological information about the airport. / Cleveland Hopkins Information Kilo, 1755 Zulu Automated Weather, Wind 260 at 15 gust 19, Visibility 6, light snow, 2,600 broken, 3,500 overcast, Temperature -5, Dewpoint -11, Altimeter 2999. /


curvature |noun| a curved shape - curvature of the earth > the curving of the Earth’s surface due to the spherical form of the Earth


customary |adjective| normal or usual / It is customary for the senior cabin supervisor to introduce herself to passengers at the start of a flight. /


customer service manager |noun| the chief cabin attendant on board a large aircraft


customs |noun| an official department of government concerned with movement of people and freight across national borders - customs aerodrome > an aerodrome, usually near a border or coast, with customs facilities


customs duty |noun| same as import duty / the duty payable on a carton of cigarettes /


cycle |noun| a series of actions which end at the same point as they begin / With the piston engine, the cycle is intermittent, whereas in the gas turbine, each process is continuous. / - life cycle of the thunderstorm cell > the process of formation, development and decay of a thunderstorm


cyclic, cyclical |adjective| referring to or happening in a cycle / Off-shore and on-shore wind patterns are cyclic. /


cyclone |noun| a system of winds rotating inwards to an area of low barometric pressure / These areas of low pressure are called hurricanes in the Atlantic Ocean, cyclones in the Indian Ocean and Bay of Bengal, and typhoons in the China Sea. / Also called: low, depression


cyclonic |adjective| referring to air movement, which turns in the same direction as the Earth and which, when seen from above, is anticlockwise in the northern hemisphere and clockwise in the southern hemisphere / In winter the sub-tropical high retreats and gives way to cyclonic pressure patterns which produce cool unsettled conditions with rain at times. /


cylinder |noun| a device shaped like a tube, in which a piston moves / Smaller aircraft have a static hydraulic system similar to a car, with a master cylinder and individual brake cylinders at each wheel. / - cylinder block > the casing containing the cylinders in a internal combustion engine - cylinder head > the removable top part of a piston engine cylinder containing plugs, inlet and exhaust connections and valves


cylindrical |adjective| with the shape of a cylinder / The modern jet engine is basically cylindrical in shape. /

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