I
IAF |abbreviation| initial approach fix
IAS |abbreviation| indicated airspeed
IATA |abbreviation| International Air Transport Association
IAW |abbreviation| in accordance with, in agreement with, in compliance with, following
I-beam |noun| a large bar of metal or some other strong substance with a cross-section shaped like the letter ‘I’
ICAO |abbreviation| International Civil Aviation Organization
ice |noun| frozen water
ice crystal |noun| a type of precipitation composed of crystals in the form of needles, plates or columns
ice patches |noun| intermittent ice cover on the ground
icing |noun| a process by which part of the aircraft becomes covered in ice while in flight / Engine icing can be extremely hazardous to flight. Airframe icing can be encountered in wave cloud. /
ideal |adjective| perfect, as good as can be expected or the best possible - an ideal situation > a very good situation - ideal flying conditions > very good flying conditions
ident |noun| a function on the transponder panel which helps a controller to identify the aircraft / The ident is suppressed until the standby VOR is fully run-up and has passed its monitor checks. / Full form: identity
identical |adjective| exactly the same - identical computers > computers which are exactly the same
identification |noun| the process by which a person, aircraft, etc., is recognized - identification of ground features > means by which particular features on a chart, such as railway lines or bridges, are matched with the real feature on the ground
identification beacon |noun| an aeronautical beacon which gives out a Morse signal which enables a pilot to establish their location in relation to the beacon / Civil and military aerodrome identification beacons can be distinguished by color. /
identifier |noun| a grouped number/letter code by which a weather station or beacon can be recognized / When a TAF requires amendment, the amended forecast is indicated by inserting AMD (amended) after TAF in the identifier and this new forecast covers the remaining validity period of the original TAF. /
identify |verb| to recognize / Crew members can be identified by their uniforms. In conditions of poor visibility, it is sometimes difficult to identify ground features. /
identity |noun| the name and details of a person, aircraft, etc. / The air traffic controllers are trying to establish the identity of the aircraft. /
IDG |abbreviation| Integrated Drive Generator
idle |noun| the state of an engine when it is running but not delivering power to move the vehicle or aircraft - |verb| to turn over slowly without providing enough power to move the vehicle or aircraft / After starting a piston engine from cold, it is good practice to allow it to idle for a short time before opening the throttle wide. /
idle cut-off |noun| a position on the mixture control of a light aircraft which allows the engine to be shut down without leaving a combustible fuel/air mixture in the engine
idle rpm |noun| the speed at which a piston engine turns when it is not running fast enough to move the vehicle or aircraft, i.e. on a light aircraft when the throttle is almost closed
idling |noun| a state in which the engine is turning over slowly without providing enough power to move the vehicle or aircraft
idling speed |noun| the rpm of the engine when it is idling / After start-up, the engine accelerates up to idling speed. Before the engine is stopped, it should normally be allowed to run for a short period at idling speed to ensure gradual cooling. /
IF |abbreviation| 1. instrument flying 2. intermediate frequency
IFR |abbreviation| instrument flight rules
ignite |verb| to burn or cause to burn / The spark plug ignites the fuel/air mixture. The air/fuel mixture ignites. /
igniter |noun| a device for starting gas turbine engines / An electric spark from the igniter plug starts combustion. /
ignition |noun| 1. the starting of burning of a substance / Satisfactory ignition depends on the quality of the fuel. / 2. the moment, in an internal combustion engine, when a spark from the spark plug causes the fuel/air mixture to burn / Ignition should occur just before top-dead-center. / 3. an electrical system, usually powered by a battery or magneto, that provides the spark to ignite the fuel mixture in an internal combustion engine / Ignition problems are a source of many engine failures. / 4. a switch that activates the ignition system - the key is in the ignition > the key is in its position in the ignition lock
ignition key |noun| a key used to switch on the ignition
ignition lock |noun| a key-operated switch for activating the ignition circuit of an aircraft or a vehicle
illuminate |verb| 1. to give light to an otherwise dark area / A flare illuminates the ground below it. / 2. to show a light or become bright / When the aircraft is 5 knots above stalling speed, a warning lamp illuminates. /
illumination |noun| light / Batteries provide about 20 minutes illumination for the lamp. / - daylight illumination > the amount of light in normal daytime conditions
illustrate |verb| 1. to demonstrate or explain clearly, often by using pictures / Contour charts illustrate the horizontal distribution of height above mean sea level. / 2. to show as an example / A number of aviation disasters have illustrated the importance of clear, correct use of language in R/T (Radio-telephony) communications. /
illustration |noun| 1. a picture which explains something / The illustration on page 23 shows a cross section of a typical gas-turbine engine. / 2. an example / The mechanics of the föhn wind provide a good illustration of the adiabatic process in action. /
ILS |abbreviation| instrument landing system
ILS CAT II, CAT III, CAT IIIC |noun| the various degrees of automation which aircraft and airports are equipped with, and flight crew are qualified to use. These categories involve different landing minima, i.e. vertical and horizontal visibility
ILS critical area |noun| an area which an ATCO may instruct an aircraft to hold short of in order to avoid interference with an ILS signal
ILS glide-slope |noun| a radio beam in an ILS which gives vertical guidance / The angle of the glide slope is usually about three degrees to the horizontal. /
ILS locator beacon |noun| a non-directional beacon used for final approach / Power output can be as little as 15 watts for an ILS locator beacon. /
ILS transmitters |noun| the localizer and glide-slope transmitters. The localizer transmitter is aligned with the runway center-line within the airport perimeter some distance from the runway threshold. The glide-slope antenna is located perhaps some 100 meters to the left or right of a runway to the side of the touchdown zone.
IM |abbreviation| inner marker
image |noun| a reproduction of the form of an object or person / Although difficult to see, the photograph shows the image of the aircraft with part of the fin missing. /
imaginary |adjective| not real / The equator is an imaginary line around the earth. /
IMC |abbreviation| instrument meteorological conditions
immediate |adjective| 1. happening at once or instantly / Fire extinguishers should be ready for immediate use in the event of an emergency. / - in the immediate future > in the very near future 2. nearby, close at hand / The immediate area surrounding the Earth is known as the atmosphere. /
immerse |verb| to cover completely in liquid, to submerge / Fuel is pumped from the main tanks via fully immersed booster pumps mounted on the base of the fuel tank. /
imminent |adjective| due to happen in a very short time / The transmission made it clear that the aircraft was in imminent danger. A message from the flight deck informs cabin staff that take-off is imminent. /
impact |noun| the striking of one body against another, a collision - on impact > as soon as it hit something / One of the tires burst on impact (with the ground). Super-cooled water droplets start to freeze on impact with an aircraft surface. /
impact resistance |noun| the ability of a material to withstand an impact
impair |verb| to cause to become less effective / Constant exposure to very loud noise impairs the hearing. The pilot’s vision may be temporarily impaired by lightning flashes. An incorrect grade of fuel impairs engine performance. /
impairment |noun| a lessening of effectiveness /De-icing equipment is used to prevent impairment of the lifting surfaces through ice formation./
impart |verb| to give, to pass on / A rotating propeller imparts rearward motion to a mass of air. /
impedance |noun| total electrical resistance to current flow in an alternating current circuit / Impedance will vary with changes in frequency. /
impede |verb| to hinder or obstruct progress / Hills and mountains impede the horizontal flow of air. /
impeller |noun| a rotor used to force a fluid in a particular direction
importance |noun| significance, strong effect or influence / Upper winds are of great importance in meteorology. / (NOTE: The expressions of fundamental importance, of great importance, of prime importance, of utmost importance, of vital importance all mean very important.)
import duty |noun| payment made to a government on particular goods imported or exported / the duty payable on a carton of cigarettes / Also called: customs duty
impose |verb| 1. to force something upon a person or thing / The trimmer is used to ease the loads imposed on the flying controls during flight. / 2. - to impose a fine > to require somebody to pay a sum of money as punishment - to impose restrictions > to place limitations on somebody’s actions
improve |verb| to make or become better / Turbochargers improve aircraft performance. The trainee’s flying skills improved a lot in a short period of time. /
improvement |noun| the process of becoming better, or something that makes a thing better / An improvement in weather conditions enabled the flight to depart. /
impulse |noun| a force of short duration / A magneto is designed to produce electrical impulses one after another at precise intervals, so that each separate impulse can be used to provide a spark at a spark plug. /
impulse magneto |noun| a magneto with a mechanism to give a sudden rotation and thus produce a strong spark
inability |noun| the fact of being unable to do something
inactive |adjective| not switched on, in a passive state / At the time of the accident the autopilot was inactive. /
inadequate |adjective| not good enough, not of a sufficient quantity. / There was inadequate warning of the trench being dug along the side of the taxiway. /
inadvertent |adjective| not intended, not meant, accidental / A safety mechanism prevents inadvertent retraction of the undercarriage while the aircraft is on the ground. /
inboard |adverb| closer to the center of an aircraft rather than the sides or edges
inboard / outboard spoilers |noun| the spoilers on the upper surface of the wing. There are several surfaces and they are commonly identified as inboard or inner and outboard or outer spoilers
inbound |adverb|,|adjective| towards a destination / The aircraft flies outbound from the beacon along the airway and inbound to the facility at the other end of the leg. / - inbound traffic > aircraft flying towards an airfield
incapacitated |adjective| unconscious or too ill to function properly / The Captain was incapacitated as the result of a stroke (obstruction of an artery to the brain). /
incapacity |noun| the inability to do what is needed, not having the necessary power to do something - crew incapacity > an injury to a crew member which prevents him or her from performing his or her normal duties / Accident research has shown that crew incapacity greatly increases the risk to passengers’ safety. /
inch |noun| a British Imperial System unit of length, also used in the US, equal to 25.4 millimeters or 2.54 centimeters or 1/12 of a foot. Abbreviation: in (NOTE: The plural form is inches, usually written in or " with numbers, 5ft 6in or 5’ 6". Say five foot six inches.)
incidence |noun| the frequency of occurrence / The incidence of structural failure has decreased with the introduction of modern construction materials and techniques. /
incident |noun| an event or happening which interrupts normal procedure / A violent passenger had to be removed from the aircraft before departure, and details of the incident were reported in the local newspapers. /
inclination |noun| a slope or slant from the horizontal or vertical
incline |verb| to slope or slant from the horizontal or vertical, to tilt / The runway inclines slightly upwards. / - |noun| a slope or slant / There is a steep incline at the end of the runway. /
inclinometer |noun| the lower part of a turn coordinator, in which a ball in a sealed curved tube indicates if a turn is coordinated. Also called: rudder ball.
include |verb| to take in as a part, to count along with others / Solid particles in the atmosphere include dust, sand, volcanic ash and atmospheric pollution. A fuel system includes tanks, fuel lines, fuel pumps, fuel filters and a carburetor or fuel injection system. / Opposite: exclude
inclusive |adjective| taking in the extremes in addition to the part in between - bearings 180° to 270° inclusive > bearings 180° and 270° are part of the range of bearings mentioned
incoming |adjective| something which is being received, e.g. radio waves or solar radiation / There is a fall of temperature until about one hour after dawn when incoming solar radiation balances outgoing terrestrial radiation. / Opposite: outgoing
incorporate |verb| to include as part of something which already exists / Some types of outflow valve incorporate safety valves. Warning lamps often incorporate a press-to-test facility. /
incorrect |adjective| not correct, not right / If the trim position is incorrect, a warning horn will sound when number three thrust lever is advanced. /
increase |noun| a rise to a greater number or degree / Decreasing engine rpm results in an increase in the rate of descent. / Opposite: reduction - |verb| to become greater or more, to rise / As you increase height, the countryside below you appears to flatten out. / Opposite: reduce - opposite (all senses) > decrease
increment |noun| something added / The minimum detection range of a pulse radar system is equal to half the pulse length plus a small increment. /
incur |verb| to acquire or to receive something, often something unwanted / Fuel penalties can be incurred if fuel surplus to requirements is carried. In some aircraft, the datum shift is operated automatically to cater for any large trim changes incurred by operating undercarriage, flaps, etc. / (NOTE: incurring – incurred) - to incur a financial loss > to lose money, in a business or commercial sense
indefinite |adjective| without limits - an indefinite period of time > a period of time which, in reality, may have no end
independent |adjective| free from the influence or effects of other people or things / Airspeed is independent of wind and is the same regardless whether the aircraft is flying upwind, downwind or at any angle to the wind. / - independent system > a system which can operate by itself
index |noun| an alphabetical list of references to page numbers found at the end of a book or long document (NOTE: The plural form is indexes or indices.)
index letter, index number |noun| a letter or number which makes it easier to reference or look up information / Each observing meteorological station is shown on the chart as a small circle, identified by its own index number. /
indicate |verb| 1. to show or point out / A lamp on the instrument panel will indicate when the pump is operating. The needle indicated to zero. / 2. to serve as a sign or symptom / Black smoke from the exhaust may indicate a rich mixture or worn piston rings. /
indicated airspeed |noun| the airspeed shown by the cockpit or flight-deck instrument / The aircraft stalls at an indicated airspeed of 50 knots. / Abbreviation: IAS
indication |noun| 1. pointing out / Indication of altitude is given on the altimeter. / 2. a sign or symptom / A drop in engine rpm is an indication of ice forming in the carburetor. / - audible indication > a sound which serves as a warning, e.g. a bleep
indicator |noun| something which shows information
individual |adjective| existing as a separate thing / The hydraulic braking system consists of a master cylinder with individual brake cylinders at each wheel. There is a maintenance manual for each individual engine. / - |noun| a separate human being considered as one rather than as a member of a larger group / The instructor regards her trainees as a number of individuals rather than a group. /
induce |verb| to bring about, to cause to happen / If a coil carrying a changing current is placed near another coil, the changing magnetic field cuts the other coil and induces a voltage in it. Unequal deposits on moving parts can induce severe vibration especially on propellers and helicopter rotors. /
induced drag |noun| part of total drag, created by lift / There are two basic types of drag, induced drag and parasite drag. / (NOTE: Induced drag is created when high-pressure air below a wing rotates around the tip to the low-pressure area above and increases as airspeed decreases and angle of attack increases.)
inductance |noun| a measure of a conductor’s ability to bring a voltage into itself when carrying a changing current, e.g. during short times when the circuit is switched on or off / At low frequencies, the rate of collapse of the magnetic field will be slow and the inductance will be low. /
induction |noun| 1. the process by which the fuel/air mixture is drawn into the cylinders of an internal combustion engine / The four strokes of the engine are induction, compression, combustion and exhaust. / 2. the production of electrical current in a conductor by a change of magnetic field / A transformer is a static device that changes the amplitude or phase of an alternating voltage or current by electromagnetic induction. /
inductive |adjective| referring to the production of electrical current in a conductor by a change of magnetic field / One side effect of low frequency in an inductive circuit is that excess heat may be produced. /
inductor |noun| a component in the ignition system that produces electrical current in itself by a change of magnetic field
inert |adjective| not reacting with other substance
inert gas |noun| a gas that does not react with other substances / Inert gases, dust, smoke, salt, volcanic ash, oxygen and nitrogen together constitute 99% of the atmosphere. / (NOTE: The inert gases include helium, neon, argon, krypton and xenon.)
inertia |noun| the tendency of a body at rest to stay at rest or of a moving body to continue moving in a straight line unless acted on by an outside force / Inertia switches operate automatically when a particular g (acceleration due to Earth’s gravity) loading occurs. /
inertial |adjective| referring to inertia
inertial navigation system |noun| a navigation system which calculates aircraft position by comparing measurements of acceleration with stored data, using gyros rather than radios. Abbreviation: INS
inferential |adjective| obtained by deduction / The inferential method of ice detection is used in flight trials for aircraft certification. /
inflammable |adjective| easily set on fire / Petrol is an inflammable liquid. / (NOTE: Flammable and inflammable mean the same thing.) - highly inflammable > very easily set on fire, and therefore hazardous
inflate |verb| to blow air into something and thereby increase its size / A sharp pull on the cord will discharge the gas bottle and inflate the life jacket. / Opposite: deflate
inflation |noun| 1. the act of blowing air into something, e.g. a balloon or a tire, and so increasing its size / Tire inflation pressures should be maintained within 4% limits. / 2. a continuing increase in the price of things and a decrease in the buying power of money / Annual inflation is 4%. / Opposite: deflation
in-flight |adjective| taking place during a flight / in-flight emergency, in-flight oil loss /
in-flight turn-back |noun| a situation that occurs when the crew decides to return to the airport of departure. This is dangerous because the aircraft is likely to be full of fuel and therefore over its maximum landing weight. The certified value above which fuel must be jettisoned or burnt off if landing becomes urgently necessary and structural damage is to be avoided.
influence |noun| a power which affects people or things / The Atlantic Ocean has a great influence on the climate of the British Isles. / - |verb| to have an effect on, to change / In an emergency, a crew member’s power of command will influence the reaction of passengers. /
inform |verb| to tell somebody something / After a particularly heavy landing, the pilot should inform an engineer so that checks can be made to the aircraft structure. /
information |noun| a collection of facts or data / Meteorological visibility gives information on the transparency of the atmosphere to a stationary ground observer. / (NOTE: Information has no plural form.)
Information Kilo, Lima, Mike etc. |phrase| identifies a specific ATIS (Automatic Terminal Information Service) broadcast in a series A, B, C, D etc. giving up-to-date information about conditions at the airport
infra- |prefix| below or beneath
infrared, infra-red |adjective| referring to the range of invisible radiation wavelengths from about 750 nanometers to 1 millimeter / Solar radiation is short wave and of high intensity while terrestrial radiation is infra-red. /
infrequent |adjective| not often / In northern Europe, thunderstorms are infrequent in winter time. /
ingest |verb| to take in, or to absorb into, something such as a jet engine through the intake / Jet engines may be damaged by ingested chunks of ice. /
ingestion |noun| the act of taking something into something such as a jet engine through the intake / Ingestion of birds may seriously damage the blades of turbo-fan engines. /
inherent |adjective| existing as a basic or fundamental characteristic / A boiling point of 100°C is an inherent characteristic of water. /
in hg |noun| the unit for measuring absolute pressure. Full form: inch(es) of mercury
inhibit |verb| to prevent or to limit the effect of something / Cloud cover inhibits cooling of the Earth’s surface at night. /
inhibition |noun| the prevention or limitation of the effect of something / Fuel contains chemicals for the inhibition of fungal growth. /
inhibitor |noun| a device or substance which prevents or limits the effect of something - icing inhibitor > a substance added to fuel to prevent fuel system icing
initial |adjective| relating to or occurring at the beginning, the first - initial climb > the period of climb immediately after take-off - initial letter > the first letter of a word - initial stage > first stage - |noun| the first letter of a word
initial approach fix |noun| the point from which the initial segment of an ILS approach begins Abbreviation: IAF
initials |plural noun| the first letters of a name / His name is John Smith, his initials are JS. /
initiate |verb| to get something going by taking the first step, to start / In a serious emergency, a member of the cabin crew may initiate an evacuation of the aircraft. /
initiation |noun| the act of getting something going by taking the first step, starting / Normally speaking, the captain is responsible for the initiation of emergency procedures. /
initiative |noun| the power or ability to begin or to follow through competently with a plan or task / Crew members must be able to act collectively and with initiative in unusual situations. /
inject |verb| to force or drive a fluid into something / An accelerator pump, operated by the movement of the throttle lever, injects fuel into the choke tube. /
injection |noun| the forcing of fluid into something / Power output can be boosted to a value over 100% maximum power, by the injection of a water methanol mixture at the compressor inlet or at the combustion chamber inlet. /
injector |noun| a device that will force or drive a fluid into something
injury |noun| damage or harm done to a person / Escape slides are designed to minimize the risk of injury to passengers when leaving the aircraft. /
inland |adjective|,|adverb| referring to the interior of a country or land mass / Sea fog can extend for considerable distances inland. /
inlet |noun| 1. an opening which allows an intake of something / Air enters the cabin through an inlet. / 2. a coastal feature such as at the mouth of a river
inlet valve |noun| the valve in a piston engine which allows fuel to enter the cylinder
in line |adjective,adverb| queuing, stopped, standing by. / We are in line on Taxiway Golf behind a Cathay Pacific 747 and an Etihad A330 number three for departure. /
inner |adjective| positioned farther inside - inner wing > the part of the wing near the fuselage
inner marker |noun| an ILS marker beacon placed between the middle marker and the end of the ILS runway
inoperative |adjective| not functioning / To prevent accidental retraction of the undercarriage, a safety switch is fitted in such a way to the oleo, that when it is compressed on the ground, the ‘undercarriage up’ selection is inoperative. /
input |noun| something such as energy, electrical power or information, put into a system to achieve output or a result / Pumps require high input current. If the number of turns on the secondary winding is greater than the number of turns on the primary, the output voltage from the secondary will be greater than the input voltage to the primary. / - pilot control input > movements on the flying controls made by the pilot
INS |abbreviation| inertial navigation system
INS check point |noun| a remote location with well-defined geographical coordinates where an aircraft’s inertial navigation system (INS) can be reset
INS warning |noun| a warning about a malfunction in the Inertial Navigation System, i.e. the main system using gyros and geographical coordinates to calculate the aircraft’s precise position
insert |verb| to put in or into / To prevent tire explosion due to overheating, fusible plugs are inserted into the wheel assemblies. Insert your telephone number in the space provided on the form. Insert the key in the lock and turn it. /
insertion |noun| the act of putting in or into / There is a space on the form for the insertion of a postal address. When the contours for a particular pressure level have been drawn in, the chart is completed by insertion of spot temperatures and wind speed information. /
insignificant |adjective| not important, of no consequence / Minor changes in wind speed or direction are insignificant. /
inspect |verb| to look at something closely and to check for problems or defects / Propellers should be inspected prior to flight. /
inspection |noun| a careful check for problems / Before flight, the pilot should carry out a careful inspection of the aircraft. /
instability |noun| a condition in which a body or mass moves easily, and with increasing speed, away from its original position / Atmospheric instability often results in strong vertical currents of air. The built-in instability of some modern fighter aircraft makes them highly maneuverable but difficult to control without fly-by-wire technology. /
install |verb| to put in position, connect and make ready for use / Most carburetors are installed in a warm position to help against icing. / - installed battery > a battery in position in the aircraft
installation |noun| 1. the act of putting equipment or devices into position and connecting them for use / The installation of the computer took three hours. / 2. equipment or devices which are installed / In some auxiliary-power-unit installations the air intake area is protected against ice formation by bleeding a supply of hot air from the compressor over the intake surfaces. /
instance |noun| an example which is used to provide evidence of something / Failure to check fuel levels before take-off is an instance of bad airmanship. / - for instance > e.g.
instant |adjective| immediate, happening immediately - |noun| a very short period of time / The pilot has to act in an instant to counteract the severe downdrafts of a micro-burst. /
instinctive |adjective| natural, rather than thought-out / In most modern light aircraft, use of the trim wheel is instinctive, i.e. forwards for nose down and backwards for nose up. /
instinctive disconnect push button |noun| a small red push-button on the control wheel or side-stick used to disconnect the autopilot quickly
instruct |verb| to give information or knowledge, usually in a formal setting such as a lesson or briefing / The safety officer instructs employees on the use of the breathing equipment. The training captain instructs trainee pilots in the simulator. /
instruction |noun| 1. the act of giving information or knowledge, usually in a formal setting such as a lesson or briefing / Trainees receive first-aid instruction. / 2. information on how something should be operated or used / You must follow the instructions. /
instruction manual |noun| a book containing information on how something should be operated or used
instructor |noun| a person who gives information or knowledge, usually in a formal setting such as a lesson or briefing
instrument |noun| a device for recording, measuring or controlling, especially functioning as part of a control system / Airspeed is given on an instrument called the airspeed indicator. /
instrument approach procedure |noun| a set of procedures which a pilot must follow when approaching an airport under instrument flight rules
instrumentation |noun| a set of specialized instruments on an aircraft / Instrumentation in some basic light aircraft is restricted to a few instruments only. Some modern light aircraft have very sophisticated instrumentation. /
instrument error |noun| the difference between indicated instrument value and true value
instrument flight rules |plural noun| regulations which must be followed when weather conditions do not meet the minimum for visual flight / The flight from Manchester to London was conducted under instrument flight rules. / Abbreviation: IFR
instrument flying |noun| flying using no references other than the flight instruments / Some conditions require instrument flying. When in cloud, instrument flying is required. / Abbreviation: IF
instrument landing |noun| the landing of an aircraft when a pilot is relying on information obtained from instruments rather than from what can be seen outside the aircraft
instrument landing system |noun| aids for an instrument landing approach to an airfield, consisting of a localiser, glide slope, marker beacons and approach lights / The instrument landing system provides both horizontal and vertical guidance to aircraft approaching a runway. / Abbreviation: ILS (NOTE: The ILS is the most used precision approach system in the world.)
instrument meteorological conditions |plural noun| meteorological conditions of visibility and distance from cloud ceiling which are less than those for visual meteorological conditions / The basic license does not permit the pilot to fly in instrument meteorological conditions. / Abbreviation: IMC
instrument rating |noun| an additional qualification added to a license, such as PPL, allowing a pilot to fly in instrument meteorological conditions / He gained his instrument rating in 1992. / Abbreviation: I/R (NOTE: An instrument rating is required for operating in clouds or when the ceiling and visibility are less than those required for flight under visual flight rules (VFR).)
insufficient |adjective| not enough / Insufficient height resulted in the pilot landing short of the runway. /
insulate |verb| 1. to prevent the passing of heat, cold or sound into or out of an area 2. to prevent the passing of electricity to where it is not required, especially by using a non-conducting material / Bus bars are insulated from the main structure and are normally provided with some form of protective covering. /
insulating |adjective| preventing the unwanted passage of heat, cold, sound or electricity
insulating tape |noun| special adhesive tape which is used to insulate electrical wires / Insulating tape was used to prevent the electrical wires from touching. /
insulation |noun| an act of or state of preventing the passing of heat, cold, sound or electricity from one area to another / For continuous supersonic flight, fuel tank insulation is necessary to reduce the effect of kinetic heating. /
insulator |noun| a substance which will insulate, especially which will not conduct electricity / Wood is a good insulator. /
intake |noun| an opening through which a fluid is allowed into a container or tube
intake guide vane |noun| a device to direct the flow of air at the air-intake
intake lip |noun| the rim or edge of the air intake of a jet engine / As sonic speed is approached, the efficiency of the intake begins to fall because of shock waves at the intake lip. /
intake temperature gauge |noun| an instrument to indicate the temperature of air entering an engine
integral |adjective| which completes the whole or which belongs to a whole / Meteorology is an integral part of a flying training course. / - integral fuel tanks > tanks which are located within the structure of the aircraft
Integrated Drive Generator |noun| the main source of A.C. (alternating current) electrical power on the aircraft. It is a combination of a constant speed drive and an electrical generator driven by the engine through the accessory gearbox. Abbreviation: IDG
integrity |noun| the state of being complete and in good working condition / The engine fire warning system is checked to test its integrity. The integrity of an aid used to conduct procedural approaches must be high. /
intend |verb| to have a particular plan, aim or purpose / A battery is intended to supply only limited amounts of power. / - intended track > desired course of flight
intense |adjective| 1. extreme in amount - intense heat > very high heat - intense wind > very strong wind 2. - intense concentration > very hard or deep concentration
intensity |noun| the amount or strength of heat, light, radiation / Surface air temperatures depend mostly on the intensity and duration of solar radiation. /
intention |noun| the course of action one means or plans to follow / It is not the intention of this chapter to give a detailed description of world weather. Our intention is to provide safe, cost-effective flying. /
inter- |prefix| between
interact |verb| to act on each other / Angle of attack and the profile of the wing section interact to produce lift. Direct and reflected path signals can interact to cause bending of the localiser and/or generation of a false glide-path. /
intercept |verb| to stop or interrupt the intended path of something / When a radio transmission is made from a moving platform, there will be a shift in frequency between the transmitted and intercepted radio signals. /
intercept heading |noun| the heading the crew must follow in order to capture and follow the ILS or visual approach flight path
intercept ILS |verb| to capture the localizer and glide-slope radio transmitter beams which guide the aircraft during an ILS approach
interconnect |verb| to connect together / The fire extinguishers for each engine are interconnected, so allowing two extinguishers to be used on either engine. /
inter-crew |adjective| - inter-crew communications > communications between members of the crew / The lack of inter-crew communication contributed to the accident. /
interfere |verb| - to interfere with > to get in the way of something or come between things and thus create a problem / An engine intake close to another surface, such as the fuselage tail section, must be separated from that surface so that the slower boundary layer air does not interfere with the regular intake flow. /
interference |noun| the prevention of reception of a clear radio signal / Some equipment, such as generators and ignition systems, will cause unwanted radio frequency interference. / - precipitation interference > interference caused by rain, snow or hail
interlock |noun| a series of switches and/or relays / Interlocks operate in a specific sequence to ensure satisfactory engagement of the autopilot. / - |verb| to connect together parts of a mechanism, so that the movement or operation of individual parts affects each other / The two parts interlock to create a solid structure. /
intermediate |adjective| 1. in a position between two others 2. between beginners and advanced - he is at an intermediate stage in his studies > he is in the middle of his course of study - an intermediate level language student > a second language learner who has reached a level between elementary and advanced level
intermediate approach |noun| the part of the approach from arriving at the first navigational fix to the beginning of the final approach
intermediate frequency |noun| the frequency in a radio receiver to which the incoming received signal is transformed. Abbreviation: IF
intermittent |adjective| stopping and starting at intervals /The cycle of induction, compression, combustion and exhaust in the piston engine is intermittent, whereas in the gas turbine, each process is continuous./
internal |adjective| referring to the inside or interior of something Opposite: external
internal combustion engine |noun| type of engine in which the fuel is burnt within the cylinders of the engine, as opposed to the steam engine
international |adjective| between countries - international call > a telephone call between people in two different countries
International Air Transport Association |noun| an international organization that supervises and coordinates air transport and to which most major airlines belong. Abbreviation: IATA
International Calling / Distress Frequency |noun| 2182 kHz or 500 kHz
International Civil Aviation Organization |noun| an organization established in 1947 by governments that ‘agreed on particular principles and arrangements in order that international civil aviation may be developed in a safe and orderly manner…’ / Air navigation obstructions in the United Kingdom are shown on ICAO aeronautical charts. / Abbreviation: ICAO (NOTE: ICAO is based in Montreal (Canada).)
international standard atmosphere |noun| an internationally agreed unit of pressure used in the calibration of instruments and the measurement of aircraft performance / For en-route weather the datum chosen is international standard atmosphere at mean sea level. / Abbreviation: ISA
inter-phone |noun| an internal telephone communications system within an aircraft that enables members of the crew to speak to one another
interpolation |noun| the estimation of a middle value by reference to known values each side / Spot temperatures at positions other than those printed are obtained by interpolation. /
interpret |verb| to understand something presented in code or symbolic form / Aircrew must be able to interpret information printed on a contour chart. /
interpretation |noun| an understanding of something presented in code or symbolic form / Synoptic charts require interpretation in order to understand the information given. /
interrogate |verb| to transmit SSR or ATC signals to activate a transponder / Secondary surveillance radar interrogates the aircraft equipment which responds with identification and height information. /
interrogation |noun| the transmission of a SSR or ATC signal to activate a transponder / A transponder replies to interrogation by passing a four-digit code. /
interrogator |noun| a ground-based surveillance radar beacon transmitter/receiver / The questioner, better known as the interrogator, is fitted on the ground, while the responder, also known as the transponder, is an airborne installation. /
interrupt |verb| to break the continuity of something / The conversation was interrupted by a telephone call. In the northern hemisphere, the westerly flow of air is interrupted by variations which occur in pressure patterns. /
interruption |noun| a break in the continuity of something / Because of the summer holiday, there was an interruption in the flying training course. /
intersect |verb| to cut across each other / Meridians intersect at the poles and cross the equator at right angles. /
intersection |noun| the point at which two lines cross each other / The aircraft came to a stop at the intersection between runways 09 and 16. The intersection of the drift line and the wind vector gives the drift point. /
inter-tropical convergence zone |noun| the boundary between the trade winds and tropical air masses from the northern and southern hemispheres / The inter-tropical convergence zone is the zone in which the trade winds from the two hemispheres approach each other. / Abbreviation: ITCZ
interval |noun| 1. the amount of space between places or points / The intervals at which contours are drawn depends on the scale of the chart and this interval, known as the vertical interval, is noted on the chart. / 2. the period of time between two events / A precise interval is essential to obtain correct ignition timing on all cylinders. /
intoxicated |adjective| under the effects of drugs or alcohol, drunk / There is a very intoxicated and belligerent passenger in the rear. /
introduction |noun| 1. something written which comes at the beginning of a report, chapter, etc., or something spoken which comes at the beginning of a talk / In his introduction, the chief executive praised the efforts of the workforce over the previous 12 months. / 2. the act of bringing into use / The introduction of fly-by-wire technology has made the pilot’s task easier. /
inverse |adjective| reversed in order or effect / There is an inverse relationship between altitude and temperature, i.e. temperature decreases as altitude increases. /
inversion |noun| 1. an atmospheric phenomenon where cold air is nearer the ground than warm air / Smog is smoke or pollution trapped on the surface by an inversion of temperature with little or no wind. / 2. turning something upside down / Inversion of the aircraft in flight may result in fuel stoppage. /
inversion layer |noun| a layer of the atmosphere in which the temperature increases as altitude increases
invert |verb| to turn upside down / A glass tube is sealed at one end, filled with mercury and then inverted so that the open end is immersed in a bowl containing mercury. /
investigate |verb| to examine or look into something in great detail / If the starter engaged light stays on after starting, it means that power is still connected to the starter and, if it is still on after 30 seconds, the cause must be investigated. /
investigation |noun| a detailed inquiry or close examination of a matter - accident investigation > process of discovering the cause of accidents ‘…accident investigation by the FAA and the German LBA revealed that the crashed aircraft had been completely repainted in an unauthorized paint shop’
investigator |noun| a person who investigates / Accident investigators found poor coordination between controllers. /
invisible |adjective| impossible to see / Oxygen is an invisible gas. /
involve |verb| to include / In large transport aircraft, because of the distance and numbers of people involved, effective and rapid communications are required between flight crew and cabin crew and between cabin crew and passengers. Two aircraft were involved in an accident. /
involved |adjective| over-complex, difficult / The procedure for replacing a lost passport is very involved. /
inward |adjective| directed to or moving towards the inside or interior / To provide protection against smoke and other harmful gases, a flow of 100% oxygen is supplied at a positive pressure to avoid any inward leakage of poisonous gases at the mask. /
inwards |adverb| towards the inside or the interior / The door opens inwards. / Opposite: outwards
ion |noun| an atom or a group of atoms that has obtained an electric charge by gaining or losing one or more electrons / Ultra-violet light from the sun can cause electrons to become separated from their parent atoms of the gases in the atmosphere, the atoms left with resultant positive charges being known as ions. /
ionization |noun| the process of producing ions by heat or radiation / The intensity of ionization depends on the strength of the ultra-violet radiation and the density of the air. /
ionosphere |noun| the part of the atmosphere 50 km above the surface of the earth / Since the strength of the sun’s radiation varies with latitude, the structure of the ionosphere varies over the surface of the earth. /
ionospheric |adjective| referring to the ionosphere
ionospheric attenuation |noun| loss of signal strength to the ionosphere
ionospheric refraction |noun| a change in direction as the wave passes through an ionized layer
I/R |abbreviation| instrument rating
irregular |adjective| not regular / Pilots of long-haul flights are subject to an irregular sleep pattern. /
irrespective, irrespective of |preposition| taking no account of, regardless of / Rescue flights continue their work irrespective of the weather conditions. /
ISA |abbreviation| international standard atmosphere
isobar |noun| a line on a weather chart joining points of equal atmospheric pressure / Isobars are analogous to contour lines. /
isobaric |adjective| referring to or showing isobars / isobaric charts /
isolate |verb| to separate something from other things or somebody from other people / The low-pressure fuel cock isolates the airframe fuel system from the engine fuel system to enable maintenance and engine removals to be carried out. /
isolated |adjective| separate - isolated rain showers > well spaced out rain showers
isolation |noun| the state of being separated from something or somebody / Isolation of the aircraft’s passengers and crew from the reduced atmospheric pressure at altitude is achieved by pressurization of the cabin. /
isotach |noun| a line of equal wind speed on charts (NOTE: Wind speed is normally given in the form of isotachs.)
isotherm |noun| a line of equal temperature on charts / Ascent of stable air over high ground may result in a lowering of the 0°C isotherm. /
issue |noun| a number or copy / The article was in last month’s issue of the magazine. / - |verb| 1. to give out / The captain issued the evacuate command. / 2. to publish / The magazine is issued monthly. / 3. to give out, to grant / The Civil Aviation Authority issue licenses. /
ITCZ |abbreviation| inter-tropical convergence zone
item |noun| a single article or unit in a collection, on a list, etc. / Before practicing stalls, the pilot should secure all loose items in the cockpit. /
