Alpha
Bismillah
Charlie Delta
Echo
Foxtrot
Golf
Hotel
insaallah Juliett Kilo
Lima Mike November Oscar
Piaggio Quebec Romeo
Sierra Turks Uniform
Victory Water X-ray
Yankee Zulu Main Page
I beam
A structural beam constructed of extruded metal or wood, whose cross section resembles the letter I.I say again During communications, this indicates that the message will be repeated.
ice The solid state or condition of water when the temperature is 0 C or 32 F.
ice crystal process The process by which cloud particles grow to precipitation size. This can only occur where ice crystals and water droplets coexist and the temperature is below 0 C.
ice crystals Small ice particles that float in the air in clear cold weather. Also referred to as ice needles.
ice fog Fog composed of minute suspended particles of ice; occurs at very low temperatures.
ice light A light mounted on an aircraft in such a way that it shines on the leading edge of the wing, allowing the pilot to see the buildup of ice on the wing at night.
ice needles Small ice particles that float in the air in clear cold weather. Also referred to as ice crystals.
ice pellets Small, transparent or translucent, round or irregularly shaped pellets of ice. They can be hard grains that rebound on striking a hard surface or pellets of snow encased in ice.
icebox rivet Rivets made of 2024 or 2017 aluminum alloy, which are too hard to drive unless they are in a softened condition. These rivets must be heat-treated, quenched, and held in a subzero icebox until they are driven.
ice-up A condition in flight in which ice forms on the aircraft structure.
icing The accumulation of airframe ice.
a. Types of icing are:
Rime Ice Rough, milky, opaque ice formed by the instantaneous freezing of small supercooled water droplets.
Clear Ice A glossy, clear, or translucent ice formed by the relatively slow freezing of large supercooled water droplets.
Mixed A mixture of clear ice and rime ice.
b. Intensity of ice includes:
Trace Ice becomes perceptible. Rate of accumulation is slightly greater than the rate of sublimation. Deicing/ anti-icing equipment is not utilized unless encountered for an extended period of time (over 1 hour).
Light The rate of accumulation may create a problem if flight is prolonged in this environment (over 1 hour). Occasional use of deicing/anti-icing equipment removes/prevents accumulation. It does not present a problem if the deicing/anti-icing equipment is used.
Moderate The rate of accumulation is such that even short encounters become potentially hazardous and use of deicing / anti-icing equipment or flight diversion is necessary.
Severe The rate of accumulation is such that deicing/ anti-icing equipment fails to reduce or control the hazard. Immediate flight diversion is necessary.
ideal cycle A cycle in which no pressure loss occurs across the combustion section. However, this is not practical for the gas turbine where a slight pressure loss is needed for correct cooling air.
ident A request for a pilot to activate the aircraft transponder identification feature. This will help the controller to confirm an aircraft identity or to identify an aircraft.
ident feature The special feature in the Air Traffic Control Radar Beacon System (ATCRBS) equipment. It is used to immediately distinguish one displayed beacon target from other beacon targets. See also ident.
Identification, Friend or Foe (IFF) A transponder feature that allows a classified code to be set into selected transponders to identify friendly aircraft to interrogating units.
identification symbol A symbol used in an aircraft drawing to correlate a specific item with its description in the bill of materials or the revision block.
idiot light A slang term for warning lights that are used instead of digital or analog instruments to indicate the condition or pressure of a system.
idle In gas turbine engines, a percent rpm setting, the value of which changes from engine to engine. It is the lowest engine operating speed authorized.
idle cut off That position of the mixture control in which fuel is prevented from flowing from the metering system into the engine.
idle mixture A fuel-air mixture used by an aircraft engine to provide proper operation at the idle RPM.
idle speed The RPM of an aircraft engine when the throttle or power control lever is fully closed.
idle thrust The jet thrust obtained with the engine power control lever set at the stop for the least thrust (idle stop) position.
idler gear A gear used in a gear train to drive another gear in a reverse direction of rotation without changing the speed of rotation and without adding to or taking away power from the gear train.
idler pulley The idler pulley changes angular relationships between pulleys but does not change the direction of rotation of either pulley. An idler pulley is also used to adjust the tension on the belt that joins a drive pulley with a driven pulley.
idling current A low output or operating current that flows in an electronic circuit when there is no input signal or output signal.
if no transmission received for (time) Used by ATC in radar approaches to prefix procedures that should be followed by the pilot in event of lost communications.
IF/IAWP Intermediate Fix/Initial Approach Waypoint. The waypoint where the final approach course of a T approach meets the crossbar of the T. When designated (in conjunction with a TAA) this waypoint will be used as an IAWP when approaching the airport from certain directions, and as an IFWP when beginning the approach from another IAWP.
IFR aircraft An aircraft conducting flight in accordance with instrument flight rules.
IFR conditions Weather conditions below the minimum for flight under visual flight rules.
IFR departure procedure See IFR takeoff minimums and departure procedures.
IFR flight See IFR aircraft.
IFR landing minimums See landing minimums.
IFR military training routes (IR) Routes used by the Department of Defense and associated Reserve and Air Guard units for the purpose of conducting low-altitude navigation and tactical training in both IFR and VFR weather conditions below 10,000 feet MSL at airspeeds in excess of 250 knots IAS.
IFR over-the-top With respect to the operation of aircraft, means the operation of an aircraft over-the-top on an IFR flight plan when cleared by air traffic control to maintain VFR conditions or VFR conditions on top.
IFR takeoff minimums and departure procedures Federal Aviation Regulations, Part 91, prescribes standard takeoff rules for certain civil users. At some airports, obstructions or other factors require the establishment of nonstandard takeoff minimums, departure procedures, or both, to assist pilots in avoiding obstacles during climb to the minimum enroute altitude. Those airports are listed in NOS/DOD Instrument Approach Charts (IAPs) under a section entitled IFR Takeoff Minimums and Departure Procedures. The NOS/DOD IAP chart legend illustrates the symbol used to alert the pilot to nonstandard takeoff minimums and departure procedures. When departing IFR from such airports, or from any airports where there are no departure procedures, DPs, or ATC facilities available, pilots should advise ATC of any departure limitations. Controllers may query a pilot to determine acceptable departure directions, turns, or headings after takeoff. Pilots should be familiar with the departure procedures and must assure that their aircraft can meet or exceed any specified climb gradients.
igniter The electrical device used to provide the spark for starting combustion in a turbine engine. Some igniters resemble spark plugs while others, called glow plugs, have a coil of resistance wire that glows red hot when electrical current flows through the coil.
igniter plug In gas turbine engines, an electrical sparking device used to start the burning of the fuel-air mixture in a combustor.
ignition The process whereby the fuel-air mixture in either a turbine or reciprocating aircraft engine is ignited.
ignition harness The complete set of wires that carry high-voltage current from the magneto to the spark plugs.
ignition timing The timing of the fuel-air mixture s ignition in the cylinders of a reciprocating engine that ensures the mixture will be burning before the piston reaches the top of its stroke and the maximum pressure will be produced in the cylinder as the piston starts downward.
illumination The light output of a light source.
illustrated parts catalog (IPC) A required document produced by a manufacturer. It has an exploded view of the parts and the part numbers for identification. It does not contain approved data.
illustrated parts list (IPL) An exploded-view drawing included in a service manual showing every part of a component, along with its proper name, part number, and number required for assembly. This is FAA-approved data and using parts not included in this list jeopardizes the airworthiness of the component.
illustrated talk An oral presentation where the speaker relies heavily on visual aids to convey ideas to the listeners.
ILS categories
a. ILS Category I An ILS approach procedure which provides for approach to a height above touchdown of not less than 200 feet and with runway visual range of not less than 1,800 feet.
b. ILS Category II An ILS approach procedure which provides for approach to a height above touchdown of not less than 100 feet and with runway visual range of not less than 1,200 feet.
ILS PRM approach An instrument landing system (ILS) approach conducted to parallel runways whose extended centerlines are separated by less than 4,300 feet and the parallel runways have a Precision Runway Monitoring (PRM) system that permits simultaneous independent ILS approaches.
I M SAFE checklist Personal Checklist ― I m physically and mentally safe to fly; not being impaired by illness, medication, stress, alcohol, fatigue, or eating.
image frequency The image produced in a super heterodyne receiver when an unwanted signal of a specific frequency is mixed with the oscillator frequency, it produces an intermediate frequency equal to the intermediate frequency of the desired input frequency.
immediately Used by ATC or pilots when such action compliance is required to avoid an imminent situation.
immersion heater An electrical heater used to heat liquids by immersing the heater in the liquid to keep it warm. Insures adequate temperature and flow during cold weather operations.
immersion-type oil heater An electrical heater immersed in the engine oil reservoir to keep the oil warm when the engine is not operating and ensure an adequate flow of lubricant for starting in extremely cold weather.
immiscible Liquids that do not mix with each other such as oil and water.
impact area That portion of a damaged structure that has received the majority of the damage from a collision or other impact.
impact extrusion Metal forming in which hard metal is forced through a die by striking it with a hard blow.
impact ice Ice that forms on the wings and control surfaces or on the carburetor heat valve, the walls of the air scoop, or the carburetor units during flight. Impact ice collecting on the metering elements of the carburetor can upset fuel metering or stop carburetor fuel flow.
impact pressure In pitot-static systems, the difference between pitot pressure and static pressure.
impact test A test to determine the energy absorbed in fracturing a test bar at high velocity. The test may be in tension or in bending, or it may properly be a notch test if a notch is present, creating multi-axial stresses.
impact wrench A power wrench, usually air-driven, used to spin nuts onto bolts. Its torque forces are in a series of blows or impacts. Because of the uneven torque it produces, it should not be used for any threaded fastener where the amount of torque is critical.
impedance coupling The use in electronics of an impedance matching transformer to connect a power source with a load that has a different impedance.
impedance matching The matching of the impedance of a source of electrical power with the impedance of the load that uses the power. Allows maximum transfer of power to occur.
impedance matching transformer An electronic device used to connect a load and a source of electrical power
that differ in their impedance. It consists of a transformer with a primary winding that matches the impedance of the source and a secondary winding that matches the load.
impedance triangle The graphical representation of resistance, reactance, and impedance in an electrical circuit. Resistance in ohms is drawn as the horizontal base of the triangle and reactance in ohms is drawn vertically at 90 degrees to the resistance. Impedance in ohms is the hypotenuse of the triangle. The angle between it and horizontal is called the phase angle.
impedance (Z) The vector sum of the opposition to the flow of AC caused by circuit resistance, capacitive reactance, and inductive reactance.
impeller A vaned disc that picks up and accelerates the air outwardly to increase the pressure in a supercharger for a reciprocating engine, or to provide the pressurized air for a centrifugal-type turbine engine.
impingement starting A turbine engine starting process requiring no enginemounted starter. Air from a source separate from the engine to be started is directed onto the turbine wheel(s) to cause engine rotation for starting and then the air source is removed.
implode To burst inward. The reverse of explosion.
impregnate In reinforcing plastics, to saturate the reinforcement with a resin.
impulse A change in momentum caused by a surge or pulse of energy.
impulse coupling A spring-loaded coupling between a magneto and its drive gear that causes the magneto to produce a hot and late spark for starting the engine. When the engine is being turned over slowly, the magnet is restrained by stops, and the spring is wound. At the proper time for the starting spark to occur, the spring is released and the magnet is spun, producing a hot, late spark. When the engine starts, centrifugal force holds the coupling engaged so that it acts as a solid unit.
impulse turbine A stator vane and rotor blade arrangement whereby the vanes form convergent ducts and the blades form straight ducts. The rotor is then turned by impulse as gases impinge on the blades. A design common to turbine driven accessories such as air starters.
impulse-reaction turbine A stator vane and rotor blade arrangement whereby the base area is an impulse design and the tip is a reaction design. This design is common to flight engines.
impulsive A learning style where a student makes a quick assessment and then decides to take action. Impulsive students may not read each question or all of the answer choices entirely. As a result, they tend to select the first choice that appears correct.
impurities 1. Undesired foreign objects in a fluid. 2. A chemical element such as arsenic or phosphorus that is added to silicon or germanium to give them some desired electrical characteristic.
in ground effect (IGE) hover In rotorcraft, hovering close to the surface (usually less than one rotor diameter distance above the surface) under the influence of ground effect.
in phase A condition in an electrical circuit where the voltage and current rise and fall together. In an AC circuit, the two pass through 0 and 180 at the same time, going in the same direction.
inactive aircraft An aircraft that is no longer operational.
inboard Toward the center of the aircraft.
incandescent Glowing because of intense heat.
incandescent lamp An electric lamp that produces light by a white hot filament enclosed in a glass bulb from which the air has been removed and replaced with an inert gas.
incerfa (uncertainty phase) [ICAO] A situation wherein uncertainty exists as to the safety of an aircraft and its occupants.
inches of mercury (in. Hg) A measurement of air pressure., normally used for atmospheric pressures. 1 in. Hg. is equal to approximately l/2 PSI.
inches per second (ips)
A velocity measurement. Used in electronic balancing.
incidence board A device used to measure the angle of incidence of a wing.
incipient stage The time when frontal cyclone development begins, pressure falls at some point along the original stationary front and counterclockwise circulation is generated.
inclined plane A machine used to gain a mechanical advantage. It consists of a flat surface positioned at an angle with the horizon.
inclinometer An instrument consisting of a curved glass tube, housing a glass ball, and damped with a fluid similar to kerosene. It may be used to indicate inclination, as a level, or, as used in the turn and slip indicator, to show the relationship between gravity and centrifugal force in a turn.
inclusions The impurities contained in a material.
incompressible fluids Any liquid such as oil or water. Liquids cannot be compressed but can be used in a regulated fluid power system such as a hydraulic system to gain a mechanical advantage.
Inconel A chromium-iron alloy similar to stainless steel, but which cannot be hardened by heat treatment.
increase speed to (speed) See speed adjustment.
incrementally Moving in steps rather than in continuous motion.
indefinite ceiling A ceiling classification denoting vertical visibility into a surface based obscuration.
indicated air temperature (IAT) Is the temperature of the air as measured by the temperature probe on the outside of the aircraft.
indicated airspeed The airspeed as indicated on the airspeed indicator with no corrections applied.
indicated altitude The altitude shown by an altimeter set to the current altimeter setting.
indicated horsepower (IHP) The total horsepower developed in the engine. It is the sum of the brake horsepower delivered to the propeller shaft and the friction horsepower required to drive the engine.
indicated mean effective pressure (IMEP) The average measured pressure inside the cylinder of an engine during the power stroke. Expressed in pounds per square inch.
indicating fuse A fuse assembly that has a small neon light installed in parallel with the fuse that shows when the fuse has blown.
indicating instrument A device such as a gauge, dial, or pointer that measures or records and also visibly indicates. An apparatus that shows fluid pressures, temperatures, or quantities.
indicator See indicating instrument.
indirect light Light reflected onto a surface from another surface.
induced current The electrical current that is generated in a conductor when it is crossed by magnetic lines of flux.
induced drag That part of the total drag that is created by the production of lift.
induced flow In rotorcraft, the component of air flowing vertically through the rotor system resulting from the production of lift.
induced voltage The voltage generated by a conductor when lines of magnetic flux cut across it.
inducer The center inlet portion of a centrifugal impeller, sometimes made of a different, harder metal than the impeller for FOD protection.
inductance The property of a conductor that causes an electromotive force or voltage to be generated when lines of magnetic force cut across it.
inductance bridge An electronic device used to accurately measure an unknown inductance by comparing it to a known inductance. An inductance bridge is similar to the Wheatstone bridge used to measure resistance.
inductance coil A coil designed to introduce inductance into a circuit.
induction compass A direction indicator that derives its signal from the lines of flux of the Earth cutting across the windings of the flux valve mounted in the airplane.
induction furnace An electric furnace that melts metal by the induction of high-frequency electromagnetic energy.
induction heating A method of heating a conducting material by passing high frequency alternating current through it.
induction icing The formation of ice on aircraft air induction ports and air filters.
induction motor An AC electric motor that has the AC line voltage connected across stationary windings in the motor housing. Current induced into the rotor causes a magnetic field that reacts with the field of the stator, and this reaction causes the rotor to turn.
induction period The time period after catalyzed material is mixed in which the material is allowed to begin curing before being sprayed onto a surface.
induction system The complete system of air passages in a reciprocating engine, from the air filter inlet to the intake valve of the cylinder.
induction system fire A fire in the carburetor or air inlet system of a reciprocating engine usually caused by flooding and a backfire.
induction vibrator A coil and set of contact points that produce pulsating DC from straight DC. Pulsating DC can be used in the primary winding of a magneto to produce a high voltage in the secondary winding.
induction welding A method of welding in which the metal is melted by the induction of high-frequency electromagnetic energy.
inductive circuit An AC circuit in which the capacitive reactance lags behind the inductive reactance.
inductive kick A slang term used for inductive reactance in a coil of wire. It is a high voltage produced across a coil when current stops flowing through the coil. When current flows through a coil, a magnetic field is set up around each of the turns of wire in the coil. But when the current stops flowing, the magnetic field collapses
across the coil producing many times the voltage that was originally in the coil. This high voltage is called an inductive kick.
inductive reactance An opposition to the flow of AC caused by the generation of an induced voltage whose polarity is opposite to that of the voltage that created it.
inductive time constant A measurement of the amount of time needed for the current induced into an inductive circuit to reach 63.2% of its maximum value.
inductive tuning A method of selecting or changing the resonance of a radio frequency circuit by changing the inductance. The circuit is tuned by rotating a tuning coil that increases or decreases the inductance.
inductor A coil or other device used to introduce inductance into a circuit.
industrial diamond A diamond used as a cutting tool.
inert agent A fire extinguishing agent that extinguishes fire by excluding the oxygen from its surface.
inert gas A gas such as argon or helium that does not form other chemical compounds when it comes into contact with other elements.
inert gas arc welding A process of arc welding in which the arc is submerged in an envelope of an inert gas such as argon to exclude the oxygen from the molten metal and prevent the formation of oxides.
inertia The tendency of a mass at rest to remain at rest, or if in motion to remain in motion, unless acted upon by some external force.
inertia anti-icer A movable vane in the induction air system that, in the extended position, causes the velocity of the incoming air to increase and change direction, thereby discharging the heavier ice overboard while directing the lighter, ice-free air into the engine plenum.
inertia force A force due to inertia, or the resistance to acceleration or deceleration.
inertia starter A starter for large reciprocating engines that uses the energy stored in a flywheel, spinning at a high rate of speed, to turn the engine for starting.
inertia switch An electrical switch built into an emergency locator transmitter (ELT). Designed to close and start the ELT when there is a sudden change in its velocity.
inertia welding An advanced technology process of welding through use of high speed rubbing friction. Developed to join super alloys that are difficult to weld with traditional methods. In inertia welding, one of the work pieces is connected to a flywheel and the other is restrained from rotating. The flywheel is accelerated to a predetermined rotational speed, storing the required energy. The drive motor is disengaged and the work pieces are forced together by the friction welding force. This causes the faying surfaces to rub together under pressure. The kinetic energy stored in the rotating flywheel is dissipated as heat through friction at the weld interface as the flywheel speed decreases.
inertial navigation Navigation by means of a self-contained, airborne device that senses changes of direction or acceleration and automatically corrects for deviations in a planned course.
inertial navigation system An RNAV system which is a form of self-contained navigation.
inflammable Able to burn and support combustion; easily inflamed. A word that has been replaced with flammable to avoid confusion.
inflight refueling A procedure used by the military to transfer fuel from one aircraft to another during flight.
inflight weather advisory See weather advisory.
informal lecture A lecture style that lends itself to active student participation.
information request A request originated by an FSS for information concerning an overdue VFR aircraft.
infrared guidance A guidance system used on heat-seeking missiles to hone in on the infra-red signature of a target.
infrared (IR) Electromagnetic radiation having wavelengths longer than red light.
infrared lamp An incandescent lamp that produces light energy in the infrared range.
infrared radiation Electromagnetic radiation having wavelengths longer than red light and shorter than microwaves.
infrasonic frequencies Frequencies below the audio frequency range. Also referred to as subsonic frequencies.
ingest To pull in something such as air or to ingest FOD in a gas turbine engine.
ingot A large cast bar of metal, as poured, with no working.
inherent stability That built-in characteristic of an aircraft that causes it, when disturbed from straight and level flight, to return to straight and level flight.
inhibited sealer A material used to exclude moisture and air from a honeycomb repair. In addition to sealing, it inhibits the formation of corrosion.
inhibitive film A film of material on the surface of a metal that inhibits or retards the formation of corrosion. It does this by providing an ionized surface that will not allow the formation of corrosive salts on the metal.
inhibitor 1. An agent added to a resin to retard its curing and increase its shelf life. 2. Any substance that slows or prevents a reaction.
initial approach fix (IAF) The fixes depicted on instrument approach procedure charts that identify the beginning of the initial approach segment(s).
initial approach segment The segment between the initial approach fix and the intermediate fix or the point where the aircraft is established on the intermediate course or final approach course.
initial approach segment [ICAO] That segment of an instrument approach procedure between the initial approach fix and the intermediate approach fix, or where applicable, the final approach fix or point.
initial climb area (ICA) The ICA is the segment of the departure procedure that starts at the departure end of the runway and proceeds along the runway centerline extended to allow the aircraft sufficient distance to reach an altitude of 400 feet above departure end runway elevation, and to allow the establishment of positive course guidance by all navigation systems. A typical straight departure ICA extends 2-5 nautical miles from the departure end of runway along the runway centerline extended. It is 500 feet wide each side of the runway centerline at departure end of runway, then splays out at 15 .
initial lift One of the two requirements for the production of a thunderstorm, the other is potential instability.
initialization To facilitate the start-up of a program. In computers it is the start-up of computer language instructions that the computer understands in order to operate as intended.
injection molding A method of forming thermoplastics by forcing resin, under high pressure, into a mold and allowing it to harden.
injection pump A high pressure fuel pump used in a reciprocating engine fuel injection system. Fuel is pumped, under high pressure, into the combustion chamber of the engine where it is atomized and ignites as it leaves the injector nozzle.
inland navigation facility A navigation aid on a North American Route at which the common route and/ or the noncommon route begins or ends.
inlet buzz An audible sound that sometimes occurs in inlets of supersonic aircraft when shock waves alternately move in and out. This condition appears when design speeds are exceeded.
inlet case The front compressor supporting member, usually one single casting.
inlet duct That portion of the structure of a turbine-powered aircraft that directs the air into the engine compressor.
inlet gearbox An auxiliary gearbox driven from and located in front of the compressor in the engine inlet area. Not all engines are configured with this gearbox.
inlet guide vane In gas turbine engines, stationary airfoil which precedes the first stage compressor rotor blades. These guide vanes form straight through passages and are present to direct air onto the blades at the optimum angle.
inlet particle separator An inlet device on some turbine powered rotorcraft that prevents sand and other FOD-causing debris from entering the engine. On some separators, the trap has to be cleaned while, on others, the debris is directed overboard.
inlet pressure (Pt2) The pressure total taken in the engine inlet as a measure of air density, a parameter sent to the fuel control for fuel scheduling purposes.
inlet screen An anti-FOD screen used on turbine powered rotorcraft and most stationary turbines. Not generally used on other aircraft installations due to icing and other aerodynamic problems that can result.
inlet spike A moveable inlet device used to control inlet geometry and shock waves. This inlet design diffuses supersonic airflow and reduces it to subsonic speed for entry into the engine.
inlet strut assembly The spoke-like stationary airfoils that are part of the inlet case. They are used to support the front bearing housing and provide passageways for oil and air line routing from outside the engine to inside.
inlet temperature (Tt2) The temperature signal taken in the engine inlet to measure air density. Used by the fuel control unit as a fuel scheduling parameter.
in-line engine An engine with all of the cylinders in a single line. The crankcase may be located either above or below the cylinders. If it is above, it is called an inverted in-line engine.
in-line reciprocating engine An engine in which all of the cylinders are arranged in a straight line, with each cylinder piston connected to a separate throw of the crankshaft.
inner exhaust cone The conical-shaped portion of a turbine engine exhaust system that is used to produce the proper area increase for the gases as they leave the engine.
inner liner Refers to can-annular combustion liner; the innermost section.
inner marker A marker beacon used with an ILS (CAT II) precision approach located between the middle marker and the end of the ILS runway, transmitting a radiation pattern keyed at six dots per second and indicating to the pilot, both aurally and visually, that he is at the designated decision height (DH), normally 100 feet above the
touchdown zone elevation, on the ILS CAT II approach. It also marks progress during a CAT III approach.
inner marker beacon See inner marker.
inner tube An air-tight rubber tube that has a stem for inflating it. Used inside a pneumatic tire to hold the air that inflates the tire.
inoperative Not working.
inoperative components The lowest landing minimums on an approach are authorized when all components and visual aids are operating. If some components are inoperative, higher landing minimums may be required. If more than one component is inoperative, apply only the greatest increase in altitude and/or visibility required by the failure of a single component.
inoperative equipment Equipment in the aircraft that is not functional.
input capacitance Capacitance measured across the input terminals of a circuit.
input circuit A circuit that provides appropriate power and impedance matching between an input device and the signal source.
input impedance Impedance measured across the input terminals of a circuit.
input transformer An electronic device that isolates a signal source from an input device and matches the impedance. See also impedance matching transformer.
inrush current The high current that flows in an electrical machine or circuit when the switch is first closed.
inside caliper A measuring instrument with two adjustable legs used to determine an inside measurement. Once the distance has been established, the actual measurement is made with a steel scale, a micrometer, or a vernier caliper.
inside diameter The diameter measured from one inside surface, through center, and to the opposite inside surface.
inside micrometer -A micrometer caliper used to measure the inside diameter of a circular object such as a cylinder bore. It measures in increments of l/1,000 or smaller. It works on the same principle as an outside micrometer caliper.
insight The grouping of perceptions into meaningful wholes. Creating insight is one of the instructor s major responsibilities.
insolation Solar radiation received at the surface of the Earth.
inspect To determine the condition of something by sight, feel, measurement, or other means.
Inspection Authorization (IA) An authorization issued by the FAA to experienced A&P technicians meeting certain requirements. This authorization allows them to return aircraft to service after annual inspections or certain major repairs.
inspection door A small door or hinged plate on the surface of an aircraft structure that can be opened for inspecting the interior of the aircraft.
inspection hole A hole in the skin of an aircraft, closed with an inspection plate that is held in place with screws on metal skins and with friction clamps on fabric skins. The hole can be opened for inspection or repair inside the structure.
inspection plate A cover over an inspection hole that is held in place with screws on metal skins and with friction clamps on fabric skins.
instability 1. The characteristic of an aircraft that causes it, when disturbed from a condition of level flight, to depart further from this condition. 2. In meteorology, a general term to indicate various states of the atmosphere in which spontaneous convection will occur when prescribed criteria are met; indicative of turbulence. See also absolute instability, conditionally unstable air.
installation drawing A drawing that shows all of the parts in their proper relationship for installation.
installation error An error in pitot static instruments (the airspeed indicator, the altimeter, and the rate of climb indicator) caused by a change in alignment of the static pressure port with the airflow as the aircraft s angle of attack changes.
instantaneous rate of climb indicator (IVSI) A vertical speed indicator that uses internal accelerometer-type air pumps to overcome the inherent lag of this type of instrument and to provide an instantaneous indication of altitude changes due to pitch attitude changes.
instructional aids Devices that assist an instructor in the teaching-learning process. They are supplementary training devices and are not self-supporting.
instrument A device using an internal mechanism to show visually or aurally the attitude, altitude, or operation of an aircraft or aircraft part. It includes electronic devices for automatically controlling an aircraft in flight.
instrument approach See instrument approach procedure.
instrument approach procedure A series of predetermined maneuvers for the orderly transfer of an aircraft under instrument flight conditions from the beginning of the initial approach to a landing or to a point from which a landing may be made visually. It is prescribed and approved for a specific airport by competent authority.
a. U.S. civil standard instrument approach procedures are approved by the FAA as prescribed under FAR 97, and are available for public use.
b. U.S. military standard instrument approach procedures are approved and published by the Department of Defense.
c. Special instrument approach procedures are approved by the FAA for individual operators, but are not published in FAR 97 for public use.
instrument approach procedure [ICAO] A series of predetermined maneuvers by reference to flight instruments with specified protection from obstacles from the initial approach fix, or where applicable, from the beginning of a defined arrival route to a point from which a landing can be completed and thereafter, if a landing is not completed, to a position at which holding or enroute obstacle clearance criteria apply.
instrument approach procedures charts Portray the aeronautical data which is required to execute an instrument approach to an airport. These charts depict the procedures, including all related data, and the airport diagram. Each procedure is designated for use with a specific type of electronic navigation system including NDB, TACAN, VOR, ILS/ MLS, and RNAV. These charts are identified by the type of navigational aid(s) which provide final approach guidance.
instrument approach waypoint Fixes used in defining RNAV IAPs, including the feeder waypoint (FWP), the initial approach waypoint (IAWP), the intermediate waypoint (IWP), the final approach waypoint (FAWP), the RWY WP, and the APT WP, when required.
instrument departure procedure (DP) A preplanned instrument flight rule (IFR) air traffic control departure procedure printed for pilot use in graphic and/or textual form. DP s provide transition from the terminal to the appropriate enroute structure.
instrument departure procedure (DP) charts Charts designed to expedite clearance delivery and to facilitate transition between takeoff and enroute operations. Each DP is presented as a separate chart and may serve a single airport or more than one airport in a given geographical location.
instrument flight rules (IFR) Rules that govern the procedure for conducting flight in instrument weather conditions. When weather conditions are below the minimums prescribed for VFR, only instrument-rated pilots may fly in accordance with IFR.
Instrument Flight Rules (IFR) conditions Weather conditions considered unsafe for flight under visual flight rules.
Instrument Flight Rules (IFR) flight Aircraft flight conducted entirely by reference to instruments and radio navigation.
instrument ground instructor A person certificated by the FAA who is authorized to provide the following: ground training in the aeronautical knowledge areas required for issuance of an instrument rating under Part 61; ground training required for an instrument proficiency check; and a recommendation for a knowledge test required for issuance of an instrument rating under Part 61.
instrument interpretation One of the fundamental skills of basic attitude instrument flying. The three fundamental skills include: instrument cross-check, instrument interpretation, and aircraft control. Interpretation involves an awareness of the instrument indications that represent the desired pitch and bank attitudes for the aircraft.
instrument landing system (ILS) A precision instrument approach system that consists of the following electronic components and visual aids:
a. Localizer
b. Glide Slope
c. Outer Marker
d. Middle Marker
e. Approach Lights
instrument meteorological conditions (IMC) Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling less than the minima specified for visual meteorological conditions.
instrument panel A panel, typically located in front of the pilot, that holds all of the indicating instruments that show the condition of the aircraft flight and mechanical systems.
instrument proficiency check An evaluation ride based on the instrument rating practical test standard. Required to regain instrument flying privileges when the privileges have expired due to lack of currency.
instrument runway A runway equipped with electronic and visual navigation aids for which a precision or nonprecision approach procedure having straight-in landing minimums has been approved.
instrument shunt An electrical shunt used with an ammeter to make it possible for it to measure current.
instrument training That time in which instrument training is received from an authorized instructor under actual or simulated instrument conditions.
instrumentation The installation or use of indicating instruments.
insulated gate field effect transistor (IGFET) A semiconductor whose gate is insulated from the channel. The IGFET is now called a MOSFET (Metal Oxide Field Effect Transistor). The MOSFET has an extremely large input impedance. Because the insulating oxide layer is extremely thin, the MOSFET is susceptible to destruction by electrostatic charges. Special precautions are necessary when handling or transporting MOS devices.
insulating electrical tape A flexible, adhesive-backed tape made of a polyvinylchloride material used as insulation over wire terminals and wire splices.
insulation A heavy material used in an aircraft to prevent the conduction of heat into or out of any of its operating components.
insulation blanket 1. A layer of fireproof insulating material used to keep the heat of a jet engine tail pipe from radiating into the engine compartment. 2. Any material such as fiberglass or aluminum used to insulate against sound, heat, or cold.
insulation grip A plastic-covered, thin metal reinforcing sleeve on a pre-insulated terminal lug that grips the insulation of the wire when the lug is crimped, adding strength and durability to the installation.
insulation resistance The electrical resistance of an insulating material separating two conductors.
insulation strength A statement of the electrical insulating property of a substance. Usually stated as the voltage an insulator can withstand without breaking down.
insulator A material or device used to prevent passage of heat, electricity, or sound from one medium to another.
intake valve A reciprocating engine valve, located in the head of a cylinder, which provides the passage of the fuel-air mixture into the combustion chamber.
integral fuel tank A portion of the aircraft structure, usually a wing, which is sealed off and used as a fuel tank. When a wing is used as an integral fuel tank, it is called a wet wing.
integrated circuit (IC) A microminiature circuit incorporated on a very small chip of semiconductor material through solid state technology. A number of circuit elements such as transistors, diodes, resistors, and capacitors are build into the semiconductor chip by means of photography, etching, and diffusion.
integrated engine pressure ratio (IEPR) Used on some turbofans to include fan discharge total pressure and compressor inlet total pressure.
integrated flight instruction A technique of flight instruction where students are taught to perform flight maneuvers by reference to flight instruments and to outside visual references. Handling of the controls is the same regardless of whether flight instruments or outside references are being used.
integrating circuit A network circuit whose output is proportional to the sum of its instantaneous inputs.
integrity The ability of a system to provide timely warnings to users when the system should not be used for navigation.
intensity A principle of learning where a dramatic or exciting learning experience is likely to be remembered longer than a boring experience. Students experiencing the real thing will learn more than when they are merely told about the real thing.
intensity control A cathode-ray tube control that meters the quantity of electrons in the beam that strikes the phosphorescent screen inside the cathode=ray tube. The more electrons that strike the screen, the brighter the display.
interactive video Software that responds quickly to certain choices and commands by the user. A typical system consists of a compact disc, computer, and video technology.
intercom A communication system within an airplane for the purpose of communicating between flight crew members or to passengers.
interconnector A small tube connecting multiple burner cans together for the purpose of flame propagation during starting.
intercooler A devise used to reduce the temperatures of the compressed air before it enters the fuel metering device. The resulting cooler air has a higher density, which permits the engine to be operated with a higher power setting.
intercostal A longitudinal structure similar to a stringer, but which is attached to a wing rib or fuselage frame and ends at an adjacent rib or frame. Intercostals are usually used to support access doors, equipment, etc.
intercylinder baffles Sheet metal air deflectors installed between and around air-cooled cylinders to aid in uniform cooling.
interelectrode The capacitive effect between two elements in an electron tube. At high frequencies, signals can be fed across the interelectrode capacitance between the plate and a grid.
interelectrode capacitance The capacitance that exists between two electrodes in an electron tube.
interface A surface that forms the common boundary between two parts of matter such as water interfaces in jet fuel and crystal interfaces in metals.
interference 1. A theory of forgetting where a person forgets something because a certain experience overshadows it, or the learning of similar things has intervened. 2. Barriers to effective communication that are caused by physiological, environmental, and psychological factors outside the direct control of the instructor. The instructor must take these factors into account in order to communicate effectively.
interference fit A fit between two parts in which the part being put into a hole is larger than the hole itself. In order to fit them together, the hole is expanded by heating and the part is shrunk by chilling. After being united, when the two parts reach the same temperature, they will not separate. The area around the hole is subject to tensile stress and thus vulnerable to stress corrosion.
intergranular corrosion The formation of corrosion along the grain boundaries within a metal alloy.
interim summary An interim summary can be made immediately after each topic to bring ideas together, create an efficient transition to the next topic, divert the discussion to another member of the group, or keep students on track.
interlock An automatic control device that prevents an action until the device that is protected with the interlock is actuated.
intermediate approach segment The segment of an instrument approach procedure between the intermediate fix or point and the final approach fix.
intermediate approach segment [ICAO] That segment of an instrument approach procedure between either the intermediate approach fix and the final approach fix or point, or between the end of a reversal, race track or dead reckoning track procedure and the final approach fix or point, as appropriate.
intermediate case The high-pressure compressor outer case on a turbine engine.
intermediate compressor On a triple-spool turbine engine, the N2 compressor.
intermediate fix The fix that identifies the beginning of the intermediate approach segment of an instrument approach procedure. The fix is not normally identified on the instrument approach chart as an intermediate fix (IF).
intermediate frequency A frequency generated in a superhetrodyne receiver equal to the difference between the received radio frequency signal and that produced by the local oscillator.
intermediate landing On the rare occasion that this option is requested, it should be approved. The departure center, however, must advise the ATCSCC so that the appropriate delay is carried over and assigned at the intermediate airport. An intermediate landing airport within the arrival center will not be accepted without coordination with and the approval of the ATCSCC.
intermediate position The position of some movable unit that lies in between the extreme positions of movement.
intermediate turbine temperature (ITT) The temperature taken usually at a station between the high and low pressure turbine wheels.
Intermediate-Range Ballistic Missile (IRBM) A ballistic missile with a range generally between 1,500 and 3,437 statute miles.
intermittent fault An occasional condition in which a fault in a system does not occur with consistency.
intermittent load A load that is not continually on the system.
intermittent-duty relay An electrical relay that cannot be energized over long periods of time. This precludes their use for master relays or for lighting circuits.
internal air pressure Air pressure within a vessel or container.
internal baffles The deflector plates installed inside a tank or reservoir to prevent the fluid from sloshing or surging in flight.
internal combustion engine An engine that obtains its power from heat produced by the combustion of a fuel air mixture within the cylinder of the engine.
internal control lock A device used to lock a control surface in place when the airplane is parked. It is actuated from a control in the cockpit.
internal damage Damage that occurs inside a part, component, or mechanism that is not visible externally.
internal resistance The resistance of the battery to the flow of current. It causes a voltage drop proportional to the amount of current flow.
internal resources During pilot operations, these are sources of information found within the airplane such as the pilot s operating handbook, checklists, aircraft equipment, aeronautical charts, the instructor, another pilot, and passengers, as well as one s ingenuity, knowledge, and skills.
internal supercharger A gear-driven centrifugal blower in the accessory section of a reciprocating aircraft engine. Used to increase the pressure of the induction system air.
internal thread A thread on the internal surface of a hollow cylinder or cone.
internal timing The timing of the relationship of the E-gap position of the rotating magnet and the opening of the breaker points in a magneto.
internal wrenching bolt A h i g h - s t r e n g t h steel bolt with its head recessed to allow the insertion of an Allen wrench.
international airport Relating to international flight, it means: a. An airport of entry which has been designated by the Secretary of Treasury or Commissioner of Customs as an international airport for customs service. b. A landing rights airport at which specific permission to land must be obtained from customs authorities in advance of contemplated use. c. Airports designated under the Convention on International Civil Aviation as an airport for use by international commercial air transport and/or international general aviation.
international airport (ICAO) Any airport designated by the Contracting State in whose territory it is situated as an airport of entry and departure for international air traffic, where the formalities incident to customs, immigration, public health, animal and plant quarantine and similar procedures are carried out.
International Civil Aviation Organization [ICAO] A specialized agency of the United Nations whose objective is to develop the principles and techniques of international air navigation and to foster planning and development of international civil air transport.
ICAO Regions include:
1. AFI African-Indian Ocean Region
2. CAR Caribbean Region
3. EUR European Region
4. MID/ASIA Middle East/Asia Region
5. NAM North American Region
6. NAT North Atlantic Region
7. PAC Pacific Region
8. SAM South American Region
interplane struts Struts that run vertically near the wing tips between the wings of a biplane.
interpolation The estimation of an intermediate value of a quantity that falls between marked values in a series. Example: In a measurement of length, with a rule that is marked in 1/8 s of an inch, the value falls between 3/8 inch and inch. The estimated (interpolated) value might then be said to be 7/16 inch.
interpole A field pole in a compound-wound electrical generator used to correct for armature reaction. Armature reaction is the distortion of the generator field flux by the current flowing in the windings of the armature.
interrib bracing The reinforcing tape of a fabric-covered wing that runs diagonally from the top of one wing rib to the bottom of the next throughout a truss-type wing to hold the ribs upright and in line until the rib-stitching is done.
interrogator The ground-based surveillance radar beacon transmitter-receiver, which normally scans in synchronism with a primary radar, transmitting discrete radio signals which repetitiously request all transponders on the mode being used to reply. The replies received are mixed with the primary radar returns and displayed on the same plan position indicator (radar scope). Also applied to the airborne element of the TACAN/DME system.
intersecting runways Two or more runways that cross or meet within their lengths. See also intersection.
intersection 1. Typically, the point at which two VOR radial position lines cross on a route, usually intersecting at a good angle for positive indication of position, resulting in a VOR/VOR fix. 2. A point defined by any combination of courses, radials or bearings of two or more navigational aids. 3. Used to describe the point where two runways, a runway and a taxiway, or two taxiways cross or meet.
intersection departure A departure from any runway intersection except the end of the runway.
intersection takeoff See intersection departure.
interstage transformer A transformer used to prevent the flow of DC from one stage of a multi-stage transformer system to the other. Provides the correct amount of impedance for the AC output of one stage and for the AC input of the following stage.
interstate air commerce The carriage by aircraft of persons or property for compensation or hire, or the carriage of mail by aircraft, or the operation ornavigation of aircraft in the conduct or furtherance of a business or vocation, in commerce between a place in any State of the United States, or the District of Columbia, and a place in any other State of the United States, or the District of Columbia; or between places in the same State of the United States through the airspace over any place outside thereof; or between places in the same territory or possession of the United States, or the District of Columbia.
interstate air transportation The carriage by aircraft of persons or property as a common carrier for compensation or hire, or the carriage of mail by aircraft in commerce: a. Between a place in a State or the District of Columbia and another place in another State or the District of Columbia, b. Between places in the same State through the airspace over any place outside that State; or c. Between places in the same possession of the United States; Whether that commerce moves wholly by aircraft of partly by aircraft and partly by other forms of transportation. Intrastate air transportation means the carriage of persons or property as a common carrier for compensation or hire, by turbojet-powered aircraft capable of carrying thirty or more persons, wholly within the same State of the United States.
intertropical convergence zone The boundary zone between the trade wind system of the Northern and Southern Hemispheres; it is characterized in maritime climates by showery precipitation with cumulonimbus clouds sometimes extending to great heights.
introduction The first element of an instructional lesson that sets the stage for the rest of the lesson by relating the coverage of the material to the entire course. The introduction itself is typically composed of three elements: attention, motivation, and an overview of what is to be covered.
Invar A nickel-iron alloy with an extremely small temperature coefficient of expansion.
inverse peak voltage The amount of inverse voltage a device can withstand without breakdown.
inverse square law In physics, a given physical quantity varies inversely with the square of another physical quantity (usually distance). For example, if the distance from a magnet doubles, the strength of magnetism decreases to one fourth of its original value.
inverse voltage The amount of voltage seen by a rectifier during the half cycle of AC being blocked to create pulsed DC.
inversion In meteorology, an increase in temperature with height a reversal of the normal decrease with height in the troposphere; may also be applied to other meteorological properties.
invert To reverse the position, order, or condition of something.
inverted engine A reciprocating engine whose crankshaft and crankcase are above the cylinders.
inverted spin A maneuver having the characteristics of a normal spin except that the airplane is in an inverted attitude.
inverter An electrical device that changes DC to AC.
investment casting Casting as in a vacuum furnace or spin chamber to produce a denser, better quality material. Used to produce some steels in turbine engines.
iodine A poisonous element with a symbol of I and an atomic number of 53.
ion An atom that has either gained or lost an electron. If an atom has a shortage of electrons, it is a positive ion. If it possesses an excess of electrons, it is a negative ion.
ion engine A reaction engine that ejects a stream of ionized particles to produce a forward thrust.
ionic charges The charges in solid-state junctions caused by the dissimilarity of the junction materials. The charges create barrier voltages. In order for a diode to rectify, it must be presented with an AC voltage whose peak value exceeds its barrier voltage.
ionize To convert totally or partially into ions.
ionosphere A series of atmospheric layers of ions that begins approximately 25 miles above the surface of the Earth.
IR drop The amount voltage drops in a given conductor due to the resistance of the conductor. The IR drop is found by the formula: I x R=E (voltage), or by multiplying the amount of current (I) in amps, by the amount of resistance (R) in ohms.
IRAN An acronym used by the military services for a form of maintenance known as Inspect and Repair As Necessary.
iridium An extremely hard and brittle metallic element of the platinum group, with a symbol of Ir and an atomic number of 77. Used for electrodes of fine-wire spark plugs that must operate in extreme lead-fouling conditions.
iris exhaust nozzle In turbine engines, a nozzle design similar to a camera shutter. It can be a two-position, partially-open/fully-open or a variable opening type. The widest opening is for afterburner mode. The variable
opening type is controlled to continuously seek the optimum position for existing conditions.
Irish linen A strong fabric made from flax used to cover many of the older aircraft. It is still popular in Europe, but it is no longer readily available in the United States. It may be used as a direct replacement for grade-A cotton.
iron A heavy, malleable, ductile, magnetic, silver-white metallic element with a symbol of Fe and an atomic number of 26. It is used in the production of steel and all ferrous metals.
iron-constantan thermocouple A low temperature thermocouple that operates up to about 800 C. Used in aviation primarily to measure cylinder head temperature.
iron-core coil An inductor that consists of a soft laminated iron core around which wire is wound.
iron-core transformer An electrical transformer that has coils wound around soft iron cores. The cores cut down on eddy-current losses but limit the use of the transformer to lower frequencies.
iron-vane movement An AC electric measuring instrument that depends upon a soft-iron vane or movable core operating with a coil to produce an indication of AC current flow.
irrelevant questions A question that has no relationship with the subject matter being tested. Serves only to disrupt the orderly learning process.
irreversible controls Hydraulically-controlled surfaces on an aircraft that do not provide aerodynamic feedback to the cockpit controls.
isobar A line of equal or constant barometric pressure.
isobar A line on a meteorological chart that connects points on the Earth s surface having equal barometric pressure.
isobaric metering valve A metering valve in a cabin pressurization system that maintains a constant cabin altitude.
isobaric range That range of cabin pressurization in which the cabin maintains a constant pressure, or cabin altitude, as the flight altitude changes.
isogonic lines Lines on charts that connect points of equal magnetic variation.
isogonic lines Lines on an aeronautical chart connecting points of equal magnetic declination (angle between magnetic North and true North). This angle is known as compass variation.
isoheight A line that shows contours of equal height on a constant-pressure weather chart.
isohumes Lines of equal relative humidity.
isolation mount A rubber and metal composite used to prevent vibration transfer from one component to another.
isolation transformer An electrical transformer with equal numbers of turns in the primary and secondary coils. This type transformer is used to isolate a piece of equipment from its power source.
isolation valve A valve in an aircraft pneumatic system that can be shut off to isolate the components from the source of air pressure so maintenance can be performed without discharging the system.
isoline A line on a weather chart showing contours of equal values of some quantity. It could be equal height (isoheight), barometric pressure (isobar), temperature (isotherm), wind (isotach), etc.
isometric drawing The representation of an object in isometric projection in which the lines parallel to the edges of the object are drawn to true length.
isometric projection A three-dimensional projection in which the three faces of an object are equally inclined to the surface of the drawing, and all of the edges are equally foreshortened.
iso-octane A hydrocarbon (C8H18) that has a very high critical pressure and temperature. It is used as a reference for measuring the anti-detonation characteristics of a fuel.
isopleth A line connecting points of constant or equal value.
isopropyl alcohol Fluid that prevents the formation of ice on the blades during flight. Used in anti-icing systems for propeller blades.
isostatic forging A similar process to isothermal forging.
isotach A line of equal or constant wind speed.
isotherm A line on a meteorological chart that denotes locations having the same temperature.
isothermal forging A hot forging method that uses super alloy production. Materials and dies are heated to the same temperature usually in a vacuum or highly controlled atmosphere to prevent oxidation. One such process utilizes an alloy in powder form, which when compressed, results in closer, near-net-shape than older methods. This results in the production of hot section parts with less waste during final machining.
isothermal layers A layer in the atmosphere where the temperature is the same from the bottom of the layer to the top of the layer.
isotopes An atom that has the same atomic number as a chemical element, but a different atomic mass and different physical properties.