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
gain
The increase in signal power through a circuit.galling Fretting or chafing of a mating surface by sliding contact with another surface or body. The heat friction causes the material from one surface to be welded or deposited onto the other surface, ultimately damaging the surface area.
gallon 1. Imperial: A unit of liquid measurement used outside of the United States. One Imperial gallon is equal to 277.4 cu. in., 4.55 liters, or 1.201 U.S. gallons. 2. U.S.: A unit of liquid measurement used in the United States. One U.S. gallon is equal to 231 cu. in., 128 fl. oz., or 3.785 liters.
galvanic action Electron flow because of a difference of electrode potential between different substances.
galvanic corrosion Corrosion due to the presence of dissimilar metals in contact with each other in the presence of an electrolyte such as water.
galvanic couple Dissimilar metals that produce an electrical voltage when they are both in contact with the same electrolyte. When dissimilar metals are in this condition, one metal forms the anode and the other metal forms the cathode, thereby producing a current between the two metals.
galvanic electricity The electricity produced by chemical action such as that produced in a dry-cell battery or storage battery.
galvanic grouping An arrangement of metals in a series according to their electrode potential difference.
galvanizing A method of protecting steel parts from corrosion by dipping them in a vat of molten zinc or by electroplating them. The protection actually comes from sacrificial corrosion of the zinc.
galvanometer An electrical measuring instrument in which electrical current is measured by the reaction of its electromagnetic field to the field of a permanent magnet.
gamma rays Electromagnetic radiation that results from nuclear fission.
ganged tuning A mechanical arrangement that permits the simultaneous tuning of two or more electronic circuits.
gap The distance between two objects.
garnet paper An abrasive polishing paper consisting of a sheet of flexible paper with a layer of finely crushed garnet.
gas 1. A fluid that assumes the shape of the container it is placed in and fills the container. 2. The physical condition of matter in which a material takes the shape of its container and expands to fill the entire container. Oxygen and nitrogen are two chemical elements that are gases at normal room temperature and pressure. The air we breathe is a physical mixture of gases, primarily nitrogen and oxygen.
gas generator The basic power producing portion of a gas turbine engine excluding sections such as the inlet duct, the fan section, free power turbines, and the tailpipe. Each manufacturer designates what is included in the gas generator, but generally it consists of the compressor, diffuser, combustor, and turbine.
gas generator turbine In gas turbine engines, high pressure turbine wheel(s) which drive the compressor of a turboshaft or turboprop engine.
gas path The airflow or open portion of the engine front to back where air is compressed, combusted, and exhausted.
gas path analysis (GPA) A computer analysis of engine parameters on some airliners. It is designed to assist the modular maintenance and on-condition maintenance concepts by giving continuous on-condition data. Also used for predicting engine component airworthiness.
gas storage cylinders Long bottles of high-strength steel used to store compressed gases.
gas turbine Engine consisting of a compressor, combustor and turbine, using a gaseous fluid as a working medium and producing either shaft horsepower, jet thrust, or both. The four common types of Gas Turbine Engines are Turbojet, Turbofan, Turboprop and Turboshaft.
gas turbine engine A heat engine in which burning fuel adds energy to compressed air and accelerates the air through the remainder of the engine. Some of the energy is extracted to turn the air compressor, and the remainder accelerates the air to produce thrust. A portion of this energy can be converted into torque to drive a propeller or a system of rotors for a helicopter.
gas welding The method of fusing metals together by a flame using gas as fuel. The most common types of gas welding use oxygen and acetylene gas (oxyacetylene) and oxygen and hydrogen (oxyhydrogen).
gascolator A device that removes dirt, water, and other foreign particles from the fuel. It is usually located in the fuel tank outlets or at the lowest point of an aircraft s fuel system.
gaseous Having the nature or form of gas.
gaseous breathing oxygen Oxygen that is 99.5% pure and contains practically no water vapor.
gaseous fuel Any mixture of flammable gases used for fuel.
gas-filled tube An electron tube with gas introduced into the envelope to produce certain desired operating characteristics.
gasket The static, stationary seal between two flat surfaces.
gasoline A volatile, highly flammable liquid mixture of hydrocarbons produced by the fractional distillation of petroleum and used as fuel in internal-combustion engines.
gasoline combustion heaters Aircraft cabin heaters that burn gasoline from the aircraft fuel tanks to produce the required heat.
gassing, battery The release of hydrogen and oxygen as a free gas during the charging cycle of lead-acid storage batteries.
gate 1. A logic device having one or more inputs and/or outputs. The condition of the inputs determines whether or not a voltage is present at the outputs. 2. The electrode of a silicon-controlled rectifier or a triac through which the trigger pulse is applied.
gate hold procedures Procedures at selected airports that require aircraft to hold at the gate or other ground locations whenever departure delays exceed or are anticipated to exceed 15 minutes. Departure sequence is maintained in accordance with initial call-up unless modified by flow control restrictions. Pilots should monitor the ground control/clearance delivery frequency for engine start/taxi advisories or new proposed start/taxi times if the delay changes.
gate-type check valve A one-way flow valve having a swinging gate or flapper. The gate-type check valve can isolate one of the vacuum pumps in a multi-engine aircraft from the rest of the system in the event of a failure of the pump.
gateway fix A navigation aid or fix where an aircraft transitions between the domestic route structure and the oceanic route airspace.
gauge Any of a variety of measuring instruments. Some are used to indicate the amount of air pressure, the depth of a hole or a groove, or possibly the thickness or clearance between close-fitting parts of a machine, etc.
gauge pressure Pressure measured relative to the existing atmospheric pressure. Engine oil pressure and hydraulic pressure are normally measured as gauge pressure. If gauge pressure is measured in pounds per square inch, it is referred to as PSIG (pounds per square inch, gauge). Two other types of pressure that are often used are differential pressure (PSID) and absolute pressure (PSIA). Differential pressure is the difference between two pressures and absolute pressure is a value compared to zero pressure.
gauss The unit of magnetomotive force. It is equal to one maxwell per cm2.
gear A toothed wheel or disc that meshes with another toothed wheel or disc to transmit motion.
gear and pinion mechanism A mechanical amplifying mechanism consisting of two gears, one being a pinion, which is much smaller than the other. The mechanical advantage of the mechanism is determined by the ratio between the number of teeth on the pinion and the number of teeth on the large gear. Often the large gear is only a portion of the wheel and is called a sector gear.
gear backlash The measured clearance between the teeth of meshed gears.
gear indicators Indicators in the cockpit of an airplane having retractable landing gear to inform the pilot of the position of the gear. It will indicate whether they are down and locked, in transit, or up and locked.
gear preload The pressure with which two gears mate or mesh together.
gear-driven supercharger An internal, engine-driven supercharger on a reciprocating engine driven from the crankshaft through a gear arrangement.
geared fan A design that allows a fan to rotate at a different speed than the compressor rotor. The fan being geared down allows for higher speeds in the compressor without creating excessive tip speeds on the fan.
geared fan gas turbine engine A turbofan engine that uses a set of reduction gears between the first stage of the gas generator compressor and the fan.
geared propeller A propeller driven from the crankshaft through a series of reduction gears. This allows the engine to operate at an efficient speed while holding the propeller RPM in its efficient range.
gear-type pump A power-driven fluid pump, usually a constant displacement-type pump, driven by the engine accessory drive and used to pump fluid under pressure. The gear-type pump is made up of two meshed spur gears mounted in a close-fitting housing. Fluid is taken into the inlet side of the housing and fills the space between the teeth of both gears. As the fluid is carried around the housing of the rotating gears to the discharge side of the pump, the gear teeth mesh and the fluid is forced out of the outlet side of the pump.
gel A jelly-like substance formed by the coagulation of a solution into a solid phase.
gel coat In composites, a coating of resin, generally pigmented, applied to the mold or part to produce a smooth finish. Considered a nonstructural finish.
gel time In composites, the period of time from the initial mixing of the reactants of a liquid material composition to the point in time when gelation occurs, as defined by a specific test method.
gelatinous Having the consistency of gelatin or jelly.
gelled cell battery A lead-acid battery that has a gelling agent added to the electrolyte to make it non-spillable and retain a high level of electrolyte in the battery.
genemotor A machine with two windings on a single armature that operates simultaneously as a motor with one of the windings and as a generator with the other. The armature windings are usually different so that the voltage on the generator side is different from the voltage on the motor side and the machine acts as a rotary transformer. Also referred to as a dynamotor.
general aviation The portion of the aviation industry that covers all of aviation with the exception of military, public-use aircraft, and the airlines.
General Aviation District Office (GADO) Designated FAA Field Offices staffed to serve the general public and aviation industry on matters pertaining to the certification, maintenance, and operation of general aviation.
general circulation The wind system that extends over the entire globe; it is a macroscale phenomena with a typical horizontal dimension of 10,000 nautical miles.
generator A mechanical device consisting of a conductor being turned within a magnetic field. Produces electricity by electromagnetic induction.
geodetic construction A form of aircraft construction in which the stress carrying portion of the skin is made up of a lattice work of thin metal or wood strips.
geographic poles The poles of the axis about which the Earth rotates. They form true north and true south.
geometric pitch The distance a propeller should advance in one revolution without any slip.
geostrophic balance The balance of forces that exists when Coriolis force and pressure gradient force are equal in magnitude but in the opposite direction.
geostrophic wind The wind that occurs when Coriolis force and pressure gradient are equal and opposite.
German silver Metals of the copper/nickel/zinc alloy family. Also referred to as nickel silver.
germanium A grayish-white metallic chemical with a symbol of Ge and an atomic number of 32. Often it is used in the manufacturing of semiconductor devices such as diodes and transistors.
Gigacycle Gigahertz.
Gigahertz One billion hertz.
gilbert The unit of magnetomotive force equal to approximately 0.7968 amp-turn.
gill-type cowl flap A cowl flap used on the trailing edge of each cowling of a horizontally opposed engine. Its purpose is to regulate the flow of air through the engine for cooling.
gimbal The frame in which a gyro spins. It is designed in such a way that it allows a gyroscope to remain in an upright condition while the base is tilted. Rate gyros use a single gimbal, while attitude gyros are mounted in a double gimbal.
gimlet point A threaded cone point usually having a point angle of 45 to 50 . It is used on thread-forming screws such as Type A tapping screws, wood screws, lag bolts, etc.
girt bar Part of the emergency evacuation slide/raft assembly on transport category aircraft. The girt bar enables the slide to deploy when the door is armed and allows the door to be opened without deploying when the door is disarmed.
glacier winds One of the cold downslope winds. A shallow layer of cold, dense air that rapidly flows down the surface of a glacier.
glareshield Dark, non-reflective cover of the space between the instrument panel and the windshield. Also used to describe the area surrounding the sides and top of the instrument panel.
glass cloth An aircraft fabric made from fine spun glass filaments woven into a strong, tough fabric. These fabrics are used for reinforcing plastic resins to mold various types of products.
glass fiber Filaments of fine spun glass woven into cloth or packed together into a mat used for thermal and acoustical insulation.
glaze 1. The hard, smooth surface of a finishing system. Glaze must normally be broken or roughened before another coat of material will adhere to it. 2. A hard, glass-like surface that forms on the rotating disks of a multiple-disk brake. Glaze forms when the sintered material surface is locally overheated. This slick surface does not produce uniform friction and will cause the brakes to chatter or squeal if not removed.
glide 1. A slow descent of an aircraft without the aid of the engine. 2. To descend at a normal angle of attack with little or no engine power.
glide path The path of an aircraft relative to the ground while approaching a landing.
glide path (ICAO) A descent profile determined for vertical guidance during a final approach.
glide slope (GS) Provides vertical guidance for aircraft during approach and landing. The glide slope/glidepath is based on the following:
a. Electronic components emitting signals which provide vertical guidance by reference to airborne instruments during instrument approaches such as ILS/MLS; or
b. Visual ground aids, such as VASI, which provide vertical guidance for a VFR approach or for the visual portion of an instrument approach and landing.
c. PAR, used by ATC to inform an aircraft making a PAR approach of its vertical position (elevation) relative to the descent profile.
glidepath See glideslope.
glidepath [ICAO] A descent profile determined for vertical guidance during a final approach.
glidepath intercept altitude See glideslope intercept altitude.
glider A heavier-than-air aircraft supported in flight by the dynamic reaction of the air against its lifting surfaces. Its free flight does not depend on power generated from an engine.
glideslope Provides vertical guidance for aircraft during approach and landing. The glide slope/glide path is based on the following:
a. Electronic components emitting signals which provide vertical guidance by reference to airborne instruments during instrument approaches such as ILS/MLS, or
b. Visual ground aids, such as VASI, which provide vertical guidance for a VFR approach or for the visual portion of an instrument approach and landing.
c. PAR. Used by ATC to inform an aircraft making a PAR approach of its vertical position (elevation) relative to the descent profile.
glideslope intercept altitude
The minimum altitude to intercept the glideslope/path
on a precision approach. The intersection of the
published intercept altitude with
gliding angle The angle between the flight path during a glide and a horizontal axis relative to the ground.
gliding ratio The ratio of the horizontal distance an aircraft travels while gliding for every unit of vertical distance it descends.
g-load Gust load, the incremental change in vertical acceleration of an aircraft.
global circulation system In meteorology, the combination of the general and monsoon circulations.
global navigation satellite systems (GNSS) An umbrella term adopted by the International Civil Aviation Organization (ICAO) to% encompass any independent satellite navigation system used by a pilot to perform onboard position determinations from the satellite data.
global positioning system (GPS) A space-base radio positioning, navigation, and time-transfer system. The system provides highly accurate position and velocity information, and precise time, on a continuous global basis, to an unlimited number of properly equipped users. The system is unaffected by weather, and provides a worldwide common grid reference system. The GPS concept is predicated upon accurate and continuous knowledge of the spatial position of each satellite in the system with respect to time and distance from a transmitting satellite to the user. The GPS receiver automatically selects appropriate signals from the satellites in view and translates these into three dimensional position, velocity, and time. System accuracy for civil users is normally 100 meters horizontally.
globules A tiny ball of liquid often found in suspension with some other liquid.
glow coil igniter An ignition igniter. Around a pin extending from the body of the igniter is a resistance wire wound into a coil. Direct current causes the coil to become red hot, igniting the fuel/air mixture until the device is operating at a temperature sufficient to maintain the flame. At this point current to the glow coil is automatically turned off.
glow discharge tube A glass tube with a gas such as neon under low pressure. Two electrodes are embedded in opposite ends of the tube. When a sufficiently high potential difference is applied between the electrodes, the gas will ionize and glow.
glow plug igniter An igniter that uses a coil of wire heated by high-voltage DC electricity. Air and fuel blowing through the coil is ignited to initiate combustion in the combustor section.
glue A liquid adhesive capable of holding materials together after drying.
glue blocks Wood blocks used as backing support when making repairs to a wooden structure. They distribute clamp pressure evenly over the area being glued.
glue joint Glued wood joints. Two pieces of wood joined using glue rather than a mechanical fastener.
Glyptal A registered trade name of an insulating varnish used in electrical machinery.
go ahead Proceed with your message. Not to be used for any other purpose.
go around 1. To abort a landing. 2. Instructions for a pilot to abandon his approach to landing. Additional instructions may follow. Unless otherwise advised by ATC, a VFR aircraft or an aircraft conducting visual approach should overfly the runway while climbing to traffic pattern altitude and enter the traffic pattern via the crosswind leg. A pilot on an IFR flight plan making an instrument approach should execute the published missed approach procedure or proceed as instructed by ATC, e.g., Go around (additional instructions, if required).
goals and values A perception factor that describes how a person s perception of an event depends on beliefs. Motivation toward learning is affected by how much value a person puts on education. Instructors who have some idea of the goals and values of their students will be more successful at teaching them.
go-around power or thrust setting The maximum allowable in-flight power or thrust setting identified in the performance data.
gold A malleable, ductile, yellow corrosion-resistant chemical element with a symbol of Au and an atomic number of 79. Used on critical electrical contacts because of its resistance to corrosion.
gold leaf Pure gold rolled into extremely thin sheets.
Gold Seal Flight Instructor Certificate A flight instructor certificate printed with a distinctive gold seal to recognize excellence in flight training based on a CFI s record of performance. To obtain a gold seal certificate, a CFI must have trained and recommended at least 10 students for practical tests within the previous 24 months, and at least 8 of these students must have passed on their first attempt. A CFI must also hold a ground instructor certificate with an advanced or instrument rating.
goniometer antenna A fixed-loop antenna used by automatic direction finding equipment, consisting of two coils oriented 90 to each other. It measures the angle between a known reference and the direction from which the radio signal is being received.
go/no-go gauge A measuring gauge consisting of a part having two dimensions: the minimum size and the maximum size. An opening of the correct dimension will allow one side to go, or pass through, and the other dimension will not.
gouge A cut, groove, or hole in a material. Considered to be a defect.
gouging A furrowing condition in which surface material is displaced or damaged. Usually caused by foreign material between tight fitting, moving parts.
governor A control that limits the maximum rotational speed of a device.
grade-A cotton Long-staple cotton fabric with 80 threads per inch in both the warp and fill directions. It is the standard material for covering aircraft structures.
gradient A consistent rate of change, both increasing and decreasing. This term can be applied to the ascent or descent of an aircraft or changes in temperature, pressure, or concentration levels.
gradient system A device used to give artificial feel to hydraulically boosted flight controls.
grain boundary The lines in metal that are formed by the surfaces of the grains in the metal.
grains The individual crystals of a material.
gram (g) The unit of weight or mass in the metric system. One gram equals 1/1,000 kg or about 0.035 ounce.
granular Containing or consisting of grains or granules.
graph A pictorial presentation of data, equations, and formulas.
graphic plan display (GPD) A view available with URET CCLD (User Request Evaluation Tool Core Capability Limited Deployment) that provides a graphic display of aircraft, traffic, and notification of predicted conflicts. Graphic routes for Current Plans and Trial Plans are displayed upon controller request.
graphite 1. A soft, black form of carbon that usually has a greasy feel. Graphite is commonly used as a dry lubricant. Graphite is also known as black lead and is used in making pencils. 2. A carbonized fiber used as a reinforcement. The graphitization is accomplished by heating the carbon fiber to temperatures up to 5400 F. See also carbon fiber and carbon/graphite fiber.
graupel White, round or conical ice particles 1/8 to 1/4 in diameter. They often form as a thunderstorm matures and indicate the likelihood of lightning. Also referred to as soft hail or snow pellets.
gravitational acceleration The acceleration of a free-falling object caused by the Earth s gravitational pull. The acceleration rate of a freely falling object is 32.2 ft./second 2, or 980.7 cm./second 2.
gravity 1. The force of attraction between any two objects containing mass. This force is proportional to the mass of the objects. Large objects exhibiting forces of gravity are the Earth, moon, and planets. 2. One of the four main forces acting on an aircraft. Equivalent to the actual weight of the rotorcraft. It acts downward toward the center of the earth.
gravity waves A small-scale wave of air moving in vertical oscillations caused by gravity. Occurring in a stable atmosphere gravity plays the major role in forcing the air parcels to return to their equilibrium level.
great circle The largest circle which can be drawn on the earth s surface. The shortest distance between two points on a sphere.
green run The first run of a new or freshly overhauled engine.
greenhouse effect The capture of terrestrial radiation by certain atmospheric gases. These gases are commonly called greenhouse gases.
Greenwich mean time (GMT) The time at the 0 meridian located at the Royal Observatory, London, England. Also referred to as Zulu time.
greige Dacron A synthetic, polyester fabric in its natural condition as it comes from the loom.
grid 1. The electrode of a vacuum tube where the signal is applied. 2. The framework of a plate in a lead-acid battery cell. It is made of lead and antimony with the actual plate material (spongy lead or lead peroxide) attached. 3. The electrode in an electron tube between the cathode and the anode. It is used to control the amount, shape, and velocity of the electron stream between the cathode and the anode.
grind The process of removing metal from a part with an abrasive stone or wheel.
grinder A machine with an abrasive wheel used to remove material from a part.
grinding wheel An abrasive wheel used on grinders to remove excess material.
grip length The length of the unthreaded shank of a bolt. Also, the length of a blind rivet between the manufactured head and the maximum extent of the pulled head. It is the maximum thickness of material that can be joined by a fastener.
grip range The difference between the maximum and minimum thickness of material that may be joined by a fastener.
grit blasting A process for cleaning metal in which abrasive materials such as sand, rice, baked wheat, plaster pellets, glass beads, or crushed walnut shells are forcefully blown onto the part s surface.
grommet 1. A metal or plastic eyelet used for reinforcing holes in aircraft fabric. 2. A small ring of metal, rubber, or plastic used as a fairlead and protector for tubing or wire going though a hole in a metal structure.
grooved surface A shallow, smooth channel wider than a scratch resulting from wear caused by concentrated contact stress. Abnormal relative movement between contact surfaces or by foreign material on contact surfaces creates the contact stress. The parts usually affected include cylinder barrels, valve faces, and oil seal outer sleeves.
gross thrust The thrust developed by an engine, not taking into consideration any pressure of initial air mass momentum. Also referred to as static thrust (Fg).
gross weight The total weight of a fully loaded aircraft including the fuel, oil, and cargo it is carrying.
ground 1. A reference point for voltage measurement in an electrical circuit. 2. To connect a part or component to the electrical ground (normally the airframe).
ground clutter A pattern produced on the radar scope by ground returns which may degrade other radar returns in the affected area. The effect of ground clutter is minimized by the use of moving target indicator (MTI) circuits in the radar equipment resulting in a radar presentation which displays only targets which are in motion.
ground communication outlet (GCO) An unstaffed, remotely controlled, ground/ground communications facility. Pilots at uncontrolled airports may contact ATC and FSS via VHF to a telephone connection to obtain an instrument clearance or close a VFR or IFR flight plan. They may also get an updated weather briefing prior to takeoff. Pilots will use four key clicks on the VHF radio to contact the appropriate ATC facility or six key clicks to contact the FSS. The GCO system is intended to be used only on the ground.
ground controlled approach A radar approach system operated from the ground by air traffic control personnel transmitting instructions to the pilot by radio. The approach may be conducted with surveillance radar (ASR) only or with both surveillance and precision approach radar (PAR). Usage of the term GCA by pilots is discouraged except when referring to a GCA facility. Pilots should specifically request a PAR approach when a precision radar approach is desired or request an ASR or surveillance approach when a nonprecision radar approach is desired.
ground crew The people who maintain, service, and prepare the aircraft before and after flight.
ground delay The amount of delay attributed to ATC, encountered prior to departure, usually associated with a CDT program.
ground effect The condition of slightly increased air pressure below an airplane wing or helicopter rotor system that increases the amount of lift produced. It exists within approximately one-half wing span or one-half of the rotor diameter from the ground.
ground fog In the United States, a fog that is generally less than 20 feet deep
ground idle A gas turbine engine speed usually in the 60% to 70% of the maximum RPM range, used as a minimum thrust setting for ground operations.
ground loop 1. The sudden reversal of direction of travel on the ground of an airplane having a tailwheel-type landing gear. The center of gravity swings around ahead of the wheels. 2. An undesirable flow of electrical current through the braid around a shielded wire.
ground plane The reflector used in a quarter-wave radio antenna. Serves as an additional quarter-wave element.
ground potential The zero potential (no voltage difference) of electrical circuits.
ground power unit A small gas turbine whose purpose is to provide either electrical power, air pressure for starting aircraft engines, or both. A ground unit is connected to the aircraft when needed. Similar to an aircraft installed auxiliary power unit.
ground resonance On rotorcraft, an aerodynamic phenomenon associated with fully-articulated rotor systems. Ground resonance develops when the rotor blades move out of phase with each other and cause the rotor disc to become unbalanced. This condition only occurs when the rotorcraft is in contact with the ground and can cause the craft to self-destruct in a matter of
seconds. At high RPM, immediate lift-off will stop the resonance. At low RPM, immediate closing of the throttle and lowering of the collective will stop the resonance.
ground return electrical circuit An electrical circuit that uses the structure of the aircraft as one of the conductors in the circuit.
ground speed The speed of an aircraft relative to the surface of the earth.
ground support equipment (GSE) Equipment separate from the aircraft but used in direct support to facilitate maintenance. GSE can include such items as engine hoist, auxiliary power units, testing equipment, compressed air units, etc.
ground visibility Prevailing horizontal visibility near the earth s surface as reported by the United States National Weather Service or an accredited observer.
ground wave The portion of a radio wave that travels to the receiver along the surface of the Earth.
ground-adjustable propeller A propeller with a pitch that can be adjusted and locked on the ground when the engine is not operating but cannot be changed during flight.
ground-boost engine An engine that, because of supercharging (including turbocharging), can develop more power at sea level than it could without the supercharging.
ground-controlled landing approach A directed approach to landing through instructions provided by a ground controller The controller watches the aircraft on a radar scope showing the relative position of the aircraft to the glide slope and its horizontal position. The controller gives the pilot instructions necessary for keeping the aircraft on its intended path until it lands.
grounded To declare an aircraft or airman unfit for flight.
groundspeed Speed of the aircraft in relation to the ground.
group task Part of cooperative, or group learning. Each activity your students engage in is known as a group task.
growler Test equipment used to check generator and starter armatures for shorts. The growler forms the primary of a transformer and the armature forms the secondary. Shorts show up since they cause vibration in a thin piece of metal, such as a hacksaw blade, held over the armature.
guarded switch A switch protected against accidental movement by having a guard or shroud located directly over the switch. The guard must be raised before the switch can be actuated.
gudgeon pin British for wrist pin. See wrist pin.
guide vanes In a turbine engine, stationary airfoil sections positioned radially around the inside of the engine. The airfoils direct the flow of air or gases from one major part to another.
guided discussion An educational presentation where the topic to be covered by a group is introduced and the instructor participates only as necessary to keep the group focused on the subject.
guided discussion method An educational presentation typically used in the classroom where the topic to be covered by a group is introduced and the instructor participates only as necessary to keep the group focused on the subject.
guncotton Nitrocellulose. A nitrated cotton fiber used in nitrate dope.
G-unit The unit of acceleration as a measure of the force of gravity. One G-unit is the attraction of gravity for a body.
Gunk A chemical degreaser used for loosening grease and soft carbon from the surface of metal parts.
gusset A small reinforcing member used to support the corners of a structure.
gust A sudden brief increase in wind; according to U.S. weather observing practices, gusts are reported when the variation in wind speed between peaks and lulls is at least 10 knots.
gust front The sharp boundary found on the edge of a pool of cold air that is fed by the downdrafts and spreads out below the thunderstorm. A gust front is the key to the long life of a multicell thunderstorm.
gust lock Locks used to prevent controls from being damaged by wind gusts while an airplane is parked on the ground. External locks are positioned between the movable surfaces and the fixed aircraft structure. They are usually painted red and will have a warning streamer to indicate their installation. Internal control surface locks are set in the cockpit.
gustnadoes A tornado-like vortex that sometimes occurs near gust fronts and the edge of a downburst.
guttered surface Severe erosion confined to narrow areas in the direction of the gas flow. One cause is improper valve seating that allows escape of combustion gases through a narrow area. Areas affected are valve seats, cylinder heads, pistons, and valve and spark plug inserts.
Guy-Lussac s law The volume of gas is directly proportional to the absolute temperature, provided the pressure is held constant.
gyro Short for gyroscope. A wheel or disk mounted to spin rapidly about a specific axis while rotating freely
about all axes. The gyroscope exhibits rigidity in space; therefore, it remains in the same relative position to space even as the vehicle it is mounted in changes position.
gyro horizon An attitude gyroscopic instrument that indicates rotation about the pitch and roll axes.
gyrocompass A navigational instrument that uses a gyroscope as a stable reference to keep the compass from oscillating.
Gyrocopter Trademark applied to gyroplanes designed and produced by the Bensen Aircraft Company.
gyrodyne A rotorcraft whose rotors are normally engine-driven for takeoff, hovering, and landing, and forward flight through part of its speed range. Its means of propulsion, consisting usually of conventional propellers, is independent of the rotor system.
gyroplane A rotorcraft whose rotors are not engine-driven, except for initial starting, but are made to rotate by action of the air when the rotorcraft is moving; and whose means of propulsion, consisting usually of conventional propellers, is independent of the rotor system.
gyroscopic precession An inherent quality of rotating bodies, which causes an applied force to be manifested 90 in the direction of rotation from the point where the force is applied.