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Glossary of Aviation Terms

Click on the letter below to quick be taken to the words that start with that letter:




ACCELERATED STALL - A stall which occurs at a higher than normal airspeed due to additional loads present on the wing.

AERODYNAMIC (EFFECTS) - Factors caused by the flowing of the air.

ADVERSE YAW - Yawing towards the outside of a turn (in the wrong direction) when a roll is induced.

AGL - Above Ground Level

AILERONS - Surfaces at the rear outboard area of the main wing used to deflect air and create a roll force.

AIR DENSITY - The amount of air in mass per unit volume.  Dense air has less molecules per unit volume than less dense air.  Air density decreases with altitude and with increasing temperature.

AIRFOIL - Any surface which produces a dynamic change in the air as it flows over that surface.

AIRSPEED - The speed of the aircraft in relation to the air.

AIRSPEED INDICATOR - An instrument used to display airspeed.

AIR TRAFFIC CONTROL (ATC) - A service provided by the FAA which helps promote the safe operation and orderly flow of air traffic.

ALTIMETER - An instrument which indicates your flight altitude by sensing air pressure changes and displaying it in feet.

ANABATIC WIND - A current of air which flows up a slope due to heating from the surface.

AN BOLT - Air force/Navy (AN) designated bolt with very high strength.  Three marks on the head of the bolt identify it as an AN bolt.

ANGLE OF ATTACK - The angle at which a wing meets the air or relative wind.

ANGLE OF BANK - The number of degrees from level which a wing is displaced as it moves about the longitudinal axis.

ATTITUDE - The angle the chord of a wing makes with the horizon.

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BALLOONING - A sudden, often unexpected increase in nose attitude while in ground effect caused by environmental factors or excessive lift.

BASE LEG - The leg of a traffic pattern which is 90 degrees perpendicular to the landing (final approach) leg.

BEST ANGLE OF CLIMB (Vx) - The angle of attack that provides the steepest climbing flight path.  An airspeed used during climbing which will produce the greatest gain in altitude in a given distance over the ground.

BEST GLIDE SPEED - The angle of attack that allows the aircraft to fly the farthest with the engine off.

BEST RATE OF CLIMB (Vy) - The angle of attack that achieves the most altitude in the least amount of time.

BIPLANE - An aircraft with two main wings, one atop the other.

BREAKAWAY THRUST - The amount of power required to initially move the aircraft during taxi from a complete stop.

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CAMBER - The curve of an airfoil section from the leading edge to the trailing edge.

CANARD - The small wing (on some aircraft) in front of an aircraft's main wing.

CARBURETOR - A device on an engine used for mixing air and fuel.

CATABATIC WIND - A current of air which flows down a slope due to cooling near the surface.

CEILING - The height above the ground of the lowest layer of clouds that is reported as broken or overcast and is not classified as thin or partial.

CENTER OF GRAVITY (CG) - The point where the total mass of the pilot and aircraft balances.

CENTER OF LIFT - The aerodynamic point where the force of lift is focused along the wing's chord line.

CENTRIFUGAL FORCE - An apparent force that tends to move a mass to the outside of a turn.

CENTRIPETAL FORCE - An apparent force that tends to move a mass to the inside of a turn.

CHOKE - A carburetor control that enriches the air/fuel mixture for starting.

CHORD - A measurement on a wing at each point along the wing from the leading edge to the trailing edge.

CHT - Cylinder Head Temperature.  A CHT gauge is an instrument that monitors the temperature of the engines cylinder heads.

CIRRUS - This, wispy clouds which usually develop above 30,000 feet.

CLEARANCE - A communication from Air Traffic Control authorizing a pilot to enter an area of controlled airspace.

CLEARING TURNS - Two turns of 90 degrees each, which are performed in order to look for other air traffic before any flight maneuvers involving unusual attitudes are performed.

CLOSED TRAFFIC - Remaining in the traffic pattern, usually for the purpose of practicing takeoffs and landings (touch and gos).

COLD FRONT - An advancing mass of cold air.  The boundary formed by two air masses where cold air is replacing warmer air.

CONDENSATION - A change of state of water from a gas (water vapor) to a liquid.

CONTROLLED AIRSPACE - An area of airspace which may be subject to air traffic control.  Visibility and cloud clearance requirements are higher in controlled airspace, regardless of whether communications with ATC are required or not.

CONTROL STICK - A vertical tube that the pilot moves to effect pitch and roll control.

CONVECTION - A vertical circulation of air which results from warm air rising, cooling and then descending.

COORDINATED TURN - A turn in which slip or skid does not occur.

CORIOLIS EFFECT - The apparent turning of the air to the right (left in the southern hemisphere) as it moves over a period of time.

CORROSION - The eating away of metal through chemical reaction.

COURSE - The direction of flight measured in degrees from true or magnetic north.

CRABBING - Moving at an angle (in relation to your flight path) during flight to overcome the effects of a crosswind.

CRITICAL ANGLE OF ATTACK - The designed angle of attack at which the airflow over the wing will begin to separate from its surface and create a stall.

CROSS-COUNTRY - Flying to some point not visible from the takeoff point.

CROSSWIND - A wind not meeting an aircraft directly head-on.

CUMULUS CLOUDS - Puffy clouds caused by small areas of lifting air.

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DACRON - A synthetic material made by Dupont and used to cover most ultralight wings.

DENSITY ALTITUDE - The apparent altitude at which you are flying due to pressure, humidity, and temperature effects.

DEWPOINT - The temperature to which are must be cooled in order for it to be saturated.

DIHEDRAL - An upward angling of a wing from the root outward when viewed from in front.

DISPLACED THRESHOLD - Any landing area which begins at a point other than the actual end of the runway.

DOWNWIND - The leg of a traffic pattern which is opposite but parallel to the landing runway.

DRAG - Rearward acting aerodynamic forces tending to slow an aircraft down.

DRAGELONS - Control surfaces that slow one side of a wing down by creating more drag, and thus turn the wing.

DRAG STRUT - A spar from the keel to the leading edge used to prevent the wing from folding back.

DUST DEVIL - Swirling air that picks up dust caused by thermal lifting rapidly in unstable conditions.

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EDDY - See vortex.

EGT - Exhaust Gas Temperature.  An EGT gauge measures the engines exhaust gas  temperature at the exhaust port.

ELEVATOR - A control surface used to effect pitch control.

ELEVONS - Control surfaces on flying wings used to effect both pitch and roll control.

EMPENNAGE - The tail section of an aircraft consisting of the elevators, rudder, and stabilizers.

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FINAL APPROACH - The final leg of the traffic pattern which is along the extended runway centerline in the direction of landing.

FLARE - The final adjustment to the nose attitude which allows the main wheels to touch down first on an airplane with a nosewheel.

FLEX WING - An aircraft in which the wing surface may change shape in flight.

FLOATS - Small, boat-like floating devices for operating aircraft in water.

FRONT - The boundary formed between two differing air masses.

FUSELAGE - The main body of an aircraft to which the wings and gear are attached.

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GEAR - The wheels, floats, or skis, that touch down first when landing. (Hopefully!)

GLIDE PATH - The descending flight path which the aircraft makes while approaching the runway to land.

GO AROUND - An aborted landing approach.

GRADIENT - See Wind Gradient.

GROUND EFFECT - The apparent floating of an aircraft near the earth's surface due to a suppression in tip vortices.

GROUND HANDLING - Moving an aircraft around while on the ground.

GROUND SPEED - The speed of an aircraft with respect to the ground.  Airspeed combined with windspeed equals the ground speed.

GUST FRONT - A miniature cold front caused by fallout (cold descending air) from a thunderstorm that hits the ground and spreads rapidly.

GYROSCOPIC EFFECT - The tendency for a rotating mass such as a propeller to turn on an axis 90 degrees from that at which it is turned.

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HANG GLIDER - A non-powered ultralight weighing less than 155 lbs.

HEADING - The direction the nose of the aircraft is pointing during flight.

HEADWIND - A wind blowing directly into the nose of the aircraft.

HIGH PRESSURE SYSTEM - An area of high atmospheric pressure which generally means good visibility for flying.

HORIZONTAL COMPONENT OF LIFT - Another term for centripetal force.  The center-seeking force which causes an airplane to turn.

HULL - The exterior surface of a float.

HUMIDITY - The amount of water vapor contained in the air.

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IMMINENT STALL - A flight condition where the aircraft is approaching a stall but is not allowed to fully stall.

INDICATED AIRSPEED - The speed of your aircraft as indicated on the airspeed indicator.

INDICATED ALTITUDE - The altitude shown on your altimeter above mean sea level (MSL) when it is set to the current barometric pressure.

INDUCED DRAG - The part of total drag which is the result of the production of lift.

INVERSION - A situation where the temperature increases with altitude - the opposite of the normal condition (where temperature decreases with altitude).

ISOBAR - A line connecting equal points of barometric pressure, which are usually depicted on weather maps and charts by meteorologists.

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JET STREAM - A narrow band of winds at very high altitudes which is predominantly westerly (coming from the west) and is partially responsible for the movement of pressure systems.

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KEEL - The center tube of an ultralight wing.

KEY POINT - An imaginary point at the end of the base leg where a line extending from it will intersect with the horizontal stabilizer.  This point is used as a reference during landings.

KING POST - A vertical tube on some ultralights used to support the wing (with cables) on the ground.

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L/D - Lift to Drag ratio of a wing used as a measure of performance.

LAND BREEZE - A breeze, usually occurring in the evening, that blows from land to sea.

LAPSE RATE - The change (usually a decrease) in the temperature of air with an increase in altitude.  The average lapse rate of rising air is about 3.5 degrees fahrenheit per 1,000 feet.

LATERAL AXIS - The imaginary line which extends wingtip to wingtip.  Aircraft movement about this axis results in pitch change and is controlled by the elevator.

LEADING EDGE - The first part of a wing that meets the air.

LENTICULAR - A lens shaped cloud associated with mountain wave turbulence.

LIFT - The upward directed aerodynamic forces produced as a wing moves through the air.

LOAD FACTOR - The apparent weight which the wing must support at any given time.  Load factor generally increases with increased total weight of the aircraft, during turns, abrupt maneuvers, and during periods of turbulence.

LONGITUDINAL AXIS - An imaginary line from the nose to the tail of an aircraft.  Movement about this axis results in a rolling motion and is controlled by the ailerons.

LOW PRESSURE AREA - An area of low atmospheric pressure which generally means poor visibility for flying.

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MEAN SEA LEVEL (MSL) - The average height of the sea which is used as a reference for elevations in aviation.

MECHANICAL TURBULANCE - Turbulance created by obstacles near the ground as air passes close to them.

MINIMUM SINK - An aircraft's slowest vertical sinking speed with engine off.

MOUNTAIN WINDS (DOWNSLOPE) - Winds that blow from the mountain to the valley (usually at night).

MUSH - The action of descending in a semi-stalled mode.

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NAVIGATION - Determining one's position during flight and the heading necessary to reach a given destination.

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P-FACTOR - The tendency for an aircraft to yaw when a pitch control is made due to different angles of attack on the propeller.

PARASITE DRAG - The part of total drag which is not associated with the production of lift.  The shape of the aircraft and the resistance to the air through which it is moving is an example.

PITCH (CONTROL) - A nose up or down control.  Motion about the lateral axis.

PITCH (PROPELLER) A propeller designation determined by how far a propeller would advance if no slippage occurred.

PITCH STABILITY - The tendency for an aircraft to resume level flight if disturbed by a gust or a control input.

POWER OFF STALL - A stall which typically occurs during the approach to landing phase of flight

POWER ON STALL - A stall which typically occurs following takeoff, or during the initial climbout.

POWER TO WEIGHT RATIO - The ratio of the weight of the aircraft divided by the engines horsepower.

PRE-FLIGHT - A thorough check of the aircraft prior to flight.

PRESSURE ALTITUDE - The apparent altitude which varies as air pressure (and this density) varies.

PROPELLER - A device with angled blades that is spun by the engine so as to push air backwards and thereby create forward motion or thrust.

PYLON - A marker used to mark a vertical reference point.

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RELATIVE WIND - The wind a wing sees.  Relative wind is exactly opposite the flight path in a steady flow.

RIGID WING - An aircraft whose wing is fixed in a given shape as opposed to a flex wing.

ROLL - A control in which one wing moves up or down.  Motion about the longitudinal axis.

ROLL STABILITY - The tendency for a wing to level out if one wing is lifted by a gust or a control action.

ROOT - The center or keel of a wing.

ROUND OUT - The transition from the approach attitude to the landing attitude made just prior to the flare.

RUDDER - A vertical moveable surface used to yaw an aircraft.

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SEABREEZE - A wind from sea to land that sets up during the day near large bodies of water.

SECTIONAL - A chart or map showing airports, airways, terrain features and airspace limitations.

SHEAR TURBULENCE - Rough air caused by adjacent layers of air moving with different velocities.

SIMULATOR - A device set up to simulate flight.  A flight simulator may be static or may actually move on a trailer.

SKID - A sliding motion to the outside of a turn as a result of too much rudder control applied.

SLIP - A sliding motion to the outside of a turn as a result of too little rudder or elevator control applied.

SOARING - Remaining aloft by using vertical air currents or thermals.

SPIN - A continuous uncontrolled turn caused by a stalled inside wing during a turn.

SPIRAL - A steep nose-down continuous uncontrolled turn usually resulting from a worsening spin.

SPOILERS - Control surfaces on top of a wing used to 'spoil' lift and produce a turn (when used on one side) or degrade performance (when used on both sides).

STABILITY - See Pitch, Roll, and Yaw Stability.

STABILIZER - A fixed horizontal or vertical surface at an aircraft's tail used to maintain straight and level flight.  An elevator and rudder attached to the stabilizers deflect air during maneuvers.

STALL - A sudden increase in drag and loss of lift that occurs on a wing when the angle of attack is raised too high and the airflow separates from the wing.

STANDARD PRESSURE - The average pressure normal for a given height above sea level.

STEP - The notch on the bottom of a float.  'Getting on the step' means taxiing on the front part of the float.

STRATUS CLOUDS - Widespread layer clouds formed when a layer of air rises slowly.  Usually smooth conditions are associated with stratus clouds.

STROBE - A blinking light mounted on an aircraft to improve visibility.

STRUT - A brace that runs from a wing to another portion of an aircraft.

SWEEP - An angling back of the wings when viewed from above.

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TAIL - The area of an aircraft behind the main wing consisting of stabilizers, elevator, and rudder.  Also known as empennage.

TAIL DRAGGER - An aircraft with a wheel at the tail and two main gear up front.

TAIL WIND - A wind blowing directly from the rear of the aircraft.

TAXI - To run along the ground under power.

THERMAL - A warm bubble or column of rising air.

THREE-AXIS CONTROL - A control system consisting of rudder, elevator and ailerons or spoilers.

THROTTLE - The fuel control on an engine which makes it speed up or slow down.

THRUST - The forward force produced by the propeller.

THUNDERSTORM - A local violent storm caused by large volumes of rapidly rising moist air.

TIP RUDDERS - Rudders at the tips (outside ends) of a wing.  Also called dragelons.


TORQUE - Rotational force applied to the propeller.

TORQUE EFFECT - The tendency for an aircraft to roll the opposite way the propeller is rotating due to drag on the propeller.

TRAFFIC PATTERN - A prescribed traffic flow for all aircraft landing and departing at an airfield.

TRAILING EDGE - The rearward most part of a wing.

TRICYCLE GEAR - Landing gear arranged with one wheel up front and two main gear further back.

TRIKE - A landing gear/seat/engine unit that attached to a hang glider to convert it to a powered ultralight.

TRIM SPEED - The speed at which an aircraft flies with no input from the pilot.

TURBULENCE - Random swirling of the air felt as gusts and bumps in flight.


TWO-AXIS CONTROL - A control system consisting of only rudder and elevator or weight-shift and rudder.

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ULTRALIGHT - A small single place aircraft weighing less than 155 lbs if unpowered or 254 lbs if powered (U.S. FAA Regulations)

UPWIND - Into the wind, or in the direction of the prevailing wind.

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VALLEY WINDS (UPSLOPE) - Winds that blow from a valley up a mountain during the day.

VARIOMETER - An instrument indicating how fast and aircraft is rising or descending.  Also know as a VSI - Vertical Speed Indicator.

VENTURI EFFECT - The physical property of a fluid where its pressure is decreased as a result in an increase in its velocity.  Any surface which alters the flow of air creates a venturi effect to some degree.

VERTICAL AXIS - An imaginary line extending through the center of the wing of an aircraft from top to bottom.  Movement about this axis is called yaw and is controlled by the rudder.

VORTEX - A swirl or eddy in a fluid such as air.

VORTICES - Organized swirls produced at the tips of an aircraft's wings.

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WAKE TURBULANCE - Turbulance created by the wingtip vortices as an aircraft wing creates lift.

WASHOUT - Twist held in a wing so that the angle of attack of the wing tip is always less than at the root to help avoid stalling of the wing tip.

WARM FRONT - An advancing mass of warm air.

WEATHERVANING - The tendency for an airplane to turn into the wind naturally due to a greater surface area behind the center of gravity as compared to that in front.

WIND GRADIENT - A slowing of the wind near the earth's surface due to surface roughness or drag.

WINDSPEED - The speed of the air in relation to the ground.  See AIRSPEED and GROUNDSPEED.

WING - The lifting surface of an aircraft.

WINGLET - A small wing (usually a vertical surface at the tips of the main wing).

WING LOADING - The number of pounds per square foot of wing area.

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YAW - A control in which one wing moves forward or back.  Motion about the vertical axis.

YAW STABILITY - The tendency for an aircraft to resume a given heading when disturbed by a gust or control.  Sweepback or a vertical stabilizer effect yaw stability.

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