Glossary

100-hour inspection. An inspection required by 14 CFR section 91.409 for FAA-certificated aircraft that are operated for hire, or are used for flight instruction for hire. A 100- hour inspection is similar in content to an annual inspection, but it can be conducted by an aircraft mechanic who holds an Airframe and Powerplant rating, but does not have an Inspection Authorization. A list of the items that must be included in an annual or 100-hour inspection is included in 14 CFR part 43, Appendix D.

14 CFR. See Title 14 of the Code of Federal Regulations.

14 CFR Part 1. Federal Aviation Regulation from 14 CFR, pertaining to definitions and abbreviations of terms.

14 CFR Part 61. Federal Aviation Regulation from 14 CFR, pertaining to the issuance of pilot and instructor certificates and ratings.

14 CFR Part 67. Federal Aviation Regulation from 14 CFR, pertaining to medical standards and certification for pilots.

14 CFR Part 91. Federal Aviation Regulation from 14 CFR, pertaining to general operating and flight rules.

800-WX-BRIEF. Phone number for reaching an FAA Automated Flight Service Station 24 hours a day almost anywhere in the United States.

Aborted takeoff. To terminate a planned takeoff when it is determined that some condition exists which makes takeoff or further flight dangerous.

Above ground level (AGL). The actual height above ground level (AGL) at which the aircraft is flying.

Acceleration. Force involved in overcoming inertia, and which may be defined as a change in velocity per unit of time.

AD. See Airworthiness Directive.

ADM. See aeronautical decision-making.

Adverse yaw. A flight condition at the beginning of a turn in which the nose of the aircraft starts to move in the direction opposite the direction the turn is being made, caused by the induced drag produced by the downward-deflected tip holding back the wing as it begins to rise.

Aerodynamics. The science of the action of air on an object, and with the motion of air on other gases. Aerodynamics deals with the production of lift by the aircraft, the relative wind, and the atmosphere.

Aeronautical chart. A map used in air navigation containing all or part of the following: topographic features, hazards and obstructions, navigation aids, navigation routes, designated airspace, and airports. See also Sectional Chart.

Aeronautical decision-making (ADM). A systematic approach to the mental process used by pilots to consistently determine the best course of action in response to a given set of circumstances.

A/FD. See airport/facility directory.

AFM. See aircraft flight manual.

AFSS. See automated flight service station.

Aircraft. A device that is used or intended to be used for flight in the air.

Aircraft accident. An occurrence associated with the operation of an aircraft that takes place between the time any person boards the aircraft with the intention of flight and all such persons have disembarked, and in which any person suffers death or serious injury or in which the aircraft receives substantial damage. (NTSB 830.2)

Aircraft categories. (1) As used with respect to the certification, ratings, privileges, and limitations of airmen, means a broad classification of aircraft. Examples include: powered parachute, airplane, rotorcraft, glider, lighter-than-air, and weight-shift control. (2) As used with respect to the certification of aircraft, means a grouping of aircraft based upon intended use or operating limitations. Examples include: transport, normal, utility, acrobatic, limited, restricted, and provisional.

Aircraft flight manual (AFM). Also called the Pilot’s Operating Handbook (POH), a document developed by the aircraft manufacturer and approved by the FAA. It is specific to a particular make and model aircraft by a serial number, and contains operating procedures and limitations.

Aircraft operating instructions (AOI). An alternative to the approved term, Pilot's Operating Handbook.

Airfoil. Any surface, such as a wing or propeller, which provides aerodynamic force when it interacts with a moving stream of air.

Airmanship. A sound acquaintance with the principles of flight, the ability to operate an airplane with competence and precision both on the ground and in the air, and the exercise of sound judgment that results in optimal operational safety and efficiency.

Airmanship skills. The skills of coordination, timing, control touch, and speed sense in addition to the motor skills required to fly an aircraft.

Airport. An area of land or water that is used or intended to be used for the landing and takeoff of aircraft, including its buildings and facilities, if any.

Airport/facility directory (A/FD). A publication of the Federal Aviation Administration containing information on all airports, seaplane bases, and heliports open to the public. The A/FD contains communication data, navigational facilities, and certain special notices and procedures.

Airspace. The space above a certain geographical area.

Airworthiness. A state in which an aircraft or component meets the conditions of its type design and is in a condition for safe operation.

Airworthiness Certificate. A certificate issued by the FAA to aircraft that have been proven to meet the minimum standards set down by the Code of Federal Regulations.

Airworthiness Directive (AD). A regulatory notice sent out by the FAA to the registered owner of an aircraft informing the owner of a condition that prevents the aircraft from continuing to meet its conditions for airworthiness. Compliance with AD notes must be within the required time limit, and the fact of compliance, the date of compliance, and the method of compliance must be recorded in the aircraft’s maintenance records.

Altimeter. A flight instrument that indicates altitude by sensing pressure changes.

AME. See Aviation Medical Examiner.

Ammeter. An instrument installed in series with an electrical load used to measure the amount of current flowing through the load.

Angle of attack (AOA). The acute angle between the chord line of the airfoil and the direction of the relative wind.

Angle of incidence. The angle formed by the chord line of the wing at the keel of a WSC and a line parallel to the longitudinal axis of the WSC carriage. The angle of incidence changes in the WSC controlled by the pilot.

Anhedral. A downward slant from root to tip of an aircraft’s wing opposite from dihedral.

Annual inspection. A complete inspection of an aircraft and engine, required by the Code of Federal Regulations, to be accomplished every 12 calendar months on all certificated aircraft. Only an A&P technician holding an Inspection Authorization can conduct an annual inspection.

AOA. See angle of attack.

AOI. See aircraft operating instructions.

Arm. The horizontal distance in inches from the reference datum line to the center of gravity of an item. Used in weight and loading calculations.

AROW. Certificates and documents required to be onboard an aircraft to determine airworthiness: Airworthiness certificate, Registration certificate, Operating limitations, Weight and balance data.

ASOS. See Automated Surface Observing System.

Aspect ratio. Span of a wing divided by its average chord.

Asymmetrical airfoil. An airfoil section that is not the same on both sides of the chord line.

ATC. Air traffic control.

ATIS. See Automatic Terminal Information Service.

Attitude. The position of an aircraft as determined by the relationship of its axes and a reference, usually the earth’s horizon.

Attitude of pilot. A personal motivational predisposition to respond to persons, situations, or events in a given manner that can, nevertheless, be changed or modified through training as sort of a mental shortcut to decision-making.

Attitude management of pilot. The ability to recognize hazardous attitudes in oneself and the willingness to modify them as necessary through the application of an appropriate antidote thought.

Automated flight service station. An FAA air traffic facility that provides pilot briefings, en route radio communications, and VFR search-and-rescue services.

Automated Surface Observing System (ASOS). Weather reporting system which provides surface observations every minute via digitized voice broadcasts and printed reports. Automated Weather Observing System (AWOS).

Automated weather reporting system consisting of various sensors, a processor, a computer- generated voice subsystem, and a transmitter to broadcast weather data.

Automatic Terminal Information Service (ATIS). The continuous broadcast (by radio or telephone) of recorded noncontrol, essential but routine information in selected terminal areas.

Aviation Medical Examiner (AME). A medical doctor authorized to perform aviation medical exams for aviators.

Axes of an aircraft. Three imaginary lines that pass through an aircraft’s center of gravity. The axes can be considered as imaginary axes around which the aircraft turns. The three axes pass through the center of gravity at 90° angles to each other. The axis from nose to tail is the longitudinal axis, the axis that passes side to side along the wingspan is the lateral axis and the axis that passes vertically through the center of gravity is the vertical axis.

Ballistic parachute system (BPS). An optional parachute system activated by the pilot where the parachute is extracted for the WSC by a rocket.

Balloon. The result of a roundout (flare) that is too aggressive during landing, causing the aircraft to climb.

Bank attitude. The angle of the lateral axis relative to the horizon.

Base leg. A flight path at right angles to the landing runway off its approach end. The base leg normally extends from the downwind leg to the intersection of the extended runway centerline.

Battens. The airfoil ribs of a WSC that are removed to fold up the wing.

Best-angle-of-climb speed (VX). The speed at which the aircraft produces the most gain in altitude in a given distance.

Best glide. The airspeed at which the aircraft glides the furthest for the least altitude lost when in non-powered flight.

Best-rate-of-climb speed (VY). The speed at which the aircraft produces the most gain in altitude in a given amount of time.

BPS. See ballistic parachute system.

Calibrated airspeed (CAS). Indicated airspeed corrected for installation error and instrument error. Although manufacturers attempt to keep airspeed errors to a minimum, it is not possible to eliminate all errors throughout the airspeed operating range. This error is generally greatest at low airspeeds. In the cruising and higher airspeed ranges, indicated airspeed and calibrated airspeed are approximately the same. Refer to the airspeed calibration chart to correct for possible airspeed errors.

Camber. The curvature of a wing when looking at a cross section. A wing has upper camber on its top surface and lower camber on its bottom surface.

Carburetor. (1) Pressure: A hydromechanical device employing a closed feed system from the fuel pump to the discharge nozzle. It meters fuel through fixed jets according to the mass airflow through the throttle body and discharges it under a positive pressure. Pressure carburetors are distinctly different from float-type carburetors, as they do not incorporate a vented float chamber or suction pickup from a discharge nozzle located in the venturi tube. (2) Float-type:

Consists essentially of a main air passage through which the engine draws its supply of air, a mechanism to control the quantity of fuel discharged in relation to the flow of air, and a means of regulating the quantity of fuel/air mixture delivered to the engine cylinders.

Carburetor ice. Ice that forms inside the carburetor due to the temperature drop caused by the vaporization of the fuel. Induction system icing is an operational hazard because it can cut off the flow of the fuel/air charge or vary the fuel/air ratio.

Carriage. The engine and seats, attached by a structure to wheels; sometimes referred to as the fuselage, cockpit, chaise, or airframe.

Carriage keel. The lower center tube in the carriage that runs fore and aft which connects the mast to the front tube.

CAS. See calibrated airspeed.

Cavitation. A condition that exists in a fluid pump when there is not enough pressure in the reservoir to force fluid to the inlet of the pump. The pump picks up air instead of fluid.

Center of gravity (CG). The point at which an aircraft would balance if it were possible to suspend it at that point. It is the mass center of the aircraft, or the theoretical point at which the entire weight of the WSC is assumed to be concentrated. It may be expressed in inches from the reference datum, or in percent of mean aerodynamic chord (MAC). The location depends on the distribution of weight in the aircraft.

Center of lift. The location along the chord line of an airfoil at which all the lift forces produced by the airfoil are considered to be concentrated.

Center of pressure (CP). The point along the wing chord line where lift is considered to be concentrated.

Centrifugal force. The apparent force occurring in curvilinear motion acting to deflect objects outward from the axis of rotation. For instance, when pulling out of a dive, it is the force pushing you down in your seat.

Centripetal force. The force in curvilinear motion acting toward the axis of rotation. For instance, when pulling out of a dive, it is the force that the seat exerts on the pilot to offset the centrifugal force.

Certificated Flight Instructor (CFI). A flight instructor authorized by the FAA to provide flight instruction in designated category of aircraft.

Certified Flight Instructor with a Sport Pilot Rating (CFIS). A flight instructor authorized by the FAA to provide flight instruction in designated category of aircraft for sport pilots only.

CFI. See Certified Flight Instructor.

CFIS. See Certified Flight Instructor with a Sport Pilot Rating.

CFR. See Code of Federal Regulations.

CG. See center of gravity.

Checklist. A list of procedures that provides a logical and standardized method to operate a particular make and model aircraft.

Checkride. A practical test administered by an FAA examiner or designated examiner for the purpose of issuing an FAA certificate or rating.

Chord line. An imaginary straight line drawn through an airfoil from the leading edge to the trailing edge.

Circuit breaker. A circuit-protecting device that opens the circuit in case of excess current flow. A circuit breaker differs from a fuse in that it can be reset without having to be replaced.

CL. See coefficient of lift.

Class A Airspace. Airspace from 18,000 feet MSL up to and including FL 600, including the airspace overlying the waters within 12 NM of the coast of the 48 contiguous states and Alaska; and designated international airspace beyond 12 NM of the coast of the 48 contiguous states and Alaska within areas of domestic radio navigational signal or ATC radar coverage, and within which domestic procedures are applied.

Class B Airspace. Airspace from the surface to 10,000 feet MSL surrounding the nation’s busiest airports in terms of IFR operations or passenger numbers. The configuration of each Class B airspace is individually tailored and consists of a surface area and two or more layers, and is designed to contain all published instrument procedures once an aircraft enters the airspace. For all aircraft, an ATC clearance is required to operate in the area, and aircraft so cleared receive separation services within the airspace.

Class C Airspace. Airspace from the surface to 4,000 feet above the airport elevation (charted in MSL) surrounding those airports having an operational control tower, serviced by radar approach control, and having a certain number of IFR operations or passenger numbers. Although the configuration of each Class C airspace area is individually tailored, the airspace usually consists of a 5 NM radius core surface area that extends from the surface up to 4,000 feet above the airport elevation, and a 10 NM radius shelf area that extends from 1,200 feet to 4,000 feet above the airport elevation.

Class D Airspace. Airspace from the surface to 2,500 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower. The configuration of each Class D airspace area is individually tailored, and when instrument procedures are published, the airspace will normally be designed to contain the procedures.

Class E Airspace. Airspace that is not Class A, Class B, Class C, or Class D, and is controlled airspace.

Class G Airspace. Airspace that is uncontrolled, except when associated with a temporary control tower, and has not been designated as Class A, Class B, Class C, Class D, or Class E airspace.

Clear air turbulence. Turbulence not associated with any visible moisture.

Clearance. ATC permission for an aircraft to proceed under specified traffic conditions within controlled airspace, for the purpose of providing separation between known aircraft.

Code of Federal Regulations (CFR). Regulations issued by the U.S. Federal Government as published in the Federal Register.

Coefficient of lift (CL). The ratio between lift pressure and dynamic pressure.

Cold front. The boundary between two air masses where cold air is replacing warm air.

Combustion. Process of burning the fuel/air mixture in the engine in a controlled and predictable manner.

Combustion chamber. The section of the engine into which fuel is injected and burned.

Common Traffic Advisory Frequency (CTAF). A frequency designed for the purpose of carrying out airport advisory practices while operating to or from an airport without an operating control tower. The CTAF may be a UNICOM, Multicom, automated flight service station, or tower frequency and is identified in appropriate aeronautical publications.

Controlled airspace. An airspace of defined dimensions within which air traffic control service is provided to IFR flights and to VFR flights in accordance with the airspace classification. Note: “controlled airspace” is a generic term that encompasses Class A, Class B, Class C, Class D, and Class E airspace.

Control bar. The structural part of the wing that connects the flying wires the the wing and keel. This is also used for the pilot to control the WSC pitch and roll in flight.

Control frame. The wing structural triangle which connects the control bar to the wing keel and provides the structure for the lower flying wire attachments.

Control pressure. The amount of physical exertion on the control column necessary to achieve the desired attitude.

Control tower. A terminal facility that uses air/ground communications, visual signaling, and other devices to provide ATC services to aircraft operating in the vicinity of an airport or on the movement area. Authorizes aircraft to land or takeoff at the airport controlled by the tower or to transit the Class D airspace area regardless of the flight plan or weather conditions. May also provide approach control services (radar or nonradar).

Controllability. A measure of the response of an aircraft relative to the pilot’s flight control inputs.

Course. The intended direction of flight in the horizontal plane measured in degrees from north.

Coordinated turn. Turn made by an aircraft where the horizontal component of lift is equal to the centrifugal force of the turn.

Crab angle. The angle formed between the direction an aircraft is pointed and the direction it is tracking over the ground, resulting from a crosswind component. Also called the wind correction angle.

Crewmember. A person assigned to perform duty in an aircraft during flight time.

Crew resource management (CRM). The application of team management concepts in the flight deck environment, including single pilots of general aviation aircraft. Pilots of small aircraft, as well as crews of larger aircraft, must make effective use of all available resources: human resources, hardware, and information. Human resource groups include but are not limited to pilots, dispatchers, cabin crewmembers, maintenance personnel, and air traffic controllers.

Critical angle of attack. The angle of attack at which a wing stalls regardless of airspeed, flight attitude, or weight.

CRM. See crew resource management.

Crossbar. The structural component of the WSC wing that holds the leading edges in place.

Crosswind. Wind blowing across rather than parallel to the direction of flight. In a traffic pattern, the crosswind leg is a flight path at right angles to the landing runway off its upwind end.

Crosswind component. The wind component, measured in knots, at 90° to the longitudinal axis of the runway.

Crosswind correction. Correction applied in order to maintain a straight ground track during flight when a crosswind is present.

Crosswind landing. Landing made with a wind that is blowing across rather than parallel to the landing direction.

Crosswind takeoffs. Takeoffs made during crosswind conditions.

CTAF. See Common Traffic Advisory Frequency.

Datum. An imaginary vertical plane or line from which all measurements of moment arm are taken. The datum is established by the manufacturer.

DECIDE Model. Model developed to help pilots remember the six-step decision-making process: Detect, Estimate, Choose, Identify, Do, Evaluate.

Density altitude. Pressure altitude corrected for variations from standard temperature. When conditions are standard, pressure altitude and density altitude are the same. If the temperature is above standard, the density altitude is higher than pressure altitude. If the temperature is below standard, the density altitude is lower than pressure altitude. This is an important altitude because it is directly related to the PPC’s performance.

Departure leg. The leg of the rectangular traffic pattern that is a straight course aligned with, and leading from, the takeoff runway.

Designated pilot examiner (DPE). An individual designated by the FAA to administer practical tests to pilot applicants.

Detonation. The sudden release of heat energy from fuel in an aircraft engine caused by the fuel-air mixture reaching its critical pressure and temperature. Detonation occurs as a violent explosion rather than a smooth burning process.

Dew. Moisture that has condensed from water vapor. Usually found on cooler objects near the ground, such as grass, as the near-surface layer of air cools faster than the layers of air above it.

Dewpoint. The temperature at which air reaches a state of water saturation.

Dihedral. The positive acute angle between the lateral axis of an airplane and a line through the center of a wing or horizontal stabilizer. Dihedral contributes to the lateral stability of an aircraft.

Directional stability. Stability about the vertical axis of an aircraft, whereby an aircraft tends to return, on its own, to flight aligned with the relative wind when disturbed from that equilibrium state. The wing design is the primary contributor to directional stability, causing a WSC in flight to align with the relative wind.

Ditching. Emergency landing in water.

Double-surface wing. Two pieces of fabric for most of the WSC wing which enclose the crossbar; typically used for higher speed wings.

Downwind leg. Leg of the traffic pattern flown parallel to the landing runway, but in a direction opposite to the intended landing direction.

DPE. See designated pilot examiner.

Drag. An aerodynamic force on a body acting parallel and opposite to the relative wind. The resistance of the atmosphere to the relative motion of an aircraft. Drag opposes thrust and limits the speed of the aircraft.

Drag coefficient (CD). A dimensionless number used to define the amount of total drag produced by an aircraft.

Drift angle. Angle between heading and track.

Drift correction. Correction that is applied to counter the affects of wind on an aircraft’s flight and ground track.

Dual flight. Flight time that is received and logged as training time. Dual flight time must be endorsed by a Certificated Flight Instructor.

Dynamic hydroplaning. A condition that exists when landing on a surface with standing water deeper than the tread depth of the tires. When the brakes are applied, there is a possibility that the brake will lock up and the tire will ride on the surface of the water, much like a water ski. When tires are hydroplaning, directional control and braking action are virtually impossible. An effective anti-skid system can minimize the effects of hydroplaning.

Dynamic pressure. The pressure a moving fluid would have if it were stopped. Reference 14 CFR section 61.51(h).

Dynamic stability. The property of an aircraft that causes it, when disturbed from straight-and level flight, to develop forces or moments that restore the original condition of straight and level.

EFAS. See En Route Flight Advisory Service.

EGT. See exhaust gas temperature.

E-LSA (Experimental Light-Sport Aircraft). An aircraft issued an experimental certificate under 14 CFR part 21.

ELT. See emergency locator transmitter.

Emergency frequency. Frequency that is used by aircraft in distress to gain ATC assistance.121.5 MHz is an international emergency frequency guarded by Flight Service Stations and some military and civil aircraft. Reference AIM paragraph 6-3-1.

Emergency locator transmitter (ELT). A small, self-contained radio transmitter that will automatically, upon the impact of a crash, transmit an emergency signal on 121.5, 243.0, or 406.0 MHz.

Energy management. The ability for a pilot to maintain high kinetic energy levels in turbulent air and while near the ground is energy management for WSC. Higher speed and higher power is higher energy. Lower speed and lower power is lower energy.

En Route Flight Advisory Service (EFAS). An en route weather-only AFSS service.

Encoding altimeter. A special type of pressure altimeter used to send a signal to the air traffic controller on the ground, showing the pressure altitude the aircraft is flying.

Error chain. A series of mistakes that may lead to an accident or incident. Two basic principles generally associated with the creation of an error chain are: (1) one bad decision often leads to another; and (2) as a string of bad decisions grows, it reduces the number of subsequent alternatives for continued safe flight. Aeronautical decision making is intended to break the error chain before it can cause an accident or incident.

Evaporation. The transformation of a liquid to a gaseous state, such as the change of water to water vapor.

Exhaust. The rear opening of a turbine engine exhaust duct. The nozzle acts as an orifice, the size of which determines the density and velocity of the gases as they emerge from the engine.

Exhaust gas temperature (EGT). The temperature of the exhaust gases as they leave the cylinders of a reciprocating engine.

Exhaust manifold. The part of the engine that collects exhaust gases leaving the cylinders.

FAA. See Federal Aviation Administration.

FAA inspector. FAA personnel who can administer practical and proficiency tests and can issue pilot certificates.

FAA knowledge exam. Written exam administered by the FAA as a prerequisite for pilot certification. Passing the knowledge and practical exams is required for pilot applicants to be issued FAA certificates or ratings.

Federal airways. Class E airspace areas that extend upward from 1,200 feet to, but not including, 18,000 feet MSL, unless otherwise specified.

Federal Aviation Administration (FAA). The federal agency within the Department of Transportation that has the responsibility of promoting safety in the air, by both regulation and education.

Federal Aviation Regulations (FARs). The former name of the part of 14 CFR comprised of rules prescribed by the FAA governing all aviation activities in the United States.

Field elevation. The highest point of an airport’s usable runways measured in feet from mean sea level.

Final. Leg of the traffic pattern that is a descending flightpath starting from the completion of the base-to-final turn and extending to the point of touchdown.

Fixed-pitch propellers. Propellers with fixed blade angles. Fixed-pitch propellers are designed as climb propellers, cruise propellers, or standard propellers.

Fixed-wing aircraft. An aircraft whose wing is rigidly attached to the structure. The term fixed-wing is used to distinguish these aircraft from rotary-wing aircraft, such as helicopters and autogiros.

Flare. See roundout.

Flight plan. Specified information relating to the intended flight of an aircraft that is filed orally or in writing with an FSS or an ATC facility.

Flightpath. The line, course, or track along which an aircraft is flying or is intended to be flown.

Fog. Cloud consisting of numerous minute water droplets and based at the surface; droplets are small enough to be suspended in the earth’s atmosphere indefinitely. (Unlike drizzle, it does not fall to the surface. Fog differs from a cloud only in that a cloud is not based at the surface, and is distinguished from haze by its wetness and gray color.)

Force (F). The energy applied to an object that attempts to cause the object to change its direction, speed, or motion. In aerodynamics, it is expressed as F, T (thrust), L (lift), W (weight), or D (drag), usually in pounds.

Four forces. The four fundamental forces of flight: lift, weight, drag and thrust.

Four-stroke engine. The principle of operation for some reciprocating engines involving the conversion of fuel energy into mechanical energy. The strokes are called intake, compression, power, and exhaust.

Front. The boundary between two different air masses.

Front tube. The structural member of the carriage that attaches to the top of the carriage mast to the front of the fuselage. It acts as a control stop for the control bar to avoid high angles of attack.

Fuel efficiency. Defined as the amount of fuel used to produce a specific thrust or horsepower divided by the total potential power contained in the same amount of fuel.

Fuel injection. A fuel metering system used on some aircraft reciprocating engines in which a constant flow of fuel is fed to injection nozzles in the heads of all cylinders just outside of the intake valve. It differs from sequential fuel injection in which a timed charge of high-pressure fuel is sprayed directly into the combustion chamber of the cylinder.

Fuel system. The system that delivers fuel to the carburetors or the fuel injection system composed of a fuel tank, fuel pickup, fuel filter, and fuel pump.

Fuselage. The section of the WSC carriage that consists of the cockpit, containing seats for the occupants and attachments for the landing gear and wing.

G loads. Load imposed on an airframe due to inertia (centrifugal force). 1G of load factor represents the weight of the actual aircraft. 2G represents effectively twice the aircraft’s actual weight.

Glidepath. The path of an aircraft relative to the ground while approaching a landing.

Glide ratio. The ratio of the forward distance traveled to the vertical distance an aircraft descends when it is operating without power. For example, an aircraft with a glide ratio of 10:1 will descend about 1,000 feet for every 2 miles (10,560 feet) it moves forward.

Global positioning system (GPS). A satellite based radio positioning, navigation, and time transfer system used for as a reference for navigation and measures ground speed.

Go-around. The termination of a landing approach.

Reference the AIM Pilot/Controller Glossary.

Go/No-go decision. Decision of whether or not to make a flight based on environmental, personal or mechanical factors. A focus area for human factors study.

GPS. See global positioning system.

Gross weight. The total weight of a fully loaded aircraft including the fuel, oil, crew, passengers, and cargo.

Ground-adjustable propeller. A type of aircraft propeller whose blade pitch angle can be adjusted when the engine is not running. The adjustment requires loosening the blades in the hub.

Ground effect. A condition of improved performance encountered when an airfoil is operating very close to the ground. When an airfoil is under the influence of ground effect, there is a reduction in upwash, downwash, and wingtip vortices. As a result of the reduced wingtip vortices, induced drag is reduced.

Ground track. The aircraft’s path over the ground when in flight.

Ground wires. The wires on top of the wing attached to the king post which hold up the wings on the ground and during negative loads during flight. The fore to aft ground wires which hold the king post in place fore to aft.

Groundspeed (GS). The actual speed of an aircraft over the ground. It is true airspeed adjusted for wind. Groundspeed decreases with a headwind, and increases with a tailwind. A GPS measures ground speed.

Hazardous Inflight Weather Advisory Service (HIWAS).

Recorded weather forecasts broadcast to airborne pilots over selected VORs.

Heading. The direction in which the nose of the aircraft is pointing during flight.

Headwind. A wind which blows from the direction the aircraft is flying. The ground speed of an aircraft (the speed the aircraft is moving over the ground) is less than the speed through the air by the velocity of the headwind.

Headwind component. The component of atmospheric winds that acts opposite to the aircraft’s flightpath.

HIWAS. See Hazardous Inflight Weather Advisory Service.

Horsepower. The term, originated by inventor James Watt, means the amount of work a horse could do in one second. One horsepower equals 550 foot-pounds per second, or 33,000 foot-pounds per minute.

Hour meter. An instrument installed in many aircraft to show the actual number of hours the engine has operated.

Hydroplaning. A condition that exists when landing on a surface with standing water deeper than the tread depth of the tires. When the brakes are applied, there is a possibility that the brake will lock up and the tire will ride on the surface of the water, much like a water ski. When the tires are hydroplaning, directional control and braking action are virtually impossible. An effective anti-skid system can minimize the effects of hydroplaning.

Hyperventilation. Occurs when an individual is experiencing emotional stress, fright, or pain, and the breathing rate and depth increase, although the carbon dioxide level in the blood is already at a reduced level. The result is an excessive loss of carbon dioxide from the body, which can lead to unconsciousness due to the respiratory system’s overriding mechanism to regain control of breathing.

Hypoxia. State of oxygen deficiency in the body sufficient to impair functions of the brain and other organs.

ICAO. See International Civil Aviation Organization.

Ident. Air Traffic Control request for a pilot to push the button on the transponder to identify return on the controller’s scope.

IFR. See instrument flight rules.

ILS. See instrument landing system.

IMC. See instrument meteorological conditions.

Indicated airspeed (IAS). The direct instrument reading obtained from the airspeed indicator, uncorrected for variations in atmospheric density, installation error, or instrument error. Manufacturers use this airspeed as the basis for determining airplane performance. Takeoff, landing, and stall speeds listed in the AFM or POH are indicated airspeeds and do not normally vary with altitude or temperature.

Indicated altitude. The altitude read directly from the altimeter (uncorrected) when it is set to the current altimeter setting.

Incident. An occurrence other than an accident, associated with the operation of an aircraft, which affects or could affect the safety of operations.

Induced drag. That part of total drag which is created by the production of lift. Induced drag increases with a decrease in airspeed.

Instrument flight rules (IFR). Rules governing the procedures for conducting instrument flight. Also a term used by pilots and controllers to indicate type of flight plan.

Instrument landing system (ILS). An electronic system that provides both horizontal and vertical guidance to a specific runway, used to execute a precision instrument approach procedure. Instrument meteorological conditions (IMC).

Meteorological conditions expressed in terms of visibility, distance from clouds, and ceiling less than the minimums specified for visual meteorological conditions. Flight without visual reference to the horizon.

Interference drag. Type of drag produced by placing two objects adjacent to one another. Combines the effects of form drag and skin friction.

International Civil Aviation Organization (ICAO). The United Nations agency for developing the principles and techniques of international air navigation, and fostering planning and development of international civil air transport.

International standard atmosphere (IAS). A model of standard variation of pressure and temperature.

Inversion. An increase in temperature with altitude.

Isobars. Lines which connect points of equal barometric pressure.

Jet stream. A high-velocity narrow stream of winds, usually found near the upper limit of the troposphere, which flows generally from west to east.

Keel. See wing keel and carriage keel.

Judgment. The mental process of recognizing and analyzing all pertinent information in a particular situation, a rational evaluation of alternative actions in response to it, and a timely decision on which action to take.

KIAS. Knots indicated airspeed.

Kinesthesia. The sensing of movements by feel.

King post. The post on top of the wing which is attached to the keel that holds used for the ground wires which hold up the wings on the ground and during negative loads during flight.

Knowledge exam. See FAA Knowledge Exam.

Lateral axis. An imaginary line passing through the center of gravity of a WSC and extending across the WSC from one side of the aircraft to the other side.

Leading edge. The part of an airfoil that meets the airflow first. This as a structural tube on the WSC airfoil.

Lift. One of the four main forces acting on an aircraft. On a WSC, an upward force created by the effect of airflow as it passes over and under the wing.

Lift coefficient. A coefficient representing the lift of a given airfoil. Lift coefficient is obtained by dividing the lift by the free-stream dynamic pressure and the representative area under consideration.

Lift/drag ratio. The efficiency of an airfoil section. It is the ratio of the coefficient of lift to the coefficient of drag for any given angle of attack.

Lift-off. The act of becoming airborne as a result of the wings lifting the airplane off the ground, or the pilot rotating the nose up, increasing the angle of attack to start a climb.

Light-Sport Aircraft (LSA). An aircraft that meets the requirements defined in 14 CFR section 1.1, regardless of airworthiness certification.

Limit load factor. Amount of stress, or load factor, that an aircraft can withstand before structural damage or failure occurs.

Load factor. The ratio of a specified load to the total weight of the aircraft. The specified load is expressed in terms of any of the following: aerodynamic forces, inertial forces, or ground or water reactions. Also referred to as G-loading.

Logbook. A record of activities: flight, instruction, inspection and maintenance. Reference 14 CFR part 43, 14 CFR section 61.51, and 14 CFR section 91.417.

Longitude. Measurement east or west of the Prime Meridian in degrees, minutes, and seconds. The Prime Meridian is 0° longitude and runs through Greenwich, England. Lines of longitude are also referred to as meridians.

Longitudinal axis. An imaginary line through an aircraft from nose to tail, passing through its center of gravity about which the aircraft rolls in flight. The longitudinal axis is also called the roll axis of the aircraft.

Longitudinal stability (pitching). Stability about the lateral axis. A desirable characteristic of an airplane whereby it tends to return to its trimmed angle of attack after displacement.

LSA. See Light-Sport Aircraft.

MAC. See mean aerodynamic chord.

Magnetic compass. A device for determining direction measured from magnetic north.

Magneto. A self-contained engine-driven unit that supplies electrical current to the spark plugs, completely independent of the airplane’s electrical system. Normally there are two magnetos per engine.

Make/model. Refers to the manufacturer and model of a specific aircraft.

Maneuvering altitude. An altitude above the ground that allows a sufficient margin of height to permit safe maneuvering.

Maneuvering speed (VA). The maximum speed at which full, abrupt control movement can be used without overstressing the airframe.

Maneuverability. Ability of an aircraft to change directions along a flightpath and withstand the stresses imposed upon it.

Mast. The carriage structural component that is attached to the rear of the carriage keel and the top of the front tube. The top is the carriage attachment the wing.

Maximum gross weight. The maximum authorized weight of the aircraft and all of its equipment as specified in the POH/AFM/AOI for the aircraft.

Maximum structure cruising speed (VNO). The speed not to exceed except in smooth air; the upper limit of the green arc.

Mean aerodynamic chord (MAC). The average distance from the leading edge to the trailing edge of the wing.

Mean sea level (MSL). The average height of the surface of the sea for all stages of tide. A number preceding MSL indicates altitude in feet above mean sea level.

Mechanical Turbulence. Type of turbulence caused by obstructions on the ground interfering with smooth flow of the wind. Trees, buildings and terrain can all cause mechanical turbulence.

Medical certificate. Acceptable evidence of physical fitness on a form prescribed by the Administrator.

Medium-banked turn. Turn resulting from a degree of bank (approximately 20 to 45 degrees) at which the WSC remains at a constant bank.

METAR. See Aviation Routine Weather Report.

Microburts. A strong downdraft which normally occurs over horizontal distances of 1 NM or less and vertical distances of less than 1,000 feet. In spite of its small horizontal scale, an intense microburst could induce windspeeds greater than 100 knots and downdrafts as strong as 6,000 feet per minute.

Military Operations Area (MOA). Airspace of defined vertical and lateral limits established for the purpose of separating certain military training activity from IFR traffic.

Military Training Routes (MTR). Special routes developed to allow the military to conduct low-altitude, high-speed training.

Minimum controllable airspeed. An airspeed at which any further increase in angle of attack, increase in load factor, or reduction in power, would result in an immediate stall.

Minimum drag speed (L/DMAX). The point on the total drag curve where the lift-to-drag ratio is the greatest. At this speed, total drag is minimized.

Mindset. A factor in aeronautical decision making where decision making is influenced by preconceived ideas about the outcome of events. For example, an expectation of improving weather conditions can lead to increased risk during a flight.

Mixture. The ratio of fuel to air entering the engine’s cylinders.

MOA. See Military operations Area.

Mode C transponder. A receiver/transmitter which will generate a radar reply signal upon proper interrogation; the interrogation and reply being on different frequencies. Mode C means the reply signal includes altitude information.

Moment. A force that causes or tries to cause an object to rotate. The product of the weight of an item multiplied by its arm. Moments are expressed in pound-inches (lb-in). Total moment is the weight of the PPC multiplied by the distance between the datum and the CG.

Moment arm. The distance from a datum to the applied force.

MSL. See mean sea level.

National Airspace System (NAS). The common network of United States airspace. air navigation facilities, equipment and services, airports or landing areas; sectional charts, information and services; rules, regulations and procedures, technical information; and manpower and material.

National Security Area (NSA). Area consisting of airspace of defined vertical and lateral dimensions established at locations where there is a requirement for increased security and safety of ground facilities. Pilots are requested to voluntarily avoid flying through the depicted NSA. When it is necessary to provide a greater level of security and safety, flight in NSAs may be temporarily prohibited. Regulatory prohibitions are disseminated via NOTAMs.

National Transportation Safety Board (NTSB). A United States Government independent organization responsible for investigations of accidents involving aviation, highways, waterways, pipelines, and railroads in the United States. NTSB is charged by congress to investigate every civil aviation accident in the United States.

NAVAID. Naviagtional aid.

NAV/COM. Navigation and communication radio.

Newton’s Third Law of Motion. Whenever one body exerts a force on another, the second body always exerts on the first, a force that is equal in magnitude but opposite in direction.

Nontowered Airport. An airport that does not have an operating control tower. Two-way radio communications are not required at uncontrolled airports, although it is good operating practice for pilots to transmit their intentions on the specified frequency.

NOTAM. See Notice to Airmen.

Notice to Airmen. A notice containing information concerning facilities, services, or procedures, the timely knowledge of which is essential to personnel concerned with flight operations.

Notice To Airman (NOTAM). Notice to Airman that is regulatory in nature.

Octane. The rating system of gasoline with regard to its antidetonating qualities.

Operating limitations. Limitations published by aircraft manufacturers to define limitations on maneuvers, flight load factors, speeds and other limits. Presented in the aircraft in the form of placards and printed in the limitations section of the aircraft flight manual.

Overcontrolling. Using more movement in the control column than is necessary to achieve the desired pitch-and-bank condition.

Overshooting. The act of over flying an intended spot for landing or flying through a course intended for intercept.

Overspeed. A condition in which an engine has produced more rpm than the manufacturer recommends, or a condition in which the actual engine speed is higher than the desired engine speed as set on the propeller control.

Overtemp. A condition in which a device has reached a temperature above that approved by the manufacturer or any exhaust temperature that exceeds the maximum allowable for a given operating condition or time limit. Can cause internal damage to an engine.

Parallel runways. Two or more runways at the same airport whose centerlines are parallel. In addition to runway number, parallel runways are designated as L(left) and R(right) or if three parallel runways exist, L(left), C (center) and R(right).

Parasite drag. That part of total drag created by the design or shape of PPC parts. Parasite drag increases with an increase in airspeed.

Pattern altitude. The common altitude used for aircraft maneuvering in the traffic pattern. Usually 1,000 above the airport surface.

Personality tendencies. Personal traits and characteristics of an individual that are set at a very early age and extremely resistant to change.

P-factor. A tendency for an aircraft to yaw to the left due to the descending propeller blade on the right producing more thrust than the ascending blade on the left. This occurs when the aircraft’s longitudinal axis is in a climbing attitude in relation to the relative wind. The P-factor would be to the right if the aircraft had a counterclockwise rotating propeller.

PIC. See pilot in command.

Pilotage. Navigational technique based on flight by reference to ground landmarks.

Pilot in command. The pilot responsible for the operation and safety of an aircraft.

Pilot’s Operating Handbook (POH). A document developed by the aircraft manufacturer and contains the Aircraft Flight Manual (AFM) information or Aircraft Operating Instructions (AOI) information.

Pitch. The rotation of a WSC about its lateral axis.

Pitch angle. The angle between the wing and the horizontal plane of the earth.

Pitch attitude. The angle of the longitudinal axis relative to the horizon. Pitch attitude serves as a visual reference for the pilot to maintain orchange airspeed.

Placards. Small statements or pictorial signs permanently fixed in the cockpit and visible to the pilot. Placards are used for operating limitations (e.g., weight or speeds) or to indicate the position of an operating lever (e.g., landing gear retracted or down and locked).

Planform. The shape or form of a wing as viewed from above. It may be long and tapered, short and rectangular, or various other shapes.

POH. See Pilot's Operating Handbook.

Positive Dynamic Stability. The tendency over time for an aircraft to return to a predisturbed state.

Position lights. Lights on an aircraft consisting of a red light on the left wing, a green light on the right wing, and a white light on the tail. The Code of Federal Regulations requires that these lights be displayed in flight from sunset to sunrise.

Positive static stability. The initial tendency to return to a state of equilibrium when disturbed from that state.

Porpoising. Oscillating around the lateral axis of the aircraft during landing.

Powered parachute (PPC). A powered aircraft comprised of a flexible or semi-rigid wing connected to a fuselage (cart) so that the wing is not in position for flight until the aircraft is in motion. The fuselage of a powered parachute contains the aircraft engine, a seat for each occupant and is attached to the aircraft’s landing gear.

Power-off descent. Aircraft configuration where a descent occurs with power at idle.

Powerplant. A complete engine and propeller combination with accessories.

PPC. See powered parachute.

PPCL. Powered parachute land.

PPCS. Powered parachute sea.

Practical test. Flight test administered by an FAA examiner or designated examiner as a prerequisite for pilot certification. Successful completion of the practical test is required to earn a pilot certificate or rating. Commonly known as a checkride.

Practical Test Standards (PTS). An FAA published document of standards that must be met for the issuance of a particular pilot certificate or rating. FAA inspectors and designated pilot examiners use these standards when conducting pilot practical tests, and flight instructors use the PTS while preparing applicants for practical tests.

Preflight inspection. Aircraft inspection conducted to determine if an aircraft is mechanically and legally airworthy.

Preignition. Ignition occurring in the cylinder before the time of normal ignition. Preignition is often caused by a local hot spot in the combustion chamber igniting the fuel/air mixture.

Pressure altitude. The altitude indicated when the altimeter setting window (barometric scale) is adjusted to 29.92. This is the altitude above the standard datum plane, which is a theoretical plane where air pressure (corrected to 15 ºC) equals 29.92 "Hg. Pressure altitude is used to compute density altitude, true altitude, true airspeed, and other performance data.

Private airport. Airport that is privately owned and not available to the public without prior permission. They are depicted on sectional charts for emergency and landmark purposes.

Private Pilot Certificate. An FAA-issued pilot certificate permitting carriage of passengers on a not-for-hire basis. Reference 14 CFR part 61.

Prohibited area. Designated airspace within which flight of aircraft is prohibited.

Propeller. A device for propelling an aircraft that, when rotated, produces by its action on the air, a thrust approximately perpendicular to its plane of rotation. It includes the control components normally supplied by its manufacturer.

Propeller blade angle. The angle between the propeller chord and the propeller plane of rotation.

Propeller blast. The volume of air accelerated behind a propeller producing thrust.

Propeller slipstream. The volume of air accelerated behind a propeller producing thrust.

PTS. See Practical Test Standards.

Public airport. Airport that is available to the aviation public.

Pusher configuration. Propeller configuration where the propeller shaft faces the rear of the aircraft. Thrust produced by the propeller pushes the aircraft, rather than pulling it.

Reciprocating engine. An engine that converts the heat energy from burning fuel into the reciprocating movement of the pistons. This movement is converted into a rotary motion by the connecting rods and crankshaft.

Reduction gear. The gear arrangement in an aircraft engine that allows the engine to turn at a faster speed than the propeller.

Reflex. The opposite curvature of the airfoil at the trailing edge which produces a positive pitching moment of the WSC airfoil.

Reflex lines. Wires attached to the top of the king post and the trailing edge of the airfoil to maintain the reflex of the airfoil, used on some wings for trim by raising and lowering the trailing edge of the wing.

Region of reverse command. Flight regime in which flight at a higher airspeed requires a lower power setting and a lower airspeed requires a higher power setting in order to maintain altitude.

Registration certificate. A federal certificate that documents aircraft ownership.

Relative humidity. The ratio of the existing amount of water vapor in the air at a given temperature to the maximum amount that could exist at that temperature; usually expressed in percent.

Relative wind. The direction the wind strikes an airfoil. If a wing moves forward horizontally, the relative wind moves backward horizontally. Relative wind is parallel to and opposite the flightpath of the airplane.

Restricted area. Airspace designated under 14 CFR part 73 within which the flight of aircraft, while not wholly prohibited, is subject to restriction.

Ribs. The parts of an aircraft wing structure that give the wing its aerodynamic cross section. WSC has battens that are inserted in to the sail that act as ribs.

Risk. The future impact of a hazard that is not eliminated or controlled.

Risk elements. The four fundamental areas of exposure to risk: the pilot, the aircraft, the environment, and the type of operation that comprise any given aviation situation.

Risk management. The part of the decision making process which relies on situational awareness, problem recognition, and good judgment to reduce risks associated with each flight.

Roll. The rotation of an aircraft about its longitudinal axis. It is controlled by moving the control bar side to side.

Roundout (flare). The slow, smooth transition from a normal approach attitude to a landing attitude. This maneuver is accomplished in a WSC by easing forward on the control bar from approach speed as the WSC gets near the ground for landing to reduce the descent rate to zero as the back whels are inches above the ground, continuing to move the control bar forward reducing speed as the back wheels are inches above the landing surface, and continuing to push the control bar full forward until the back wheels settle to the surface for touchdown.

RPM. Revolutions per minute for the engine crankshaft. A measure of rotational speed. One rpm is one revolution made in one minute.

Runway. A defined rectangular area on a land airport prepared for the landing and takeoff run of aircraft along its length. Runways are normally numbered in relation to their magnetic direction rounded off to the nearest 10 degrees (e.g., Runway 1, Runway 25).

Runway incursion. Any occurrence at an airport involving an aircraft, vehicle, person, or object on the ground that creates a collision hazard or results in loss of separation with an aircraft taking off, intending to takeoff, landing, or intending to land.

Runway threshold markings. Runway threshold markings come in two configurations. They either consist of eight longitudinal stripes of uniform dimensions disposed symmetrically about the runway centerline, or the number of stripes is related to the runway width. A threshold marking helps identify the beginning of the runway that is available for landing. In some instances, the landing threshold may be displaced.

Safety directive. A manufacturer issued change to a S-LSA that must be complied with. This is similar to an airworthiness directive which is a regulatory notice sent out by the FAA to the registered owner of an aircraft informing the owner of a condition that prevents the aircraft from continuing to meet its conditions for airworthiness. Airworthiness Directives (AD notes) must be complied with within the required time limit, and the fact of compliance, the date of compliance, and the method of compliance must be recorded in the aircraft’s maintenance records.

SAR. See search and rescue.

Scan. A procedure used by the pilot to visually identify all resources of information in flight.

Scanning. Systematic means of searching for other aircraft. Scanning is most effective when successive areas of the sky are brought into focus using a series of short, regularly spaced eye movements.

Scenario-based training. The instructor provides pilot, aircraft, environment, and operational risk elements to train the student to utilize ADM in making the best decision for the given set of circumstances.

SD. See safety directave.

Sea level. A reference height used to determine standard atmospheric conditions and altitude measurements.

Search and rescue (SAR). A lifesaving service provided through the combined efforts of the federal agencies signatory to the National SAR plan along with state agencies.

Sectional charts. Designed for visual navigation of slow or medium speed aircraft. Topographic information on these charts features the portrayal of relief, and a judicious selection of visual check points for VFR flight. Aeronautical information includes visual and radio aids to navigation, airports, controlled airspace, restricted areas, obstructions and related data.

See and avoid. When weather conditions permit, pilots operating IFR or VFR are required to observe and maneuver to avoid other aircraft. Right-of-way rules are contained in 14 CFR part 91.

Segmented circle. A visual indicator around a windsock or tetrahedron designed to show the traffic pattern for each runway.

Shallow-banked turn. Turns in which the bank is less than approximately 20 degrees.

Single Pilot Resource Management (SRM). Area of human factors study that addresses application of management skills in the cockpit. Single pilots of small aircraft must make effective use of all available resources; human resources, hardware, and information.

Single surface wing. one piece of fabric for most of the airfoil on a WSC with the cross bar exposed to the airflow. Typically used for slower wings.

Situational awareness. The accurate perception and understanding of all the factors and conditions within the four fundamental risk elements that affect safety before, during, and after the flight.

Skills and procedures. The procedural, psychomotor, and perceptual skills used to control a specific aircraft or its systems. They are the airmanship abilities that are gained through conventional training, are perfected, and become almost automatic through experience.

Skin. The outside covering of an aircraft airframe.

Skin friction drag. The type of parasite drag resulting from a rough surface which deflects the streamlines of air on the surface, causing resistance to smooth airflow.

S-LSA (Special Light-Sport Aircraft). An aircraft issued a special airworthiness certificate in accordance with 14 CFR section 21.290 in the light-sport category. These aircraft meet the ASTM industry-developed consensus standards.

Solo flight. Flight that is conducted and logged when a pilot is the sole occupant of an aircraft.

Spatial disorientation. Specifically refers to the lack of orientation with regard to the position, attitude, or movement of the WSC in space.

Special flight permit. A flight permit issued to an aircraft that does not meet airworthiness requirements but is capable of safe flight. A special flight permit can be issued to move an aircraft for the purposes of maintenance or repair, buyer delivery, manufacturer flight tests, evacuation from danger, or customer demonstration. Also referred to as a ferry permit.

Special Use Airspace (SUA). Airspace that exists where activities must be confined because of their nature. Consists of prohibited, restricted, warning, military operations, and alert areas.

Speed. The distance traveled in a given time.

Sport Pilot Certificate. An FAA-issued pilot certificate, allowing the holder to operate a light-sport aircraft in the category, class, make and model for which they are endorsed to do so.

SRM. See Single Pilot Resource Management.

Stabilized Approach. A landing approach in which the pilot establishes and maintains a constant angle glidepath towards a predetermined point on the landing runway. It is based on the pilot’s judgment of certain visual cues, and depends on the maintenance of a constant final descent airspeed and configuration.

Stall. A rapid decrease in lift caused by the separation of airflow from the wing’s surface brought on by exceeding the critical angle of attack. A stall can occur at any pitch attitude or airspeed.

Stalling speed. For WSC, the power-off stall speed at the maximum takeoff weight (the lower limit of the green arc).

Standard airport traffic pattern. The left-hand turn traffic flow that is prescribed for aircraft landing at, taxiing on, or taking off from an airport. Reference 14 CFR section 91.126 (a)(1) and AIM chapter 4, section 3.

Standard Atmosphere. Consisting of those atmospheric conditions at sea level that include a barometric pressure of 29.92 inches of mercury ("Hg) or 1013.2 millibars, and a temperature of 15 °C (59 °F). Pressure and temperature normally decrease as altitude increases. The standard lapse rate in the lower atmosphere for each 1,000 feet of altitude is approximately 1 "Hg and 2 °C (3.5 °F). For example, the standard pressure and temperature at 3,000 feet mean sea level (MSL) is 26.92 "Hg (29.92 – 3) and 9 °C (15 – 6).

Static pressure. The pressure of air that is still, or not moving, measured perpendicular to the surface exposed to the air.

Static stability. The initial tendency an aircraft displays when disturbed from a state of equilibrium.

Stationary front. A front that is moving at a speed of less than 5 knots.

Steep turn. Turn resulting from a degree of bank of 45 degrees or more.

Straight-in approach. Entry into the traffic pattern by interception of the extended runway centerline (final approach course) without executing any other portion of the traffic pattern.

Stress management. The personal analysis of the kinds of stress experienced while flying, the application of appropriate stress assessment tools, and other coping mechanisms.

Strobe. A high-intensity white flashing light. Strobe lights are located on aircraft wingtips to increase aircraft visibility in low light conditions.

Strut. Wing structural member used to hold the wings in place instead of the flying and ground wires for some designs. The “strutted wing” does not use a kingpost.

Student Pilot Certificate. An FAA issued certificate that permits student pilots to exercise solo pilot privileges with limitations. This can be a student’s FAA third class medical or a student pilot certificate issued for flying an LSA using a driver’s license as medical eligibility.

SUA. See special use airspace.

Surface analysis chart. A report that depicts an analysis of the current surface weather. Shows the areas of high and low pressure, fronts, temperatures, dewpoints, wind directions and speeds, local weather, and visual obstructions.

Tailwind. Wind blowing in the same direction the aircraft is moving. When an aircraft is flying with a tailwind, its speed over the ground is equal to its speed through the air, plus the speed the air is moving over the ground.

Takeoff clearance. ATC authorization for an aircraft to depart a runway. It is predicated on known traffic and known physical airport conditions.

Taxi. The movement of an aircraft under its own power while on the ground.

Taxiway. Airport area designated for aircraft surface movement.

Temporary flight restriction (TFR). Designated airspace of specified dimension where flight is temporarily restricted or prohibited. NOTAMs are issued to advise airmen of local TFR restrictions.

Terminal aerodrome forecast (TAF). A report established for the 5 statute mile radius around an airport. Utilizes the same descriptors and abbreviations as the METAR report.

Terminal Radar Service Area (TRSA). Area where participating pilots can receive additional radar services, the purpose of which is to provide separation between all IFR operations and participating VFR aircraft.

TFR. See temporary flight restriction.

Thermal. A buoyant plume or bubble of rising air.

Throttle. The control in an aircraft that regulates the power or thrust the pilot wants the engine to develop from the valve in a carburetor or fuel control unit that determines the amount of fuel-air mixture that is fed to the engine.

Thrust. The force which imparts a change in the velocity of a mass. A forward force which propels the WSC through the air.

Thrust line. An imaginary line passing through the center of the propeller hub, perpendicular to the plane of the propeller rotation.

Title 14 of the Code of Federal Regulations (14 CFR).

That portion of the code formerly called the Federal Aviation Regulations (FAR) governing the operation of aircraft, airways, and airmen.

Torque. (1) A resistance to turning or twisting. (2) Forces that produce a twisting or rotating motion. (3) In a WSC, the tendency of the aircraft to turn (roll) in the opposite direction of rotation of the engine and propeller.

Total drag. The sum of the parasite and induced drag.

Touch and go. An operation by an aircraft that lands and takes off without stopping.

Touchdown point. The point or intended point at which an aircraft first makes contact with the landing surface.

Touchdown zone. The portion of a runway, beyond the threshold, where it is intended landing aircraft first contact the runway.

Towered airport. An airport that has an operating control tower.

Track. The actual path made over the ground in flight.

Traffic pattern. The traffic flow that is prescribed for aircraft landing at or taking off from an airport.

Traffic pattern indicators. Ground based visual indicators that identify traffic pattern direction at certain airports.

Trailing edge. The aft edge of the airfoil. In normal flight, it is the portion of the airfoil where airflow over the upper surface rejoins the lower surface airflow.

Training bars. An attachment to the control frame which allows the instructor in the rear seat to move the control bar and control the pitch and bank with a solid attachment.

Transponder. The airborne portion of the secondary surveillance radar system. The transponder emits a reply when queried by a radar facility.

Tricycle gear configuration. Landing gear configuration employing a third wheel located on the nose of the aircraft.

True airspeed. Actual airspeed, determined by applying a correction for pressure altitude and temperature to the CAS. Because air density decreases with an increase in altitude, an airplane has to be flown faster at higher altitudes to cause the same pressure difference between pitot impact pressure and static pressure. Therefore, for a given calibrated airspeed, true airspeed increases as altitude increases; or for a given true airspeed, calibrated airspeed decreases as altitude increases.

True altitude. The vertical distance of the airplane above sea level. the actual altitude. It is often expressed as feet above mean sea level (MSL). Airport, terrain, and obstacle elevations on sectional charts are true altitudes.

TRSA. See Terminal Radar Service Area.

Tuck. A nose down situation in a WSC where the pitch angle is over 90 degrees down resulting from a whip stall or severe turbulence.

Tumble. The WSC rotating uncontrollably around its lateral axis from a whip stall or severe turbulence. Results of a tumble would probably cause a structural failure with catastrophic consequences.

Turbulence. An occurrence in which a flow of fluid is unsteady.

Twist. The design of the WSC wing in which a wing is twisted so its angle of attack is less at the tip than at the root.

This decreases the lift the wing produces at the tip to improve the stall characteristics of the wing. Also called washout.

Two-stroke engine. A simple form of reciprocating engine that completes its operating cycle in two strokes of its piston, one down and one up. Two-stroke-cycle engines are inefficient in their use of fuel, but their simplicity makes them popular for powering light-sport aircraft and ultralight vehicles where light weight and low cost are paramount.

Ultralight. A single person only vehicle as defined by 14 CFR section 103.1.

Uncontrolled airspace. Class G airspace that has not been designated as Class A, B, C, D, or E. It is airspace in which air traffic control has no authority or responsibility to control air traffic; however, pilots should remember there are VFR minimums which apply to this airspace.

Unicom. A nongovernment air/ground radio communication station which may provide airport information at public use airports where there is no tower or automated flight service station.

Unusable fuel. Fuel that cannot be consumed by the engine. This fuel is considered part of the empty weight of the aircraft.

Useful load. The weight of the pilot, copilot, passengers, baggage, usable fuel, and drainable oil. It is the basic empty weight subtracted from the maximum allowable gross weight. This term applies to general aviation aircraft only.

Unstabilized approach. The final approach of an aircraft that has not achieved a stable rate of descent or controlled flight track by a predetermined altitude, usually 500 feet AGL.

Unusual attitude. An unintentional, unanticipated, or extreme aircraft attitude.

Useful load. The weight of the pilot, copilot, passengers, baggage, usable fuel, and drainable oil. It is the basic empty weight subtracted from the maximum allowable gross weight. This term applies to general aviation aircraft only.

User-defined waypoints. Waypoint location and other data which may be input by the user, this is the only GPS database information that may be altered (edited) by the user.

Upwind Leg. A flight path parallel to the landing runway in the direction of landing.

Vapor lock. A problem that mostly affects gasoline-fuelled internal combustion engines. It occurs when the liquid fuel changes state from liquid to gas while still in the fuel delivery system. This disrupts the operation of the fuel pump, causing loss of feed pressure to the carburetor or fuel injection system, resulting in transient loss of power or complete stalling. Restarting the engine from this state may be difficult. The fuel can vaporise due to being heated by the engine, by the local climate, or due to a lower boiling point at high altitude.

VASI. See visual approach slope indicator.

Vehicle. Manmade means of transportation; an ultralight aircraft (not a light-sport aircraft).

Venturi. A specially shaped restriction in a tube designed to speed up the flow of fluid passing through in accordance with Bernoulli’s principle. Venturis are used in carburetors and in many types of fluid control devices to produce a pressure drop proportional to the speed of the fluid passing through them.

Venturi Effect. The effect of Bernoulli’s principle, which states that the pressure of a fluid decreases as it is speeded up without losing or gaining any energy from the outside.

Verified. Confirmation of information or configuration status.

Vertical axis (yaw). An imaginary line passing vertically through the center of gravity of an aircraft. The vertical axis is called the z-axis or the yaw axis.

Vertical speed indicator (VSI). An instrument that uses static pressure to display a rate of climb or descent in feet per minute. The VSI can also sometimes be called a vertical velocity indicator (VVI).

Vertigo. A type of spatial disorientation caused by the physical senses sending conflicting signals to the brain. Vertigo is especially hazardous when flying under conditions of poor visibility and may cause pilot incapacitation, but may be minimized by confidence in the indication of the flight instruments.

VFR. See visual flight rules.

VFR Terminal Area Charts. Charts designated to depict Class B airspace in greater detail and greater scale than sectional charts.

Vg diagram. A chart that relates velocity to load factor. It is valid only for a specific weight, configuration and altitude and shows the maximum amount of positive or negative lift the airplane is capable of generating at a given speed. Also shows the safe load factor limits and the load factor that the aircraft can sustain at various speeds.

VNE. See never-exceed speed.

VNO. See maximum structural cruising speed.

VS. See stalling speed.

VX. See best angle-of-climb speed.

VY. See best rate-of-climb speed.

Victor airways. Airways based on a centerline that extends from one VOR or VORTAC navigation aid or intersection, to another navigation aid (or through several navigation aids or intersections); used to establish a known route for en route procedures between terminal areas.

Visual approach slope indicator (VASI). A visual aid of lights arranged to provide descent guidance information during the approach to the runway. A pilot on the correct glideslope will see red lights over white lights.

Visual flight rules (VFR). Rules in the Code of Federal Regulations that govern the procedures for conducting flight under visual conditions.

Visual meteorological conditions (VMC). Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling meeting or exceeding the minimums specified for VFR.

VSI. See vertical speed indicator.

Wake turbulence. Wingtip vortices that are created when an aircraft generates lift. When an aircraft generates lift, air spills over the wingtips from the high pressure areas below the wings to the low pressure areas above them. This flow causes rapidly rotating whirlpools of air called wingtip vortices or wake turbulence.

Warm front. The boundary area formed when a warm air mass contacts and flows over a colder air mass. Warm fronts cause low ceilings and rain.

Warning area. An area containing hazards to any aircraft not participating in the activities being conducted in the area. Warning areas may contain intensive military training, gunnery exercises, or special weapons testing.

Waypoint. A designated geographical location used for route definition or progress-reporting purposes and is defined in terms of latitude/longitude coordinates.

Washout. The design of the WSC wing in which a wing is twisted so its angle of attack is less at the tip than at the root. Washout decreases the lift the wing produces at the tip to improve the stall characteristics of the wing. Also called twist.

Washout strut. The structural member attached to the leading edges which holds the tip twist for the wing at low or negative angles of attack.

WCA. See wind correction angle.

Weather briefing. Means for pilots to gather information vital to the nature of the flight from a flight service station specialist.

Weathervane. The tendency to point into the wind.

Weight. A measure of the heaviness of an object. One of the four main forces acting on an aircraft. The force by which a body is attracted downward toward the center of the Earth (or another celestial body) by gravity. Weight is equal to the mass of the body times the local value of gravitational acceleration.

Weight-Shift Control Aircraft. Powered aircraft with a framed pivoting wing and a fuselage controllable only in pitch and roll by the pilot’s ability to change the aircraft’s center of gravity with respect to the wing. Flight control of the aircraft depends on the wing’s ability to flexibly deform rather than the use of control surfaces.

Whip stall. A pitch attitude that is too high for a WSC, at which the tips would stall from flying outside the WSC limitations or flying in extreme/severe turbulence.

Wind correction angle. Correction applied to the course to establish a heading so that track will coincide with course. Also called the Crab angle.

Wind direction indicators. Indicators that include a wind sock, wind tee, or tetrahedron. Visual reference will determine wind direction and runway in use.

Wind drift correction. Correction applied to the heading of the aircraft necessary to keep the aircraft tracking over a desired track. Also called the wind correction angle or crab angle.

Wind shear. A sudden, drastic shift in wind speed, direction, or both that may occur in the horizontal or vertical plane.

Wing. A fabric skin with an aluminum frame that produces the lift necessary to support the WSC in flight; including the flight wires/control frame below and the ground wires/king post above.

Wing keel. The WSC structural component in the longitudinal center of the wing that connects the two leading edges together at the nose and connects the carriage to the wing.

Wing loading. The amount of weight that a wing must support to provide lift.

Wingspan. The maximum distance from wingtip to wingtip.

Wing twist. A design feature of the WSC that reduces the angle of attack from the root to the tip.

Wingtip vortices. The rapidly rotating air that spills over an aircraft’s wings during flight. The intensity of the turbulence depends on the aircraft’s weight, speed, and configuration. It is also referred to as wake turbulence. Vortices from heavy aircraft may be extremely hazardous to small aircraft.

World Aeronautical Charts (WAC). A standard series of aeronautical charts covering land areas of the world at a size and scale convenient for navigation (1:1,000,000) by moderate speed aircraft. Topographic information includes cities and towns, principal roads, railroads, distinctive landmarks, drainage, and relief. Aeronautical information includes visual and radio aids to navigation, airports, airways, restricted areas, obstructions and other pertinent data.

WSC. See weight-shift control.

Weight-Shift Control—Land (WSCL). WSC that takes off and lands on land. This can be wheels or ski equipped.

Weight-Shift Control—Sea (WSCS). WSC that takes of the water. This can be pontoons or a boat configuration.

Yaw. Rotation about the vertical axis of an aircraft.

Zulu time. A term used in aviation for Coordinated Universal Time (UTC) which places the entire world on one time standard.