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 (C D). 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.