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Flashcards in C Deck (70):

Cabin altitude

Cabin pressure in terms of equivalent altitude above sea level.



The black markings on the ball instrument indicating
its neutral position.



The instrument indication compared with a
standard value to determine the accuracy of the instrument.


Calibrated orifice

A hole of specific diameter used to delay
the pressure change in the case of a vertical speed indicator.


Calibrated airspeed (CAS)

The speed at which the aircraft
is moving through the air, found by correcting IAS for
instrument and position errors.



The camber of an airfoil is the characteristic curve
of its upper and lower surfaces. The upper camber is more
pronounced, while the lower camber is comparatively flat.
This causes the velocity of the airflow immediately above the
wing to be much higher than that below the wing.



A horizontal surface mounted ahead of the main
wing to provide longitudinal stability and control. It may
be a fixed, movable, or variable geometry surface, with or
without control surfaces.


Canard configuration

A configuration in which the span
of the forward wings is substantially less than that of the
main wing.



A wing designed to carry loads without external struts.



The height above the earth’s surface of the lowest
layer of clouds, which is reported as broken or overcast, or
the vertical visibility into an obscuration.


Center of Gravity (CG)

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


Center of gravity limits

The specified forward and aft points
within which the CG must be located during flight. These
limits are indicated on pertinent airplane specifications.


Center of gravity range

The distance between the
forward and aft CG limits indicated on pertinent airplane


Center of pressure

A point along the wing chord line
where lift is considered to be concentrated. For this reason,
the center of pressure is commonly referred to as the center
of lift.


Centrifugal flow compressor

An impeller-shaped device
that receives air at its center and slings the air outward at high
velocity into a diffuser for increased pressure. Also referred
to as a radial outflow compressor.


Centrifugal force

An outward force, that opposes centripetal
force, resulting from the effect of inertia during a turn.


Centripetal force

A center-seeking force directed inward
toward the center of rotation created by the horizontal
component of lift in turning flight.


Changeover Point (COP)

A point along the route or
airway segment between two adjacent navigation facilities
or waypoints where changeover in navigation guidance
should occur.



A tool that is used as a human factors aid in
aviation safety. It is a systematic and sequential list of all
operations that must be performed to properly accomplish
a task.


Chord line

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


Circling approach

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


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 airpsace

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 is normally 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 airpsace

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.


Clean configuration

A configuration in which all flight
control surfaces have been placed to create minimum drag.
In most aircraft this means flaps and gear retracted.



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


Clearance delivery

y. Control tower position responsible for
transmitting departure clearances to IFR flights


Clearance limit

The fix, point, or location to which an
aircraft is cleared when issued an air traffic clearance.


Clearance on request

An IFR clearance not yet received
after filing a flight plan.1


Clearance void time

Used by ATC, the time at which the
departure clearance is automatically canceled if takeoff has
not been made. The pilot must obtain a new clearance or
cancel the IFR flight plan if not off by the specified time.


Clear ice

Glossy, clear, or translucent ice formed by the
relatively slow freezing of large, supercooled water droplets.


Coefficient of lift

The ratio between lift pressure and
dynamic pressure.


Cold front

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


Compass course

A true course corrected for variation and
deviation errors.


Compass locator

A low-power, low- or medium-frequency
(L/MF) radio beacon installed at the site of the outer or middle
marker of an ILS.


Compass rose

A small circle graduated in 360° increments,
to show direction expressed in degrees.


Complex aircraft

An aircraft with retractable landing gear,
flaps, and a controllable pitch propeller.


Compressor pressure ratio

The ratio of compressor
discharge pressure to compressor inlet pressure.


Compressor stall

In gas turbine engines, a condition in
an axial-flow compressor in which one or more stages of
rotor blades fail to pass air smoothly to the succeeding
stages. A stall condition is caused by a pressure ratio that is
incompatible with the engine rpm. Compressor stall will be
indicated by a rise in exhaust temperature or rpm fluctuation,
and if allowed to continue, may result in flameout and
physical damage to the engine.


Computer navigation fix

A point used to define a
navigation track for an airborne computer system such as


Concentric rings

Dashed-line circles depicted in the plan
view of IAP charts, outside of the reference circle, that show
en route and feeder facilities.



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


Condensation nuclei

Small particles of solid matter in the air on which water vapor condenses.


Cone of confusion

A cone-shaped volume of airspace
directly above a VOR station where no signal is received,
causing the CDI to fluctuate.



This is a general term, which normally refers to the position of the landing gear and flaps.


Constant-speed propellor

A controllable-pitch propeller
whose pitch is automatically varied in flight by a governor
to maintain a constant rpm in spite of varying air loads.


Continuous flow oxygen system

System that supplies
a constant supply of pure oxygen to a rebreather bag that
dilutes the pure oxygen with exhaled gases and thus supplies a
healthy mix of oxygen and ambient air to the mask. Primarily
used in passenger cabins of commercial airliners.


Control and performance

A method of attitude instrument
flying in which one instrument is used for making attitude
changes, and the other instruments are used to monitor the
progress of the change.


Control display unit

A display interfaced with the master
computer, providing the pilot with a single control point
for all navigations systems, thereby reducing the number of
required flight deck panels.



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


Controlled airspace

An airspace of defined dimensions
within which ATC service is provided to IFR and VFR flights
in accordance with the airspace classification. It includes
Class A, Class B, Class C, Class D, and Class E airspace.


Control pressures

The amount of physical exertion on the control column necessary to achieve the desired altitude.


Convective weather

Unstable, rising air found in cumiliform clouds.


Convective SIGMET

Weather advisory concerning
convective weather significant to the safety of all aircraft,
including thunderstorms, hail, and tornadoes.


Conventional landing gear

Landing gear employing a third
rear-mounted wheel. These airplanes are also sometimes
referred to as tailwheel airplanes.


Coordinated flight

t. Flight with a minimum disturbance of
the forces maintaining equilibrium, established via effective
control use.


Coriolis illusion

The illusion of rotation or movement in an
entirely different axis, caused by an abrupt head movement,
while in a prolonged constant-rate turn that has ceased to
stimulate the brain’s motion sensing system.


Couples ailerons and rudder

Rudder and ailerons are
connected with interconnected springs in order to counteract
adverse yaw. Can be overridden if it becomes necessary to
slip the aircraft.



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


Cowl flaps

Shutter-like devices arranged around certain
air-cooled engine cowlings, which may be opened or closed
to regulate the flow of air around the engine.


Crew Resource Management (CRM)

The application of
team management concepts in the flight deck environment.
It was initially known as cockpit resource management,
but as CRM programs evolved to include cabin crews,
maintenance personnel, and others, the phrase “crew
resource management” was adopted. This includes single
pilots, as in most 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. A current definition includes
all groups routinely working with the flight crew who
are involved in decisions required to operate a flight
safely. These groups include, but are not limited to pilots,
dispatchers, cabin crewmembers, maintenance personnel,
and air traffic controllers. CRM is one way of addressing
the challenge of optimizing the human/machine interface
and accompanying interpersonal activities.


Critical altitude

The maximum altitude under standard
atmospheric conditions at which a turbocharged engine can
produce its rated horsepower.


Critical angle of attack

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


Critical areas

Areas where disturbances to the ILS localizer
and glideslope courses may occur when surface vehicles or
aircraft operate near the localizer or glideslope antennas.



The first fundamental skill of instrument flight,
also known as “scan,” the continuous and logical observation
of instruments for attitude and performance information


Cruise clearance

An ATC clearance issued to allow a
pilot to conduct flight at any altitude from the minimum
IFR altitude up to and including the altitude specified in the
clearance. Also authorizes a pilot to proceed to and make an
approach at the destination airport.


Current induction

An electrical current being induced into,
or generated in, any conductor that is crossed by lines of flux
from any magnet.