Aeronautical Terms beginning with C

C/A

Coarse Acquisition

CAA

Civil Aeronautics Administration

CAASD

Center For Advanced Aviation Systems Development

Cabin altitude

Cabin pressure in terms of equivalent altitude above sea level.

Cabin Pressurization

A condition where pressurized air is forced into the cabin simulating pressure conditions at a much lower altitude and increasing the aircraft occupants comfort.

Cage

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

Cage

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

Calculated Landing Time

A term that may be used in place of tentative or actual calculated landing time, whichever applies.

Calendar Month

A time period used by the FAA for certification and currency purposes. A calendar month extends from a given day until midnight of the last day of that month.

Calibrated

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

Calibrated

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

Calibrated airspeed

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

Calibrated airspeed

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

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. At certain airspeeds and with certain flap settings, the installation and instrument errors may total several knots. 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.

Calibrated orifice

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

Calibrated orifice

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

Call For Release

Wherein the overlying ARTCC requires a terminal facility to initiate verbal coordination to secure ARTCC approval for release of a departure into the en route environment.

Calm

The absence of wind or of apparent motion of the air.

Camber

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.

Cambered

CAMP

Continuous Airworthiness Maintenance Program.

CAMs

The manuals containing the certification rules under the Civil Air Regulations.

Canard

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.

Cantilever

A wing designed to carry loads without external struts.

Cap cloud

Also called cloud cap. A standing or stationary cap-like cloud crowning a mountain summit.

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.

Cardinal Altitudes

“Odd” or “Even” thousand-foot altitudes or flight levels; e.g., 5,000, 6,000, 7,000, FL 250, FL 260, FL 270.

Cardinal Flight Levels

Cardinal Altitudes. “Odd” or “Even” thousand-foot altitudes or flight levels; e.g., 5,000, 6,000, 7,000, FL 250, FL 260, FL 270.

CARF

Central Altitude Reservation Function

CARTS

Common Automated Radar Terminal System (ARTS) (to include ARTS IIIE and ARTS IIE)

CAS

Calibrated Airspeed.

CAS

Calibrated Airspeed.

Cascade Reverser

A thrust reverser normally found on turbofan engines in which a blocker door and a series of cascade vanes are used to redirect exhaust gases in a forward direction.

CAT

Clear Air Turbulence

CAT II

Category II.

Catch Point

A fix/waypoint that serves as a transition point from the high altitude waypoint navigation structure to an arrival procedure (STAR) or the low altitude ground-based navigation structure.

Category A

With respect to transport category rotorcraft, multiengine rotorcraft designed with engine and system isolation features specified in Part 29 and utilizing scheduled takeoff and landing operations under a critical engine failure concept which assures adequate designated surface area and adequate performance capability for continued safe flight in the event of engine failure.

Category A

An Aircraft Approach Category. Speed less than 91 knots.

Category B

With respect to transport category rotorcraft, single-engine or multiengine rotorcraft which do not fully meet all Category A standards. Category B rotorcraft have no guaranteed stay-up ability in the event of engine failure and unscheduled landing is assumed.

Category B

An Aircraft Approach Category. Speed 91 knots or more but less than 121 knots.

Category C

An Aircraft Approach Category. Speed 121 knots or more but less than 141 knots.

Category D

An Aircraft Approach Category. Speed 141 knots or more but less than 166 knots.

Category E

An Aircraft Approach Category. Speed 166 knots or more.

Category II operations

With respect to the operation of aircraft, a straight-in ILS approach to the runway of an airport under a Category II ILS instrument approach procedure issued by the Administrator or other appropriate authority.

Category III operations

With respect to the operation of aircraft, an ILS approach to, and landing on, the runway of an airport using a Category III ILS instrument approach procedure issued by the Administrator or other appropriate authority.

Category IIIa operations

An ILS approach and landing with no decision height (DH), or a DH below 100 feet (30 meters), and controlling runway visual range not less than 700 feet (200 meters).

Category IIIb operations

An ILS approach and landing with no DH, or with a DH below 50 feet (15 meters), and controlling runway visual range less than 700 feet (200 meters), but not less than 150 feet (50 meters).

Category IIIc operations

An ILS approach and landing with no DH and no runway visual range limitation.

CDI

Course Deviation Indicator.

CDI

Course Deviation Indicator

CDM

Collaborative Decision Making

CDM

Collaborative Decision Making. Cooperative effort between the various components of aviation transportation, both government and industry, to exchange information for better decision making.

CDR

Coded Departure Routes. Predefined routes used to route air traffic around areas of severe weather.

CDTI

Cockpit Display of Traffic Information

CDU

Control Display Unit

Ceiling

In meteorology in the U.S., (1) the height above the surface of the base of the lowest layer of clouds or obscuring phenomena aloft that hides more than half of the sky, or (2) the vertical visibility into an obscuration.

Ceiling

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.

Ceiling balloon

A small balloon used to determine the height of a cloud base or the extent of vertical visibility.

Ceiling light

An instrument which projects a vertical light beam onto the base of a cloud or into surface-based obscuring phenomena; used at night in conjunction with a clinometer to determine the height of the cloud base or as an aid in estimating the vertical visibility.

Ceilometer

A cloud-height measuring system. It projects light on the cloud, detects the reflection by a photo-electric cell, and determines height by triangulation.

Celsius temperature scale (abbreviated C)

A temperature scale with zero degrees as the melting point of pure ice and 100 degrees as the boiling point of pure water at standard sea level atmospheric pressure.

CENRAP

Center Radar Arts Processing

Center

Air Route Traffic Control Center.

Center of Gravity (CG)

(GAMA) The point at which an airplane would balance if suspended. Its distance from the reference datum is determined by dividing the total moment by the total weight of the airplane. It is the mass center of the aircraft, or the theoretical point at which the entire weight of the aircraft is assumed to be concentrated. It may be expressed in percent of MAC (mean aerodynamic cord) or in inches from the reference 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 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 specifications.

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.

Center Weather Advisory

An unscheduled weather advisory issued by Center Weather Service Unit meteorologists for ATC use to alert pilots of existing or anticipated adverse weather conditions within the next 2 hours. A CWA may modify or redefine a SIGMET.

Center Weather Advisory (CWA)

An unscheduled weather advisory issued by NWS meteorologists for use by ATC in alerting pilots to existing or anticipated adverse weather conditions within the next 2 hours. A CWA may modify a SIGMET.

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 specifications.

Center’s Area

The specified airspace within which an air route traffic control center (ARTCC) provides air traffic control and advisory service.

Centigrade temperature scale

Same as Celsius temperature scale—a temperature scale with zero degrees as the melting point of pure ice and 100 degrees as the boiling point of pure water at standard sea level atmospheric pressure.

Central East Pacific

An organized route system between the U.S. West Coast and Hawaii.

Centrifugal Flow Compressor

An impeller-shaped device that receives air at its center and slings 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.

Centroid

The distance in inches aft of the datum of the center of a compartment or a fuel tank for weight and balance purposes.

CFA

Controlled Firing Area

CFIT

Controlled Flight Into Terrain

CFIT

Controlled Flight into Terrain

CFR

Code of Federal Regulations

CFR

Code of Federal Regulations

CFR

Call For Release

CG

Center Of Gravity.

CG Arm

(GAMA) The arm obtained by adding the airplane’s individual moments and dividing the sum by the total weight.

CG Limits

(GAMA) The extreme center of gravity locations within which the aircraft must be operated at a given weight. These limits are indicated on pertinent FAA aircraft type certificate data sheets, specifications, or weight and balance records.

CG Limits Envelope

An enclosed area on a graph of the airplane loaded weight and the CG location. If lines drawn from the weight and CG cross within this envelope, the airplane is properly loaded.

CG Moment Envelope

An enclosed area on a graph of the airplane loaded weight and loaded moment. If lines drawn from the weight and loaded moment cross within this envelope, the airplane is properly loaded.

CGD

Combined Graphic Display

Chaff

Pertaining to radar, (1) short, fine strips of metallic foil dropped from aircraft, usually by military forces, specifically for the purpose of jamming radar; (2) applied loosely to echoes resulting from chaff.

Chaff

Thin, narrow metallic reflectors of various lengths and frequency responses, used to reflect radar energy. These reflectors when dropped from aircraft and allowed to drift downward result in large targets on the radar display.

Change of state

In meteorology, the transformation of water from one form, i.e., solid (ice), liquid, or gaseous (water vapor), to any other form. There are six possible transformations designated by the five terms following: condensation, evaporation, freezing, melting, or sublimation.

Changeover Point (COP)

A COP indicates the point where a frequency change is necessary between navigation aids when other than the midpoint on an airway, to receive course guidance from the facility ahead of the aircraft instead of the one behind. These COPs divide an airway or route segment and ensure continuous reception of navigational signals at the prescribed minimum en route IFR altitude.

Charted VFR Flyways

Charted VFR Flyways are flight paths recommended for use to bypass areas heavily traversed by large turbine-powered aircraft. Pilot compliance with recommended flyways and associated altitudes is strictly voluntary. VFR Flyway Planning charts are published on the back of existing VFR Terminal Area charts.

Charted Visual Flight Procedure Approach

An approach conducted while operating on an instrument flight rules (IFR) flight plan which authorizes the pilot of an aircraft to proceed visually and clear of clouds to the airport via visual landmarks and other information depicted on a charted visual flight procedure. This approach must be authorized and under the control of the appropriate air traffic control facility. Weather minimums required are depicted on the chart.

Chase Aircraft

An aircraft flown in proximity to another aircraft normally to observe its performance during training or testing.

CHDO

An FAA Flight Standards Certificate Holding District Office.

Checklist

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.

Chinook

A warm, dry foehn wind blowing down the eastern slopes of the Rocky Mountains over the adjacent plains in the U.S. and Canada.

Chord

A straight-line distance across a wing from leading edge to trailing edge.

Chord Line

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

CIGS

Ceilings. The height above the ground of the base of the lowest layer of clouds when over half of the sky is obscured.

Circle To Runway (Runway Number)

Used by ATC to inform the pilot that he/she must circle to land because the runway in use is other than the runway aligned with the instrument approach procedure. When the direction of the circling maneuver in relation to the airport/runway is required, the controller will state the direction (eight cardinal compass points) and specify a left or right downwind or base leg as appropriate; e.g., “Cleared VOR Runway Three Six Approach circle to Runway Two Two,” or “Circle northwest of the airport for a right downwind to Runway Two Two.”

Circle-To-Land Maneuver

A maneuver initiated by the pilot to align the aircraft with a runway for landing when a straight-in landing from an instrument approach is not possible or is not desirable. At tower controlled airports, this maneuver is made only after ATC authorization has been obtained and the pilot has established required visual reference to the airport.

Circling approach

A maneuver initiated by the pilot to align the aircraft with a runway for landing when a straight- in landing from an instrument approach is not possible or is not desirable.

Circling Minima

Landing Minimums [for a circling approach].

Circuit Breaker

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

Cirriform

All species and varieties of cirrus, cirrocumulus, and cirrostratus clouds; descriptive of clouds composed mostly or entirely of small ice crystals, usually transparent and white; often producing halo phenomena not observed with other cloud forms. Average height ranges upward from 20,000 feet in middle latitudes.

Cirrocumulus

A cirriform cloud appearing as a thin sheet of small white puffs resembling flakes or patches of cotton without shadows; sometimes confused with altocumulus.

Cirrostratus

A cirriform cloud appearing as a whitish veil, usually fibrous, sometimes smooth; often produces halo phenomena; may totally cover the sky.

Cirrus

A cirriform cloud in the form of thin, white feather-like clouds in patches or narrow bands; have a fibrous and/or silky sheen; large ice crystals often trail downward a considerable vertical distance in fibrous, slanted, or irregularly curved wisps called mares’ tails.

Civil Air Regulation (CAR)

Predecessor to the Federal Aviation Regulations.

Civil aircraft

Aircraft other than public aircraft.

Civil twilight

The period of time before sunrise and after sunset when the sun is not more than 6° below the horizon.

Class

(1) As used with respect to the certification, ratings, privileges, and limitations of airmen, a classification of aircraft within a category having similar operating characteristics. Examples include: single engine; multiengine; land; water; gyroplane; helicopter; airship; and free balloon; and
(2) As used with respect to the certification of aircraft, a broad grouping of aircraft having similar characteristics of propulsion, flight, or landing. Examples include: airplane; rotorcraft; glider; balloon; landplane; and seaplane.

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 A airspace

Class B airspace

Airspace from the surface to 10,000 feet MSL surrounding the nations 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 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 C airspace

Class C Service

This service provides, in addition to basic radar service, approved separation between IFR and VFR aircraft, and sequencing of VFR aircraft, and sequencing of VFR arrivals to the primary airport.

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 D airspace

Class D Airspace

Controlled Airspace.

Class E

Generally, if the airspace is not Class A, Class B, Class C, or Class D, and it is controlled airspace, it is Class E airspace. Class E airspace extends upward from either the surface or a designated altitude to the overlying or adjacent controlled airspace. When designated as a surface area, the airspace will be configured to contain all instrument procedures. Also in this class are Federal airways, airspace beginning at either 700 or 1,200 feet AGL used to transition to/from the terminal or en route environment, en route domestic, and offshore airspace areas designated below 18,000 feet MSL. Unless designated at a lower altitude, Class E airspace begins at 14,500 MSL over the United States, including that airspace overlying the waters within 12 nautical miles of the coast of the 48 contiguous States and Alaska, up to, but not including 18,000 feet MSL, and the airspace above FL 600.

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.

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.

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.

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.

Clear air turbulence

Turbulence encountered in air where no clouds are present; more popularly applied to high level turbulence associated with wind shear. (abbreviated CAT)

Clear Air Turbulence (CAT)

Turbulence encountered in air where no clouds are present. This term is commonly applied to high-level turbulence associated with wind shear. CAT is often encountered in the vicinity of the jet stream.

Clear ice

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

Clear ice

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

Clear Ice

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

Clear Ice

A glossy, clear, or translucent ice formed by the relatively slow freezing of supercooled water drops. The terms “clear” and “glaze” have been used for essentially the same type of ice accretion, although some reserve “clear” for thinner accretions, which lack horns and conform to the airfoil. If the freezing becomes more rapid, clear ice will turn cloudy as small bubbles of air become trapped in the ice. If the conditions persist, the ice would be classified as mixed.

Clear icing (or clear ice)

Generally, the formation of a layer or mass of ice which is relatively transparent because of its homogeneous structure and small number and size of air spaces; used commonly as synonymous with glaze, particularly with respect to aircraft icing. Compare with rime icing. Factors which favor clear icing are large drop size, such as those found in cumuliform clouds, rapid accretion of supercooled water, and slow dissipation of latent heat of fusion.

Clear Of The Runway

A. Taxiing aircraft, which is approaching a runway, is clear of the runway when all parts of the aircraft are held short of the applicable runway holding position marking.
B. A pilot or controller may consider an aircraft, which is exiting or crossing a runway, to be clear of the runway when all parts of the aircraft are beyond the runway edge and there are no restrictions to its continued movement beyond the applicable runway holding position marking.
C. Pilots and controllers shall exercise good judgement to ensure that adequate separation exists between all aircraft on runways and taxiways at airports with inadequate runway edge lines or holding position markings.

Clearance

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

Clearance

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

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.

Clearance Void If Not Off By (Time)

Used by ATC to advise an aircraft that the departure clearance is automatically canceled if takeoff is not made prior to a specified time. The pilot must obtain a new clearance or cancel his/her IFR flight plan if not off by the specified time.

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.

Cleared (Type Of) Approach

ATC authorization for an aircraft to execute a specific instrument approach procedure to an airport; e.g., “Cleared ILS Runway Three Six Approach.”

Cleared Approach

ATC authorization for an aircraft to execute any standard or special instrument approach procedure for that airport. Normally, an aircraft will be cleared for a specific instrument approach procedure.

Cleared As Filed

Means the aircraft is cleared to proceed in accordance with the route of flight filed in the flight plan. This clearance does not include the altitude, DP, or DP Transition.

Cleared For Takeoff

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

Cleared For The Option

ATC authorization for an aircraft to make a touch-and-go, low approach, missed approach, stop and go, or full stop landing at the discretion of the pilot. It is normally used in training so that an instructor can evaluate a student’s performance under changing situations.

Cleared Through

ATC authorization for an aircraft to make intermediate stops at specified airports without refiling a flight plan while en route to the clearance limit.

Cleared To Land

ATC authorization for an aircraft to land. It is predicated on known traffic and known physical airport conditions.

Clearway

(1) For turbine engine powered airplanes certificated after August 29, 1959, an area beyond the runway, not less than 500 feet wide, centrally located about the extended centerline of the runway, and under the control of the airport authorities. The clearway is expressed in terms of a clearway plane, extending from the end of the runway with an upward slope not exceeding 1.25 percent, above which no object nor any terrain protrudes. However, threshold lights may protrude above the plane if their height above the end of the runway is 26 inches or less and if they are located to each side of the runway.
(2) For turbine engine powered airplanes certificated after September 30, 1958, but before August 30, 1959, an area beyond the takeoff runway extending no less than 300 feet on either side of the extended centerline of the runway, at an elevation no higher than the elevation of the end of the runway, clear of all fixed obstacles, and under the control of the airport authorities.

Climate

The statistical collective of the weather conditions of a point or area during a specified interval of time (usually several decades); may be expressed in a variety of ways.

Climatology

The study of climate.

Climb Gradient

The ratio between distance traveled and altitude gained.

Climb To VFR

ATC authorization for an aircraft to climb to VFR conditions within Class B, C, D, and E surface areas when the only weather limitation is restricted visibility. The aircraft must remain clear of clouds while climbing to VFR.

Climbout

That portion of flight operation between takeoff and the initial cruising altitude.

Climbout speed

With respect to rotorcraft, a referenced airspeed which results in a flight path clear of the height-velocity envelope during initial climbout.

Clinometer

An instrument used in weather observing for measuring angles of inclination; it is used in conjunction with a ceiling light to determine cloud height at night.

Close Parallel Runways

Two parallel runways whose extended centerlines are separated by less than 4,300 feet, having a Precision Runway Monitoring (PRM) system that permits simultaneous independent ILS approaches.

Closed Runway

A runway that is unusable for aircraft operations. Only the airport management/military operations office can close a runway.

Closed Traffic

Successive operations involving takeoffs and landings or low approaches where the aircraft does not exit the traffic pattern.

Cloud

A cloud is a visible accumulation of minute water droplets and/or ice particles in the atmosphere above the Earth’s surface. Cloud differs from ground fog, fog, or ice fog only in that the latter are, by definition, in contact with the Earth’s surface.

Cloud bank

Generally, a fairly well-defined mass of cloud observed at a distance; it covers an appreciable portion of the horizon sky, but does not extend overhead.

Cloud cap

Also called a cap cloud. A standing or stationary cap-like cloud crowning a mountain summit.

Cloud detection radar

A vertically directed radar to detect cloud bases and tops.

Cloudburst

In popular terminology, any sudden and heavy fall of rain, almost always of the shower type.

CLSD

Closed

CLT

Calculated Landing Time

Clutter

In radar operations, clutter refers to the reception and visual display of radar returns caused by precipitation, chaff, terrain, numerous aircraft targets, or other phenomena. Such returns may limit or preclude ATC from providing services based on radar.

CNF

Computer Navigation Fix

CNS

Communication,Navigation, and Surveillance

COA

Certificate of Waiver or Authorization

Coastal Air Defense Identification Zone

An ADIZ over the coastal waters of the United States.

Cockpit display of traffic information (CDTI)

The display and user interface for information about air traffic within approximately 80 miles. It will typically combine and show traffic data from TCAS, TIS-B, and ADS-B. Depending on features, the display may also show terrain, weather, and navigation information.

Cockpit Resource Management

Techniques designed to reduce pilot errors and manage errors that do occur utilizing cockpit human resources. The assumption is that errors are going to happen in a complex system with error-prone humans.

Coefficient Of Lift

See Lift Coefficient.

Coffin Corner

The flight regime where any increase in airspeed will induce high speed mach buffet and any decrease in airspeed will induce low speed mach buffet.

Cognitive domain

A grouping of levels of learning associated with mental activity. In order of increasing complexity, the domains are knowledge, comprehension, application, analysis, synthesis, and evaluation.

Cold front

Any non-occluded front which moves in such a way that colder air replaces warmer air.

Cold Front

Any nonoccluded front that moves in such a way that colder air replaces warmer air.

Collision Hazard

A condition, event, or circumstance that could induce an occurrence of a collision or surface accident or incident.

Columns

See Database Columns

Combustion Chamber

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

Commercial operator

A person who, for compensation or hire, engages in the carriage by aircraft in air commerce of persons or property, other than as an air carrier or foreign air carrier or under the authority of Part 375 of this title. Where it is doubtful that an operation is for “compensation or hire”, the test applied is whether the carriage by air is merely incidental to the person’s other business or is, in itself, a major enterprise for profit.

Common ARTS

Includes ARTS IIE, ARTS IIIE; and ARTS IIIE with ACD (see DTAS) which combines functionalities of the previous ARTS systems.

Common Point

A significant point over which two or more aircraft will report passing or have reported passing before proceeding on the same or diverging tracks. To establish/maintain longitudinal separation, a controller may determine a common point not originally in the aircraft’s flight plan and then clear the aircraft to fly over the point.

Common Route

Typically the portion of a RNAV STAR between the en route transition end point and the runway transition start point; however, the common route may only consist of a single point that joins the en route and runway transitions.

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, FSS, or tower frequency and is identified in appropriate aeronautical publications.

Compass course

A true course corrected for variation and deviation errors.

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 instrument landing system (ILS). It can be used for navigation at distances of approximately 15 miles or as authorized in the approach procedure.

Compass rose

A small circle graduated in 360 increments, printed on navigational charts to show the amount of compass variation at different locations, or on instruments to indicate direction.

Compass Rose

A circle, graduated in degrees, printed on some charts or marked on the ground at an airport. It is used as a reference to either true or magnetic direction.

Complex Aircraft

An aircraft with retractable landing gear, flaps, and a controllable-pitch propeller, or is turbine powered.

Complex aircraft

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

Comply With Restrictions

An ATC instruction that requires an aircraft being vectored back onto an arrival or departure procedure to comply with all altitude and/or speed restrictions depicted on the procedure. This term may be used in lieu of repeating each remaining restriction that appears on the procedure.

Composite Flight Plan

A flight plan which specifies VFR operation for one portion of flight and IFR for another portion. It is used primarily in military operations.

Comprehensiveness

The degree to which a test measures the overall objective.

Compression Ratio

1. In a reciprocating engine, the ratio of the volume of an engine cylinder with the piston at the bottom center to the volume with the piston at top center. 2. In a turbine engine, the ratio of the pressure of the air at the discharge to the pressure of air at the inlet.

Compressor Bleed Air

See Bleed Air.

Compressor Bleed Valves

See Bleed Valve.

Compressor pressure ratio

The ratio of compressor discharge pressure to compressor inlet pressure.

Compressor Section

The section of a turbine engine that increases the pressure and density of the air flowing through the engine.

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 r.p.m. Compressor stall will be indicated by a rise in exhaust temperature or r.p.m. fluctuation, and if allowed to continue, may result in flameout and physical damage to the engine.

Compressor Surge

A severe compressor stall across the entire compressor that can result in severe damage if not quickly corrected. This condition occurs with a complete stoppage of airflow or a reversal of airflow.

Compulsory Reporting Points

Reporting points which must be reported to ATC. They are designated on aeronautical charts by solid triangles or filed in a flight plan as fixes selected to define direct routes. These points are geographical locations which are defined by navigation aids/fixes. Pilots should discontinue position reporting over compulsory reporting points when informed by ATC that their aircraft is in “radar contact.”

Computer navigation fix

A point used to define a navigation track for an airborne computer system such as GPS or FMS.

Computer navigation fix

A point used to define a navigation track for an airborne computer system such as GPS or FMS.

Computer-assisted instruction

Instruction in which the instructor is responsible for the class and uses the computer to assist in the instruction.

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.

Condensation

The change of water vapor to liquid water.

Condensation level

The height at which a rising parcel or layer of air would become saturated if lifted adiabatically.

Condensation nuclei

Small particles in the air on which water vapor condenses or sublimates.

Condensation trail (or contrail) (also called vapor trail)

A cloud-like streamer frequently observed to form behind aircraft flying in clear, cold, humid air.

Condition

The second part of a performance-based objective which describes the framework under which the skill or behavior will be demonstrated.

Condition Lever

In a turbine engine, a powerplant control that controls the flow of fuel to the engine. The condition lever sets the desired engine r.p.m. within a narrow range between that appropriate for ground and flight operations.

Conditionally unstable air

Unsaturated air that will become unstable on the condition it becomes saturated.

Conduction

The transfer of heat by molecular action through a substance or from one substance in contact with another; transfer is always from warmer to colder temperature.

Cone of confusion

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

Cone of confusion

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

Confidence Maneuver

A confidence maneuver consists of one or more turns, a climb or descent, or other maneuver to determine if the pilot in command (PIC) is able to receive and comply with ATC instructions.

Configuration

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

Configuration, Maintenance, and Procedures (CMP) document

A document approved by the FAA that contains minimum configuration, operating, and maintenance requirements, hardware life-limits, and Master Minimum Equipment List (MMEL) constraints necessary for an airplane-engine combination to meet ETOPS type design approval requirements.

Conflict Alert

A function of certain air traffic control automated systems designed to alert radar controllers to existing or pending situations between tracked targets (known IFR or VFR aircraft) that require his/her immediate attention/action.

Conflict Resolution

The resolution of potential conflictions between aircraft that are radar identified and in communication with ATC by ensuring that radar targets do not touch. Pertinent traffic advisories shall be issued when this procedure is applied. Note: This procedure shall not be provided utilizing mosaic radar systems.

Confusion between the symbol and the symbolized object.

Results when a word is confused with what it is meant to represent. Words and symbols create confusion when they mean different things to different people.

Consensus standard

For the purpose of certificating light-sport aircraft, an industry-developed consensus standard that applies to aircraft design, production, and airworthiness. It includes, but is not limited to, standards for aircraft design and performance, required equipment, manufacturer quality assurance systems, production acceptance test procedures, operating instructions, maintenance and inspection procedures, identification and recording of major repairs and major alterations, and continued airworthiness.

CONSOL or CONSOLAN

A kind of low or medium frequency long range navigational aid.

Consolan

A low frequency, long-distance NAVAID used principally for transoceanic navigations.

Constant pressure chart

A chart of a constant pressure surface; may contain analyses of height, wind, temperature, humidity, and/or other elements.

Constant Speed Propeller

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

Constant-speed propeller

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.

Contact

A. Establish communication with (followed by the name of the facility and, if appropriate, the frequency to be used).
B. A flight condition wherein the pilot ascertains the attitude of his/her aircraft and navigates by visual reference to the surface.

Contact Approach

An approach where an aircraft on an IFR flight plan, having an air traffic control authorization, operating clear of clouds with at least one mile flight visibility, and a reasonable expectation of continuing to the destination airport in those conditions, may deviate from the instrument approach procedure and proceed to the destination airport by visual reference to the surface. This approach will only be authorized when requested by the pilot and the reported ground visibility at the destination airport is at least one statute mile.

Contaminated Runway

A runway is considered contaminated whenever standing water, ice, snow, slush, frost in any form, heavy rubber, or other substances are present. A runway is contaminated with respect to rubber deposits or other friction-degrading substances when the average friction value for any 500-foot segment of the runway within the ALD fails below the recommended minimum friction level and the average friction value in the adjacent 500-foot segments falls below the maintenance planning friction level.

Conterminous U.S.

The 48 adjoining States and the District of Columbia.

Continental polar air

Also called polar air. An air mass with characteristics developed over high latitudes, especially within the subpolar highs. Continental polar air (cP) has cold surface temperatures, low moisture content, and, especially in its source regions, has great stability in the lower layers. It is shallow in comparison with Arctic air.

Continental tropical air

Also called tropical air. An air mass with characteristics developed over low latitudes. Continental tropical (cT) is produced over subtropical arid regions and is hot and very dry.

Continental United States

The 49 States located on the continent of North America and the District of Columbia.

Continue

When used as a control instruction should be followed by another word or words clarifying what is expected of the pilot. Example: “continue taxi,” “continue descent,” “continue inbound,” etc.

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.

Contour

In meteorology, (1) a line of equal height on a constant pressure chart; analogous to contours on a relief map; (2) in radar meteorology, a line on a radar scope of equal echo intensity.

Contouring circuit

On weather radar, a circuit which displays multiple contours of echo intensity simultaneously on the plan position indicator or range-height indicator scope. A line on a radar scope of equal echo intensity.

Contrail

Contraction for condensation trail.

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 Area [ICAO]

A controlled airspace extending upwards from a specified limit above the earth.

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.

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.

Control pressures

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

Control pressures

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

Control Sector

An airspace area of defined horizontal and vertical dimensions for which a controller or group of controllers has air traffic control responsibility, normally within an air route traffic control center or an approach control facility. Sectors are established based on predominant traffic flows, altitude strata, and controller workload. Pilot-communications during operations within a sector are normally maintained on discrete frequencies assigned to the sector.

Control Touch

The ability to sense the action of the airplane and its probable actions in the immediate future, with regard to attitude and speed variations, by sensing and evaluation of varying pressures and resistance of the control surfaces transmitted through the cockpit flight controls.

Controllability

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

Controllable Pitch Propeller

A propeller in which the blade angle can be changed during flight by a control in the cockpit.

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.

Controlled airspace

Controlled Firing Area

A controlled firing area is established to contain activities, which if not conducted in a controlled environment, would be hazardous to nonparticipating aircraft.

Controlled Flight Into Terrain (CFIT)

A situation where a mechanically normally functioning airplane is inadvertently flown into the ground, water, or an obstacle. There are two basic causes of CFIT accidents; both involve flight crew situational awareness. One definition of situational awareness is an accurate perception by pilots of the factors and conditions currently affecting the safe operation of the aircraft and the crew. The causes of CFIT are the flight crews lack of vertical position awareness or their lack of horizontal position awareness in relation to terrain and obstacles.

Controlled Time Of Arrival

Arrival time assigned during a Traffic Management Program. This time may be modified due to adjustments or user options.

Controller

Air Traffic Control Specialist.

Convection

(l) In general, mass motions within a fluid resulting in transport and mixing of the properties of that fluid. (2) In meteorology, atmospheric motions that are predominantly vertical, resulting in vertical transport and mixing of atmospheric properties; distinguished from advection.

Convection

An atmospheric motion resulting in the transport and mixing of atmospheric properties.

Convective cloud

Cumuliform. A term descriptive of all convective clouds exhibiting vertical development in contrast to the horizontally extended stratiform types.

Convective condensation level (abbreviated CCL)

The lowest level at which condensation will occur as a result of convection due to surface heating. When condensation occurs at this level, the layer between the surface and the CCL will be thoroughly mixed, temperature lapse rate will be dry adiabatic, and mixing ratio will be constant.

Convective instability

The state of an unsaturated layer of air whose lapse rates of temperature and moisture are such that when lifted adiabatically until the layer becomes saturated, convection is spontaneous.

Convective SIGMET

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

Convective SIGMET

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

Convective SIGMET

A weather advisory concerning convective weather significant to the safety of all aircraft. Convective SIGMETs are issued for tornadoes, lines of thunderstorms, embedded thunderstorms of any intensity level, areas of thunderstorms greater than or equal to VIP level 4 with an area coverage of 4/10 (40%) or more, and hail 3/4 inch or greater.

Convective weather

Unstable, rising air found in cumuliform clouds.

Conventional Landing Gear

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

Convergence

The condition that exists when the distribution of winds within a given area is such that there is a net horizontal inflow of air into the area. In convergence at lower levels, the removal of the resulting excess is accomplished by an upward movement of air; consequently, areas of low-level convergent winds are regions favorable to the occurrence of clouds and precipitation. Compare with divergence.

Cooperative or group learning

An instructional strategy which organizes students into small groups so that they can work together to maximize their own and each other’s learning.

Coordinated Flight

Application of all appropriate flight and power controls to prevent slipping or skidding in any flight condition.

Coordinated flight

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

Coordinated flight

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

Coordinates

The intersection of lines of reference, usually expressed in degrees/minutes/seconds of latitude and longitude, used to determine position or location.

Coordination

The ability to use the hands and feet together subconsciously and in the proper relationship to produce desired results in the airplane.

COP

Changeover Point.

Copter

Helicopter.

Core Airflow

Air drawn into the engine for the gas generator.

Coriolis force

A deflective force resulting from earth’s rotation; it acts to the right of wind direction in the Northern Hemisphere and to the left in the Southern Hemisphere.

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 stimulating the brains motion sensing system.

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.

Corona

A prismatically colored circle or arcs of a circle with the sun or moon at its center; coloration is from blue inside to red outside (opposite that of a halo); varies in size (much smaller) as opposed to the fixed diameter of the halo; characteristic of clouds composed of water droplets and valuable in differentiating between middle and cirriform clouds.

Corposant

St. Elmo’s Fire. A luminous brush discharge of electricity from protruding objects, such as masts and yardarms of ships, aircraft, lightning rods, steeples, etc., occurring in stormy weather. Also called corposant.

Corrected altitude

Indicated altitude of an aircraft altimeter corrected for the temperature of the column of air below the aircraft, the correction being based on the estimated departure of existing temperature from standard atmospheric temperature; an approximation of true altitude.

Correction

An error has been made in the transmission and the correct version follows.

Correlation

A basic level of learning where the student can associate what has been learned, understood, and applied with previous or subsequent learning.

COTS

Commercial Off The Shelf

Coupled 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.

Coupled Approach

A coupled approach is an instrument approach performed by the aircraft autopilot which is receiving position information and/or steering commands from onboard navigation equipment. In general, coupled nonprecision approaches must be discontinued and flown manually at altitudes lower than 50 feet below the minimum descent altitude, and coupled precision approaches must be flown manually below 50 feet AGL. Note: Coupled and autoland approaches are flown in VFR and IFR. It is common for carriers to require their crews to fly coupled approaches and autoland approaches (if certified) when the weather conditions are less than approximately 4,000 RVR.

Course

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

Course Controlled Airspace

A. The intended direction of flight in the horizontal plane measured in degrees from north. B. The ILS localizer signal pattern usually specified as the front course or the back course. C. The intended track along a straight, curved, or segmented MLS path.

Course of training

A complete series of studies leading to attainment of a specific goal, such as a certificate of completion, graduation, or an academic degree.

Cowl Flaps

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

CPDLC

Controller Pilot Data Link Communications

CPDLC

Controller Pilot Data Link Communications

Crab

A flight condition in which the nose of the airplane is pointed into the wind a sufficient amount to counteract a crosswind and maintain a desired track over the ground.

Crazing

Small fractures in aircraft windshields and windows caused from being exposed to the ultraviolet rays of the sun and temperature extremes.

CRC

Cyclic Redundancy Check

CRCT

Collaborative Routing Coordination Tool

Crew resource management (CRM)

The effective use of all available resources human, hardware, and information.

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” has been 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 cockpit 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.

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.

Crewmember

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

Criteria

The third part of a performance-based objective, descriptions of standards that will be used to measure the accomplishment of the objective.

Criterion-referenced testing

System of testing where students are graded against a carefully written, measurable standard or criterion rather than against each other.

Critical Altitude

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

Critical altitude

The maximum altitude at which, in standard atmosphere, it is possible to maintain, at a specified rotational speed, a specified power or a specified manifold pressure. Unless otherwise stated, the critical altitude is the maximum altitude at which it is possible to maintain, at the maximum continuous rotational speed, one of the following:
(1) The maximum continuous power, in the case of engines for which this power rating is the same at sea level and at the rated altitude.
(2) The maximum continuous rated manifold pressure, in the case of engines, the maximum continuous power of which is governed by a constant manifold pressure.

Critical Angle Of Attack

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

Critical angle of attack

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

Critical areas

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

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.

Critical Engine

The engine whose failure has the most adverse effect on directional control.

Critical Engine

The engine which, upon failure, would most adversely affect the performance or handling qualities of an aircraft.

CRM

Crew Resource Management.

CRM

Crew Resource Management.

CRM

Crew Resource Management.

Cross (Fix) At (Altitude)

Used by ATC when a specific altitude restriction at a specified fix is required.

Cross (Fix) At Or Above (Altitude)

Used by ATC when an altitude restriction at a specified fix is required. It does not prohibit the aircraft from crossing the fix at a higher altitude than specified; however, the higher altitude may not be one that will violate a succeeding altitude restriction or altitude assignment.

Cross (Fix) At Or Below (Altitude)

Used by ATC when a maximum crossing altitude at a specific fix is required. It does not prohibit the aircraft from crossing the fix at a lower altitude; however, it must be at or above the minimum IFR altitude.

Cross Controlled

A condition where aileron deflection is in the opposite direction of rudder deflection.

Cross-check

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

Crossfeed

A system that allows either engine on a twin-engine airplane to draw fuel from any fuel tank.

Crosswind

A. When used concerning the traffic pattern, the word means “crosswind leg.” B. When used concerning wind conditions, the word means a wind not parallel to the runway or the path of an aircraft.

Crosswind Component

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

Crosswind Leg

A flight path at right angles to the landing runway off its upwind end.

Cruise

Used in an ATC clearance to authorize a pilot to conduct flight at any altitude from the minimum IFR altitude up to and including the altitude specified in the clearance. The pilot may level off at any intermediate altitude within this block of airspace. Climb/descent within the block is to be made at the discretion of the pilot. However, once the pilot starts descent and verbally reports leaving an altitude in the block, he/she may not return to that altitude without additional ATC clearance. Further, it is approval for the pilot to proceed to and make an approach at destination airport and can be used in conjunction with: a. An airport clearance limit at locations with a standard/special instrument approach procedure. The CFRs require that if an instrument letdown to an airport is necessary, the pilot shall make the letdown in accordance with a standard/special instrument approach procedure for that airport, or b. An airport clearance limit at locations that are within/below/outside controlled airspace and without a standard/special instrument approach procedure. Such a clearance is NOT AUTHORIZATION for the pilot to descend under IFR conditions below the applicable minimum IFR altitude nor does it imply that ATC is exercising control over aircraft in Class G airspace; however, it provides a means for the aircraft to proceed to destination airport, descend, and land in accordance with applicable CFRs governing VFR flight operations. Also, this provides search and rescue protection until such time as the IFR flight plan is closed.

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.

Cruise Climb

A climb technique employed by aircraft, usually at a constant power setting, resulting in an increase of altitude as the aircraft weight decreases.

Cruising Altitude

An altitude or flight level maintained during en route level flight. This is a constant altitude and should not be confused with a cruise clearance.

Cruising Level

Cruising Altitude. An altitude or flight level maintained during en route level flight. This is a constant altitude and should not be confused with a cruise clearance.

CTAF

Common Traffic Advisory Frequency

CTAF

Common Traffic Advisory Frequency

CTD

Controlled Time of Departure

Cumuliform

A term descriptive of all convective clouds exhibiting vertical development in contrast to the horizontally extended stratiform types.

Cumulonimbus

A cumuliform cloud·type; it is heavy and dense, with considerable vertical extent in the form of massive towers; often with tops in the shape of an anvil or massive plume; under the base of cumulonimbus, which often is very dark, there frequently exists virga, precipitation and low ragged clouds (scud), either merged with it or not; frequently accompanied by lightning, thunder, and sometimes hail; occasionally produces a tornado or a waterspout; the ultimate manifestation of the growth of a cumulus cloud, occasionally extending well into the stratosphere.

Cumulonimbus mamma

A cumulonimbus cloud having hanging protuberances, like pouches, festoons, or udders, on the under side of the cloud; usually indicative of severe turbulence.

Cumulus

A cloud in the form of individual detached domes or towers which are usually dense and well defined; develops vertically in the form of rising mounds of which the bulging upper part often resembles a cauliflower; the sunlit parts of these clouds are mostly brilliant white; their bases are relatively dark and nearly horizontal.

Cumulus Clouds

Clouds in the form of detached domes or towers that are usually well defined. Cumulus clouds develop vertically in the form of rising mounds of which the bulging upper part often resembles a cauliflower; the sunlit parts of these clouds are mostly brilliant white. Their bases may be relatively dark and nearly horizontal.

Cumulus fractus

Cumulus clouds ( Clouds in the form of individual detached domes or towers which are usually dense and well defined) in the form of irregular shreds, appearing as if torn; have a clearly ragged appearance; applies only to stratus and cumulus, i.e., cumulus fractus and stratus fractus.

Current Flight Plan [ICAO]

The flight plan, including changes, if any, brought about by subsequent clearances.

Current Icing Product (CIP)

A graphical planning product that combines sensor and numerical model data to provide a three-dimensional diagnosis of the probability and severity of icing, plus the potential for the presence of supercooled large drops (SLD). This product is automatically produced with no human modification. More information can be found on the Aviation Weather Center (AWC) Aviation Digital Data Service (ADDS) Web site.

Current induction

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

Current Limiter

A device that limits the generator output to a level within that rated by the generator manufacturer.

Current Plan

The ATC clearance the aircraft has received and is expected to fly.

Curriculum

A set of courses in an area of specialization offered by an educational institution. A curriculum for a pilot school usually includes courses for the various pilot certificates and ratings.

Curtailment

An operator created and FAA-approved operational loading envelope that is more restrictive than the manufacturer’s CG envelope. It ensures that the aircraft will be operated within limits during all phases of flight. Curtailment typically accounts for, but is not limited to, in-flight movement of passengers and crew, service equipment, cargo variation, seating variation, etc.

Cut-away

Model of an object that is built in sections so it can be taken apart to reveal the inner structure.

CVFP

Charted Visual Flight Procedure

CVFP

Charted Visual Flight Procedure

CVRS

Computerized Voice Reservation System

CWA

Center Weather Advisory

CWSU

Center Weather Service Unit

Cyclogenesis

Any development or strengthening of cyclonic circulation in the atmosphere.

Cyclone

(l) An area of low atmospheric pressure,. which has a closed circulation that is cyclonic, i.e., as viewed from above, the circulation is counterclockwise in the Northern Hemisphere, clockwise in the Southern Hemisphere, undefined at the Equator. Because cyclonic circulation and relatively low atmospheric pressure usually co-exist, in common practice the terms cyclone and low are used interchangeably. Also, because cyclones often are accompanied by inclement (sometimes destructive) weather, they are frequently referred to simply as storms. (2) Frequently misused to denote a tornado. (3) In the Indian Ocean, a tropical cyclone of hurricane or typhoon force.

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