Aeronautical Terms beginning with C
Cage
The black markings on the ball instrument indicating its neutral position.
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 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.
CARF
Central Altitude Reservation Function
CAS
Calibrated Airspeed.
CAT
Category
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.
CDI
Course Deviation Indicator.
CDM
Collaborative 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
CENRAP
Center Radar Arts Processing
CFIT
Controlled Flight Into Terrain
CFR
Code of Federal Regulations
CFR
Call For Release
CGD
Combined Graphic Display
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 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.
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.
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 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 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 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 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.
Clear ice
Glossy, clear, or translucent ice formed by the relatively slow freezing of large, supercooled water droplets.
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 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.
CNF
Computer Navigation Fix
CNS
Communication,Navigation, and Surveillance
Columns
See Database Columns
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.
Compass course
A true course corrected for variation and deviation errors.
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.
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.
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.
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.
Cone of confusion
A cone-shaped volume of airspace directly above a VOR station where no signal is received, causing the CDI to fluctuate.
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.
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.
Control pressures
The amount of physical exertion on the control column necessary to achieve the desired attitude.
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 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.
Convective SIGMET
Weather advisory concerning convective weather significant to the safety of all aircraft, including thunderstorms, hail, and tornadoes.
Coordinated flight
Flight with a minimum disturbance of the forces maintaining equilibrium, established via effective control use.
COP
Changeover Point.
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.
COTS
Commercial Off The Shelf
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 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.
CPDLC
Controller Pilot Data Link Communications
CRC
Cyclic Redundancy Check
CRCT
Collaborative Routing Coordination Tool
Crew resource management (CRM)
The effective use of all available resources human, hardware, and information.
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.
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-check
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.
CTAF
Common Traffic Advisory Frequency
CTD
Controlled Time of Departure
Current Flight Plan [ICAO]
The flight plan, including changes, if any, brought about by subsequent clearances.
Current Plan
The ATC clearance the aircraft has received and is expected to fly.
CVFP
Charted Visual Flight Procedure
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