C Charlie

camber - (1) The curvature of an airfoil section relative to its chord; usually expressed as the ratio of the height of the curved line (mean line) between the leading and trailing edges to the length of a straight line between the same two points. (2) An inclination of landing wheels away from the vertical plane. an inclination of landing wheels away from the vertical plane.

capacity - (1) The largest number of passengers an aircraft can safely transport under a given set of circumstances. (2) The total number of aircraft handled by an airport under a given set of circumstances.

carbon dioxide - CO2; A gaseous byproduct caused by burning fossil fuels.

CARF (Central Altitude Reservation Function) - CARF supports United States peace and war plan objectives and other special activities. The CARF is responsible for coordinating military and civilian altitude reservations for operations within the NAS.

Category I - According to the FARs, this is a category applied to aircraft that distinguishes each according to size, weight and propulsion. This category refers to light-weight, single-engine, propeller-driven aircraft.

Category II - According to the FARs, this is a category applied to aircraft that distinguishes each according to size, weight and propulsion. This category refers to light-weight, twin-engine aircraft weighing 12,500 pounds or less.

Category III - According to the FARs, this is a category applied to aircraft that distinguishes each according to size, weight and propulsion. This category refers to basically all remaining aircraft: high-performance, single-engine, propeller airplanes, large multi-engine propeller aircraft and all turbine-powered aircraft.

CDI (Course Deviation Indicator) - The vertical needle of a VOR indicator which shows the aircraft's relative to the selected VOR radio.

CDM (Collaborative Decision Making) - A philosophy on how to conduct business between various components of aviation transportation within both government and industry.

ceiling - (1) The clarity of the air for looking upward, as in "ceiling and visibility unlimited." (2) The maximum altitude at which a given aircraft can be operated safely. (3) The maximum height at which a vehicle or its crew can fly under given conditions. (3) The height above the Earth's surface of the lowest layer of clouds or obscuring phenomena that is reported as "broken", "overcast", or "obscuration", and not classified as "thin" or "partial".

Celsius (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.

Center - Short for ARTCC.

center of gravity - The force of gravity acts on every individual part of an object, like an airplane. On an airplane it is the point at which all weight is considered to be concentrated. It is the point of balance. This center point is located along the longitudinal centerline. Its exact location is affected by such things as the amount of fuel it is holding, where its load is placed and the load's weight. A shift in the aircraft's center of gravity during flight will have an effect on the aircraft's stability and performance.
chord line - An imaginary line connecting an airfoil's leading edge with its trailing edge.

Charlie - Designator for the letter "C" in the International Phonetic Alphabet.

cirrus - High-level clouds (16,000 feet or more), composed of ice crystals appearing in the form of white, delicate filaments or white or mostly white patches or narrow bands.

cirrocumulus - Clouds appearing as small white puffs resembling flakes or patches of cotton without shadows.

cirrostratus - A uniform layer of dark veiled clouds.

Class "B" airspace - Generally, that airspace from the surface to 10,000 feet MSL surrounding the nation's busiest airports in terms of airport operations or passenger enplanements. The configuration of each Class B airspace area is individually tailored and consists of a surface area and two or more layers (some Class B airspace areas resemble upside-down wedding cakes), and is designed to contain all published instrument procedures once an aircraft enters the airspace. An ATC clearance is required for all aircraft to operate in the area, and all aircraft that are so cleared receive separation services within the airspace. The cloud clearance requirement for VFR operations is "clear of clouds."

Class "C" airspace - Generally, that airspace from the surface to 4,000 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower, are serviced by a radar approach control, and that have a certain number of IFR operations or passenger enplanements. Although the configuration of each Class C area is individually tailored, the airspace usually consists of a surface area with a 5 nautical mile (NM) radius, an outer circle with a 10NM radius that extends from 1,200 feet to 4,000 feet above the airport elevation and an outer area. Each person must establish two-way radio communications the ATC facility providing air traffic services prior to entering the airspace and thereafter
maintain those communications while within the airspace. VFR aircraft are only separated from IFR aircraft within the airspace.

clearance - An authorization by air traffic control for an aircraft to proceed under specified conditions within controlled airspace. Before a pilot is allowed to execute a maneuver, the pilot must receive permission (clearance) from air traffic control.

clearance delivery - The controller stationed at the ATCT who gives to pilots the approval of their flight plan, then hands them off to the local controller for push-back and taxiing procedures.

climb rate - The rate of ascent in feet per nautical mile. Usually the optimum speed and angle of attack at which a certain type of aircraft can safely ascend.

clouds - A visible collection of minute particle matter, such as water droplets and/or ice crystals, in the free air. A cloud forms in the atmosphere as a result of condensation of water vapor. Condensation nuclei, such as in smoke or dust particles, form a surface upon which water vapor can condense.

cockpit - A compartment in the front of the airplane where the flight crew performs their job of flying the aircraft.

commercial aviation - The business of operating aircraft that carry passengers by commercial companies. Airline companies such as American Airlines, United Airlines and many others are examples of commercial aviation. A Boeing 747 is an example of an airplane that is owned by a company and operated in commercial aviation.

commuter aircraft - Small aircraft with a passenger capacity of 30 or fewer..

commuter - An air carrier operator operating under 14 CFR 135 that carries passengers on at least five round trips per week on at least one route between two or more points according to its published flight schedules that specify the times, day of the week, and places between which these flights are performed. The aircraft that a commuter operates has 30 or fewer passenger seats and a payload capability of 7,500 pounds or less.

commuter flights - Usually short flights to and/or from small airports.

compass - A device used to discover geographic direction, usually having a magnetic needle(s) that is horizontally mounted or suspended and free to pivot until aligned with the magnetic field of the earth.

compressibility - The ability of air (or a substance) to have its molecules reduced in size or volume by pressure.

Computational Fluid Dynamics (CFD) - The science of using supercomputers to solve complex mathematical equations that predict how an object like an aircraft responds to the air flowing around it. CFD is a Tool of Aeronautics that enables engineers to "fly an aircraft in a computer".

computer - An electronic machine that receives, processes and presents data. A computer can be programmed to perform complicated tasks, like solving complex mathematical equations or controlling a flight simulator.

contrails - A white trail of condensed water vapor that sometimes forms in the wake of an aircraft; vapor trail.

control surfaces - Parts of an aircraft that are activated by the controls to change the airflow around the surfaces of the aircraft. The changes in airflow cause the aircraft to roll, pitch, or yaw. Examples of control surfaces are: ailerons, elevators and rudders.

controls - Devices which allow the pilot to direct the movements of an aircraft. Examples of controls are: rudder pedals that control the rudders and cause the airplane to yaw; throttles that control the engines which generate thrust for the airplane; and the control stick that controls the ailerons and elevators which cause the airplane to roll and pitch.

control tower - See ATCT (Airport Traffic Control Tower)

convection - The rising of warm air and the sinking of cool air. Heat mixes and moves air. When a layer of air receives enough heat from the Earth's surface, it expands and moves upward. Colder, heavier air flows under it which is then warmed, expands, and rises. The warm rising air cools as it reaches higher, cooler regions of the atmosphere and begins to sink. Convection causes local breezes.

convection process - The circular motion of air that results when warm air rises and is replaced by cool air. These atmospheric motions are predominantly vertical, resulting in vertical transport and mixing of atmospheric properties.

Convective SIGMET - see WST

corridor - A defined route through a country's airspace which is permissible for foreign aircraft to use.

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

course line - (1) a line extending in the direction of the course. (2) a line of position on or parallel to the course.

crabbing - A common course correction technique of turning into the wind in order to establish and maintain flight along a straight track or bearing.

crosswind leg - A flight path at right angles to the runway off its takeoff end.

CTAS - Center-TRACON Automation System, sophisticated software developed by NASA and the FAA that uses complex algorithms to produce many flight predictions for incoming aircraft to assist controllers in efficiently producing a safe and expeditious flow of traffic.

cumulonimbus - A heavy dense cloud with considerable vertical extent in the form of massive towers.

cumulus - A cloud in the form of individual detached domes or towers which are usually dense and well defined.