## C 

Cabin altitude. Cabin pressure in terms of equivalent altitude above sea level. 

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

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

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. 

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. 

CAS.  Calibrated airspeed. 

CDI.  Course deviation indicator. 

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. 

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

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

Center of gravity range. The distance between the forward and aft CG limits indicated on pertinent airplane 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. 

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

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

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

CG. See center of gravity. 

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

Chart Supplement U.S. (formerly Airport/Facility Directory).  An FAA publication containing information on all airports, communications, and NAVAIDs. 

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. 

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

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. 

