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.  Carriage.  The engine and seats, attached by a structure  to wheels; sometimes referred to as the fuselage, cockpit,  chaise, or airframe. Carriage keel.  The lower center tube in the carriage that runs  fore and aft which connects the mast to the front tube. CAS.  See calibrated airspeed. Cavitation.  A condition that exists in a fluid pump when  there is not enough pressure in the reservoir to force fluid  to the inlet of the pump. The pump picks up air instead of  fluid. Center of gravity (CG).  The point at which an aircraft would  balance if it were possible to suspend it at that point. It is the  mass center of the aircraft, or the theoretical point at which  the entire weight of the WSC is assumed to be concentrated.  It may be expressed in inches from the reference datum, or  in percent of mean aerodynamic chord (MAC). The location  depends on the distribution of weight in the aircraft. 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 pressure (CP).  The point along the wing chord  line where lift is considered to be concentrated. Centrifugal force.  The apparent force occurring in  curvilinear motion acting to deflect objects outward from the  axis of rotation. For instance, when pulling out of a dive, it  is the force pushing you down in your seat. Centripetal force.  The force in curvilinear motion acting  toward the axis of rotation. For instance, when pulling out  of a dive, it is the force that the seat exerts on the pilot to  offset the centrifugal force. Certificated Flight Instructor (CFI). A flight instructor  authorized by the FAA to provide flight instruction in  designated category of aircraft. Certified Flight Instructor with a Sport Pilot Rating  (CFIS).  A flight instructor authorized by the FAA to provide  flight instruction in designated category of aircraft for sport  pilots only. CFI.  See Certified Flight Instructor. CFIS.  See Certified Flight Instructor with a Sport Pilot  Rating. CFR.  See Code of Federal Regulations. CG.  See center of gravity. Checklist.  A list of procedures that provides a logical and  standardized method to operate a particular make and model  aircraft. Checkride.  A practical test administered by an FAA  examiner or designated examiner for the purpose of issuing  an FAA certificate or rating. Chord line.  An imaginary straight line drawn through an  airfoil from the leading edge to the trailing edge. Circuit breaker.  A circuit-protecting device that opens  the circuit in case of excess current flow. A circuit breaker  differs from a fuse in that it can be reset without having to  be replaced. C$_{L}$.  See coefficient of lift. Class A Airspace.  Airspace from 18,000 feet MSL up to  and including FL 600, including the airspace overlying the  waters within 12 NM of the coast of the 48 contiguous states  and Alaska; and designated international airspace beyond  12 NM of the coast of the 48 contiguous states and Alaska  within areas of domestic radio navigational signal or ATC  radar coverage, and within which domestic procedures are  applied. Class B Airspace.  Airspace from the surface to 10,000 feet  MSL surrounding the nation’s busiest airports in terms of  IFR operations or passenger numbers. The configuration of  each Class B airspace is individually tailored and consists  of a surface area and two or more layers, and is designed to  contain all published instrument procedures once an aircraft  enters the airspace. For all aircraft, an ATC clearance is  required to operate in the area, and aircraft so cleared receive  separation services within the airspace.   G-4