AOA—See ANGLE OF ATTACK. ARM—The horizontal distance in inches from the  reference datum line to the center of gravity of an  item. Used in weight and loading calculations. AROW— The mnemonic aid to remember the  certificates and documents required to be onboard  an aircraft to determine airworthiness: Airworthi- ness certificate, Registration certificate, Operating  limitations, Weight and balance data. ASOS—See AUTOMATED SURFACE OBSERV- ING SYSTEM. ASPECT RATIO—Span of a wing divided by its  average chord. ASYMMETRICAL AIRFOIL—An airfoil section  that is not the same on both sides of the chord line. ATIS—See AUTOMATIC TERMINAL INFORMA- TION SERVICE. AUTOMATED SURFACE OBSERVING SYS- TEM (ASOS)—Weather reporting system which  provides surface observations every minute via  digitized voice broadcasts and printed reports. AUTOMATED WEATHER OBSERVING SYSTEM  (AWOS)—Automated weather reporting system  consisting of various sensors, a processor, a com- puter-generated voice subsystem, and a transmitter  to broadcast weather data. AUTOMATIC TERMINAL INFORMATION SER- VICE (ATIS)—The continuous broadcast (by ra- dio or telephone) of recorded noncontrol, essential  but routine, information in selected terminal areas. AVIATION MEDICAL EXAMINER (AME)—A  medical doctor authorized to perform aviation  medical exams for aviators. BANK ATTITUDE—The angle of the lateral axis  relative to the horizon. BASE LEG—A flight path at right angles to the  landing runway off its approach end. The base leg  normally extends from the downwind leg to the  intersection of the extended runway centerline. CAMBER—The curvature of a wing when look- ing at a cross section. A wing has upper camber  on its top surface and lower camber on its bottom  surface. CANOPY—The fabric body of a parachute. CARBURETOR ICE—Ice that forms inside the car- buretor 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. CART—The engine and seats, attached by a struc- ture to wheels; sometimes referred to as the fuse- lage, cockpit, chaise, or airframe. 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 PPC 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 pro- duced by the airfoil are considered to be concen- trated. 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 cen- trifugal force. CERTIFICATED FLIGHT INSTRUCTOR (CFI)— A flight instructor authorized by the FAA to  provide flight instruction in designated category of  aircraft. CFI—See CERTIFIED FLIGHT INSTRUCTOR. 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. CLASS A AIRSPACE—Airspace from 18,000 feet  MSL up to and including FL600, including the  airspace overlying the waters within 12 NM of the  G-2