Aircraft categories. (1) As used with respect to the certification, ratings, privileges, and limitations of airmen, means a broad classification of aircraft. Examples include: powered parachute, airplane, rotorcraft, glider, lighter-than- air, and weight-shift control. (2) As used with respect to the certification of aircraft, means a grouping of aircraft based upon intended use or operating limitations. Examples include: transport, normal, utility, acrobatic, limited, restricted, and provisional. 

Aircraft flight manual (AFM).  Also called the Pilot’s Operating Handbook (POH), a document developed by the aircraft manufacturer and approved by the FAA. It is specific to a particular make and model aircraft by a serial number, and contains operating procedures and limitations. 

Aircraft operating instructions (AOI). An alternative to the approved term, Pilot's Operating Handbook. 

Airfoil.  Any surface, such as a wing or propeller, which provides aerodynamic force when it interacts with a moving stream of air. 

Airmanship.  A sound acquaintance with the principles of flight, the ability to operate an airplane with competence and precision both on the ground and in the air, and the exercise of sound judgment that results in optimal operational safety and efficiency. 

Airmanship skills.  The skills of coordination, timing, control touch, and speed sense in addition to the motor skills required to fly an aircraft. 

Airport.  An area of land or water that is used or intended to be used for the landing and takeoff of aircraft, including its buildings and facilities, if any. 

Airport/facility directory (A/FD).  A publication of the Federal Aviation Administration containing information on all airports, seaplane bases, and heliports open to the public. The A/FD contains communication data, navigational facilities, and certain special notices and procedures. 

Airspace.  The space above a certain geographical area. 

Airworthiness . A state in which an aircraft or component meets the conditions of its type design and is in a condition for safe operation. 

Airworthiness Certificate . A certificate issued by the FAA to aircraft that have been proven to meet the minimum standards set down by the Code of Federal Regulations. 

Airworthiness Directive (AD) . A regulatory notice sent out by the FAA to the registered owner of an aircraft informing the owner of a condition that prevents the aircraft from continuing to meet its conditions for airworthiness. Compliance with AD notes must be within the required time limit, and the fact of compliance, the date of compliance, and the method of compliance must be recorded in the aircraft’s maintenance records. 

Altimeter. A flight instrument that indicates altitude by sensing pressure changes. 

AME. See Aviation Medical Examiner. 

Ammeter. An instrument installed in series with an electrical load used to measure the amount of current flowing through the load. 

Angle of attack (AOA).  The acute angle between the chord line of the airfoil and the direction of the relative wind. 

Angle of incidence. The angle formed by the chord line of the wing at the keel of a WSC and a line parallel to the longitudinal axis of the WSC carriage. The angle of incidence changes in the WSC controlled by the pilot. 

Anhedral. A downward slant from root to tip of an aircraft’s wing opposite from dihedral. 

Annual inspection.  A complete inspection of an aircraft and engine, required by the Code of Federal Regulations, to be accomplished every 12 calendar months on all certificated aircraft. Only an A&P technician holding an Inspection Authorization can conduct an annual inspection. 

AOA.  See angle of attack. 

AOI. See aircraft operating instructions. 

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. Certificates and documents required to be onboard an aircraft to determine airworthiness: Airworthiness certificate, Registration certificate, Operating limitations, Weight and balance data. 

ASOS.  See Automated Surface Observing System. 

Aspect ratio. Span of a wing divided by its average chord. 

