MAC—See MEAN AERODYNAMIC CHORD. INTERFERENCE DRAG—Type of drag produced  by placing two objects adjacent to one another.  Combines the effects of form drag and skin friction. INVERSION—An increase in temperature with  altitude. MAGNETO—A self-contained engine-driven unit  that supplies electrical current to the spark plugs. MAKE/MODEL—Refers to the manufacturer and  model of a specific aircraft. JUDGMENT—The mental process of recognizing  and analyzing all pertinent information in a par- ticular situation, a rational evaluation of alternative  actions in response to it, and a timely decision on  which action to take. MANEUVERING ALTITUDE—An altitude above  the ground that allows a sufficient margin of  height to permit safe maneuvering. MAXIMUM GROSS WEIGHT—The maximum au- thorized weight of the aircraft and all of its equip- ment as specified in the TCDS for the aircraft. KINESTHESIA—The sensing of movements by  feel. KITE—To pressurize and raise the wing overhead  the PPC cart. MEAN AERODYNAMIC CHORD (MAC)—The  average distance from the leading edge to the trail- ing edge of the wing. MECHANICAL TURBULENCE—Type of tur- bulence caused by obstructions on the ground  interfering with smooth flow of the wind. Trees,  buildings and terrain can all cause mechanical  turbulence. KITING—Taxiing the PPC on the ground with the  wing inflated and overhead. KNOWLEDGE EXAM—See FAA KNOWLEDGE  EXAM. LATERAL AXIS—An imaginary line passing  through the center of gravity of a PPC and extend- ing across the PPC from one side of the aircraft to  the other side. MEDICAL CERTIFICATE—Acceptable evidence  of physical fitness on a form prescribed by the  Administrator. MEDIUM-BANKED TURN—Turn resulting from  a degree of bank (approximately 20 to 45 degrees)  at which the PPC remains at a constant bank. LEADING EDGE—The part of an airfoil that meets  the airflow first. LIFT—One of the four main forces acting on an  aircraft. On a powered parachute, an upward force  created by the effect of airflow as it passes over  and under the wing. MILITARY TRAINING ROUTES (MTR)—Special  routes developed to allow the military to conduct  low-altitude, high speed training. MILITARY OPERATIONS AREA (MOA)—Air- space of defined vertical and lateral limits es- tablished for the purpose of separating certain  military training activity from IFR traffic. LIGHT-SPORT AIRCRAFT (LSA)—An aircraft  that meets the requirements defined in 14 CFR  1.1, regardless of airworthiness certification. LINE-OVERS—A dangerous situation when the  suspension line goes over the top of the wing  instead of going straight from the wing to the riser  system. This condition will prevent proper infla- tion of the wing. MINDSET—A factor in aeronautical decision  making where decision making is influenced by  preconceived ideas about the outcome of events.  For example, an expectation of improving weather  conditions can lead to increased risk during a  flight. MOA—See MILITARY OPERATIONS AREA. MODE C TRANSPONDER—A receiver/transmit- ter which will generate a radar reply signal upon  proper interrogation; the interrogation and reply  being on different frequencies. Mode C means the  reply signal includes altitude information. LINE TWISTS—When the PPC suspension lines on  both sides of the wing are spiraled together. Flying  with a line twist is unsafe; the wing is unairworthy  until it is corrected. LOC—A preflight check: L – Lines Free, O – Cells  Open, C – Wing Centered.  LOGBOOK—A record of activities: flight, instruc- tion, inspection and maintenance. Reference 14  CFR 43, 14 CFR 61.51, and 14 CFR 91.417. LONGITUDINAL AXIS—An imaginary line  through an aircraft from nose to tail, passing  through its center of gravity. The longitudinal axis  is also called the roll axis of the aircraft. MOMENT— A force that causes or tries to cause  an object to rotate. The product of the weight  of an item multiplied by its arm. Moments are  expressed in pound-inches (lb-in). Total moment  is the weight of the PPC multiplied by the distance  between the datum and the CG. NEWTON’S THIRD LAW OF MOTION—When- ever one body exerts a force on another, the sec- LSA—See LIGHT-SPORT AIRCRAFT. G-6