Fixed-pitch propellers.  Propellers with fixed blade angles.  Fixed-pitch propellers are designed as climb propellers,  cruise propellers, or standard propellers. Fixed-wing aircraft.  An aircraft whose wing is rigidly  attached to the structure. The term fixed-wing is used to  distinguish these aircraft from rotary-wing aircraft, such as  helicopters and autogiros. Flare.  See roundout. Flight plan.  Specified information relating to the intended  flight of an aircraft that is filed orally or in writing with an  FSS or an ATC facility. Flightpath.  The line, course, or track along which an aircraft  is flying or is intended to be flown. Fog.  Cloud consisting of numerous minute water droplets  and based at the surface; droplets are small enough to be  suspended in the earth’s atmosphere indefinitely. (Unlike  drizzle, it does not fall to the surface. Fog differs from a  cloud only in that a cloud is not based at the surface, and is  distinguished from haze by its wetness and gray color.) Force (F).  The energy applied to an object that attempts to  cause the object to change its direction, speed, or motion.  In aerodynamics, it is expressed as F, T (thrust), L (lift), W  (weight), or D (drag), usually in pounds. Four forces.  The four fundamental forces of flight: lift,  weight, drag and thrust. Four-stroke engine.  The principle of operation for some  reciprocating engines involving the conversion of fuel  energy into mechanical energy. The strokes are called intake,  compression, power, and exhaust. Front.  The boundary between two different air masses. Front tube.  The structural member of the carriage that  attaches to the top of the carriage mast to the front of the  fuselage. It acts as a control stop for the control bar to avoid  high angles of attack. Fuel efficiency.  Defined as the amount of fuel used to produce  a specific thrust or horsepower divided by the total potential  power contained in the same amount of fuel. Fuel injection.  A fuel metering system used on some aircraft  reciprocating engines in which a constant flow of fuel is fed  to injection nozzles in the heads of all cylinders just outside  of the intake valve. It differs from sequential fuel injection in  which a timed charge of high-pressure fuel is sprayed directly  into the combustion chamber of the cylinder. Fuel system.  The system that delivers fuel to the carburetors  or the fuel injection system composed of a fuel tank, fuel  pickup, fuel filter, and fuel pump. Fuselage.  The section of the WSC carriage that consists of the  cockpit, containing seats for the occupants and attachments  for the landing gear and wing. G loads.  Load imposed on an airframe due to inertia  (centrifugal force). 1G of load factor represents the weight  of the actual aircraft. 2G represents effectively twice the  aircraft’s actual weight. Glidepath.  The path of an aircraft relative to the ground  while approaching a landing. Glide ratio.  The ratio of the forward distance traveled to the  vertical distance an aircraft descends when it is operating  without power. For example, an aircraft with a glide ratio of  10:1 will descend about 1,000 feet for every 2 miles (10,560  feet) it moves forward. Global positioning system (GPS).  A satellite based radio  positioning, navigation, and time transfer system used for as  a reference for navigation and measures ground speed. Go-around.  The termination of a landing approach.  Reference the AIM Pilot/Controller Glossary. Go/No-go decision.  Decision of whether or not to make  a flight based on environmental, personal or mechanical  factors. A focus area for human factors study. GPS.  See global positioning system. Gross weight.  The total weight of a fully loaded aircraft  including the fuel, oil, crew, passengers, and cargo. Ground-adjustable propeller.  A type of aircraft propeller  whose blade pitch angle can be adjusted when the engine is  not running. The adjustment requires loosening the blades  in the hub. Ground effect.  A condition of improved performance  encountered when an airfoil is operating very close to the  ground. When an airfoil is under the influence of ground   G-8