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—The slow, smooth transition from a normal approach attitude to a landing attitude. This ma- neuver is accomplished in a PPC by pulling down on the steering lines to increase drag, reducing the forward speed and decreasing the rate of descent. 

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. 

FOUR FORCES—The four fundamental forces of flight: lift, weight, drag and thrust. 

FOUR-STROKE ENGINE—The principle of opera- tion for some reciprocating engines involving the conversion of fuel energy into mechanical energy. The strokes are called intake, compression, power, and exhaust. 

FSS—FAA Flight Service Station. 

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 de- scends 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. 

G LOADS—Loads imposed on an airframe due to inertia (centrifugal force). 1G of load factor repre- sents the weight of the actual aircraft. 2G repre- sents effectively twice the aircraft’s actual weight. 

GLOBAL POSITION SYSTEM (GPS)—A satellite- based radio positioning, navigation, and time- transfer system. 

GO-AROUND—The termination of a landing approach. Reference the AIM Pilot/Controller Glossary. 

GO OR 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 POSITION SYSTEM. 

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 per- formance encountered when an airfoil is operating very close to the ground. When an airfoil is under the influence of ground effect, there is a reduction in upwash, downwash, and wingtip vortices. As a result of the reduced wingtip vortices, induced drag is reduced. 

GROUNDSPEED (GS)—The actual speed of an air- craft over the ground. It is true airspeed adjusted for wind. Groundspeed decreases with a head- wind, and increases with a tailwind. 

GROUND TRACK—The aircraft’s path over the ground when in flight. 

HAZARDOUS INFLIGHT WEATHER ADVISORY SERVICE (HIWAS)—Recorded weather forecasts broadcast to airborne pilots over selected VORs. 

HEADWIND—A wind which blows from the direc- tion the aircraft is flying. The ground speed of an aircraft (the speed the aircraft is moving over the ground) is less than the speed through the air by the velocity of the headwind. 

HIWAS—See HAZARDOUS INFLIGHT WEATH- ER ADVISORY SERVICE. 

HOUR METER—An instrument installed in many aircraft to show the actual number of hours the engine has operated. The hour meter is an electri- cal clock that starts when the engine oil pressure builds up, and runs until the engine is shut down and the oil pressure drops to zero. 

HYPERVENTILATION—Occurs when an indi- vidual is experiencing emotional stress, fright, or pain, and the breathing rate and depth increase, although the carbon dioxide level in the blood is already at a reduced level. The result is an exces- sive loss of carbon dioxide from the body, which can lead to unconsciousness due to the respiratory system’s overriding mechanism to regain control of breathing. 

HYPOXIA—State of oxygen deficiency in the body sufficient to impair functions of the brain and other organs. 

IFR—See INSTRUMENT FLIGHT RULES. 

INCIDENT—An occurrence other than an accident, associated with the operation of an aircraft, which affects or could affect the safety of operations. 

INDUCED DRAG—That part of total drag which is created by the production of lift. Induced drag increases with a decrease in airspeed. 

INSTRUMENT FLIGHT RULES (IFR)—Rules governing the procedures for conducting instru- ment flight. Also a term used by pilots and con- trollers to indicate type of flight plan. 

