Aviation Terminology
This is a companion page to the acronym list. The acronym list page comprises the many acronyms used in aviation. This page contains much of the terminology used in aviation. Although much of the material found on this page is also found on the EAA website, a lot of the terms have been sourced elsewhere, too, such as at AOPA, the FAA, from list serves and from reading. This page is a work in progress and was created mainly to help me for when I actually begin my pilot's licence training, but may prove useful to others. Please note, both this and the acronym page need a lot of formatting work still at this time.Note - Terms are arranged alphabetically
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z |A
| A |
|---|
Absolute ceiling
The highest altitude an airplane can sustain level flight, or altitude above which the cabin pressurization system can no longer maintain a sufficient oxygen level for passengers and crew, and where the pressure differential is so great as to put severe stress on the pressure cabin of the aircraft. Most commercial jetliners have a ceiling of about 42,000 feet (12,802 meters) while some business jets can reach 52,000 feet or higher (15,850 meters.) Also see Service ceilingAccelerated stall
Any stall made to occur at anything other than 1g. Also see High-speed stall and Secondary stallAccessories
Mechanical and electrical units mounted on an engine that are necessary for its operation, for example: starter, magnetos, fuel pump or other systems such as an alternator, vacuum pump, etc.Adverse yaw
Yaw generated when the ailerons are used. The lifting wing generates more drag, causing an airplane to yaw (turn) toward it.AGL
AGL is an abbreviation for Above Ground Level. AGL is a measurement of altitude above a specific land mass, and differentiated from MSL. AGL is what skydivers commonly use as their reference point and they set their AADs and their altimeters before take off at the dropzone.Aileron
The movable areas of a Wingform that control or affect the roll of an aircraft by working opposite to one another—up-aileron on the right wing and down-aileron on the left wing.Airspeed Indicator
The airspeed indicator, or as it is also known by its abbreviation, ASI, is an instrument that measures the air speed of an aircraft through the air. It should not be confused with its ground speed.Alodine
A non-anodic protective coating. Alodine, which is also known as Iridite, or Chromate Conversion, is a microscopic thin film added to aluminium. It provides an excellent surface prep for paint, aids in corrosion resistance and provides desired electrical resistance characteristics. The the process requires an initial acid etching before the AL applying the alodine conversion coating. Alodine is a strong oxidizer and produces a chemical conversion of the surface (it oxidizes it). Paint bonds to the alodined surface well. (The correct type of paint, of course)Alclad
Alclad is a trademark of Alcoa, but is also used as a generic term to describe corrosion-resistant aluminum sheet formed from high-purity aluminium surface layers that have been metallurgically bonded to high-strength aluminium alloy core material. These sheets are commonly used by the aircraft industry. Described in NACA-TN-259 in August 1927 in the following way: A new corrosion resistant aluminum product which is markedly superior to the present strong alloys. Its use should result in greatly increased life of a structural part. Alclad is a heat-treated aluminum, copper, manganese, magnesium alloy that has the corrosion resistance of pure metal at the surface and the strength of the strong alloy underneath. Of particular importance is the thorough character of the union between the alloy and the pure aluminum. Preliminary results of salt spray tests (24 weeks of exposure) show changes in tensile strength and elongation of Alclad 17ST, when any occurred, to be so small as to be well within the limits of experimental error.Angle of attack
The angle of attack or AOA is the acute angle at which a moving airfoil meets the airstream.Angle of incidence
The angle of incidence or AOI is the angle at which an airfoil is normally fixed in relation to the longitudinal axis of an aircraft.Anhedral
The downward angle of a wing in relation to a horizontal cross-section line; also sometimes known as cathedral. See Dihedral.Anodize
Anodize or anodising, is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts. Anodizing increases corrosion resistance and wear resistance, and provides better adhesion for paint primers and glues than bare metal. Anodic films can also be used for a number of cosmetic effects, either with thick porous coatings that can absorb dyes or with thin transparent coatings that add interference effects to reflected light. Anodizing is also used to prevent galling of threaded components and to make dielectric films for electrolytic capacitors. Anodic films are most commonly applied to protect aluminium alloys, although processes also exist for titanium, zinc, magnesium, and niobium. See also AnodizingatHome for how to anodize and dye a part at home.Anti-servo tab
A small portion of a flight-control surface that deploys in such a way that it works to resist the motion of the entire flight-control surface from the direction that the pilot or other forces apply to it. An anti-servo tab, unlike a traditional trim tab, is a dynamic device that increases resistance as the control surface is deployed further. Its function has a stabilizing effect. On some aircraft with all-flying stabilators, an anti-servo tab acts as a trimming device. In this use, some manufacturers term it a “balance tab” or “anti-balance tab.”Arm
In aircraft weight and balance, as well as load distribution, it is the distance from the Center of Gravity, also known as the CG or CofG. For computations, arms measured forward from the CofG are positive (+n) and those measured aft of the CofG are negative (-n).Aspect ratio
The ratio of the span to the chord of an airfoil. A high-aspect ratio wing has wide span and narrow chord, while a low-aspect ratio wing has a short span and wide chord.Autogyro
An autogyro is an aircraft, often wingless, usually with unpowered rotary airfoil blades that auto-rotate and serve as wings as they move through the air. On a powered aircraft, a propellor providing thrust provides the forward movement through the air, spinning the rotor, which then provides lift. Some autogyros are able to divert power on the ground to the rotor to begin spinning the rotor, which when coupled with cyclic control can provide a jump liftoff or vertical take off. Autogiro is a trademark of the Autogiro Corporation and how they name their craft.Auto-rotation
Automatic rotation of rotary blades on a helicopter in an unpowered glide or the forward movement of an autogyro .Avgas
An abbreviation for Aviation Gasoline. A high-octane aviation fuel used for aircraft. Avgas is distinguished from mogas (automobile or motor gasoline), which is the everyday gasoline used in cars, in that it has a certified production and transportation process and also contains lead as an anti-knock additive. Avgas is typically used in aircraft with internal combustion engines. The lead in avgas is a cause of concern to the EPA and alternatives to avgas are being sought. Turbine and diesel engines are designed to use kerosene-based jet fuel.Axial
Motion along a real or imaginary straight line on which an object supposedly or actually rotates.B
| B |
|---|
Balanced control surface
A movable control surface, as an aileron or rudder, having an added physical extension or weights forward of the hinge-point to reduce forces on a joystick or yoke and to lessen the chance for aerodynamic flutter. See Elephant ears.Bernoulli Effect or Law or Theorem
Since the pressure of a fluid is proportional to its velocity, airflow over the upper surface of an airfoil causes suction Lift because the airstream has sped up in relation to positive pressure of the airflow on the lower surface.Bleed air
Hot air at high pressure, usually from the bypass section of a autogyro engine, for de-icing, heating, and other uses.Boundary-layer Control
The design or control of slotted or perforated wings with suction methods to reduce undesirable aerodynamic effects caused by the boundary layer—that region adjacent to the boundary where shear stresses dominate in the airflow over a Wingform.Bowden Cable
A bowden cable is a type of flexible cable used to transmit mechanical force or energy by the movement of an inner cable (most commonly of steel or stainless steel) relative to a hollow outer cable housing. The housing is generally of composite construction, consisting of a helical steel wire, often lined with plastic, and with a plastic outer sheath.Boxer or Boxer Engine
Any horizontally opposed engine in which the corresponding pistons reach top dead center simultaneously, such as those found in most light general aviation aircraft. Examples include Lycoming, Continental, and Franklin engines, as well as Jabiru and Rotax. The Corvair engine is an example of an automobile engine that also fall into the category and are commonly converted for aircraft use. Others include the air-cooled Volkswagen engines, Porsche, and Subaru. Lesser-known boxer engines include the Citroën 2CV for automobiles and BMW and Honda (Gold Wing) for motorcycles. Boxer engines should not be confused with the less popular opposed piston engine designs, (sometimes referred to as “180° V engines” and almost never found in engines with less than eight cylinders) in which corresponding pistons share a crank pin, and thus each will reach top dead center half a crankshaft revolution after the other.Brake specific fuel consumption - BSFC
As with brake horsepower BHP , brake specific fuel consumption BSFC , or SFC refers to the specific fuel consumption when the power is measured by an external brake - in other words, a dynamometer. BSFC is the ratio between the engine’s fuel mass consumption and the crankshaft power it is producing. This makes it both a valuable fuel efficiency indicator and one more useful tool in gauging an engine’s state-of-tune. In the United States, the fuel flow for BSFC calculations is normally expressed in pounds per hour (lb/hr) while the output units are in horsepower HP . So, the U.S. standard formula for BSFC becomes lb/hp-hr. For an engine producing 200 hp, while burning 100 pounds of gasoline per hour, the equation would yield 100/200 = 0.50 BSFC, which is universally considered to be average or normal, while some would argue that a more accurate 0.51 lb/hr is correct. Fuel weighs approximately 6 pounds per gallon, so 100 pounds works out to be 16.7 gallons. Therefore, if an aircraft engine manufacturer claims fuel consumption better than 16.7 gallons per hour GPH for a 200-hp engine, it is probably being less than truthful, unless it has the dynamometer records to prove both horsepower and BSFC.Brayton Cycle
A thermodynamic cycle consisting of two constant-pressure processes interspersed with two constant-entropy processes. Also known as complete-expansion Diesel cycle, or Joule cycle. It is named after George Brayton (1830–1892), the American engineer who developed it, although it was originally proposed and patented by Englishman John Barber in 1791.Bumped cowling
An engine fairing, generally circular, with welts or compound shapes in its surface to accommodate cylinder heads.C
| C |
|---|
Cabane Strut
One of several structural members, usually vertical and sometimes streamlined, that support or otherwise connect the wing center-section from the fuselage, typically found in high-wing or biplane open-cockpit configurations.Calibrated Airspeed
Also known by the acronym CAS. The indicated airspeed of an aircraft, corrected for position and instrument error. CAS is equal to true airspeed in standard atmosphere at sea level. Compare Indicated Airspeed or IAS and True Airspeed or TAS .Camber
The convex or concave curvature of an airfoil.Canard
An arrangement in which the horizontal stabilizer and elevators of an aircraft are mounted ahead of the main wing(s).Carson's speed
The term Carson’s speed refers to the paper Fuel Efficiency of Small Aircraft (AIAA-80-1847, 1980) by Professor Bud Carson of the U.S. Naval Academy, which, using prior work by Gabrielli and von Karman, defines this speed as the maximum speed per unit of fuel burned. Carson’s speed can be calculated as 1.316 times the speed for maximum lift to drag ratio, which, in turn, is 1.316 times the speed for minimum power and minimum sink rate. Carson’s speed is also defined as the tangent point on a line that is tangent to the drag polar and passes through the origin.Cathedral
See anhedral Ceiling The term has two meanings:- The heights above the earth's surface of the lowest layer of clouds or obscuring phenomena that is reported as "broken," "overcast," or "obscuration," and not classified as "thin" or "partial".
- The maximum height above sea level in Standard Air attainable by an aircraft under given conditions—see Absolute ceiling, Service ceiling.
Center of Gravity
The center of gravity - CG or CofG - is the longitudinal and lateral point in an aircraft where it is stable; the static balance point. See also arm. CHORD - The measurable distance between the leading and trailing edges of a WINGFORM. COAMING - A padded, protective rim around an open cockpit. COLLECTIVE PITCH - A cockpit control that changes the PITCH of a helicopter's rotor blades; used in climbing or descending. COLLECTOR RING - A circular duct on a radial engine into which exhaust gases from its cylinders are safely discharged. CONSTANT-SPEED PROPELLER - A hydraulically or electrically controlled propeller that can change its blade pitch to take better advantage of the power supplied by an engine in much the same way that a transmission in a car takes better advantage of its power source. The mechanism varies depending on the aircraft, but the desired effect is to change the angle of attack of the propeller blades to take a smaller or larger "bite" of air as it rotates. CONTACT! Magazine - An independant, non-profit experimental aviation magazine started by Mick Myal in 1991. It's published bimonthly by it's editor, Patrick Panzera. Read More COWL, COWLING - A removable FAIRING around an aircraft engine for the purposes of streamling or cooling. COWL FLAP - A controllable louver to regulating airflow through an engine's COWLING.D
| D |
|---|
Dihedral
Dihedral is the acute angle, usually upward, between the wing of an airplane and a horizontal cross-section line. It is the opposite of anhedral. DOPE - Preservative and pigmented coloring for fabric aircraft covering and paints, generally nitrate lacquer but generically used to denote all early shellac and coal-tar mixtures on up to present-day acrylics. DORSAL FIN - A lateral fin/rudder extension on the top of a fuselage. Opposite of VENTRAL FIN. DOWNWASH - The air deflected perpendicular to the direction of movement of an airfoil. DOWNWIND TURN - Long a point of contest among pilots, there is in reality no such thing as far as the airplane is concerned. Proponents claim that airplanes lose air speed and gets pushed from behind (potentially causing a stall) when turning downwind, while opponents (and the laws of physics) argue that an airplane, like a boat in a river whose speed is only relative to the water and not the shore, is unaffected within the movement of an air mass and that it gains only ground speed. DRAG - The resisting force exerted on an aircraft in its line of flight opposite in direction to its motion. Compare THRUST. DRAG WIRE - A wire designed to resist DRAG forces, usually running from a forward inboard point to an outboard aft point. DRY WEIGHT - The weight of an engine exclusive of any fuel, oil, and coolant. DURAL - Originally a tradename for a wrought aluminum-copper alloy created by Bausch Machine Tool Co, now fallen into generic use as any aluminum alloy containing 3.0-4.5% copper, 0.4-1.0% magnesium, and 0.1-0.7% manganese. Alcoa's version is commonly referred to as "Duraluminum," popularly used in aircaft manufacture. DZUS FASTENER - ("Zoose") A generic term for any number of quick-acting, screw-type fasteners typically used for the securing of cowlings, inspection plates and other panels, requiring no special tool other than a slotted screwdriver or a coin, usually only requiring a quarter-turn to lock or unlock.E
| E |
|---|
Elephant ear
- An air intake characterized by twin inlets, one on each side of the fuselage.
- A type of balanced aileron in which the outer edges are noticeably larger than the control itself.
- See Balanced control surface and the picture example to the right.
F
| F |
|---|
Fairing
An added streamlining structure or auxiliary member, most often of light metal, whose only purpose is to reduce drag. Fairings are not load-bearing and, therefore, are not meant to carry any principal air loads placed on the airplane structure. FBO - Fixed-Base Operator (or Fixed Base Operation). A commercial operator supplying fuel, maintenance, flight training, and other services at an airport. FEATHERING - In the event of engine failure, the process of adjusting a controllable-pitch propeller to a pitch position where the blade angle is about 90° to the plane of rotation in order to stop its windmilling and lessen drag. FEDERAL AIR REGULATION (FAR) FAR Part 91 - General Aviation (portions apply to all operators) FAR Part 103 - Ultralight Vehicles FAR Part 105 - Parachute Jumping FAR Part 108 - Airplane Operator Security FAR Part 119 - Certification: Air Carriers and Commercial Operators FAR Part 121 - Domestic, Flag, and Supplemental Air Carriers and Commercial Operators of Large Aircraft FAR Part 123 - Travel Clubs FAR Part 125 - US Civil Airplanes, seating 20 or more passengers or a maximum payload capacity 6,000# or more FAR Part 127 - Air Carriers using helicopters for scheduled interstate flights (within the 48 contiguous states) FAR Part 129 - Foreign Air Carrier and Foreign Operators of US registered aircraft engaged in common carriage FAR Part 133 - Rotorcraft External Load Operations FAR Part 135 - Air Taxi Operators and Commercial Operators FAR Part 137 - Agricultural Aircraft Operations FAR Part 141 - Pilot School FERRY FLIGHT - A flight for the purpose of (1) returning an aircraft to base; (2) delivering an aircraft from one location to another; (3) moving an aircraft to and from a maintenance base. Ferry flights, under certain conditions, may be conducted under terms in a special flight permit. FIN - The fixed part of a vertical airfoil that controls the yaw of an aircraft; the movable part being the RUDDER. Sometime referred to as Vertical Stabilizer. FIREWALL - A fire-resistant bulkhead that isolates the engine from other parts of an airplane's structure. FISHTAILING - A rudder-controlled side-to-side [yawing] motion to reduce air speed, generally prior to landing. FLAP - A movable, usually hinged AIRFOIL set in the trailing edge of an aircraft wing, designed to increase LIFT and/or DRAG by changing the CAMBER of the wing or used to slow an aircraft during landing by increasing lift. Also see FOWLER FLAP, SLOTTED FLAP, and SPLIT FLAP. FLAPERON - A control surface combining the functions of a FLAP and an AILERON. FLARE - A simple maneuver performed moments before landing in which the nose of an aircraft is pitched up to minimize the touchdown rate of speed. FLIGHT ENVELOPE - An aircraft's performance limits, specifically the curves of speed plotted against other variables to indicate the limits of speed, altitude, and acceleration that a particular aircraft cannot safely exceed. FLOATPLANE - A water-based aircraft with one or more mounted pontoons, as differentiated from a hulled SEAPLANE [Flying Boat], but often used generically. FLYING WIRES - Interplane bracing wires that help support wing loads when the plane is in flight. Direction of travel is upward and outward from the fuselage to the interplane struts. Also known as LIFT WIRES, the opposite of LANDING WIRES.Flutter
A self-starting and potentially destructive vibration where aerodynamic forces on an object couple with a structure's natural mode of vibration to produce rapid periodic motion. FOWLER FLAP - Trademark name of a flap attached to a wing's trailing edge with a system of tracks and rollers to slide backwards before hinging downwards, thereby increasing both camber and chord, creating a larger wing surface better tuned for lower speeds. Named for its inventor, USAF engineer Harland D Fowler. FRISE AILERON - A type of aileron that has a beveled or contoured leading edge projecting beyond its inset hinges. When the trailing edge is lowered, it forms an extension of the wing surface; when raised, its nose protrudes below the wing surface, protruding into the airflow increasing DRAG and reducing YAW. Named for its inventor, British engineer Leslie George Frise. Unfortunately, as well as reducing adverse yaw, Frise ailerons will increase the overall drag of the aircraft, and therefore they are less popular in aircraft where minimizing drag is important (e.g. in a glider) FUSELAGE - An aircraft's main body structure housing the flight crew, passengers, and cargo and to which the wings, tail and, in most single-engine airplanes, engine are attached. French: fuselé, tapering.G
| G |
|---|
Glider
An unpowered aircraft capable of maintaining altitude only briefly after release from tow, then gliding to earth. Compare SAILPLANE. GROSS WEIGHT - The total weight of an aircraft when fully loaded, including fuel, cargo, and passengers; aka Takeoff Weight. GROUND CUSHION see GROUND EFFECT GROUND EFFECT - Increased lift generated by the interaction between a lift system and the ground when an aircraft is within a wingspan distance above the ground. It affects a low-winged aircraft more than a mid- or high-winged aircraft because its wings are closer to the ground; aka GROUND CUSHION. GROUNDSPEED - The actual speed that an aircraft travels over the ground—its "shadow speed"; it combines the aircraft's AIRSPEED and the wind's speed relative to the aircraft's direction of flight. GULL-WING - Descriptive of wing in frontal view bent as the wing of a seagull; a distinctive shallow, inverted "V" shape—see Stinson SR-10 or inverted gull-wing Vought F4U . GYROPLANE - A rotorcraft whose rotors are not engine-driven, except for initial starting, but are made to rotate by action of the air when the rotorcraft is moving and whose means of propulsion, usually a conventional propeller, is independent of the rotor system. Similar to AUTOGYRO.H
| H |
|---|
Helicopter
A helicopter is a wingless aircraft acquiring its lift from revolving blades driven by an engine about a near-vertical axis. A rotorcraft acquiring its primary motion from engine-driven rotors that accelerate the air downward, providing a reactive lift force, or accelerate the air at an angle to the vertical, providing lift and thrust. HIGH BLOWER - A blower-type SUPERCHARGER set at high rpm.High-speed stall
Any stall made to occur at more than 1g, such as pulling out of a dive or while turning. Also see Secondary stall or Accelerated stall. HORSEPOWER – (HP) The motive energy required to raise 550# one foot in one second, friction disregarded. With any rotating engine HP can be determined by multiplying the torque and the revolutions per minute (RPM) and dividing by 5,252. Torque (ft. lbs) x RPM HP = -------------------------------- 5252 HYPERSONIC - Speed of flight at or greater than Mach 5.0, exceeding SUPERSONIC.I
| I |
|---|
Indicated Airspeed
Also known as IAS. A direct instrument reading obtained from an air speed indicator uncorrected for altitude, temperature, atmospheric density, or instrument error. Compare Calibrated Airspeed and True Airspeed. INDUCED DRAG - is caused by that element of the air deflected downward which is not vertical to the flight path but is tilted slightly rearward from it. As the angle of attack increases, so does drag; at a critical point, the angle of attack can become so great that the airflow is broken over the upper surface of the wing, and lift is lost while drag increases. INERTIA FORCE - A force due to inertia, or the resistance to acceleration or deceleration.J
| J |
|---|
K
| K |
|---|
L
| L |
|---|
M
| M |
|---|
N
| N |
|---|
O
| O |
|---|
P
| P |
|---|
Planform
The planform or plan view is a vertical orthographic projection of an object on a horizontal plane, like a map. In aviation, the planform is the shape and layout of an airplane's wing and fuselage. Of all the many planforms used, they can typically be grouped into those used for low-speed flight found on general aviation aircraft, and those used for high-speed flight, found mainly on military aircraft and airliners. See also wingform. POBEREZNY, PAUL HOWARD (b. September 14, 1921 in Leavenworth County/Kansas) is a US aviator and aircraft designer famous for his work in establishing the Experimental Aircraft Association (EAA) in 1953 and promoting homebuilt aircraft. POWER LOADING - The GROSS WEIGHT of an airplane divided by the rated horsepower, computed for Standard Air density. PROPELLER SPEED REDUCTION UNIT (PSRU) - A gearbox or a belt and pulley device used to reduce the output rotational speed (rpm) when compared to the higher input rpm of the powerplant. These arrangements allow the use of relatively small' displacement, high-revving, internal combustion automotive engines to turn propellers within an efficient speed range. Certified aircraft engines, where the propeller most commonly is fastened directly to the engine crankshaft, develop peak power near the peak safe and efficient speed for the propeller--2,500 to 3,000 rpm. This speed is considered the typical maximum rpm for a single engine aircraft propeller. Note that there are examples of factory certified aircraft that have used a PSRU. The Cessna 170 used a a geared unit during its production run the 1970s. PUSHER - A propeller mounted in back of its engine, pushing an aircraft through the air, as opposed to a TRACTOR configuration.Q
| Q |
|---|
R
| R |
|---|
Rotorcraft
A heavier-than-air aircraft that depends principally for its support in flight on the lift generated by one or more rotors. Includes helicopters and gyroplanes. RUDDER - The movable part of a vertical airfoil which controls the YAW of an aircraft; the fixed part being the FIN. RUDDERVATOR / RUDDERVATORS - The control surfaces on an airplane with a V-tail configuration. They are located at the trailing edge of each of the two airfoils making up the tail of the plane. The name derives from a combination of the word rudder and elevator. In traditional aircraft tail configurations, the rudder provides horizontal (yaw) control and the elevator provides vertical (pitch) control. Ruddervators provide the same control effect, albeit through a more complex control system by mixing the control inputs. Yaw is achieved through deflecting both ruddervators in the same direction (left or right) as viewed from either the front or the rear of the plane - one toward the centerline of the craft and the other away from the centerline. Pitch is achieved through deflecting both ruddervators in opposite directions - both toward centerline for up elevator and both away from centerline for down elevator.S
| S |
|---|
Safety Wire
Safety wire is used to secure nuts on bolts and prevent them from coming loose as a result of vibration.Sailplane
An unpowered, soaring aircraft capable of maintaining level flight for long periods of time after release from tow and of gaining altitude using wind currents, as opposed to a glider.Scramjet
An acronym for Supersonic Combustion Ramjet, in which combustion occurs at supersonic air velocities through the engine.Seaplane
A water-based aircraft with a boat-hull fuselage, often amphibious. The term is also used generically to define a similar flying Boat and a pontoon FLOATPLANE.Secondary stall
Any stall resulting from pulling back too soon and too hard while recovering from any other stall. Usually a high-speed stall or accelerated stall.Service Ceiling
This is the density altitude at which flying in a clean configuration, at the best rate of climb airspeed for that altitude and with all engines operating and producing maximum (available) continuous power, will produce a 100 feet per minute climb. Margin to stall at service ceiling is 1.5g. The one engine inoperative (OEI) service ceiling of a twin-engine, fixed-wing aircraft is the density altitude at which flying in a clean configuration, at the best rate of climb airspeed for that altitude with one engine producing maximum continuous power and the other engine shut down and feathered, will produce a 50 feet per minute climb. However some performance charts will define the service ceiling as the pressure altitude at which the aircraft will have the capability of climbing at 50 fpm with one propeller feathered. Also see Absolute Ceiling SERVO TAB - A small portion of a flight-control surface that deploys in such a way that it helps to move the entire flight-control surface in the direction that the pilot wishes it to go. A servo tab is a dynamic device that deploys to decrease the pilot’s workload and destabilize the aircraft. SESQUI-WING - A lesser-span additional wingform, generally placed below the main planes of an aircraft, generally a biplane. SHOULDER-WING - A mid-wing monoplane with its wing mounted directly to the top of the fuselage without use of CABANE STRUTs. SINK, SINKING SPEED - The speed at which an aircraft loses altitude, especially in a glide in still air under given conditions of equilibrium. SLATS - Movable vanes or auxiliary airfoils, usually set along the leading edge of a wing but able to be lifted away at certain angles of attack. SLIPSTREAM - The flow of air driven backward by a propeller or downward by a rotor. Compare DOWNWASH. SLOT or SLAT- A long, narrow, spanwise gap in a wing, usually near the leading edge, to improve airflow at high angles of attack for slower landing speeds. A higher coefficient of lift is produced as a product of angle of attack and speed, so by deploying slats an aircraft can fly slower or take off and land in a shorter distance. They are usually used while landing or performing maneuvers which take the aircraft close to the stall, but are usually retracted in normal flight to minimize drag. SLOTTED FLAP - A flap that, when depressed, exposes a SLOT and increases airflow between itself and the rear edge of the wing. SMOH - "Since Major Overhaul," an acronym seen in reference to the operating hours, or time remaining, on an engine. SPLIT FLAP - A FLAP built into the underside of a wing, as opposed to a Full Flap wherein a whole portion of the trailing edge is used. SPOILER - A long, movable, narrow plate along the upper surface of an airplane wing used to reduce lift and increase drag by breaking or spoiling the smoothness of the airflow. SPORT PILOT - Special FAA certification enabling "budget" pilotry; see LIGHT SPORT AIRCRAFT and LSA feature. SPONSON - A short, wing-like protuberance on each side of a seaplane fuselage to increase lateral stability. STABILATOR - A movable horizontal tail that combines the actions of a stabilizer and elevator, increasing longitudinal stability while creating a pitching moment. STABILIZER - The fixed part of a horizontal airfoil that controls the pitch of an aircraft; the movable part being the ELEVATOR. STAGGER - The relative longitudinal position of the wings on a biplane. Positive Stagger is when the upper wing's leading edge is in advance of that of the lower wing [eg: Waco YKS], and vice versa for Negative Stagger [eg: Beechcraft D17]. STALL - (1) Sudden loss of lift when the angle of attack increases to a point where the flow of air breaks away from a wing or airfoil, causing it to drop. (2) A maneuver initiated by the steep raising of an aircraft's nose, resulting in a loss of velocity and an abrupt drop. STANDARD DAY (Standard Atmosphere) - An arbitrary atmosphere established for calibration of aircraft instruments. Standard Air Density is 29.92 inches of mercury and temperature of 59° F, equivalent to an atmospheric air pressure of 14.7# per square inch. STATIC WIRE - A clip-on wire used to ground an aircraft by drawing off static electricity, a potential fire hazard, during refueling. STOICHIOMETRIC - or theoretical combustion is the ideal combustion process during which a fuel is burned completely. A complete combustion is a process that converts all carbon (C) to carbon dioxide (CO2), all hydrogen (H) to water (H2O ), and all sulfur (S) to sulfur dioxide (SO2). If there are unburned components in the exhaust gas such as C, H2, or CO, the combustion process is uncompleted. SUPERCHARGER - An air pump or blower in the intake system of an internal combustion engine. Its purpose is to increase the air-charge weight and therefore the power output from an engine of a given size. In an aircraft engine, the supercharger counteracts the power loss that results from the decrease of atmospheric pressure with increase of altitude. Various types of pumps and compressors may be used as superchargers, which are either mechanically driven by the engine crankshaft or powered by the engine exhaust gas. Also see TURBOCHARGER SUPERSONIC - Speed of flight at or greater than Mach 1.0; literally, faster than the speed of sound. SWEEPBACK - A backward inclination of an airfoil from root to tip in a way that causes the leading edge and often the trailing edge to meet relative wind obliquely, as WINGFORMs that are swept back. SWING-WING - A wing whose horizontal angle to the fuselage centerline can be adjusted in flight to vary aircraft motion at differing speeds.T
| T |
|---|
True Air Speed
Or TAS . Because an air speed indicator indicates true air speed only under standard sea-level conditions, true air speed is usually calculated by adjusting an Indicated Air speed according to temperature, density, and pressure. Compare Calibrated Airspeed and Indicated Airspeed. THRUST - The driving force of a propeller in the line of its shaft or the forward force produced in reaction to the gases expelled rearward from a jet or rocket engine. Opposite of DRAG. THRUST HORSEPOWER - The force-velocity equivalent of the thrust developed by a jet or rocket engine. The thrust of an engine-propeller combination expressed in horsepower; it differs from the shaft horsepower of the engine by the amount the propeller efficiency varies from 100 percent. (Naval architecture) The product of the speed of advance of a marine propeller through the water, in feet per second, and the thrust delivered by the propeller, in pounds, divided by 550. TORQUE - A twisting, gyroscopic force acting in opposition to an axis of rotation, such as with a turning propeller; aka Torsion. TRACTOR - A propeller mounted in front of its engine, pulling an aircraft through the air, as opposed to a PUSHER configuration. TRAILING EDGE - The rearmost edge of an AIRFOIL. TRIKE - Nickname for a weight-shift-control aircraft, such as a paraglider. TRIM TAB - A small, auxiliary control surface in the trailing edge of a WINGFORM, adjustable mechanically or by hand, to counteract ("trim") aerodynamic forces on the main control surfaces. TRUE AIRSPEED (TAS)- The speed of an aircraft along its flight path, in respect to the body of air (air mass) through which the aircraft is moving. Also see CALIBRATED AIRSPEED, GROUND SPEED, and INDICATED AIRSPEED. TURBOCHARGER – (Turbo) An air compressor or SUPERCHARGER on an internal combustion piston engine that is driven by the engine exhaust gas to increase or boost the amount of fuel that can be burned in the cylinder, thereby increasing engine power and performance. On an aircraft piston engine, the turbocharger allows the engine to retain its sea-level power rating at higher altitudes despite a decrease in atmospheric pressure. Also see SUPERCHARGER. TURBOJET - An aircraft having a jet engine in which the energy of the jet operates a turbine that in turn operates the air compressor. TURBOPROP - An aircraft having a jet engine in which the energy of the jet operates a turbine that drives the propeller.U
| U |
|---|
V
| V |
|---|
W
| W |
|---|
Wingform
A wingform is the shape and layout of an airplane's wings as viewed from above or below. Ailerons form part of the wingform. Also see Planform. WINGLET - A small, stabilizing, rudder-like addition to the tips of a wing to control or employ air movement. WING LOADING - The maximum take-off gross weight of an aircraft divided by its wing area.X
| X |
|---|
Y
| Y |
|---|
Z
| Z |
|---|
Unsorted stuff
Unsorted terms terms and definitions to add and edit used in association with civil flight obtained from the Code of Federal Regulations, Federal Aviation Regulations, and many other sourcesABSOLUTE ALTITUDE - The measureable height of an aircraft above the actual terrain.
ABSOLUTE CEILING - The maximum altitude above sea level at which an aircraft can maintain level flight under Standard Air conditions.
ACCELERATED STALL - Any stall made to occur at other than 1g.
ACCESSORY GROUP - Mechanical and electrical units mounted on an engine necessary for its operation, such as starter, magnetos, fuel pumps, etc.
ADCOCK RANGE - National low-frequency radio navigation system (c.1930-c.1950) replaced by an omnirange (VOR) system. It consisted of four segmented quadrants broadcasting Morse Code "A" (dot-dash) and "N" (dash-dot) signals in opposing quadrants so that pilots could orient their position relative to a "beam" broadcasting a steady tone, and a Morse Code station identifier. Using a "build-and-fade" technique, a pilot could (ideally) pinpoint his location by the strength or weakness of a signal. Read about it here.
ADF - Automatic Direction Finding via automated radio.
ADIABATIC LAPSE RATE - The rate at which ascending air cools and descending air warms, given that no heat is added or taken away. The rate for dry air (DALR) is based on 5.4° F per 1000' altitude (1° per 100 meters). Moist or saturated rates (SALR) vary with barometric pressures and temperatures and must be adjusted for accuracy.
ADVERSE YAW - Yaw generated when the ailerons are used. The lifting wing generates more drag, causing an airplane to yaw (turn) toward it.
AGL - Above Ground Level, as a measurement of altitude above a specific land mass, and differentiated from MSL.
AILERON - The movable areas of a wingform that control or affect the roll of an aircraft by working opposite one another—up-aileron on the right wing and down-aileron on the left wing. French: aileron small wing, diminutive of aile, from Latin: ala, wing. The word "aisle" also derives from the same root. (Above pic proves that birds invented ailerons long before man did.)
AIR DEFENSE IDENTIFICATION ZONE (ADIZ) - The area of airspace over land or water, extending upward from the surface, within which the ready identification, the location, and the control of aircraft are required in the interest of national security.
Domestic Air Defense Identification Zone - An ADIZ within the United States along an international boundary of the United States.
Coastal Air Defense Identification Zone - An ADIZ over the coastal waters of the United States.
Distant Early Warning Identification Zone (DEWIZ) - An ADIZ over the coastal waters of the State of Alaska. ADIZ locations and operating and flight plan requirements for civil aircraft operations are specified in FAR Part 99.
AIRFOIL - The shape of any flying surface, but principally a wing, as seen in side-view ("cross-section"). Its characteristics are Center of Pressure (CP), DRAG (CD), LIFT (CL), Lift-Drag Ratio (L/D), and Moment (CM).
AIR ROUTE TRAFFIC CONTROL CENTER (ARTCC) or "CENTER" - A facility established to provide air traffic control service to aircraft operating on IFR flight plans within controlled airspace and principally during the en route phase of flight. When equipment capabilities and controller workload permit, certain advisory/assistance services may be provided to VFR aircraft.
AIR SPEED INDICATOR - An instrument or device that measures the air speed of an aircraft through an air mass, but not its ground speed.
AIR TAXI - An aircraft operator who conducts operations for hire or compensation in accordance with FAR Part 135 in an aircraft with 30 or fewer passenger seats and a payload capacity of 7,500# or less. An air taxi operates on an on-demand basis and does not meet the "flight scheduled" qualifications of a commuter.
AIR TRAFFIC CONTROL (ATC) - A service operated by the appropriate authority to promote the safe, orderly, and expeditious flow of air traffic.
AIRPORT TRAFFIC CONTROL TOWER (ATCT) - A terminal facility that uses air/ground communications, visual signaling, and other devices to provide ATC services to aircraft operating in the vicinity of an airport or on the movement area. Authorizes aircraft to land or takeoff at the airport controlled by the tower or to transit the Class D airspace area regardless of flight plan or weather conditions (IFR or VFR). A tower may also provide approach control services (radar or non-radar).
ALCLAD - Trademark name of Alcoa for high-strength sheet aluminum clad with a layer (approximately 5.5% thickness per side) of high-purity aluminum, popularly used in airplane manufacture.
ALPHABET (PHONETIC) - Devised for reasons of clarity in aviation voice radio, this is the current NATO version in global use:
ALFA BRAVO CHARLEY DELTA ECHO FOXTROT GOLF
HOTEL INDIA JULIET KILO LIMA MIKE NOVEMBER
OSCAR PAPA QUEBEC ROMEO SIERRA TANGO
UNIFORM VICTOR WHISKY X-RAY YANKEE ZULU
The original, from early in World War 2, was:
ABLE BAKER CHARLEY DOG EASY FOX GEORGE
HOW ITEM JIG KING LOVE MIKE NAN OBOE
PETER QUEEN ROGER SUGAR TARE UNCLE VICTOR
WILLIAM X-RAY YOKE ZEBRA
ALTIMETER - An adjustable aneroid-barometric cockpit instrument used to measure an aircraft's altitude.
AMPHIBIAN, AMPHIBION - A SEAPLANE or FLOATPLANE with retractable wheels for use on land, as well. The latter spelling was used in the '20s and '30s but has since fallen out of favor.
ANGLE OF ATTACK - The acute angle at which a moving airfoil meets the airstream.
ANGLE OF INCIDENCE - The angle at which an airfoil is normally fixed in relation to the longitudinal axis of an aircraft.
ANHEDRAL - The downward angle of a wing in relation to a horizontal cross-section line; aka CATHEDRAL. See DIHEDRAL.
APPROACH CONTROL see RADIO NAVIGATION
APRON - The hard-surfaced or paved area around a hangar.
ARM - In aircraft weight and balance, as well as load distribution, it is the distance from the CENTER OF GRAVITY (c/g) to some point. For computations, arms measured forward from the c/g are positive (+n) and those measured aft of the c/g are negtive (-n).
ARSA see CONTROLLED AIRSPACE
ARTIFICIAL HORIZON - A vacuum-powered panel instrument that displays pitch and roll movements about the lateral and longitudinal axes; aka Attitude Indicator.
ASPECT RATIO - The ratio of the span to the chord of an airfoil—a high-aspect ratio wing has wide span and narrow chord, and vice-versa for a low-aspect ratio wing.
ATA see CONTROLLED AIRSPACE
ATC - (1) Aircraft license as Approved Type Certificate, see ATC; (2) AIR TRAFFIC CONTROL.
ATIS see AUTOMATIC TERMINAL INFORMATION SERVICE
AUTOGYRO, AUTOGIRO - An aircraft, often wingless, with unpowered rotary airfoil blades that auto-rotate and serve as wings as they move through the air when mounted on a powered aircraft (or, in some cases, a glider). The latter spelling is a trademark of the Autogiro Corporation.
AUTO-ROTATION - Automatic rotation of rotary blades from a helicopter in an unpowered glide or the forward movement of an autogyro.
AUTOMATIC TERMINAL INFORMATION SERVICE (ATIS) - Continuous broadcast of recorded non-control information in selected terminal areas, to improve controller effectiveness and to relieve frequency congestion by automating repetitive transmissions of essential but routine information.
BALANCED CONTROL SURFACE - A movable control surface, as an aileron or rudder, having an added physical extension or weights forward of the hinge-point to reduce forces on a joystick or yoke. See ELEPHANT EARS (2).
BERNOULLI EFFECT or LAW or THEOREM - Since the pressure of a fluid is proportional to its velocity, airflow over the upper surface of an airfoil causes suction [lift] because the airstream has been speeded up in relation to positive pressure of the airflow on the lower surface.
BLEED AIR - Hot air at high pressure, usually from the bypass section of a gas turbine engine, for de-icing, heating, and other uses.
BOUNDARY-LAYER CONTROL - The design or control of slotted or perforated wings with suction methods to reduce undesirable aerodynamic effects caused by the boundary layer—that region adjacent to the boundary where shear stresses dominate in the airflow over a wingform.
BUMPED COWLING - An engine FAIRING, generally circular, with welts or compound shapes in its surface to accommodate cylinder heads.
CABANE STRUT - Wing strut attached to the fuselage.
CALIBRATED AIRSPEED (CAS) - The indicated airspeed of an aircraft, corrected for position and instrument error. CAS is equal to true airspeed in standard atmosphere at sea level. Compare INDICATED AIRSPEED and TRUE AIRSPEED.
CAMBER - The convex or concave curvature of an airfoil.
CANARD - An arrangement in which the horizontal stabilizer and elevators of an aircraft are mounted in front of the main wing(s).
CAT - Clear-Air Turbulence.
CATHEDRAL see ANHEDRAL
CAVU - Ceiling and Visibility Unlimited; ideal flying weather.
CEILING - (1) The heights above the earth's surface of the lowest layer of clouds or obscuring phenomena that is reported as "broken," "overcast," or "obscuration," and not classified as "thin" or "partial". (2) The maximum height above sea level in STANDARD AIR attainable by an aircraft under given conditions—see ABSOLUTE CEILING, SERVICE CEILING.
CENTER - An Air Route Traffic Control Center (ARTCC).
CENTER OF GRAVITY (c/g) - The longitudinal and lateral point in an aircraft where it is stable; the static balance point.
CERTIFICATED AIRPORT - An airport operating under FAR Part 139. The FAA issues airport operating certificates to all airports serving scheduled or unscheduled air carrier aircraft designed for more than 30 passenger seats. Certificated airports must meet minimum safety standards in accordance with FAR Part 139.
CHORD - The measurable distance between the leading and trailing edges of a wingform.
CLASS G AIRSPACE (Uncontrolled Airspace) - Airspace not designated as Class A, B, C, D or E CONTROLLED AIRSPACE.
COAMING - A padded, protective rim around an open cockpit.
COLLECTIVE PITCH - A cockpit control that changes the PITCH of a helicopter's rotor blades; used in climbing or descending.
COLLECTOR RING - A circular duct on a radial engine into which exhaust gases from its cylinders are safely discharged.
COMMON TRAFFIC ADVISORY FREQUENCY (CTAF) - A frequency designed for the purpose of carrying out airport advisory practices while operating to or from an airport without an operating control tower. The CTAF may be a UNICOM, Multicom, FSS, or tower frequency and is identified in appropriate aeronautical publications.
COMMUTER - An air carrier operator operating under 14 CFR 135 that carries passengers on at least five round trips per week on at least one route between two or more points according to its published flight schedules that specify the times, day of the week, and places between which these flights are performed. The aircraft that a commuter operates has 30 or fewer passenger seats and a payload capability of 7,500# or less.
COMPASS COURSE - A bearing as indicated by the horizontal angle between the compass needle and the centerline of the aircraft. A Compass Course is equal to a True Course ± variation and deviation; also equal to a Magnetic Course ± deviation.
COMPASS NORTH - The North point at which a liquid compass needle points, rather than Geographical, or True, North. Compare MAGNETIC NORTH.
CONE OF SILENCE - Click the Adcock page.
CONSTANT-SPEED PROPELLER - A hydraulically-controlled propeller that governs an engine at its optimum speed by the blade pitch being increased or decreased automatically.
CONTACT FLIGHT - Navigation in which altitude and flight path can be maintained by visual reference to the ground and its landmarks. Similar to VFR.
CONTOUR FLIGHT - Contact Flight in and around mountainous areas following visual reference to the terrain's countours.
CONTRAIL - Trailing streak of condensed water vapor created in the air by heat from an aircraft engine at high altitudes; aka VAPOR TRAIL.
CONTROLLED AIRSPACE - An airspace of defined dimensions within which air traffic control service is provided to IFR flights and to VFR flights in accordance with the airspace classification. Controlled airspace is a generic term that covers Class A, B, C, D, and E airspace. Controlled airspace is also that airspace within which all aircraft operators are subject to certain pilot qualifications, operating rules, and equipment requirements in FAR Part 91. For IFR operations in any class of controlled airspace, a pilot must file an IFR flight plan and receive an appropriate ATC clearance. Each B, C, and D airspace area designated for an airport contains at least one primary airport around which the airspace is designated (for specific designations and descriptions of the airspace classes, refer to FAR Part 71).
Class A (formerly PCA - Positive Control Area) generally, that airspace from 18,000' mean sea level (MSL) up to and including flight level (FL) 600 (60,000' pressure altitude), including the airspace overlying the waters within 12 nautical miles of the coast of the 48 contiguous States and Alaska. Unless otherwise authorized, all persons must operate their aircraft under IFR.
Class B (formerly TCA - Terminal Control Area) Generally, that airspace from the surface to 10,000' MSL surrounding the nation's busiest airports in terms of airport operations or passenger enplanements. The configuration of each Class B airspace area is individually tailored and consists of a surface area and two or more layers (some Class B airspace areas resemble upside-down wedding cakes), and is designed to contain all published instrument procedures once an aircraft enters the airspace. An ATC clearance is required for all aircraft to operate in the area, and all aircraft that are so cleared receive separation services within the airspace. The cloud clearance requirement for VFR operations is "clear of clouds."
Class C (formerly ARSA - Airport Radar Service Area) Generally, that airspace from the surface to 4,000' MSL above the airport elevation surrounding those airports that have an operational control tower, are serviced by a radar approach control, and that have a certain number of IFR operations or passenger enplanements. Although the configuration of each Class C area is individually tailored, the airspace usually consists of a surface area with a 5 nautical mile (nm) radius, an outer circle with a 10 nm radius that extends from 1,200' to 4,000' above the airport elevation and an outer area. Each person must establish two-way radio communications with the ATC facility providing air traffic services prior to entering the airspace and thereafter maintain those communications while within the airspace. VFR aircraft are only separated from IFR aircraft within the airspace.
Class D (formerly ATA - Airport Traffic Area and CZ - Control Zone) Generally, that airspace from the surface to 2,500' MSL above the airport elevation surrounding those airports that have an operational control tower. The configuration of each Class D airspace area is individually tailored and when instrument procedures are published, the airspace will normally be designed to contain the procedures. Arrival extensions for instrument approach procedures may be Class D or E airspace. Unless otherwise authorized, each person must establish two-way radio communications with the ATC facility providing air traffic services prior to entering the airspace and thereafter maintain those communications while in the airspace. No separation services are provided to VFR aircraft.
Class E (formerly General Controlled Airspace) Generally, if the airspace is not Class A, B, C, or D, and is controlled airspace, it is Class E airspace. Class E airspace extends upward from either the surface or a designated altitude to the overlying or adjacent controlled airspace. When designated as a surface area, the airspace will be configured to contain all instrument procedures. Also in this class are Federal airways, airspace beginning at either 700' or 1,200' AGL used to transition to/from the terminal or enroute environment, enroute domestic, and offshore airspace areas designated below 18,000' MSL. Unless designated at a lower altitude, Class E airspace begins at 14,500' MSL over the USA, including that airspace overlying the waters within 12 nautical miles of the coast of the 48 contiguous States and Alaska, up to, but not including 18,000' MSL, and the airspace above Flight Level 600.
CONVENTIONAL GEAR - Having two main landing wheels at the front and a tailwheel or tailskid at the rear as opposed to having a tricycle gear with three main wheels. Such an aircraft is popularly called a TAILDRAGGER.
COWL, COWLING - A circular, removable FAIRING around an aircraft engine (generally radial) for the purposes of streamling or cooling; aka RING COWLING.
COWL FLAP - A controllable louvre to regulating airflow through an engine's cowling.
CRAB - A rudder-controlled yawing motion to compensate for a crosswind in maintaining a desired flight path, as in a landing approach.
CTAF see COMMON TRAFFIC ADVISORY FREQUENCY
DEAD RECKONING - In pioneer flight before radio, beacons, and accurate maps, flying distances much by instinct and guesswork, and referring to whatever landmarks were below, was quite routine. The "dead" part simply meant "straight," as in the nautical "dead ahead," and pilots often relied heavily on the IRON COMPASS for cross-country flights over unfamiliar territory.
DEADSTICK - Descending flight with engine and propeller stopped.
DECALAGE - The difference in angular settings [Angles of Attack] of the wings of a biplane or multiplane.
DECISION HEIGHT - With respect to the operation of aircraft, the height at which point a decision must be made during an instrument approach to either continue the approach or to execute a missed approach [abort].
DELTA-WING - A triangularly-shaped aircraft wing having a low aspect ratio, a sharply-tapered leading edge, a straight trailing edge, and a pointed tip.
DEPARTURE CONTROL see RADIO NAVIGATION
DEPARTURE STALL - A stall in the takeoff configuration with power.
DEVIATION (MAGNETIC) - The error of a Magnetic Compass due to inherent magnetic influences in the structure and equipment of an aircraft.
DEWIZ see AIR DEFENSE IDENTIFICATION ZONE
DIHEDRAL - The acute angle, usually upward, between the wing of an airplane and a horizontal cross-section line. Opposite of ANHEDRAL.
DIRECTIONAL GYRO - A panel instrument providing a gyroscopic reading of an aircraft's compass heading.
DIRIGIBLE - A lighter-than-air craft capable of being propelled and steered for controlled flight. Latin: dirigo,to steer.
DME - Distance Measuring Equipment, a radio navigation device that determines an aircraft's distance from a given ground station, as well as its groundspeed and time to/from the station.
DOPE - Preservative and pigmented coloring for fabric aircraft covering and paints, generally nitrate lacquer but generically used to denote all early shellac and coal-tar mixtures on up to present-day acrylics.
DORSAL FIN - A lateral fin/rudder extension on the top of a fuselage. Opposite of VENTRAL FIN.
DOWNWASH - The air deflected perpendicular to the direction of movement of an airfoil.
DRAG - The resisting force exerted on an aircraft in its line of flight opposite in direction to its motion. Compare THRUST.
DRAG WIRE - A wire designed to resist DRAG forces, usually running from a forward inboard point to an outboard aft point.
DRIFT - The angle between the heading of an aircraft and its Track [flight path] over the ground as affected by winds.
DRY WEIGHT - The weight of an engine exclusive of any fuel, oil, and coolant.
DURAL - Originally a tradename for a wrought aluminum-copper alloy created by Bausch Machine Tool Co, now fallen into generic use as any aluminum alloy containing 3.0-4.5% copper, 0.4-1.0% magnesium, and 0.1-0.7% manganese. Alcoa's version is commonly referred to as "Duraluminum," popularly used in aircaft manufacture.
DZUS FASTENER - ("Zoose") Very singular to aircraft, a patented slotted screw that binds to a wire for fast release and securing of cowlings and inspection plates, requiring no special tool other than a quarter coin.
EARTH-INDUCTOR COMPASS - One whose indications depend on the current generated in a coil revolving in the earth's magnetic field.
ELEPHANT EAR - (1) An air intake characterized by twin inlets, one on each side of the fuselage. (2) A type of balanced aileron in which the outer edges are noticeably larger than the control itself. See BALANCED CONTROL SURFACE and example Travel Air 4000.
ELEVATOR - The movable part of a horizontal airfoil which controls the pitch of an aircraft, the fixed part being the STABILIZER.
ELEVON - A hinged device on the rear portion of an aircraft wing combining the functions of an elevator and an aileron. Usually found on delta-wing aircraft, it can be moved in the same direction on either side of the aircraft to obtain longitudinal control, or differentially to obtain lateral control. Also see FLAPERON.
ELT - Emergency Locator Transmitter
EMPENNAGE - An aircraft's tail group, includes rudder and fin, and stabilizer and elevator. Old French: empenner, to feather an arrow, from Latin penna, feather.
EN ROUTE AIR TRAFFIC CONTROL SERVICES - Air traffic control services provided aircraft on IFR flight plans, generally by centers, when these aircraft are operating between departure and destination terminal areas. When equipment, capabilities, and controller workload permit, certain advisory/assistance services may be provided to VFR aircraft.
ETA - Estimated Time of Arrival.
ETD - Estimated Time of Departure.
FAIRING - An added streamlining structure or auxiliary member, most often of light metal, whose only purpose is to reduce drag. Fairings are not load-bearing and, therefore, are not meant to carry any principal air loads placed on the airplane structure.
FBO - Fixed-Base Operator. A commercial operator supplying fuel, maintenance, flight training, and other services at an airport.
FAN MARKER see RADIO NAVIGATION
FEATHERING - In the event of engine failure, the process of adjusting a controllable-pitch propeller to a pitch position where the blade angle is about 90° to the plane of rotation in order to to stop its windmilling and lessen drag.
FEDERAL AIR REGULATION (FAR)
FAR Part 91 - General Aviation (portions apply to all operators)
FAR Part 103 - Ultralight Vehicles
FAR Part 105 - Parachute Jumping
FAR Part 108 - Airplane Operator Security
FAR Part 119 - Certification: Air Carriers and Commercial Operators
FAR Part 121 - Domestic, Flag, and Supplemental Air Carriers and Commercial Operators of Large Aircraft
FAR Part 123 - Travel Clubs
FAR Part 125 - US Civil Airplanes, seating 20 or more passengers or a maximum payload capacity 6,000# or more
FAR Part 127 - Air Carriers using helicopters for scheduled interstate flights (within the 48 contiguous states)
FAR Part 129 - Foreign Air Carrier and Foreign Operators of US registered aircraft engaged in common carriage
FAR Part 133 - Rotorcraft External Load Operations
FAR Part 135 - Air Taxi Operators and Commercial Operators
FAR Part 137 - Agricultural Aircraft Operations
FAR Part 141 - Pilot School
FERRY FLIGHT - A flight for the purpose of (1) returning an aircraft to base; (2) delivering an aircraft from one location to another; (3) moving an aircraft to and from a maintenance base. Ferry flights, under certain conditions, may be conducted under terms in a special flight permit.
FIN - The fixed part of a vertical airfoil that controls the yaw of an aircraft; the movable part being the RUDDER. Sometime referred to as Vertical Stabilizer.
FIREWALL - A fire-resistant bulkhead that isolates the engine from other parts of an airplane's structure.
FISHTAILING - A rudder-controlled side-to-side [yawing] motion to reduce air speed, generally prior to landing.
FIVE-BY-FIVE (5x5) - In radio jargon, affirms that a radioed transmission was received as clear and loud. Rated one to five, with the first figure for clearness and the second second for loudness.
FLAP - A movable, usually hinged AIRFOIL set in the trailing edge of an aircraft wing, designed to increase LIFT or DRAG by changing the CAMBER of the wing or used to slow an aircraft during landing by increasing lift. Also see FOWLER FLAP, SLOTTED FLAP, and SPLIT FLAP.
FLAPERON - A control surface combining the functions of a FLAP and an AILERON.
FLARE - A simple maneuver performed moments before landing in which the nose of an aircraft is pitched up to minimize the touchdown rate of speed.
FLIGHT ENVELOPE - An aircraft's performance limits, specifically the curves of speed plotted against other variables to indicate the limits of speed, altitude, and acceleration that a particular aircraft cannot safely exceed.
FLIGHT LEVEL (FL) - A level of constant atmospheric pressure related to a reference datum of 29.92 inches of mercury. Each is stated in three digits that represent hundreds of feet—flight level 250 represents a barometric altimeter indication of 25,000', flight level 255 as 25,500'.
FLIGHT PLAN - Specified information relating to the intended flight of an aircraft, filed orally or in writing with an FSS or an ATC facility.
FLIGHT SERVICE STATION (FSS) - Air traffic facilities which provide pilot briefing, enroute communications and VFR search and rescue services, assist lost aircraft and aircraft in emergency situations, relay ATC clearances, originate Notices to Airmen, broadcast aviation weather and NAS information, receive and process IFR flight plans, and monitor NAVAIDs. In addition, at selected locations, FSSs provide Enroute Flight Advisory Service (Flight Watch), take weather observations, issue airport advisories, and advise Customs and Immigration of transborder flights.
FLOATPLANE - A water-based aircraft with one or more mounted pontoons, as differentiated from a hulled SEAPLANE [Flying Boat], but often used generically.
FLYING WIRES - Interplane bracing wires that help support wingloads when the plane is in flight. Direction of travel is upward and outward from the fuselage to the interplane struts. Also known as LIFT WIRES, the opposite of LANDING WIRES.
FOWLER FLAP - Trademark name of a split-flap attached to a wing's trailing edge with a system of tracks and rollers to roll the FLAP backward and downward, increasing the wing area. Named for its inventor, USAAF engineer Harland D Fowler.
FRISE AILERON - A type of aileron that has a beveled leading edge projecting beyond its inset hinges. When lowered, it forms an extension of the wing surface; when raised, its nose protrudes below the wing, increasing DRAG and reducing YAW. Named for its inventor, British engineer Leslie George Frise.
FSS see FLIGHT SERVICE STATION
FUSELAGE - An aircraft's main body structure housing the flight crew, passengers, and cargo and to which the wings, tail and, in most single-engined airplanes, engine are attached. French: fuselé, tapering.
g or G see LOAD FACTOR
GAP - The distance between two adjacent wings of a biplane or multiplane.
GCA - Ground-Controlled Approach; part of ILS.
GENERAL AVIATION - That portion of civil aviation which encompasses all facets of aviation except air carriers holding a certificate of public convenience and necessity from the Civil Aeronautics Board and large aircraft commercial operators.
GEOGRAPHIC NORTH - The northern axis around which the Earth revolves; aka "Map North" and TRUE NORTH. Also see MAGNETIC NORTH.
GLASS COCKPIT - Said of an aircraft's control cabin which has all-electronic, digital and computer-based, instrumentation.
GLIDER - An unpowered aircraft capable of maintaining altitude only briefly after release from tow, then gliding to earth. Compare SAILPLANE.
GLIDE SLOPE - (1) The angle between horizontal and the glide path of an aircraft. (2) A tightly-focused radio beam transmitted from the approach end of a runway indicating the minimum approach angle that will clear all obstacles; one component of an instrument landing system (ILS).
GPS - Global Positioning System; satellite-based navigation.
GREEN LIGHT - Approval for landing. A carryover expression from days when aircraft for the most part had no radios, and communication from a control tower was by means of a light-gun that beamed various green, red, and yellow signals to pilots in the air and on the ground. A popular phrase, "3 green lights," refers to the instrument panel lights verifying that all three gears (in a tri-gear aircraft) are down and locked for safe landing.
GROSS WEIGHT - The total weight of an aircraft when fully loaded, including fuel, cargo, and passengers; aka Takeoff Weight.
GROUND CONTROL - Tower control, by radioed instructions from air traffic control, of aircraft ground movements at an airport.
GROUND CUSHION see GROUND EFFECT
GROUND EFFECT - Increased lift generated by the interaction between a lift system and the ground when an aircraft is within a wingspan distance above the ground. It affects a low-winged aircraft more than a mid- or high-winged aircraft because its wings are closer to the ground; aka GROUND CUSHION.
GROUNDSPEED - The actual speed that an aircraft travels over the ground—its "shadow speed"; it combines the aircraft's AIRSPEED and the wind's speed relative to the aircraft's direction of flight.
GULL-WING - Descriptive of wing in frontal view bent as the wing of a seagull; a distinctive shallow, inverted "V" shape—see Stinson SR-10 or inverted gull-wing Vought F4U .
GYROPLANE - A rotorcraft whose rotors are not engine-driven, except for initial starting, but are made to rotate by action of the air when the rotorcraft is moving and whose means of propulsion, usually a conventional propeller, is independent of the rotor system. Similar to AUTOGYRO.
HANGAR - An enclosed structure for housing aircraft. Originated with lake-based floating homes of the original German Zeppelins in which they were "hung" from cables, which explains the erroneous, oft-seen spelling of "hanger." French: hangar, shed, outbuilding, from Latin: angarium, shed.
HELICOPTER - A wingless aircraft acquiring its lift from revolving blades driven by an engine about a near-vertical axis. A ROTORCRAFT acquiring its primary motion from engine-driven rotors that accelerate the air downward, providing a reactive lift force, or accelerate the air at an angle to the vertical, providing lift and thrust.
HIGH BLOWER - A blower-type supercharger set at high rpm.
HIGH-SPEED STALL - Any stall made to occur at more than 1g, such as pulling out of a dive or while turning.
HORSEPOWER - The motive energy required to raise 550# one foot in one second, friction disregarded.
HYPERSONIC - Speed of flight at or greater than Mach 5.0, exceeding SUPERSONIC.
HYPOXIA - Deprivation of oxygen, aka "altitude sickness," which can adversely affect human judgment and movement at altitudes above 12,000' with symptoms ranging from light dizziness to unconsciousness, even death at the extreme. It was a principal reason for pressurized aircraft.
IFR - Instrument Flight Rules, governing flight under instrument meteorological conditions.
ILS - Instrument Landing System. A radar-based system allowing ILS-equipped aircraft to find a runway and land when clouds may be as low as 200' (or lower for special circumstances).
INDICATED AIRSPEED (IAS) - A direct instrument reading obtained from an air speed indicator uncorrected for altitude, temperature, atmospheric density, or instrument error. Compare CALIBRATED AIRSPEED and TRUE AIRSPEED.
INSTRUMENT METEOROLOGICAL CONDITIONS (IMC) - Meteorological conditions expressed in terms of visibility, distance from clouds, and ceiling less than minima specified for visual meteorological conditions (VMC).
IRON COMPASS - Railroad tracks, favored by pilots of yore as a dependable aid to surface navigation before radio.
JOYSTICK - A single floor- or roof-mounted control stick—sideways movement produces ROLL, and forward/backward movement produces PITCH (rudder pedals produce YAW).
KNOT - One nautical mile, about 1.15 statute miles (6,080'); eg: 125kts = 143.9mph.
LAMINAR-FLOW AIRFOIL - A low-drag airfoil designed to maintain laminar (smooth, continuous) flow over a high percentage of the CHORD about itself. Often relatively thin, especially along the leading edge, with most of its bulk near the center of the chord.
LANDING WIRES - Interplane bracing wires that help support wingloads when the plane is on the ground. Direction of travel is downward and outward from the fuselage. Opposite of FLYING WIRES.
LIFT - The force exerted on the top of a moving airfoil as a low-pressure area [vacuum] that causes a wingform to rise. AIRFOILs do not "float" on air, as is often assumed—like a boat hull floats on water—but are "pulled up" [lifted] by low air pressures trying to equalize.
LIFT-DRAG RATIO - The lift coefficient of a wing divided by the drag coefficient, as the primary measure of the efficiency of an aircraft; aka L/D Ratio.
LIFT WIRES - Interplane bracing wires that help support wingloads when the plane is in flight. Direction of travel is upward from the bottom of the fuselage to the top of the interplane struts. Also known as FLYING WIRES, the opposite of LANDING WIRES.
LIGHT SPORT AIRCRAFT - Special FAA certification class (LSA) for an aircraft other than a helicopter or powered-lift—single-engine aircraft, airship, balloon, GLIDER, GYROCOPTER, ROTORCRAFT, weight-shift-control aircraft. While limiting the types of aircraft that could be flown by a Sport Pilot, it simplified requirements for a obtaining a pilot license and did not require a medical examination. See LSA feature.
LIQUID COMPASS - A non-electronic, calibratable compass floating in a liquid as a panel instrument; aka WET COMPASS.
LOAD FACTOR (g) - The proportion between lift and weight commonly seen as g (sometimes capitalized)—a unit of force equal to the force of gravity times one.
LOFTING - Design or fabrication of a complex aircraft component, as with sheet metal, using actual-size patterns or plans, generally laid out on a floor. The term was borrowed from boat builders.
LONGERON - A principal longitudinal member of a fuselage's framing, usually continuous across a number of supporting points.
LOOP ANTENNA - A circular radio antenna, either in the open or in a streamlined, teardrop housing, remotely turned 360° to fine-tune a station in league with other radio-directive devices. See also RADIO COMPASS, RADIO DIRECTION FINDER.
LORAN - Long Range Navigation system, which utilizes timing differences between multiple low-frequency transmissions to provide accurate latitude/longitude position information to within 50'.
LTA - Lighter-than-air craft, generally referring to powered blimps and dirigibles, but often also includes free balloons.
LUNKENHEIMER VALVE - A manual fuel drain placed handily along a fuel line for checking avgas, such as for water or sediment contaminations.
Mach or m. - A number representing the ratio of the speed of an object to the speed of sound in the surrounding air or medium in which it is moving.
MAGNETIC COMPASS - The most common liquid-type compass, capable of calibration to compensate for magnetic influences within the aircraft.
MAGNETIC COURSE - COMPASS COURSE ± deviation.
MAGNETIC NORTH - The magnetic North pole, located near 71° North latitude and 96° West longitude, that attracts a magnetic compass which is not influenced by local magnetic attraction, as opposed to GEOGRAPHIC NORTH.
MAGNETO, MAG - An accessory that produces and distributes a high-voltage electric current for ignition of a fuel charge in an internal combustion engine.
MAGNUS EFFECT - The effect on a spinning cylinder or sphere moving through a fluid, in which force acts perpendicular to the direction of motion and to the direction of spin. This is used to advantage in baseball, in which the trajectory of a pitched ball is a distinct curve. Applied to aeronautics in experimental wingforms, the Magnus Theory states that if air is directed against a smooth, revolving cylinder, whose circumferential speed is greater than that of the air current, a force is directed against one side of the cylinder—air compressed on one side and vacuum formed on the other—creating lift. Named for physicist Heinrich Gustav Magnus (1802-70).
MARKER BEACON see RADIO NAVIGATION
MEAN SEA LEVEL see MSL
METAR - Acronym in FAA pilot briefings and weather reports simply means an "aviation routine weather report," but nobody seems certain about the original source. The format was introduced by the French on 1 Jan 1968, but was not adopted by USA and Canada until 1 July 1996, and is thought to be a contraction from MÉTéorologique ("Weather") Aviation Règuliére ("Routine"). FAA and NOAA specifically define METAR as "an approximate translation from the French."
MOA see SPECIAL USE AIRSPACE
MONOCOQUE - Type of fuselage design with little or no internal bracing other than bulkheads, where the outer skin bears the main stresses; usually round or oval in cross-section. Additional classifications are (1) Semi-Monocoque, where the skin is reinforced by longerons or bulkheads, but with no diagonal web members, and (2) Reinforced Shell, in which the skin is supported by a complete framework or structural members. French: monocoque, single shell.
MSL - Mean Sea Level. The average height of the surface of the sea for all stages of tide; used as a reference for elevations, and differentiated from AGL.
NACELLE - A streamlined enclosure or housing to protect something such as the crew, engine, or landing gear. French: nacelle, from Latin, navicella, little ship.
NATIONAL AIRSPACE SYSTEM (NAS) - The common network of US airspace; air navigation facilities, equipment and services, airports or landing areas; aeronautical charts, information and services; rules, regulations and procedures, technical information, and human resources and material. Included are system components shared jointly with the military.
NDB - Non-Directional Beacon. An LF, MF, or UHF radio beacon transmitting non-directional signals whereby the pilot of an aircraft equipped with direction finding equipment can determine his bearing to or from the radio beacon and "home" on or track to or from the station. When the radio beacon is installed in conjuncion with the Instrument Landing System (ILS) marker, it is normally called a Compass Locator.
ON THE BEAM - A leftover phrase from ADCOCK Radio Range days still means the same thing today—"You are headed in the right direction," as when you you hear a steady broadcast tone beamed from your target radio transmitter. Also as RIDING THE BEAM. Read about it here.
OVERSHOOT - To land beyond a runwway or planned spot. Opposite of UNDERSHOOT.
PANTS - A popular word for streamlined, non-load bearing fairings to cover landing wheels. Also sometimes called Spats or, when fully enclosing the wheel struts, Skirts.
PAR - Precision Approach Radar, a ground-radar-based instrument approach providing both horizontal and vertical guidance
PATTERN - The path of aircraft traffic around an airfield, at an established height and direction. At tower-controlled fields the pattern is supervised by radio (or, in non-radio or emergency conditions by red and green light signals) by air traffic controllers.
PAYLOAD - Anything that an aircraft carries beyond what is required for its operation during flight, theoretically that from which revenue is derived, such as cargo and passengers.
PCA see CONTROLLED AIRSPACE
PHONETICS see ALPHABET
PILOT IN COMMAND (PiC ) - The pilot responsible for the operation and safety of an aircraft during flight time.
PITCH - (1) Of the three axes in flight, this specifies the vertical action, the up-and-down movement. Compare ROLL and YAW. (2) The angle of a propeller or rotor blade in relation to its arc; also the distance advanced by a blade in one full rotation.
PITOT TUBE - More accurately but less popularly used, Pitot-Static Tube, a small tube most often mounted on the outward leading edge of an airplane wing (out of the propeller stream) that measures the impact pressure of the air it meets in flight, working in conjuction with a closed, perforated, coaxial tube that measures the static pressure. The difference in pressures is calibrated as air speed by a panel instrument. Named for French scientist Henri Pitot (1695-1771).
POSITIVE CONTROL - The separation of all air traffic within designated airspace by air traffic control.
POWER LOADING - The GROSS WEIGHT of an airplane divided by the rated horsepower, computed for Standard Air density.
PUSHER - A propeller mounted in back of its engine, pushing an aircraft through the air, as opposed to a TRACTOR configuration.
QUADRAPLANE, QUADRUPLANE - An aircraft having four or more wingforms.
RADAR APPROACH CONTROL FACILITY (RAPCON) - A terminal ATC facility that uses radar and non-radar capabilities to provide approach control services to aircraft arriving, departing, or transiting airspace controlled by the facility. This facility provides radar ATC services to aircraft operating in the vicinity of one or more civil/military airports in a terminal area. The facility may provide services of a ground-controlled approach (GCA). A radar approach control facility may be operated by FAA or a military service, or jointly. Specific facility nomenclatures are used for administrative purposes only and are related to the physical location of the facility and the operating service generally:
Army Radar Approach Control (ARAC) (Army)
Radar Air Traffic Control Facility (RATCF) (Navy/FAA)
Radar Approach Control (RAPCON) (Air Force/FAA)
Terminal Radar Approach Control (TRACON) (FAA)
Tower/Airport Traffic Control Tower (ATCT) (FAA only towers delegated approach control authority)
RAMJET - An aerodynamic duct in which fuel is burned to produce a high-velocity propulsive jet. It needs to be accelerated to high speed before it can become operative.
RIDING THE BEAM see ON THE BEAM.
RING COWLING - A circular engine FAIRING.
ROGALLO WING - A flexible, delta-wing plan in which three rigid members are shaped in the form of an arrowhead and joined by a flexible fabric, which inflates upward under flight loads. Originally specific to paragliders, but now found on some powered aircraft.
ROLL - Of the three axes in flight, this specifies the action around a central point. Compare PITCH and YAW.
ROTARY ENGINE - A powerplant that rotates on a stationary propeller shaft. An American invention by Adams-Farwell Co (1896), it was first used for buses and trucks in the US (1903), then copied by French engineers for early aircraft engines (1914).
ROTORCRAFT - A heavier-than-air aircraft that depends principally for its support in flight on the lift generated by one or more rotors. Includes helicopters and gyroplanes.
RUDDER - The movable part of a vertical airfoil which controls the YAW of an aircraft; the fixed part being the FIN.
SAILPLANE - An unpowered, soaring aircraft capable of maintaining level flight for long periods of time after release from tow and of gaining altitude using wind currents, as opposed to a GLIDER.
SCRAMJET - Acronym for supersonic combustion ramjet, in which combustion occurs at supersonic air velocities through the engine.
SCUD - A low, foglike cloud layer.
SEAPLANE - A water-based aircraft with a boat-hull fuselage, often amphibious.The term is also used generically to define a similar Flying Boat and a pontoon FLOATPLANE.
SECONDARY STALL - Any stall resulting from pulling back too soon and too hard while recovering from any other stall. Usually a HIGH-SPEED or ACCELERATED STALL.
SERVICE CEILING - The height above sea level at which an aircraft with normal rated load is unable to climb faster than 100' per minute under Standard Air conditions.
SESQUI-WING - A lesser-span additional wingform, generally placed below the main planes of an aircraft, generally a biplane.
SHOULDER-WING - A mid-wing monoplane with its wing mounted directly to the top of the fuselage without use of CABANE STRUTs.
SIDESLIP - A movement of an aircraft in which a relative flow of air moves along the lateral axis, resulting in a sideways movement from a projected flight path, especially a downward slip toward the inside of a banked turn.
SINK, SINKING SPEED - The speed at which an aircraft loses altitude, especially in a glide in still air under given conditions of equilibrium.
SKID - Too shallow a bank in a turn, causing an aircraft to slide outward from its ideal turning path.
SLATS - Movable vanes or auxiliary airfoils, usually set along the leading edge of a wing but able to be lifted away at certain angles of attack.
SLIP - Too steep a bank in a turn, causing an aircraft to slide inward from its ideal turning path.
SLIPSTREAM - The flow of air driven backward by a propeller or downward by a rotor. Compare DOWNWASH.
SLOT - A long, narrow, spanwise gap in a wing, usually near the leading edge, to improve airflow at high angles of attack for slower landing speeds.
SLOTTED FLAP - A flap that, when depressed, exposes a SLOT and increases airflow between itself and the rear edge of the wing.
SMOH - "Since Major Overhaul," an acronym seen in reference to the operating hours, or time remaining, on an engine.
SPECIAL USE AIRSPACE (SUA) - Airspace of defined dimensions identified by an area on the surface of the earth wherein activities must be confined because of their nature and/or wherein limitations may be imposed upon aircraft operations that are not a part of those activities:
Alert Area - Airspace which may contain a high volume of pilot training activities or an unusual type of aerial activity, neither of which is hazardous to aircraft. Alert Areas are depicted on aeronautical charts for the information of non-participating pilots. All activities within an Alert Area are conducted in accordance with Federal Aviation Regulations, and pilots of participating aircraft as well as pilots transiting the area are equally responsible for collision avoidance.
Military Operations Area (MOA) - Airspace established outside of Class A airspace area to separate or segregate certain non-hazardous military activities from IFR traffic and to identify for VFR traffic where these activities are conducted.
Prohibited Area - Airspace designated under part 73 within which no person may operate an aircraft without the permission of the using agency.
Restricted Area - Airspace designated under FAR Part 73, within which the flight of aircraft, while not wholly prohibited, is subject to restriction. Most restricted areas are designated joint use and IFR/VFR operations in the area may be authorized by the controlling ATC facility when it is not being utilized by the using agency. Restricted areas are depicted on enroute charts. Where joint use is authorized, the name of the ATC controlling facility is also shown.
Warning Area - A warning area is airspace of defined dimensions extending from 3 nautical miles outward from the coast of the USA, that contains activity that may be hazardous to non-participating aircraft. The purpose of such warning area is to warn non-participating pilots of the potential danger. A warning area may be located over domestic or international waters or both.
SPLIT FLAP - A FLAP built into the underside of a wing, as opposed to a Full Flap wherein a whole portion of the trailing edge is used.
SPOILER - A long, movable, narrow plate along the upper surface of an airplane wing used to reduce lift and increase drag by breaking or spoiling the smoothness of the airflow.
SPORT PILOT - Special FAA certification enabling "budget" pilotry; see LIGHT SPORT AIRCRAFT and LSA feature.
SPONSON - A short, winglike protuberance on each side of a seaplane fuselage to increase lateral stability.
SQUAWK - A four-digit number dialed into his transponder by a pilot to identify his aircraft to air traffic controllers
STABILATOR - A movable horizontal tail that combines the actions of a stabilizer and elevator, increasing longitudinal stability while creating a pitching moment.
STABILIZER - The fixed part of a horizontal airfoil that controls the pitch of an aircraft; the movable part being the ELEVATOR.
STAGGER - The relative longitudinal position of the wings on a biplane. Positive Stagger is when the upper wing's leading edge is in advance of that of the lower wing [eg: Waco YKS], and vice versa for Negative Stagger [eg: Beechcraft D17].
STALL - (1) Sudden loss of lift when the angle of attack increases to a point where the flow of air breaks away from a wing or airfoil, causing it to drop. (2) A maneuver initiated by the steep raising of an aircraft's nose, resulting in a loss of velocity and an abrupt drop.
#StandardAir STANDARD AIR (Standard Atmosphere) - An arbitrary atmosphere established for calibration of aircraft instruments. Standard Air Density is 29.92 inches of mercury and temperature of 59° F, equivalent to an atmospheric air pressure of 14.7# per square inch.
STANDARD RATE TURN - A turn in which the heading of an aircraft changes 3° per second, or 360° in two minutes.
STATIC WIRE - A clip-on wire used to ground an aircraft by drawing off static electricity, a potential fire hazard, during refueling.
SUA see SPECIAL USE AIRSPACE
SUPERSONIC - Speed of flight at or greater than Mach 1.0; literally, faster than the speed of sound.
SWEEPBACK - A backward inclination of an airfoil from root to tip in a way that causes the leading edge and often the trailing edge to meet relative wind obliquely, as wingforms that are swept back.
SWING-WING - A wing whose horizontal angle to the fuselage centerline can be adjusted in flight to vary aircraft motion at differing speeds.
TAILDRAGGER see CONVENTIONAL GEAR
TARMAC - (1) A bituminous material used in paving; a trade name for Tar MacAdam . (2) An airport surface paved with this substance, especially a runway or an APRON at a hangar.
TAS - True Air Speed. Because an air speed indicator indicates true air speed only under standard sea-level conditions, true air speed is usually calculated by adjusting an Indicated Air speed according to temperature, density, and pressure. Compare CALIBRATED AIR SPEED and INDICATED AIR SPEED.
TCA see CONTROLLED AIRSPACE
TERMINAL RADAR SERVICE AREA (TRSA) - Airspace surrounding designated airports wherein ATC provides radar vectoring, sequencing, and separation on a full-time basis for all IFR and participating VFR aircraft. Service provided at a TRSA is called Stage III Service. TRSAs are depicted on VFR aeronautical charts. Pilot participation is urged but is not mandatory.
TETRAHEDRON - Ground-based, free-rotating, triangular-shaped wind direction indicator, generally placed near a runway, often lighted at major airports.
THRUST - The driving force of a propeller in the line of its shaft or the forward force produced in reaction to the gases expelled rearward from a jet or rocket engine. Opposite of DRAG.
TORQUE - A twisting, gyroscopic force acting in opposition to an axis of rotation, such as with a turning propeller; aka Torsion.
TOUCH-AND-GO - Landing practice in which an aircraft does not make a full stop after a landing, but proceeds immediately to another take-off.
TRACTOR - A propeller mounted in front of its engine, pulling an aircraft through the air, as opposed to a PUSHER configuration.
TRAILING EDGE - The rearmost edge of an AIRFOIL.
TRANSPONDER - An airborne transmitter that responds to ground-based interrogation signals to provide air traffic controllers with more accurate and reliable position information than would be possible with "passive" radar; may also provide air traffic control with an aircraft's altitude.
TRIKE - Nickname for a weight-shift-control aircraft, such as a paraglider.
TRIM TAB - A small, auxiliary control surface in the trailing edge of a wingform, adjustable mechanically or by hand, to counteract ("trim") aerodynamic forces on the main control surfaces.
TRUE AIRSPEED - The speed of an aircraft along its flight path, in respect to the body of air (air mass) through which the aircraft is moving. Also see CALIBRATED AIRSPEED, GROUND SPEED, INDICATED AIRSPEED.
TRUE NORTH - The northern direction of the axis of the Earth; aka "Map North." GEOGRAPHIC NORTH, as opposed to MAGNETIC NORTH.
TURBOJET - An aircraft having a jet engine in which the energy of the jet operates a turbine that in turn operates the air compressor.
TURBOPROP - An aircraft having a jet engine in which the energy of the jet operates a turbine that drives the propeller.
TURN & BANK INDICATOR - Primary air-driven gyro instrument, a combined turn indicator and lateral inclinometer to show forces on an aircraft in banking turns. Also referred to as "needle & ball" indicator, the needle as the gyro's pointer and a ball encased in a liquid-filled, curved tube.
TWILIGHT ZONE - Long before Rod Serling's tv series was this consumer-lever definition for a glitch in the ADCOCK RANGE, officially called a Bi-Signal Zone. It was a portion of the overlapping area of a beam where the continuous monotone "on-course" signal became temporarily overlayed with the "A" or "N" code signals. Read more here.
ULTRALIGHT - An aeronautical vehicle, operated for sport or recreational purposes, that does not require FAA registration, an airworthiness certificate, or pilot certification. Primarily single-occupant vehicles, although some two-place vehicles are authorized for training purposes. Operation of an ultralight vehicle in certain airspaces requires authorization from ATC.
UNCONTROLLED AIRSPACE - Class G Airspace; airspace not designated as Class A, B, C, D or E.
UNDERCARRIAGE - The landing gear of a land-based aircraft, including struts, frames, and wheels. A very British word that has limited use in the USA.
UNDERSHOOT - To land short of a runwway or planned landing spot. Opposite is OVERSHOOT.
UNICOM - Universal Communication. A common radio frequency (usually 121.0 mHz) used at uncontrolled (non-tower) airports for local pilot communication.
UPWASH - The slight, upward flow of air just prior to its reaching the leading edge of a rapidly moving airfoil.
UPWIND TURN - Long a point of contest among pilots, there is in reality no such thing as far as the airplane is concerned. Proponents claim that airplanes lose air speed when turning upwind, while opponents (and the laws of physics) argue that an airplane, like a boat in a river whose speed is only relative to the water and not the shore, is unaffected within the movement of an air mass and that it loses only ground speed.
USEFUL LOAD - The weight of crew, passengers, fuel, baggage, and ballast, generally excluding emergency or portable equipment and ordnance.
V - Velocity, now used in defining air speeds:
VA = Maneuvering Speed (max structural speed for full control deflection)
VD = Max Dive Speed (for certification only)
VFE = Max Flaps Extended Speed
VLE = Max Landing Gear Extended Speed
VLO = Max Landing Gear Operation Speed
VNE = Never Exceed Speed
VNO = Max Structural Cruising Speed
VS0 = Stalling Speed Landing Configuration
VS1 = Stalling Speed in a specified Configuration
VX = Best Angle of Climb Speed
VXSE = Best Angle of Climb Speed, one engine out
VY = Best Rate of Climb Speed
VYSE = Best Rate of Climb Speed, one engine out
VAPOR TRAIL see CONTRAIL
VARIOMETER - A panel instrument, often as simple as a tiny ball in a vertical tube, indicating subtle PITCH movements of an aircraft. Popular use in SAILPLANES.
VENTRAL FIN - A fin/rudder extension on the bottom of a fuselage. Opposite of DORSAL FIN.
VENTURI TUBE - A small, hourglass-shaped metal tube, usually set laterally on a fuselage in the slipstream to create suction for gyroscopic panel instruments. Now outdated by more sophisticated means.
VFR - Visual Flight Rules that govern the procedures for conducting flight under visual conditions. The term is also used in the US to indicate weather conditions that are equal to or greater than minimum VFR requirements. Also used by pilots and controllers to indicate a specific type of flight plan.
VFR ON TOP - Flight in which a cloud ceiling exists but modified VISUAL FLIGHT RULES are in effect if the aircraft travels above the cloud layer.
VISUAL METEOROLOGICAL CONDITIONS (VMC) - Meteorological conditions expressed in terms of visibility, distance from clouds, and ceiling equal to or better than specified minima.
VOR - VHF OmniRange . A ground-based navigation aid transmitting very high-frequency (VHF) navigation signals 360° in azimuth, on radials oriented from MAGNETIC NORTH. The VOR periodically identifies itself by Morse Code and may have an additional voice identification feature. Voice features can be used by ATC or FSS for transmitting information to pilots.
VORTAC - VOR + TACAN (Tactical Air Navigation); combined radio navigation aids.
VSI - Vertical Speed Indicator. A panel instrument that gauges rate of climb or descent in feet-per-minute (fpm). Also Rate Of Climb Indicator.
WASH-IN, WASH-OUT - A method of increasing lift by increasing (Wash-In) or decreasing (Wash-Out) the ANGLE OF INCIDENCE on the outer part of an airplane wing to counteract the effects of engine TORQUE.
WET COMPASS see COMPASS
WINGLET - A small, stabilizing, rudderlike addition to the tips of a wing to control or employ air movement.
WING LOADING - The maximum take-off gross weight of an aircraft divided by its wing area.
YAW - Of the three axes in flight, this specifies the side-to-side movement of an aircraft on its vertical axis, as in skewing. Compare PITCH and ROLL.
YOKE - The control wheel of an aircraft, akin to a automobile steering wheel.
| I | Attachment | Action | Size | Date | Who | Comment |
|---|---|---|---|---|---|---|
 jpg |
Elephant_ear.jpg | manage | 35.2 K | 12 May 2010 - 03:28 | NormanSmit | Example of an elephant ear |
Topic revision: r10 - 23 Apr 2011 - 03:51:21 - NormanSmit
Main Web
Create New Topic
Index
Search
Changes
Notifications
RSS Feed
Statistics
Preferences
Main
 |
|
Copyright © Smit Industries. All material on this collaboration platform is the property of Smit Industries unless otherwise agreed. Ideas, requests, problems regarding TWiki? Send feedback