Glossary of aviation
Terms
and abreviations.
ABSOLUTE 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 radio navigation system replaced
after World War 2 by the omnirange system. It consisted of
segmented quadrants broacasting 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.
ADF - Automatic Direction Finding via automated radio.
ADIABATIC LAPSE RATE - The rate at which ascending air cools
and descending air warms, given no heat is added or taken
away. The rate for dry air is based on 5.4° F per 1000'
altitude (1° per 100 meters); saturated rates 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
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-barometic 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.
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.
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 it moves through the air when driven by an engine. 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 noncontrol 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 air speed of an
aircraft, corrected for position and instrument error. CAS
is equal to true air speed 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 AIRPORTAn 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 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 SEE RADIO NAVIGATION
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.
CONTRAILS - Streaks of condensed water vapor created in the
air by aircraft flying at high altitudes; aka Vapor Trails.
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
Paragliding Spain Center
