the Aviation Dictionary

grouping of aircraft having similar characteristics of
propulsion, flight, or landing. Examples include
airplane, rotorcraft, glider, balloon, landplane, and
seaplane.
class A airspace - Controlled airspace covering the 48
contiguous United States and Alaska, within 12
nautical miles of the coasts, from 18,000 feet MSL up
to and including FL600, but not including airspace less
than 1,500 feet AGL.
class B airspace - Controlled airspace designated -
around certain major airports, extending from the
surface or higher to specified altitudes. For operations
in Class B airspace, all aircraft must receive an ATC
clearance to enter, and are subject to the rules and
pilotiequipment requirements listed in FAR Part 91.
class C airspace - Controlled airspace surrounding
designated airports where ATC provides radar
vectoring and sequencing on a full-time basis for all
IFR and VFR aircraft. Participation is mandatory, and
all aircraft must establish and maintain radio contact
with ATC , and are subject to the rules and
pilotiequipment requirements listed in FAR Part 9 1.
class D airspace - Controlled airspace around at least
one primary airport which has an operating control
tower. Aircraft operators are subject to the rules and
equipment requirements specified in FAR Part 91.
class E airspace - Controlled airspace which covers the
48 contiguous United States and Alaska, within 12
nautical miles of the coasts, from 14,500 feet MSL up
to but not including 18,000 feet MSL. Exceptions are
restricted and prohibited areas, and airspace less than
1,500 feet AGL. Class E airspace also includes Federal
airways, with a floor of 1,200 feet AGL or higher, as
well as the airspace from 700 feet or more above the
surface designated in conjunction with an airport which
has an approved instrument approach procedure.
class G airspace - Airspace that has not been
designated as Class A, B, C, D, or E, and within which
air traffic control is not exercised.
class of thread - In threaded fasteners, classes of
threads are distinguished from each other by the
amount of tolerance andlor allowance specified.
Classes lA, 2A, and 3A apply to external threads,
whereas classes IB, 2B, and 3B apply to internal
threads. Classes 2 and 3 apply to both external and
internal threads.
class A airspace . clearance
class-C amplifier - An electronic amplifier that
produces current during a small part (less than half) of
the input cycle.
claw hammer - A hammer used primarily for carpentry.
Has a claw-like device opposite the face for removing
nails.
clean and true - A term used in valve seat grinding
whereby the rough stone is used until the seat is true or
exactly matches the valve - guide and until all its.
scores, and burned areas are removed.
clean room - A room used to house manufacturing and
servicing of high-precision products. Usually has air
filtration to prevent contaminating particles from
entering the products.
cleanout - The process of cleaning out or cutting away a
damaged area to prepare it for a repair.
clear air turbulence - Turbulence that occurs in clear
air, and is commonly applied to high-level turbulence
associated with wind shear. It is often encountered near
the jet stream, and it is not the same as turbulence
associated with cumuliform clouds or thunderstorms.
clear air turbulence (CAT)- -Usually, high level (or jet
stream) turbulence encountered in air where no clouds
are present, may occur in nonconvective clouds.
clear icing (or clear ice) - Generally, the formation of a
layer or mass of ice which is relatively transparent
because of its homogeneous structure and small
number and size of air spaces; used commonly as
synonymous with glaze, particularly with respect to
aircraft icing. Compare with rime icing. Factors that
favor clear icing are large drop size, such as those
found in cumuliform clouds, rapid accretion of
supercooled water, and slow dissipation of latent heat
of fusion.
clear of the runway - 1. A taxiing aircraft, which is
approaching a runway, is clear of the runway when all
parts of the aircraft are held short of the applicable
holding position marking. 2. A pilot or controller may
consider an aircraft, which is exiting or crossing a
runway, to be clear of the runway when all parts of the
aircraft are beyond the runway edge and there is no
ATC restriction to its continued movement beyond the
applicable holding position marking. 3. Pilots and
controllers shall exercise good judgement to ensure that
adequate separation exists between all aircraft on
runways and taxiways at airports with inadequate
runway edge lines or holding position markings.
class-A amplifier - An electronic amplifier that
produces current during 100% of the input cycle.
clearance - 1. The clear space or distance between two
class-B amplifier - An electronic amplifier whose two mechanical objects or moving parts. 2. An
output devices (vacuum tubes or solid-state) conduct authorization by air traffic control, for the purpose of
one at a time to produce a composite output signal. One preventing collision between known aircraft, for an
device conducts for the positive portion of an input aircraft to proceed under specified traffic conditions
signal and the other device conducts during the within controlled airspace. The pilot-in-command of an
negative portion.
aircraft may not deviate from the provisions of a visual
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