the Aviation Dictionary

mach - The ratio of the aircraft's true airspeed to the
speed of sound.
mach cone - The cone-shaped shock wave produced by
an object exceeding the speed of sound.
mach number - The ratio of the weed of an aimlane to
the speed of sound in the same atmospheric conditions;
e.g., MACH.82, MACH 1.6.
mach technique [ICAO] - Describes a control
technique used by air traffic control whereby turbojet
aircraft operating successively along suitable routes are
cleared to maintain appropriate MACH numbers for a
relevant portion of the enroute phase of flight. The
principle objective is to achieve improved utilization of
the airspace and to ensure that separation between
successive aircraft does not decrease below the
established minima.
mach tuck - A condition that can occur when operating
a swept-wing airplane in the transonic speed range. A
shock wave could form in the root portion of the wing
and cause the air behind it to separate. This shockinduced
separation causes the center of pressure to
move aft. This, combined with the increasing amount
of nose down force at higher speeds to maintain level
flight, causes the nose to "tuck." If not corrected, the
airplane could enter a steep, sometimes unrecoverable
dive.
machine bolt - The common name for a hex head bolt
with uniform threads.
machine language - A language used in a computer
system made up of zeros and ones. A special program
called a compiler converts a programming language
into machine language that can be used by the
commter.
machine screw - A screw fastener with uniform threads
that can be screwed into a tapped hole or into a nut.
The head of a machine screw can be round, flat, truss,
oval, or a fillister-type.
machine-sewn fabric seams - Machine-sewn aircraft
fabric seams. The most common types of machinesewn
fabric seams include the French fell, folded fell,
and plain overlap.
machining - The process of forming the surface by
cutting away material by turning, planing, shaping, and
milling. Normally accomplished with machine -
opcratcd tools such as lathes, milling machines,
shapers, and planers.
machinist - A skilled person in the operation of
metal-working machine tools such as lathes, shapers,
planers, and milling machines.
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M . magnetic bearing
machmeter - A direct-reading indicator installed in the
instrument panel of high-speed aircraft that gives the
pilot an indication of his flight Mach number. The
internal mechanism of a machmeter includes a bellows
for measuring the difference between pitot pressure and
static pressure, and includes an aneroid that modifies
the output from this differential pressure bellows to
correct for the changes in altitude.
mackerel sky - A meteorological condition of clouds
that resemble the scales on a mackerel fish. The clouds
consist of rows of altocumulus or cirrocumulus clouds.
macroscale - Spatial scales of 1,000 NM or more.
magamp - A contraction of magnetic amplified. An
amplifier system using saturable reactors to control an
output to obtain amplification. See also magnetic
amplifier.
magnesium - A silver-white, malleable, ductile metallic
element with a symbol of Mg and an atomic number of
12. Used to produce light alloys for aircraft
construction.
Magnesyn system - An AC remote indicating system in
which a permanent magnet is used as the rotor. Based
upon the synchronous-motor principle, in which the
angular position of the rotor of one motor at the
measuring source is duplicated by the rotor of the
indicator motor. Used in fuel-quantity or hel-flow
measuring systems, position-indicating systems, etc.
magnet - A device or material that has the property of
attracting or repelling other magnetic materials. Lines
of magnetic flux link its external poles, and a
conductor cutting across the flux will have a voltage
induced into it.
magnet keeper - A soft iron bar placed across the north
and south poles of a U-shaped magnet. The iron bar
produces a closed path through which magnetic lines of
force pass.
magnet wire - A small-diameter, varnish-insulated
copper wire used in coil windings for electromagnets,
transformers, motors, and generators.
magnetic amplifier - An electronic control device that
uses a saturable reactor. The condition of saturation is
controlled by the input signal to modulate the flow of a
much larger current in the output circuit. It is
essentially a multi-coil transformer that controls the
amount of load current allowed to flow in the load
winding by a small amount of current in the magnetic
core. Changing the amount of DC flowing in the
magnetic core changes the permeability of the core.
This, in turn, changes the amount of inductive
reactance that opposes the AC flowing in the load
winding.
magnetic bearing - The magnetic course to go direct to
an NDB station.