MAA -- MVA
MAA- (See MAXIMUM AUTHORIZED ALTITUDE.)
MACH NUMBER- The ratio of true airspeed to the
speed of sound; e.g.,
MACH .82, MACH 1.6. (See AIRSPEED.)
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 en route 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.
MAHWP- Missed Approach Holding Waypoint
MAINTAIN-
a. Concerning altitude/flight level, the term
means to remain at the altitude/flight level
specified. The phrase "climb and"
or "descend and" normally precedes
"maintain" and the altitude assignment;
e.g., "descend and maintain 5,000."
b. Concerning other ATC instructions, the term
is used in its literal sense; e.g., maintain
VFR.
MAINTENANCE PLANNING FRICTION LEVEL- The friction
level specified in AC 150/5320-12, Measurement,
Construction, and Maintenance of Skid Resistant
Airport Pavement Surfaces, which represents
the friction value below which the runway pavement
surface remains acceptable for any category
or class of aircraft operations but which is
beginning to show signs of deterioration. This
value will vary depending on the particular
friction measurement equipment used.
MAKE SHORT APPROACH- Used by ATC to inform a pilot
to alter his traffic pattern so as to make a short
final approach.
(See TRAFFIC PATTERN.)
MANDATORY ALTITUDE- An altitude depicted on an
instrument Approach Procedure Chart requiring
the aircraft to maintain altitude at the depicted
value.
MAP- (See MISSED APPROACH POINT.)
MARKER BEACON- An electronic navigation facility
transmitting a 75 mHz vertical fan or boneshaped
radiation pattern. Marker beacons are identified
by their modulation frequency and keying code,
and when received by compatible airborne equipment,
indicate to the pilot, both aurally and visually,
that he is passing over the facility.
(See OUTER MARKER.)
(See MIDDLE MARKER.)
(See INNER MARKER.)
(Refer to AIM.)
MARSA- (See MILITARY AUTHORITY ASSUMES RESPONSIBILITY
FOR SEPARATION OF AIRCRAFT.)
MAWP- Missed Approach Waypoint
MAXIMUM AUTHORIZED ALTITUDE- A published altitude
representing the maximum usable altitude or flight
level for an airspace structure or route segment.
It is the highest altitude on a Federal airway,
jet route, area navigation low or high route,
or other direct route for which an MEA is designated
in Part 95 at which adequate reception of navigation
aid signals is assured.
MAYDAY- The international radiotelephony distress
signal. When repeated three times, it indicates
imminent and grave danger and that immediate assistance
is requested.
(See PAN-PAN-PAN.)
(Refer to AIM.)
MCA- (See MINIMUM CROSSING ALTITUDE.)
MDA- (See MINIMUM DESCENT ALTITUDE.)
MEA- (See MINIMUM EN ROUTE IFR ALTITUDE.)
METEOROLOGICAL IMPACT STATEMENT- An unscheduled
planning forecast describing conditions expected
to begin within 4 to 12 hours which may impact
the flow of air traffic in a specific center's
(ARTCC) area.
METER FIX TIME/SLOT TIME- A calculated time to
depart the meter fix in order to cross the vertex
at the ACLT. This time reflects descent speed
adjustment and any applicable time that must be
absorbed prior to crossing the meter fix.
METER LIST DISPLAY INTERVAL- A dynamic parameter
which controls the number of minutes prior to
the flight plan calculated time of arrival at
the meter fix for each aircraft, at which time
the TCLT is frozen and becomes an ACLT; i.e.,
the VTA is updated and consequently the TCLT modified
as appropriate until frozen at which time updating
is suspended and an ACLT is assigned. When frozen,
the flight entry is inserted into the arrival
sector's meter list for display on the sector
PVD/MDM. MLDI is used if filed true airspeed is
less than or equal to freeze speed parameters
(FSPD).
METERING- A method of time-regulating arrival
traffic flow into a terminal area so as not to
exceed a predetermined terminal acceptance rate.
METERING AIRPORTS- Airports adapted for metering
and for which optimum flight paths are defined.
A maximum of 15 airports may be adapted.
METERING FIX- A fix along an established route
from over which aircraft will be metered prior
to entering terminal airspace. Normally, this
fix should be established at a distance from the
airport which will facilitate a profile descent
10,000 feet above airport elevation [AAE] or above.
METERING POSITION(S)- Adapted PVD's/MDM's and
associated "D" positions eligible for
display of a metering position list. A maximum
of four PVD's/MDM's may be adapted.
METERING POSITION LIST- An ordered list of data
on arrivals for a selected metering airport displayed
on a metering position PVD/MDM.
MFT- (See METER FIX TIME/SLOT TIME.)
MHA- (See MINIMUM HOLDING ALTITUDE.)
MIA- (See MINIMUM IFR ALTITUDES.)
MICROBURST- A small downburst with outbursts of
damaging winds extending 2.5 miles or less. In
spite of its small horizontal scale, an intense
microburst could induce wind speeds as high as
150 knots
(Refer to AIM.)
MICROWAVE LANDING SYSTEM- A precision instrument
approach system operating in the microwave spectrum
which normally consists of the following components:
a. Azimuth Station.
b. Elevation Station.
c. Precision Distance Measuring Equipment.
(See MLS CATEGORIES.)
MIDDLE COMPASS LOCATOR- (See COMPASS LOCATOR.)
MIDDLE MARKER- A marker beacon that defines a
point along the glideslope of an ILS normally
located at or near the point of decision height
(ILS Category I). It is keyed to transmit alternate
dots and dashes, with the alternate dots and dashes
keyed at the rate of 95 dot/dash combinations
per minute on a 1300 Hz tone, which is received
aurally and visually by compatible airborne equipment.
(See MARKER BEACON.)
(See INSTRUMENT LANDING SYSTEM.)
(Refer to AIM.)
MID RVR- (See VISIBILITY.)
MILES-IN-TRAIL- A specified distance between aircraft,
normally, in the same stratum associated with
the same destination or route of flight.
MILITARY AUTHORITY ASSUMES RESPONSIBILITY FOR
SEPARATION OF AIRCRAFT- A condition whereby the
military services involved assume responsibility
for separation between participating military
aircraft in the ATC system. It is used only for
required IFR operations which are specified in
letters of agreement or other appropriate FAA
or military documents.
MILITARY OPERATIONS AREA- (See SPECIAL USE AIRSPACE.)
MILITARY TRAINING ROUTES- Airspace of defined
vertical and lateral dimensions established for
the conduct of military flight training at airspeeds
in excess of 250 knots IAS.
(See IFR MILITARY TRAINING ROUTES.)
(See VFR MILITARY TRAINING ROUTES.)
MINIMA- (See MINIMUMS.)
MINIMUM CROSSING ALTITUDE- The lowest altitude
at certain fixes at which an aircraft must cross
when proceeding in the direction of a higher minimum
en route IFR altitude (MEA).
(See MINIMUM EN ROUTE IFR ALTITUDE.)
MINIMUM DESCENT ALTITUDE- The lowest altitude,
expressed in feet above mean sea level, to which
descent is authorized on final approach or during
circle-to-land maneuvering in execution of a standard
instrument approach procedure where no electronic
glideslope is provided.
(See NONPRECISION APPROACH PROCEDURE.)
MINIMUM EN ROUTE IFR ALTITUDE- The lowest published
altitude between radio fixes which assures acceptable
navigational signal coverage and meets obstacle
clearance requirements between those fixes. The
MEA prescribed for a Federal airway or segment
thereof, area navigation low or high route, or
other direct route applies to the entire width
of the airway, segment, or route between the radio
fixes defining the airway, segment, or route.
(Refer to Part 91.)
(Refer to Part 95.)
(Refer to AIM.)
MINIMUM FRICTION LEVEL- The friction level specified
in AC 150/5320-12, Measurement, Construction,
and Maintenance of Skid Resistant Airport Pavement
Surfaces, that represents the minimum recommended
wet pavement surface friction value for any turbojet
aircraft engaged in LAHSO. This value will vary
with the particular friction measurement equipment
used.
MINIMUM FUEL- Indicates that an aircraft's fuel
supply has reached a state where, upon reaching
the destination, it can accept little or no delay.
This is not an emergency situation but merely
indicates an emergency situation is possible should
any undue delay occur.
(Refer to AIM.)
MINIMUM HOLDING ALTITUDE- The lowest altitude
prescribed for a holding pattern which assures
navigational signal coverage, communications,
and meets obstacle clearance requirements.
MINIMUM IFR ALTITUDES- Minimum altitudes for IFR
operations as prescribed in Part 91. These altitudes
are published on aeronautical charts and prescribed
in Part 95 for airways and routes, and in Part
97 for standard instrument approach procedures.
If no applicable minimum altitude is prescribed
in FAR 95 or FAR 97, the following minimum IFR
altitude applies:
a. In designated mountainous areas, 2,000 feet
above the highest obstacle within a horizontal
distance of 4 nautical miles from the course
to be flown; or
b. Other than mountainous areas, 1,000 feet
above the highest obstacle within a horizontal
distance of 4 nautical miles from the course
to be flown; or
c. As otherwise authorized by the Administrator
or assigned by ATC.
(See MINIMUM EN ROUTE IFR ALTITUDE.)
(See MINIMUM OBSTRUCTION CLEARANCE ALTITUDE.)
(See MINIMUM CROSSING ALTITUDE.)
(See MINIMUM SAFE ALTITUDE.)
(See MINIMUM VECTORING ALTITUDE.)
(Refer to Part 91.)
MINIMUM NAVIGATION PERFORMANCE SPECIFICATION-
A set of standards which require aircraft to have
a minimum navigation performance capability in
order to operate in MNPS designated airspace.
In addition, aircraft must be certified by their
State of Registry for MNPS operation.
MINIMUM NAVIGATION PERFORMANCE SPECIFICATION AIRSPACE-
Designated airspace in which MNPS procedures are
applied between MNPS certified and equipped aircraft.
Under certain conditions, non-MNPS aircraft can
operate in MNPSA. However, standard oceanic separation
minima is provided between the non-MNPS aircraft
and other traffic. Currently, the only designated
MNPSA is described as follows:
a. Between FL 285 and FL 420;
b. Between latitudes 27ฐN and the North Pole;
c. In the east, the eastern boundaries of the
CTA's Santa Maria Oceanic, Shanwick Oceanic,
and Reykjavik;
d. In the west, the western boundaries of CTA's
Reykjavik and Gander Oceanic and New York Oceanic
excluding the area west of 60ฐW and south of
38ฐ30'N.
MINIMUM OBSTRUCTION CLEARANCE ALTITUDE- The lowest
published altitude in effect between radio fixes
on VOR airways, off-airway routes, or route segments
which meets obstacle clearance requirements for
the entire route segment and which assures acceptable
navigational signal coverage only within 25 statute
(22 nautical) miles of a VOR.
(Refer to Part 91.)
(Refer to Part 95.)
MINIMUM RECEPTION ALTITUDE- The lowest altitude
at which an intersection can be determined.
(Refer to Part 95.)
MINIMUM SAFE ALTITUDE-
a. The minimum altitude specified in Part 91
for various aircraft operations.
b. Altitudes depicted on approach charts which
provide at least 1,000 feet of obstacle clearance
for emergency use within a specified distance
from the navigation facility upon which a procedure
is predicated. These altitudes will be identified
as Minimum Sector Altitudes or Emergency Safe
Altitudes and are established as follows:
1. Minimum Sector Altitudes. Altitudes depicted
on approach charts which provide at least
1,000 feet of obstacle clearance within a
25-mile radius of the navigation facility
upon which the procedure is predicated. Sectors
depicted on approach charts must be at least
90 degrees in scope. These altitudes are for
emergency use only and do not necessarily
assure acceptable navigational signal coverage.
(See ICAO term Minimum Sector Altitude.)
2. Emergency Safe Altitudes. Altitudes depicted
on approach charts which provide at least
1,000 feet of obstacle clearance in nonmountainous
areas and 2,000 feet of obstacle clearance
in designated mountainous areas within a 100-mile
radius of the navigation facility upon which
the procedure is predicated and normally used
only in military procedures. These altitudes
are identified on published procedures as
"Emergency Safe Altitudes."
MINIMUM SAFE ALTITUDE WARNING- A function of the
ARTS III computer that aids the controller by
alerting him when a tracked Mode C- equipped aircraft
is below or is predicted by the computer to go
below a predetermined minimum safe altitude.
(Refer to AIM.)
MINIMUM SECTOR ALTITUDE [ICAO]- The lowest altitude
which may be used under emergency conditions which
will provide a minimum clearance of 300 m (1,000
feet) above all obstacles located in an area contained
within a sector of a circle of 46 km (25 NM) radius
centered on a radio aid to navigation.
MINIMUMS- Weather condition requirements established
for a particular operation or type of operation;
e.g., IFR takeoff or landing, alternate airport
for IFR flight plans, VFR flight, etc.
(See LANDING MINIMUMS.)
(See IFR TAKEOFF MINIMUMS AND DEPARTURE PROCEDURES.)
(See VFR CONDITIONS.)
(See IFR CONDITIONS.)
(Refer to Part 91.)
(Refer to AIM.)
MINIMUM VECTORING ALTITUDE- The lowest MSL altitude
at which an IFR aircraft will be vectored by a
radar controller, except as otherwise authorized
for radar approaches, departures, and missed approaches.
The altitude meets IFR obstacle clearance criteria.
It may be lower than the published MEA along an
airway or J-route segment. It may be utilized
for radar vectoring only upon the controller's
determination that an adequate radar return is
being received from the aircraft being controlled.
Charts depicting minimum vectoring altitudes are
normally available only to the controllers and
not to pilots.
(Refer to AIM.)
MINUTES-IN-TRAIL- A specified interval between
aircraft expressed in time. This method would
more likely be utilized regardless of altitude.
MIS- (See METEOROLOGICAL IMPACT STATEMENT.)
MISSED APPROACH-
a. A maneuver conducted by a pilot when an instrument
approach cannot be completed to a landing. The
route of flight and altitude are shown on instrument
approach procedure charts. A pilot executing
a missed approach prior to the Missed Approach
Point (MAP) must continue along the final approach
to the MAP. The pilot may climb immediately
to the altitude specified in the missed approach
procedure.
b. A term used by the pilot to inform ATC that
he is executing the missed approach.
c. At locations where ATC radar service is provided,
the pilot should conform to radar vectors when
provided by ATC in lieu of the published missed
approach procedure.
(See MISSED APPROACH POINT.)
(Refer to AIM.)
MISSED APPROACH POINT- A point prescribed in each
instrument approach procedure at which a missed
approach procedure shall be executed if the required
visual reference does not exist.
(See MISSED APPROACH.)
(See SEGMENTS OF AN INSTRUMENT APPROACH PROCEDURE.)
MISSED APPROACH PROCEDURE [ICAO]- The procedure
to be followed if the approach cannot be continued.
MISSED APPROACH SEGMENT- (See SEGMENTS OF AN INSTRUMENT
APPROACH PROCEDURE.)
MLDI- (See METER LIST DISPLAY INTERVAL.)
MLS- (See MICROWAVE LANDING SYSTEM.)
MLS CATEGORIES-
a. MLS Category I. An MLS approach procedure
which provides for an approach to a height above
touchdown of not less than 200 feet and a runway
visual range of not less than 1,800 feet.
b. MLS Category II. Undefined until data gathering/analysis
completion.
c. MLS Category III. Undefined until data gathering/analysis
completion.
MM- (See MIDDLE MARKER.)
MNPS- (See MINIMUM NAVIGATION PERFORMANCE SPECIFICATION.)
MNPSA- (See MINIMUM NAVIGATION PERFORMANCE SPECIFICATION
AIRSPACE.)
MOA- (See MILITARY OPERATIONS AREA.)
MOCA- (See MINIMUM OBSTRUCTION CLEARANCE ALTITUDE.)
MODE- The letter or number assigned to a specific
pulse spacing of radio signals transmitted or
received by ground interrogator or airborne transponder
components of the Air Traffic Control Radar Beacon
System (ATCRBS). Mode A (military Mode 3) and
Mode C (altitude reporting) are used in air traffic
control.
(See TRANSPONDER.)
(See INTERROGATOR.)
(See RADAR.)
(Refer to AIM.)
(See ICAO term MODE.)
MODE (SSR MODE) [ICAO]- The letter or number assigned
to a specific pulse spacing of the interrogation
signals transmitted by an interrogator. There
are 4 modes, A, B, C and D specified in Annex
10, corresponding to four different interrogation
pulse spacings.
MODE C INTRUDER ALERT- A function of certain air
traffic control automated systems designed to
alert radar controllers to existing or pending
situations between a tracked target (known IFR
or VFR aircraft) and an untracked target (unknown
IFR or VFR aircraft) that requires immediate attention/action.
(See CONFLICT ALERT.)
MONITOR- (When used with communication transfer)
listen on a specific frequency and stand by for
instructions. Under normal circumstances do not
establish communications.
MONITOR ALERT (MA)- A function of the ETMS that
provides traffic management personnel with a tool
for predicting potential capacity problems in
individual operational sectors. The MA is an indication
that traffic management personnel need to analyze
a particular sector for actual activity and to
determine the required action(s), if any, needed
to control the demand.
MONITOR ALERT PARAMETER (MAP)- The number designated
for use in monitor alert processing by the ETMS.
The MAP is designated for each operational sector
for increments of 15 minutes.
MOVEMENT AREA- The runways, taxiways, and other
areas of an airport/heliport which are utilized
for taxiing/hover taxiing, air taxiing, takeoff,
and landing of aircraft, exclusive of loading
ramps and parking areas. At those airports/heliports
with a tower, specific approval for entry onto
the movement area must be obtained from ATC.
(See ICAO term MOVEMENT AREA.)
MOVEMENT AREA [ICAO]- That part of an aerodrome
to be used for the takeoff, landing and taxiing
of aircraft, consisting of the maneuvering area
and the apron(s).
MOVING TARGET INDICATOR- An electronic device
which will permit radar scope presentation only
from targets which are in motion. A partial remedy
for ground clutter.
MRA- (See MINIMUM RECEPTION ALTITUDE.)
MSA- (See MINIMUM SAFE ALTITUDE.)
MSAW- (See MINIMUM SAFE ALTITUDE WARNING.)
MTI- (See MOVING TARGET INDICATOR.)
MTR- (See MILITARY TRAINING ROUTES.)
MULTICOM- A mobile service not open to public
correspondence used to provide communications
essential to conduct the activities being performed
by or directed from private aircraft.
MULTIPLE RUNWAYS- The utilization of a dedicated
arrival runway(s) for departures and a dedicated
departure runway(s) for arrivals when feasible
to reduce delays and enhance capacity.
MVA- (See MINIMUM VECTORING ALTITUDE.)
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