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Aeronautical Information Manual (AIM), page 672

Pilot/Controller Glossary 12/10/15

imminent and grave danger and that immediate
assistance is requested.
(See PAN-PAN.)
(Refer to AIM.)

MCA-
(See MINIMUM CROSSING ALTITUDE.)

MDA-

(See MINIMUM DESCENT ALTITUDE.)
MEA-

(See MINIMUM EN ROUTE IFR ALTITUDE.)

MEARTS-
(See MICRO-EN ROUTE AUTOMATED RADAR
TRACKING SYSTEM.)

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 ARC- A semicircle, equidistant from
a meter fix, usually in low altitude relatively close to
the meter fix, used to help CTAS/HOST calculate a
meter time, and determine appropriate sector meter
list assignments for aircraft not on an established
arrival route or assigned a meter fix.

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-
(See ARRIVAL SECTOR ADVISORY LIST.)
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 PVDs/

MDMs and associated "D" positions eligible for
display of a metering position list. A maximum of
four PVDs/MDMs 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.)

MICRO-EN ROUTE AUTOMATED RADAR
TRACKING SYSTEM (MEARTS)- An automated
radar and radar beacon tracking system capable of
employing both short-range (ASR) and long-range
(ARSR) radars. This microcomputer driven system
provides improved tracking, continuous data record-
ing, and use of full digital radar displays.
MID RVR-
(See VISIBILITY.)

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

PCG M-2

Page 672 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

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