Pilot/Controller Glossary
12/2/21
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 TBFM/ERAM 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 REFERENCE ELEMENT (MRE)
−
A
constraint point through which traffic flows are
managed. An MRE can be the runway threshold, a
meter fix, or a meter arc.
METER REFERENCE POINT LIST (MRP)
−
A list
of TBFM delay information conveyed to the
controller on the situation display via the Meter
Reference Point View, commonly known as the
“Meter List.”
METERING
−
A method of time
−
regulating traffic
flows in the en route and terminal environments.
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.
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.)
MICROEN ROUTE AUTOMATED RADAR
TRACKING SYSTEM (MEARTS)
−
An automated
radar and radar beacon tracking system capable of
employing both shortrange (ASR) and longrange
(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
1300 Hz tone, which is received aurally and visually
by compatible airborne equipment.
(See INSTRUMENT LANDING SYSTEM.)
(See MARKER BEACON.)
(Refer to AIM.)
MILESINTRAIL
−
A specified distance between
aircraft, normally, in the same stratum associated
with the same destination or route of flight.
MILITARY AUTHORITY ASSUMES RESPONSI
BILITY FOR SEPARATION OF AIRCRAFT
(MARSA)
−
A condition whereby the military
services involved assume responsibility for separa
tion 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 LANDING ZONE
−
A landing strip used
exclusively by the military for training. A military
landing zone does not carry a runway designation.
PCG M
−
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