Pilot/Controller Glossary

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 14 CFR Part 95 at which
adequate reception of navigation aid signals is assured.
MAXIMUM GROSS OPERATING WEIGHT (MGOW)- The maximum gross weight of an aircraft, including
fuel and any external objects, at any point during the flight.
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.)
(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.
MGOW-
(See MAXIMUM GROSS OPERATING WEIGHT.)

MHA-
(See MINIMUM HOLDING ALTITUDE.)

MIA-
(See MINIMUM IFR ALTITUDES.)