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12/2/21 

Pilot/Controller Glossary 

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 (MCA)

 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 (MDA)

 The 

lowest altitude, expressed in feet above mean sea 
level, to which descent is authorized on final 
approach or during circle­to­land maneuvering in 
execution of a standard instrument approach 
procedure where no electronic glideslope is provided. 

(See NONPRECISION APPROACH 

PROCEDURE.) 

MINIMUM EN ROUTE IFR ALTITUDE (MEA)

 

The lowest published altitude between radio fixes 
which assures acceptable navigational signal cover­
age 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 14 CFR Part 91.) 
(Refer to 14 CFR Part 95.) 
(Refer to AIM.) 

MINIMUM FRICTION LEVEL

 The friction level 

specified in AC 150/5320­12, Measurement, Con­
struction, 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, communica­
tions, and meets obstacle clearance requirements. 

MINIMUM IFR ALTITUDES (MIA)

 Minimum 

altitudes for IFR operations as prescribed in 14 CFR 
Part 91. These altitudes are published on aeronautical 
charts and prescribed in 14 CFR Part 95 for airways 
and  routes,  and  in  14 CFR  Part 97  for  standard 
instrument approach procedures. If no applicable 
minimum altitude is prescribed in 14 CFR Part 95 or 
14 CFR  Part 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 CROSSING ALTITUDE.) 
(See MINIMUM EN ROUTE IFR ALTITUDE.) 
(See MINIMUM OBSTRUCTION CLEARANCE 

ALTITUDE.) 

(See MINIMUM SAFE ALTITUDE.) 
(See MINIMUM VECTORING ALTITUDE.) 
(Refer to 14 CFR Part 91.) 

MINIMUM OBSTRUCTION CLEARANCE ALTI­
TUDE (MOCA)

 The lowest published altitude in 

effect between radio fixes on VOR airways, 
off­airway 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 14 CFR Part 91.) 
(Refer to 14 CFR Part 95.) 

MINIMUM RECEPTION ALTITUDE (MRA)

 The 

lowest altitude at which an intersection can be 
determined. 

(Refer to 14 CFR Part 95.) 

MINIMUM SAFE ALTITUDE (MSA)

 

PCG M