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Pilot/Controller Glossary

3/29/18

PCG M−4

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,

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 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)−

a. The minimum altitude specified in 14 CFR

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. These altitudes will be identified as

Minimum Safe Altitudes or Emergency Safe

Altitudes and are established as follows:

1. Minimum Safe Altitude (MSA). Altitudes

depicted on approach charts which provide at least

1,000 feet of obstacle clearance within a 25-mile

radius of the navigation facility, waypoint, or airport

reference point upon which the MSA is predicated.

MSAs are for emergency use only and do not

necessarily assure acceptable navigational signal

coverage.

(See ICAO term Minimum Sector Altitude.)

2. Emergency Safe Altitude (ESA). 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 or waypoint used as

the ESA center. These altitudes are normally used

only in military procedures and are identified on

published procedures as “Emergency Safe

Altitudes.”
MINIMUM SAFE ALTITUDE WARNING

(MSAW)− A function of the ARTS III computer that

aids the controller by alerting him/her 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 IFR CONDITIONS.)
(See IFR TAKEOFF MINIMUMS AND

DEPARTURE PROCEDURES.)

(See LANDING MINIMUMS.)
(See VFR CONDITIONS.)
(Refer to 14 CFR Part 91.)
(Refer to AIM.)

MINIMUM VECTORING ALTITUDE (MVA)−

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 be-

tween 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