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Pilot/Controller Glossary 

12/2/21 

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 EAS and STARS 

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 
landing. The route of flight and altitude are shown on 
instrument approach procedure charts. A pilot 
executing a missed approach prior to the Missed 
Approach Point (MAP) must continue along the final 
approach to the MAP. 

b. 

A term used by the pilot to inform ATC that 

he/she is executing the missed approach. 

c. 

At locations where ATC radar service is 

provided, the pilot should conform to radar vectors 
when provided by ATC in lieu of the published 
missed approach procedure. 

(See MISSED APPROACH POINT.) 
(Refer to AIM.) 

MISSED APPROACH POINT (MAP)

 A point 

prescribed in each instrument approach procedure at 
which a missed approach procedure shall be executed 
if the required visual reference does not exist. 

(See MISSED APPROACH.) 
(See SEGMENTS OF AN INSTRUMENT 

APPROACH PROCEDURE.) 

MISSED APPROACH PROCEDURE [ICAO]

 The 

procedure to be followed if the approach cannot be 
continued. 

PCG M