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 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 

