8/15/19 7/16/20 7/16/20  Pilot/Controller Glossary Pilot/Controller Glossary  c.  As otherwise authorized by the Administrator  or assigned by ATC.  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.  MINIMUM RECEPTION ALTITUDE (MRA)- The  lowest altitude at which an intersection can be  determined.  (Refer to 14 CFR Part 95.)  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.  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.  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.  a.  A maneuver conducted by a pilot when an  instrument approach cannot be completed to a  MIS- (See METEOROLOGICAL IMPACT  STATEMENT.)  MISSED APPROACH- (Refer to 14 CFR Part 91.)  (Refer to 14 CFR Part 95.)  (See ICAO term Minimum Sector Altitude.)  (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.)  (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.)  PCG M-4  MINIMUM SAFE ALTITUDE (MSA)-