Ref: RAC 8.5
MEA: minimum en-route altitude
-The altitude ASL between specified fixes on airways/air routes that assures acceptable navigational signal coverage AND that meets the IFR obstacle clearance requirements.
-It is published on aeronautical charts
-MEAs have been established for all designated low level airways and air routes
-Unless the MEA is one which is consistent with the direction of flight, it is not to be used in the flight plan or flight itinerary
MOCA: minimum obstacle clearance altitude
-The altitude ASL between specified fixed on airways/air routes that meets the IFR obstacle clearance requirements for the route segment in question.
-It is published on aeronautical charts
-It provides 1000′, 1500′, and 2000′ clearance depending on the area
-The MOCA provides 1000′ obstacle clearance above the highest obstacle for:
-airways outside DMRs
-air routes outside DMRs
-segments of airways inside DMRs (for arrival/departure phase of flight)
-segments of air routes outside DMRs (for arrival/departure phase of flight)
-Safe Altitude 100 NM outside of DMR
-all MSA
-instrument approach transitions (including DME arcs)
-radar vectoring areas
-AMA outside of DMRs as shown on the Enroute and Terminal Area Charts
-The MOCA provides 1500′ obstacle clearance above the highest obstacle for:
-airways within DMRs 2,3,4
-air routes within DMRs 2,3,4
-Safe Altitude 100 NM within DMRs 2,3,4
-The MOCA provides 2000′ obstacle clearance above the highest obstacle for:
-airways within DMRs 1,5
-air routes within DMRs 1,5
-Safe Altitude 100 NM within DMRs 1,5
-certain radar vectoring areas within DMRs
-AMA within DMRs as shown on the Enroute and Terminal Area Charts
MRA: minimum reception altitude
-In regards to a specific VHF/UHF intersection, the lowest altitude ASL at which acceptable navigational signal coverage is received to determine the intersection.
GASA: geographic area safe altitude
IFR Rating 