minimum obstacle clearance altitude

minimum obstacle clearance altitude (MOCA)

The lowest published altitude in effect between radio fixes on VOR (very high frequency omnidirection radio-range) airways, off-airway routes, or route segments that meets obstacle clearance requirements for the entire route segment and ensures acceptable navigational signal coverage only of a VOR. In the United States and some other countries, this coverage is only within 22 NM of a VOR. It is depicted on aeronautical charts as shown in the illustration.