Definition

Minimum obstacle clearance altitude (MOCA). The minimum altitude for a defined segment that provides the required obstacle clearance. 

Source: ICAO Doc 8168 PANS-OPS

Description

The MOCA is the sum of the terrain/obstacle elevation (whichever is higher) and the minimum obstacle clearance (MOC). It provides the required clearance above obstacles contained inside the obstacle clearance areas. Charting accuracies are taken into account when establishing minimum altitudes by adding both a vertical and a horizontal tolerance to the depicted objects on the chart.

The MOC value to be applied in the primary area for the en-route phase of an IFR flight is 1000 ft (300 m). In mountainous areas, the minimum obstacle clearance applied is as follows: