The grid MORA provides an obstacle clearance altitude within a latitude and longitude grid block, usually one degree by one degree. The minimum vertical distance between the Grid MORA and the highest obstacle in the grid block is either 1,000 ft or 2,000 ft, depending on the elevation of the terrain and obstacles below:
| Terrain / obstacles height | Obstacle clearance |
|---|---|
| ≤ 5,000 ft | 1,000 ft |
| > 5,000 ft | 2,000 ft |