Plain English Meaning

Ground that rises or falls very steeply near the area where an instrument procedure is flown. Because the land changes height so quickly, procedure designers add extra altitude cushion to keep aircraft safely clear of it.

Full Definition

Terrain characterized by an elevation change of 2,000 feet or more within a 6 nautical mile radius of the obstacle evaluation area used to design an instrument procedure. The presence of precipitous terrain may require the FAA to add an additional buffer to obstacle clearance values, because steep, abrupt terrain creates unpredictable wind effects, altimetry errors, and reduced margins for error.

Context Anchor

Seen in instrument procedure and discussions when a or holding area is near steep mountains, cliffs, or sharply rising ground.