MOCA stands for which altitude concept?

• A. Missed Obstacle Clearance Area
• B. Minimum Obstruction Clearance Altitude
• C. Maximum Obstruction Clearance Altitude
• D. Minimum Obstruction Control Altitude

Answer: (B)

MOCA stands for Minimum Obstruction Clearance Altitude. It’s the lowest published altitude on an IFR airway that still provides the required clearance from obstacles along that route segment, typically about 1,000 feet above non-mountainous terrain (2,000 feet in mountainous terrain). An added feature is that MOCA guarantees reception of VOR navigation signals within 100 nautical miles of the VOR used for the airway, aiding navigation. Beyond that 100 NM range, the navigation guarantee isn’t ensured, though the altitude still exists as the obstacle-clearance figure. This makes MOCA the specific term that describes the lowest safe altitude with guaranteed obstacle clearance, and the distinction from other options is that it uses “Obstruction” and “Altitude” in that exact sense.