Based on operational considerations, a margin may be added to the OCA of a non-precision approach. The result is then called:

• A. MDA
• B. DH
• C. DA
• D. MDH

Answer: (A)

In a non-precision approach there is no vertical guidance, so obstacle clearance is provided by maintaining a safe altitude along the final approach path. To account for uncertainties in navigation and pilot technique, a margin is added to the published obstacle clearance altitude (OCA). The resulting altitude is the minimum descent altitude. This MDA is the lowest altitude you can descend to on the final approach, but you may continue descent only if the required visual references to the runway are in sight; if not, you must go around. Decision heights or decision altitudes apply to approaches with vertical guidance, so they’re not used here. MDH is a related term sometimes used to express height in different ways, but the standard term for this scenario is minimum descent altitude.