Definition
The lowest altitude, expressed in feet above mean sea level (MSL), to which a pilot may descend during a circling maneuver while flying an instrument approach. The aircraft must remain at or above this altitude until in a position from which a normal descent to landing on the intended runway can be made using normal maneuvers, and the required visual references are continuously in sight.
Plain English
When the instrument approach lines you up with one runway but you need to land on a different one, you fly a visual circle around the airport at a published minimum altitude. This altitude is the floor for that circle — you stay at or above it until you're set up to land normally.
Context Anchor
Seen on instrument approach charts and in approach briefings when the planned landing runway is not aligned with the straight-in instrument approach path.
Derivation
‘Circling’ describes the visual maneuver of flying around the airport to align with a different runway. ‘Minimum descent altitude’ comes from non-precision approach terminology — the lowest altitude you may descend to without continuous vertical guidance. Combined, the term names the MDA that applies specifically while circling.
Why Pilots Care
Descending below this altitude before being properly positioned to land — or losing sight of the airport during the circle — is a leading cause of circling approach accidents. The altitude exists to keep the aircraft clear of obstacles within the circling protected area until a normal landing descent can begin.
Grounding Statement
During circling, this altitude acts like a hard floor until the pilot can safely continue visually to the runway.
Intuition Check
Do not read “minimum” as “best” or “normal.” Here it means “do not go below this altitude yet.”
Example Sentence 1
After breaking out of the clouds, the pilot leveled off at the circling approach minimum descent altitude and maneuvered visually to align with runway 27.
Example Sentence 2
Because the runway lights were not visible at the circling approach minimum descent altitude, the crew initiated the missed approach.