What’s MDA/MDH – Minimum Descent Altitude/Minimum Descent Height?
A specified altitude or height in a non-precision approach or circling approach below which descent must not be made without the required visual reference.
Minimum descent altitude (MDA) is referenced to mean sea level (MSL) ;
Minimum descent height (MDH) is referenced to the aerodrome elevation or to the threshold elevation if that is more than 2m (7ft) below the aerodrome elevation. A minimum descent height for a circling approach is referenced to the aerodrome elevation.
- For convenience when both expressions are used they may be written in the form “minimum descent altitude/height” abbreviated “MDA/H.”
- Circling approach / Circle-to-Land Maneuver —
An extension of an instrument approach procedure which provides for visual circling of the aerodrome prior to landing
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