Below Minimums

Below minimums refers to meteorological conditions at an aerodrome that are below the published minima for an instrument approach procedure — meaning the reported ceiling and/or visibility are insufficient to permit the approach to be continued to a landing. An aircraft must execute a missed approach if the required visual references are not established upon reaching the applicable minimum altitude.

Precision vs. Non-Precision Minimums

• Precision approach (ILS, LPV): Minimum expressed as Decision Height (DH) — the altitude at which the pilot must decide to land or go missed
• Non-precision approach (VOR, NDB, RNAV LNAV): Minimum expressed as Minimum Descent Altitude (MDA) — the lowest altitude the aircraft may descend to before the required visual reference is established

Required Visual Reference

To continue below DH or MDA, the pilot must have the required visual reference — typically the runway environment or approach lighting. Flying an approach when the field is reporting below published minimums is illegal and extremely dangerous. The legal alternate requirement ensures a suitable diversion is available before the flight departs.

Related Terms

See also: Decision Height, Minimum Descent Altitude, Minimums/Minima, Missed Approach.