From Glossary of Meteorology
The minimum ceiling and/or visibility under which an aircraft may be landed with the use of ground-controlled approach (GCA).
The pilot must be qualified to use GCA (and the aircraft must be equipped with the necessary radio equipment) before GCA minimums are applicable to the particular flight. At most airports GCA minimums are less than other minimums because of the double check on the "glide path" position of the aircraft.
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