Plain English Meaning
The lowest height you can descend to, and the least visibility you can have, on an approach that gives you both side-to-side and up-and-down guidance. If you reach that height and still can't see the runway, you have to go around.
Full Definition
The lowest altitude and visibility values authorized for a precision instrument approach — that is, an approach that provides both lateral (left/right) and vertical (up/down) electronic guidance to the runway, such as an ILS. Precision minimums are published as a Decision Altitude (DA) or Decision Height (DH) and a required visibility, below which the pilot must execute a missed approach if the runway environment is not in sight.
Context Anchor
Seen on instrument approach charts and in side-step maneuver discussions, especially when comparing the lower minimums for the runway served by the precision approach with the usually higher side-step minimums for a nearby parallel runway.
Derivation
Precision' here refers to the approach providing precise vertical guidance, not to the minimums themselves being more exact. The contrast is with 'non-precision' approaches, which give only lateral guidance.
Why Pilots Care
They determine whether a landing can be completed or a missed approach must be flown, directly affecting safety and go/no-go decisions.
Intuition Check
Precision minimums do not mean “the pilot must fly precisely.” They mean the published lowest altitude and visibility limits for a precision approach.
Example Sentence 1
Because the ILS was in service, the crew briefed the precision minimums of 200 feet DA and 1/2 mile visibility.
Example Sentence 2
Review the approach chart to verify the precision minimums before starting the final approach segment.