Definition
Instrument approach procedures that provide both lateral (course) and vertical (glidepath) electronic guidance to the runway, meeting ICAO Annex 10 precision standards. Examples include the Instrument Landing System (ILS), Precision Approach Radar (PAR), and the GBAS Landing System (GLS). They allow descent to lower minimums than non-precision approaches because the pilot is guided down a defined glidepath rather than relying on step-down altitudes.
Plain English
An instrument approach that gives the pilot guidance both side-to-side and up-and-down, all the way down toward the runway. Because the descent path is electronically defined, the pilot can fly closer to the ground before needing to see the runway than on approaches that only provide left-right guidance.
Context Anchor
Seen in instrument approach, radio altimeter, and approach warning-system discussions, especially when the aircraft is close to the ground near landing.
Derivation
"Precision" comes from the Latin praecisio, meaning "a cutting off" or "exactness." In this context it refers to the exactness of the vertical guidance — the approach defines a precise glidepath in space, not just a horizontal track.
Why Pilots Care
They permit descent to a lower decision height than approaches lacking vertical guidance, improving safety in reduced visibility.
Intuition Check
Do not read “precision approach” as just “an approach flown carefully.” In aviation, it means a specific kind of published instrument approach that gives both runway alignment and descent-path guidance.
Example Sentence 1
Because the weather was reporting a 300-foot ceiling, the crew briefed the ILS — a precision approach procedure — rather than the RNAV approach with only lateral guidance.
Example Sentence 2
Following the precision approach procedures allowed the aircraft to reach decision height aligned with the runway.