Definition
A standard instrument approach procedure that provides precise lateral guidance (alignment with the runway centerline) and precise vertical guidance (a defined glide path to the runway) using ground-based or satellite-based navigation systems. Examples include ILS (Instrument Landing System), PAR (Precision Approach Radar), and GLS (GNSS Landing System).
Plain English
An instrument approach to a runway in which the pilot receives accurate side-to-side and up-and-down guidance all the way down to the landing decision point, allowing a safe descent in low visibility.
Context Anchor
Seen in instrument training, approach briefings, and published approach charts when a pilot is preparing to land using cockpit instruments instead of outside visual references.
Derivation
‘Precision’ comes from Latin praecisio, meaning ‘a cutting off’ — a clean, exact measurement. In approach terminology, it signals that vertical guidance is exact and continuous, not just lateral.
Why Pilots Care
It sets the lowest allowable decision altitude and visibility minimums for that runway, directly affecting whether a landing can be completed safely in marginal weather.
Intuition Check
Do not read “precision” as simply “very accurate flying.” In this term, “precision” means the approach procedure itself provides approved guidance for both runway alignment and descent path.
Example Sentence 1
The ILS to Runway 27 is a precision instrument approach procedure, so the pilot can descend to a 200-foot decision height in low visibility.
Example Sentence 2
During the instrument proficiency check the examiner requested a precision instrument approach procedure to the lowest published minimums.