Definition
A class of precision instrument approach that provides vertical and lateral guidance allowing descent to a decision height (DH) no lower than 200 feet above the touchdown zone, with a runway visual range (RVR) generally no less than 1,800 feet (with appropriate lighting, otherwise 2,400 feet). Category I (CAT I) approaches can be flown using ILS, and with the Wide Area Augmentation System (WAAS), suitably equipped GPS receivers can also fly approaches to CAT I minimums via LPV procedures.
Plain English
The most common type of precision approach. The pilot can descend through cloud or low visibility to 200 feet above the runway before having to see the runway environment. If the runway isn't in sight by then, the pilot must go around.
Context Anchor
Seen in instrument flying when comparing WAAS-based approach capability with traditional precision approaches such as an ILS.
Derivation
Category' here is a classification level. CAT I is the least demanding precision approach category, with CAT II and CAT III allowing progressively lower decision heights and visibilities for aircraft, crews, and airports certified for them.
Why Pilots Care
Most general aviation pilots fly only CAT I approaches. Knowing the 200-foot decision height and visibility minimums tells the pilot exactly when they must see the runway environment to continue, and when they must go missed. WAAS made CAT I-equivalent vertical guidance available at thousands of runways that never had ILS.
Grounding Statement
On a Category I precision approach, you follow guidance toward the runway until the published decision point, then either continue visually to land or climb away.
Intuition Check
Category I does not mean “beginner level” or “first choice”; it is a regulated approach class with specific minimums. Precision does not just mean “very accurate”; here it means the approach provides approved left-right and descent-path guidance.
Example Sentence 1
The pilot briefed the ILS as a Category I precision approach with a decision height of 200 feet and minimum visibility of one-half mile.
Example Sentence 2
WAAS allows many GPS approaches to qualify as Category I precision approaches without ground-based ILS equipment.