Definition
A precision instrument approach and landing with a decision height not lower than 200 feet above the touchdown zone elevation and with a runway visual range not less than 1,800 feet (or visibility not less than 1/2 statute mile).
Plain English
The most basic level of precision approach. The pilot must be able to see the runway by 200 feet above the ground, with at least about half a mile of visibility, or they have to go around.
Context Anchor
Seen in instrument approach minimums and in LAAS discussions when describing what level of low-visibility approach a system can support.
Derivation
The 'Category' system was set up by ICAO to rank precision approaches by how low and how poor the visibility can be before landing becomes unsafe. Category I is the least demanding tier; Categories II and III allow lower minimums but require more capable equipment on the aircraft, the ground, and in pilot training.
Why Pilots Care
It defines the legal minimum weather conditions under which a pilot may legally continue a precision approach to landing.
Grounding Statement
A Category I approach still requires the pilot to see the runway environment before continuing below the decision height.
Intuition Check
Category I does not mean a beginner approach or a type of aircraft. It means a specific approved level of instrument approach minimums, mainly tied to decision height and visibility.
Example Sentence 1
The ILS to Runway 27 is a Category I approach, so we briefed a 200-foot decision height and 1/2 mile visibility minimum.
Example Sentence 2
LAAS provides the accuracy needed to support Category I approaches at airports without a conventional ILS.