Definition
Airport or heliport facilities certified to support Category I (CAT I) instrument landing approaches, which permit precision approaches down to a decision height of not less than 200 feet above the touchdown zone and a runway visual range of not less than 1,800 feet (or visibility of 1/2 statute mile). CAT I facilities include the ground-based equipment, lighting, markings, and obstacle protection required to safely conduct these approaches.
Plain English
An airport or heliport equipped and approved to support the most basic level of precision instrument approach, where pilots can descend to 200 feet above the landing surface before needing to see the runway environment to land.
Context Anchor
Seen in instrument approach procedure discussions, especially when comparing helicopter approach minimums or approach capability at an airport or heliport.
Derivation
Category' comes from the Greek katēgoria meaning 'a class or group.' In aviation, approach categories are numbered I, II, and III in increasing order of capability, with CAT I being the entry-level precision approach standard.
Why Pilots Care
Determines whether a helicopter can legally and safely conduct an instrument approach to a given landing site in low ceilings or visibility.
Grounding Statement
For a CAT I approach, the pilot depends on approved ground systems to provide reliable final approach guidance down to the published minimums.
Intuition Check
CAT I does not refer to an aircraft type or a helicopter-only system. Here it means Category I: a specific approved level of precision approach capability supported by airport equipment.
Example Sentence 1
The destination heliport is a CAT I facility, so we can plan the approach to a 200-foot decision height with 1/2-mile visibility minimums.
Example Sentence 2
Before filing the IFR flight plan, the pilot confirmed the airport had CAT I facilities to ensure the approach would be available if weather deteriorated.