What are the differences between CAT 1, 2, and 3 approaches?

Differences between CAT 1, 2, and 3 approaches refer to Category I, II, and III Instrument Landing System approaches in aviation that allow landing in progressively lower visibility, with stricter equipment and training requirements. CAT I approach is basic precision approach requiring decision height 200 feet and runway visual range 1800 feet, pilot must see runway at 200 feet or go around, requires standard ILS equipment. CAT II approach is more precise, decision height 100 feet and RVR 1200 feet, allows landing in denser fog, requires more accurate ground equipment, runway lighting, and aircraft with autoland and crew certified for CAT II. CAT III is most precise, subdivided into IIIA decision height below 100 feet and RVR 700 feet, IIIB below 50 feet and RVR 150 feet, and IIIC zero decision height and zero visibility, true zero-zero landing requiring full autoland and rollout guidance, with no visual reference needed. Equipment differences, CAT II and III require redundant systems, fail-operational autopilot, and special runway markings. Training differences, pilots need special certification and recency for CAT II and III. In tractor context, CAT 1,2,3 approaches could mean approach angles for hitching implements, but aviation meaning is most common, where higher category allows lower minima and more automation, enabling airports to stay open in fog.