Definition
A category of precision instrument approach and landing operation, designated Category III(c), in which an aircraft may land and taxi using onboard guidance with no decision height and no runway visual range minimum. It permits operations in essentially zero ceiling and zero visibility, provided the aircraft, crew, and airport are certified and equipped for it.
Plain English
The lowest landing minimums there are. With Category IIIc, a properly equipped aircraft and crew can land and taxi at a properly equipped airport even when the pilot cannot see anything outside.
Context Anchor
Seen in instrument approach and landing minimums discussions, especially when comparing Category I, II, and III instrument landing system operations.
Derivation
From Category III, the third and most demanding tier of precision approach minimums. The lowercase 'c' marks the third sub-level within Category III, after IIIa and IIIb, each allowing progressively lower visibility. IIIc is the final step: no minimum at all.
Why Pilots Care
Determines whether an aircraft can legally continue an approach and land when visibility drops below the limits of every other category.
Intuition Check
Do not read Iiic as a runway rating or a pilot certificate level. It is a landing approach category for specially approved low-visibility operations.
Example Sentence 1
Few airports and aircraft are certified for Category IIIc operations because they require both autoland and reliable guidance during taxi.
Example Sentence 2
Only aircraft and crews certified for Category IIIC operations may attempt a landing when both decision height and RVR are effectively zero.