Plain English Meaning

A type of approach that lets a properly equipped aircraft and crew land in very low visibility — down to about 700 feet of forward visibility along the runway — using highly accurate instruments to guide the landing.

Full Definition

A precision instrument approach and landing classification permitting operations to a decision height lower than 100 feet (or with no decision height) and a runway visual range not less than 700 feet (200 meters). CAT IIIa requires specialized airborne equipment, a qualified flight crew, an approved operator, and a runway with the necessary ground equipment and lighting.