The Air Caste of the Tau traditionally functioned as messengers, but now fill the ranks of the Tau Navy (the Kor'vattra), working as pilots and starship crews. The Air Caste lives almost entirely off-world, and due to their constant exposure to zero and low-gravity environments have developed long, slender limbs, and hollow bones and so possess a skeletal and muscular structure of reduced strength. Prior to the unification of the Tau castes, during the time of the Mont'au, the Air Caste were said to possess membranous wings, allowing them to glide on warm air currents. The Tau use the titular prefix of "Kor" to designate someone of the Air Caste. They are amongst the least encountered of the Tau castes by outsiders, presumably because of their reduced muscle mass and duties within the merchant and military fleets of the Tau Empire, unlike the Water and Fire Castes' members who more often operate outside of the borders of the empire. Tau pilots tend to be superior compared to their human counterparts because they have a better depth perception and higher acceleration-tolerance, but lack real combat experience compared to the best Imperial fighter-pilots.
- Codex: Tau (3rd Edition)
- Codex: Tau Empire (4th Edition)
- Fire Warrior (Novel) p. 120