You have to be careful of cool. It’s trickier than it looks. Ask people for cool companies, and they rattle off companies with cool ads. But there must be more to it than ads. I don’t want to call a company ”cool” on the strength of its lipstick; I want to know it has heart. Does it do decent by staff and clients, or is it stuck in ancient 20th century gladiator mode? Ease, attitude and tone is what South Africa’s low-fare airline sells.