Birds leave a trainers hand or perch willingly to fly. It is not necessary to launch a bird into flight. The bird has control and choice in the matter. Birds tails never touch or hit anything. Most birds do not like their tails to touch things.
Birds fly or sit facing into the wind or in a crosswind.
It can be very challenging for a bird to control flight in a tailwind and therefore potentially not a positive experience for the bird. Requested flight patterns are species appropriate. Different species are unable or uncomfortable flying in certain ways. Perhaps the flight angle is too steep for the species, or the distance is too far. The creance is meant to go unnoticed by the bird for the most part.