 Humans may ride some of the animals directly, use them as pack animals for carrying goods, or harness them, alone or in teams, to pull sleds or wheeled vehicles.A fixed-wing aircraft, commonly called airplane, is a heavier-than-air craft where movement of the air in relation to the wings is used to generate lift.The term is used to distinguish this from rotary-wing aircraft, where the movement of the lift surfaces relative to the air generates lift.