In the Canadian north, where the weather can change at a moment's notice, the CC138 Twin Otter provides short take-off and landing (STOL) capabilities on floats, skis or wheels. It is a highly maneuverable, light, versatile transport aircraft used primarily in northern Canada in support of Rangers and Cadets, and to transport units from southern areas of Canada to the north for exercises. Twin Otters are also used to help support Canadian Forces Station Alert, the northernmost permanent habitation in the world, by ferrying supplies and providing medevac service when needed. As well, the Twin Otter flies Search and Rescue (SAR) missions throughout the north, and generally supports Canadian Forces there.