The DHC-6 Twin Otter is a 20-passenger STOL (Short Takeoff and Landing) utility aircraft developed by de Havilland Canada. The aircraft's fixed tricycle undercarriage, STOL abilities and high rate of climb have made it a successful cargo, regional passenger airliner and MEDEVAC aircraft. In addition, the Twin Otter has been popular with commercial skydiving operations.
Twin Otters could be delivered directly from the factory with floats, skis or tricycle landing gear fittings, making them adaptable bush planes for remote and northern areas including Canada and the United States, specifically Alaska. Many Twin Otters still serve in the far north, but they can also be found in Africa, Australia, Antarctica and other regions where bush planes are the optimum means of travel. Their versatility and maneuverability have made them popular in areas with difficult flying environments, including Papua New Guinea. In Norway, the Twin Otter paved the way for the network of short-field airports, connecting the rural areas with the larger towns with outstanding reliability, and remained in service until 2000 on certain routes. Widerøe of Norway was, at one time, the world's largest operator of Twin Otters. During one period of its tenure in Norway, the Twin Otter fleet achieved over 96,000 cycles (takeoff, flight and landing) per year.
Twin Otters are a staple of Antarctic transportation. Four Twin Otters are employed by the British Antarctic Survey on research and supply flights, and several are employed by the United States Antarctic Program via contract with Kenn Borek Air. On April 24–25, 2001, two Twin Otters performed the only winter flight to Amundsen-Scott South Pole Station to perform a medical evacuation.
As of August 2006, a total of 584 Twin Otter aircraft (all variants) remain in service worldwide. Major operators include: Libyan Arab Airlines (16), Maldivian Air Taxi (17), Trans Maldivian Airways (15), Kenn Borek Air (33) and Scenic Airlines (11). Some 115 airlines operate smaller numbers of the aircraft including Yeti Airlines in Nepal and in the United Kingdom the FlyBe francise operator Loganair which uses the aircraft to service the island of Barra in the Hebrides islands. This scheduled service is unique as the aircraft lands on the beach and the schedule is partly influenced by the tide tables.
Ontario's Ministry of Natural Resources is also a long-time operator of the Otter.
Transport Canada still owns three DHC-6 Twin Otters, but they now see very limited flying time, as their role in Coastal Surveillance has been replaced by a fleet of DHC-8 aircraft.
The Twin Otter has been popular with commercial skydiving operations. It is able to carry up to 22 skydivers to over 13,500 ft (a large load compared to most other aircraft in the industry); presently, the Twin Otter is used in skydiving operations in many countries. The United States Air Force operates three Twin Otters for the United States Air Force Academy's skydiving team.