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Twin Otter

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DHC-6 Twin Otter



utility aircraft


de Havilland Canada
Viking Air - (400 series)

First flight

May 20, 1965





Number built


Unit cost

$2,000,000 USD

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.


Design and development

Development of the aircraft began in 1964, with the first flight on May 20, 1965. A twin-engined replacement for the single-engined Otter had been planned by de Havilland Canada. Twin engines not only provided improved safety but also allowed for an increase in payload while retaining the renowned STOL qualities. Design features included double slotted trailing edge flaps and ailerons that work in unison with the flaps to boost STOL performance. The availability of the 550 shp (410 kW) Pratt and Whitney Canada PT6A-20 propeller turbine engine in the early 1960s made the concept of a twin more feasible. To bush operators, the enhanced reliability of turboprop power and the enhanced performance of a twin-engined configuration made it an immediately popular alternative to the single engine, piston-powered Otter which had been flying since 1951.

The first six aircraft produced were designated Series 1, indicating that they were prototype aircraft. The initial production run consisted of Series 100 aircraft, serial number seven to 115 inclusive. In 1968, Series 200 production began with serial number 116. Changes made at the beginning of Series 200 production included improving the STOL performance, adding a longer nose that was equipped with a larger baggage compartment (except to aircraft fitted with floats) and fitting a larger door to the rear baggage compartment. All Series 1, 100 and 200 aircraft and their variants (110, 210) were fitted with the 550 shaft horsepower PT6A-20 engines.

In 1969, the 300 series was introduced, beginning with serial number 231. Both aircraft performance and payload were improved by fitting more powerful PT6A-27 engines. This was a 680 hp (510 kW) engine that was flat-rated to 620 hp (460 kW) for use in the Series 300 Twin Otter. The Series 300 proved to be the most successful variant by far, with 614 Series 300 aircraft and their sub-variants (Series 310 for United Kingdom operators, Series 320 for Australian operators, etc.) sold before production ended in 1988.

New production

After series production ended, the remaining tooling was purchased by Viking Air of Victoria, British Columbia, which manufacture replacement parts for all of the out of production de Havilland Canada aircraft. On February 24, 2006 Viking purchased the type certificates from Bombardier Aerospace for all the out of production de Havilland DHC-1 through DHC-7 aircraft. The ownership of the certificates gives Viking the exclusive right to manufacture new aircraft.

On July 17, 2006, at the Farnborough Air Show, Viking Air announced its intention to offer a "Series 400" Twin Otter. On April 2, 2007 Viking announced that with 27 orders and options in hand, it was restarting production of the Twin Otter with a more powerful Pratt & Whitney Canada PT6A-34/35 engine.

As of November 2007, 40 firm orders and 10 options have been taken and a new assembly plant has been established in Calgary, Alberta with customer deliveries commencing summer 2009. Zimex Aviation of Switzerland will receive the first aircraft.

On September 25, 2008, the Series 400 Technology Demonstrator achieved "power on" status in advance of an official rollout. First flight of the Series 400 technical demonstrator, C-FDHT, took place October 1, 2008 at Victoria Airport. Two days later, the aircraft departed Victoria for a ferry flight to Orlando, Florida, site of the 2008 National Business Aviation Association (NBAA) Conference and exhibition.

Major changes introduced with the Series 400 include Honeywell Primus Apex fully integrated avionics, deletion of the AC electrical system, deletion of the beta backup system, modernization of the electrical and lighting system, and use of composites for non-load-bearing structures such as doors.

Operational history

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 24–25 April 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.


DHC-6 Series 100 
Twin-engined STOL utility transport aircraft, powered by two 550 shp (432 kW) Pratt & Whitney Canada PT6A20 turboprop engines.
DHC-6 Series 110 
Variant of the Series 100 built to conform to BCAR (British Civil Air Regulations)
DHC-6 Series 200 
Improved version.
DHC-6 Series 300 
Twin-engined STOL utility transport aircraft, powered by two 620 shp (462 kW) Pratt & Whitney Canada PT6A-27 turboprop engines.
DHC-6 Series 300M 
Multi-role military transport aircraft. Two of these were produced as 'proof of concept' demonstrators
DHC-6 Series 310 
Variant of the Series 300 built to conform to BCAR (British Civil Air Regulations)
DHC-6 Series 320 
Variant of the Series 300 built to conform to Australian Civil Air Regulations
DHC-6 Series 300M 
Military version.
DHC-6 Series 300S 
Six demonstrator aircraft fitted with 11 seats, wing spoilers and an anti-skid braking system.
DHC-6 Series 400 
Scheduled for customer deliveries mid-2009, powered by two Pratt & Whitney Canada PT6A-34 or optional PT6A-35 Hot & High Performance engines, and available on standard landing gear, straight floats, amphibious floats, skis, wheel skis, or intermediate flotation (Tundra) landing gear.
Twin-engined STOL utility transport, search and rescue aircraft for the Canadian Forces.
Twin-engined STOL utility transport aircraft for the U.S. Army Alaska National Guard. Six built. It has been replaced by the C-23 Sherpa in US Army service.
Parachute training aircraft for the United States Air Force Academy. The United States Air Force Academy's 94th Flying Training Squadron maintains three UV-18s in its inventory as freefall parachuting training aircraft, and by the Academy Parachute Team, the Wings of Blue, for year-round parachuting operations.

Operators/Former Operators

Civil operators

  • Air Antilles Express
  • Aerolínea de Antioquia
  • Aircalin
  • Airfast Indonesia
  • Air Greenland
  • Air Iceland
  • Air Jamaica Express (defunct)
  • Air Kenya
  • Air Madagascar
  • Aeroperlas
  • Aerovias DAP
  • Air Panama
  • Air São Tomé and Príncipe
  • AirSea Lines
  • Air Serv International
  • Air Seychelles
  • Air Turks & Caicos
  • Air Vanuatu
  • Air Wisconsin
  • Aurigny Air Services (Guernsey, Channel Islands)
  • Aviastar Mandiri
  • British Antarctic Survey
  • Carib Aviation
  • Cayman Airways
  • China Flying Dragon Aviation
  • Continental Express
  • CrownAir (San Juan, PR-USA)
  • Crown Airways (Falls Creek, PA)
  • Dorado Wings
  • Eastern Metro Express/Metro Airlines (USVI)
  • Frontier Airlines (1950–1986)
  • Golden West Airlines
  • Grand Canyon Airlines
  • Harbourair (Malta)
  • Isles of Scilly Skybus
  • Kar-Air, Finland
  • Loganair operating a franchise from British Airways, or, more recently, FlyBe
  • Maldivian Air Taxi
  • Malmilento, Finland
  • MASWings subsidiary of Malaysia Airlines
  • Merpati Nusantara Airlines
  • Nature Air
  • Nepal Airlines
  • Ozark Airlines
  • Presidencia de la República del Paraguay
  • Pilgrim Airlines
  • Rocky Mountain Airways
  • Scenic Airlines
  • Seaborne Airlines
  • Solomon Airlines
  • Surinam Airways
  • Trans Maldivian Airways
  • Volcanic Air Safaris
  • Yemenia Airlines
  • Yeti Airlines
  • Widerøe
  • Windward Islands Airways

Military operators

  • Canadian Forces - CC-138
 Dominican Republic
  • French Air Force
  • French Army
 Netherlands Antilles (Sint Maarten)
 Norway (Retired from active service)
  • Panamanian Air Force (until 1988)
  • Paraguayan Air Force
 United States
  • United States Air Force
  • United States Army

Specifications (300 series)

General characteristics

  • Crew: Minimum one, commonly two. (A flight attendant must be on board if there are more than 19 passengers)
  • Capacity: 19 or 20 passengers
  • Length: 51 ft 9 in (15.77 m)
  • Wingspan: 65 ft (19.8 m)
  • Height: 19 ft 6 in (5.9 m)
  • Wing area: 420 ft² (39 m²)
  • Empty weight: between 7,000 lb (3,363 kg) and 8,000 lb (3,628 kg)
  • Max takeoff weight: 12,500 lb (5,670 kg)
  • Powerplant: 2× Pratt & Whitney PT6A-27 turboprop engines, 620 hp - 680 hp (460 kW - 507 kW) each


  • Maximum speed: 183 knots (210 mph; 338 km/h)
  • Cruise speed: 143 kt (165 mph; 265 km/h)
  • Range: 920 nautical miles (1,050 mi; 1,705 km)
  • Service ceiling: 26,700 ft (8,140 m)
  • Rate of climb: 1,600 ft/min (8.1 m/s)