de Havilland Canada DHC-6 Twin Otter

de Havilland Canada DHC-6 Twin Otter
DHC-6 Twin Otter
A West Coast Air DHC-6 Twin Otter floatplane.
Role utility aircraft
Manufacturer de Havilland Canada
Viking Air - (400 series)
First flight May 20, 1965
Introduction 1966
Produced 1965–1988 (Series 100-300)
2008–present (Series 400)
Number built 850+
Unit cost $2,000,000 USD[1]
Developed from DHC-3 Otter
Developed into de Havilland Canada Dash 7

The DHC-6 Twin Otter is a Canadian 19-passenger STOL (Short Takeoff and Landing) utility aircraft developed by de Havilland Canada and currently produced by Viking Air. 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, and it is used by the United States Army Parachute Team.


Design and development

Aerovías DAP DHC-6 Series 300 at Puerto Williams
A Twin Otter making a normal landing approach in Queensland.
First flight of the Series 400 technical demonstrator by Viking Air, October 1, 2008

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 improved reliability of turboprop power and the improved 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 Series 300 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 300 production ended, the remaining tooling was purchased by Viking Air of Victoria, British Columbia, who 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.[2] 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, equipped with a more powerful Pratt & Whitney Canada PT6A-34/35 engine.[3] As of November 2007, 40 firm orders and 10 options had been taken and a new final assembly plant established in Calgary, Alberta.[4][5] Zimex Aviation of Switzerland received the first new production aircraft, serial number 845, in July 2010.[6][7]

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.[8]

Announced orders

Possible international Twin Otter production

Over the decades several organizations were interested in production of the versatile DHC-6 Twin Otter, the rights to which were acquired in 2006, with several other de Havilland Type Certificates, by Viking Air of Victoria, British Columbia. In February 2011, PT Dirgantara Indonesia of Indonesia discussed the possibility of Twin Otter production at their facilities.[13][14]

Operational history

de Havilland Canada DHC-6 Twin Otter on Beechey Island at seamen graves of John Franklin expedition (Nunavut, Canada) c. 1997. Note the "tundra tires."

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.[15] 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.[16][17][18][19]

The Argentine Air Force used them on Antarctica [20] since the 1970s with at least one of them deployed the whole year at Marambio Base [21] The Chilean Air Force also operates the type from 1980, usually having an example based at Presidente Frei antarctic base of South Shetland islands.

Air Greenland uses one of its Twin Otters for winter supply flights to the Summit Camp polar research station

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 (22), Trans Maldivian Airways (23), Kenn Borek Air (42)[22] and Scenic Airlines (11). Some 115 airlines operate smaller numbers of the aircraft including Yeti Airlines in Nepal, Malaysia Airlines which uses the Twin Otter exclusively for passenger and freight transportation to the Kelabit Highlands region in Sarawak, and in the United Kingdom the FlyBe franchise 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. The Twin Otter is also used for landing at the world's shortest commercial runway on the Caribbean island of Saba, Netherlands Antilles.

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.[citation needed]

The Twin Otter has been popular with commercial skydiving operations. It is able to carry up to 22 skydivers to over 13,500 ft[23] (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.

On September 25, 2008, the Series 400 Technology Demonstrator achieved "power on" status in advance of an official rollout.[24][25] First flight of the Series 400 technical demonstrator, C-FDHT, took place October 1, 2008 at Victoria Airport.[26][27] 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. The first new build Series 400 Twin Otter (SN 845) made its first flight on February 16, 2010 in Calgary, Alberta.[28] Transport Canada presented Viking Air Limited with an amended DHC-6 Type Certificate including the Series 400 on July 21, 2010.[5]


Air Seychelles de Havilland Canada DHC-300 Twin Otter on Bird Island, Seychelles.
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.
Viking Air built Series 400 in 2010
DHC-6 Series 400 
First delivered in July 2010, 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 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 98th Flying Training Squadron maintains three[29] UV-18s in its inventory as freefall parachuting training aircraft,[30] and by the Academy Parachute Team, the Wings of Blue, for year-round parachuting operations.

Operators/Former Operators

Civil operators

Loganair Twin Otter in British Airways Livery at Barra Airport

Former operators are listed where possible.

  • Aeronaves Alimentadoras (defunct)
  • Aviastar Mandiri
  • Eastern Metro Express/Metro Airlines (USVI)
  • Frontier Airlines (1950–1986)
  • Presidencia de la República del Paraguay
  • Volcanic Air Safaris
 Antigua and Barbuda
 Cape Verde
  • TACV Cabo Verde Airlines - Former Operator
 Cayman Islands
  • Aerocord -operates former Los Cedros Aviacion Vistaliner
  • Barrick
  • Aerovías DAP
  • LAN-Chile -former operator, passed aircraft onto Chilean AF
  • Varmontt Air never operated though painted aircraft at Los Cerrillos during the early 2000 years.
 People's Republic of China
 Costa Rica
  • European Coastal Airlines
East African Community
  • Kar-Air
  • Malmilento
  • Air Kenya
  • KAL Aviation (KALAIR)
  • Skytrail Air Safaris
  • Air Mali (1960-1985)
  • Harbourair (Malta)
 Netherlands Antilles
  • Air Loyauté
 New Zealand
 Papua New Guinea
 Puerto Rico
 São Tomé and Príncipe
 Solomon Islands
 Sri Lanka
  • Sri Lankan Airlines
  • Seabird Airlines
 Turks and Caicos Islands
 United Kingdom
 United States
 United States Virgin Islands
  • Aeropostal - Former operator.
  • Aereotuy - Former operator.
  • Yemenia Airlines

Military operators

Twin Otter taking off from a gravel airstrip near Sila Lodge at Wager Bay (Ukkusiksalik National Park, Nunavut, Canada)
 Dominican Republic
  • Armed Forces of Haiti
 Netherlands Antilles (Sint Maarten)
  • Paraguayan Air Force
 United States
  • Ordered by Vietnamese Navy, delivery expected 2012-2014 [34]

Notable accidents and incidents

  • On March 20, 1963, a DHC-6 operated by the Saudi government crashed into a mountain in Italy, killing all 18 people on board.
  • On July 11, 1972, a Norwegian Air Force DHC-6 crashed into a mountain on Grytøya, killing all 17 people on board. The pilot was later discovered to have been drunk.
  • On January 18, 1978, a Frontier Airlines DHC-6 crashed during a training flight in Pueblo, Colorado killing all three crew members.[35]
  • On November 18, 1978, a DHC-6 flown to Guyana to rescue Americans from the Jonestown cult was shot up by cultists and abandoned on the Port Kaituma airstrip.
  • On July 31, 1981 a Panamanian Air Force (FAP-205) DHC-6 crashed during flight, killing all 7 people on board including President Omar Torrijos(seePanamanian Air Force FAP-205 crash).[36]
  • On June 18, 1986, a Grand Canyon Airlines DHC-6 collided with a Bell 206 helicopter, resulting in the death of all 20 people on board the DHC-6 and all five people on board the helicopter.
  • On April 12, 1990, Widerøe Flight 839 crashed in the ocean outside Værøy, Norway due to wind, killing all the five people on board. Værøy Airport was closed following the accident.
  • On February 14, 1991, an Ecuadorian Air Force DHC-6 crashed into a mountain, killing the pilot and all 21 passengers on board.
  • On April 22, 1992, a Perris Valley Skydiving DHC-6 lost power at Perris Valley Airport in California, crashing 200 feet (61 m) past the runway, killing 14 skydivers and two crew on board; six skydivers survived.[37]
  • On 27 October 1993, Widerøe Flight 744, operated by a Twin Otter, crashed while approaching Namsos Airport, Høknesøra en route from Trondheim Airport, Værnes, killing the crew and four passengers. A total of 13 survived the crash.
  • On 10 January 1995, a Merpati Nusantara Airlines Twin Otter (Flight 6715) disappeared on a scheduled flight from Bima Airport to Satartacik Airport, Ruteng, Indonesia with the loss of 4 crew and 10 passengers. It appears to have crashed in the Molo Strait in bad weather.[38]
  • On March 24, 2001, an Air Caraïbes DHC-6 crashed in the mountains near Gustaf III Airport on Saint Barthélemy in the French West Indies, resulting in the death of 17 passengers, two crew and one person on the ground.[39]
  • On August 9, 2007, Air Moorea Flight 1121 crashed shortly after taking off from Moorea Temae Airport in French Polynesia; the plane was bound for Tahiti. All 20 occupants, including 19 passengers and one crew member, were killed.[40]
  • On May 6, 2007, a French Air Force DHC-6 in support of the Multinational Force and Observers in the Sinai Peninsula crashed, killing one Canadian and eight French peacekeepers.[41]
  • On October 8, 2008, a Yeti Airlines DHC-6 was destroyed on landing at Lukla in Nepal; 16 passengers and 2 crew died in the incident, only the pilot survived.[42]
  • On August 2, 2009, Merpati Nusantara Airlines Flight 9760 crashed in Indonesia about 22 kilometres (14 mi) north of Oksibil. All 16 people on board were killed.[43]
  • On August 11, 2009, Airlines PNG Flight 4684 crashed whilst en route from Port Moresby to Kokoda in Papua New Guinea, killing all 13 on board.[44]
  • On December 15, 2010, a DHC-6 Crashed in Nepal. All 22 passengers and crew on board were killed.[45]
  • On January 20, 2011, a Twin Otter Crashed in Ecuador. Six military passengers died.[46]
  • On August 24, 2011, a DHC-6 Twin Otter (9M-MDM), operating as MH3516 from Miri to Lawas crash landed 5 meters short off the river at the end of the Lawas Airport runway; however, all 18 persons on board the aircraft survived, with no serious injuries.
  • On September 22, 2011, a DHC-6 float plane crashed in Yellowknife, Northwest Territories, clipping a condominium and crashing in the street killing 2 and injuring 7.[47]

Specifications (300 series)

Orthographically projected diagram of the de Havilland Canada DHC-6 Twin Otter.

Data from DHC-6 Series 300 Aircraft Flight Manual[48]

General characteristics

  • Crew: Minimum one pilot, commonly two pilots, A flight attendant must be on board if there are more than 19 passenger seats.
  • Capacity: 22 people, of which one is the pilot.
  • 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 (3,200 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


Federated system, primarily Collins

Specifications (400 series)

Data from DHC-6 Series 400 Aircraft Flight Manual[49]

General characteristics

  • Crew: Minimum one pilot, commonly two pilots are used in commercial operations. A flight attendant must be onboard if there are more than 19 passenger seats.
  • Capacity: 19 passengers plus 1 or 2 pilots
  • Length: 51 ft 9 in (15.77 m)
  • Wingspan: 65 ft (19.8 m)
  • Height: 19 ft 9 in (5.93 m)
  • Wing area: 420 ft² (39 m²)
  • Empty weight: between 7,100 lb (3,200 kg) and 7,500 lb (3,400 kg)
  • Loaded weight: 12,500 lb (5,670 kg)
  • Useful load: 5,200 lb (2,360 kg)
  • Max takeoff weight: 12,500 lb (5,670 kg)
  • Powerplant: 2 × Pratt & Whitney PT6A-34 turboprop engines, 620 hp - 750 hp (460 kW - 559 kW) each


Honeywell Primus Apex

See also

Related development
Aircraft of comparable role, configuration and era


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  9. ^
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  16. ^ "2001—Doctor Evacuated from the South Pole." Retrieved: May 15, 2010.
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  • Hotson, Fred W. The de Havilland Canada Story. Toronto: CANAV Books, 1983. ISBN 0-07-549483-3.
  • Rossiter, Sean. Otter & Twin Otter: The Universal Airplanes. Vancouver: Douglas & McIntyre, 1998. ISBN 1-55054-637-6.

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