One of the most versatile aircraft in the world, the Twin Otter is capable of operating in the harshest of conditions. Canadian aircraft manufacturer de Havilland Canada originally designed the DHC-6, as it is officially known, in the 1960s as a very robust all-purpose aircraft with the aim of building it as a kind of commuter carrier with a maximum of 20 seats. Capable of landing and taking off on the shortest of runways (STOL), it was to be operated especially from small airfields.
Thanks to its design with a high wing and a tricycle landing gear, it is possible to equip the Twin Otter with wheels, skis or floats, making it the ideal multi-purpose aircraft for hard-to-reach places. The aircraft is optimized for very short runways and requires a runway length of only 370 meters.
Twin Otter – an aircraft with an eventful history
The Twin Otter took off from the ground for the first time on May 20, 1965. Following 23 years of production, the 300 series of the time came to an end with a total of 844 aircraft having been built by then. In February 2006, Viking Air acquired the type certificates from Bombardier Aerospace for all de Havilland Canada aircraft taken out of production – at that time, 575 Twin Otters were still in service. Viking Air modernized the Twin Otter and in December 2007 launched production of the new DHC-6-400 version after a 20-year hiatus.
On October 1, 2008, the first flight of the new Twin Otter DHC-6 version took place in Victoria, Canada. The first three aircraft were delivered to Switzerland’s Zimex Aviation, Air Seychelles and Trans Maldivian Airways following official certification in the first half of 2011. By July 2022, a total of 146 DHC-6-400s have been built.
Its configuration also makes the Twin Otter suitable for general operations in Antarctica. Because of its payload and range characteristics, the aircraft is well suited for the long distances between Antarctic stations and field research sites. In addition, the Twin Otter is the only aircraft type in the world that can operate at temperatures of -60 °C (-76 °F).
For operation and maintenance, a Twin Otter requires two pilots and an engineer. Most of the aircraft are chartered from Canadian aircraft operator Kenn Borek Air, but several national Antarctic programs operate their own Twin Otter aircraft.
Twin Otters play an important role in Antarctic operations and it is hard to imagine Antarctic operations without them. They are used for transporting people, fuel, skidoos, sleds, food and scientific equipment to remote locations and are also highly suitable for setting up depots and fuel storage facilities for field research groups. The twin-engine aircraft does not require a runway – it can land with skis even on unprepared snow surfaces. Generally, depending on the project, the aircraft are deployed in Antarctica from October to March.
Rescue from the South Pole
In 2016, a spectacular rescue operation in the middle of the southern winter made history. A Twin Otter succeeded in evacuating two employees from Amundsen-Scott Base at the South Pole who urgently needed medical treatment.
According to the National Science Foundation, in June 2016, two Twin Otters flew from Calgary, Canada, to Punta Arenas, Chile, initially to fly to the British Rothera Station on the Antarctic Peninsula. As soon as weather permitted, one of the two planes took off for the South Pole to evacuate the patients. As a precaution, the second aircraft remained at Rothera for any search and rescue mission that might be required.
The risky flight to the South Pole and back – 2,400 kilometers and ten hours each way in the middle of winter at -67°C and total darkness – was successful and the Twin Otter returned to Rothera from Amundsen Scott Station on June 22, 2016 with the patients on board.
After a resting period for the aircraft’s crew of three and a member of the medical team, the two patients were flown on to Punta Arenas, where they safely reached a hospital on June 23.
For this rescue mission, the two Twin Otters flew from Calgary in Canada to the South Pole with stops in Denver (USA), Guayaquil (Ecuador), Punta Arenas (Chile) and Rothera (Antarctic Peninsula).
Such a rescue in the middle of winter had only been performed twice before, once in 2001, when the station’s only doctor was diagnosed with a potentially fatal pancreatic disease, and again in 2003. Both airlifts were successful. Earlier, in 1999, ward physician Jerri Nielsen was also airlifted out, diagnosed with breast cancer after an improvised biopsy and treated herself. However, this happened in the spring, when conditions were somewhat better.
Serious incident in East Antarctica
A serious accident occurred on January 23, 2013. At 05:23, a Twin Otter operated by Kenn Borek Air took off from Amundsen Scott Station at the South Pole on a visual flight to Italy’s Mario Zucchelli Station in Terra Nova Bay. On board had been a crew of three.
The aircraft was unable to complete its last radio check scheduled for 08:27 and the flight became overdue. At 08:56, a distress beacon signal was received from Mount Elizabeth (4,480 m.a.s.l.), located halfway up the mountain, whereupon a search and rescue operation ensued.
Severe weather conditions impeded the search and rescue operation and prevented the search and rescue team from reaching the crash site in a timely manner. Only two days later was it discovered at the scene that the aircraft had crashed into the ground and that the crew members of the Twin Otter C-GKBC had not survived. Unfavorable weather, the high altitude of the crash site (3,960 meters above sea level) and the condition of the aircraft prevented the recovery of the crew and a full investigation of the aircraft. Overflights of the accident site detected no signs of fire on the few visible parts of the aircraft.
But despite these accidents, confidence in the capabilities of the Twin Otters is unbroken and it is very likely that the small, resilient aircraft will be seen in the skies of Antarctica for a long time to come. For they are indeed reliable helpers on the white continent.
Heiner Kubny, PolarJournal
Featured image: Twin Otter in the Transantarctic Mountains, Brian Belzalel, USAP/NSF, CC BY-SA 4.0
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