Built for not-so-friendly skies | Polar Jobs

Built for not-so-friendly skies

Heiner Kubny | 21 February 2024

Antarctica is famous for a bird that doesn’t fly, and an Otter that does

(? Brian Belzalel, NSF)

The Twin Otter is an exceptionally versatile aircraft that can operate in the harshest of conditions. Not surprisingly, it is regularly deployed in the Antarctic.

De Havilland Canada originally designed the DHC-6, as it is officially known, in the 1960s as a robust, all-purpose aircraft that could serve as reliable commuter carrier. Seating up to 20 and capable of landing and taking off using the shortest of runways (as short as 370 metres), it was to be operated primarily from small airfields.

As it turns out, the Twin Otter is often used in places where there is no airfield at all. This is thanks to its high wings and its tricycle landing gear, which allow it to be kitted out with wheels, skis or floats, making it the ideal multi-purpose aircraft for hard-to-reach places.

The first Twin Otter took off on 20 May 1965. Twenty-three years later, after 844 aircraft had rolled off the assembly line—and with the vast majority still in service—production was halted, though not for good. In February 2006, Viking Air acquired the type certificates from Bombardier Aerospace for all de Havilland Canada aircraft that had been taken out of production. Viking Air modernised the Twin Otter and, in December 2007, launched production of the DHC-6-400.

The 400’s first flight took place in Victoria, Canada on 1 October 2008, and the first three aircraft were delivered to in 2011 to Switzerland’s Zimex Aviation, Air Seychelles and Trans Maldivian Airways. Today, it is turning out 18 airplanes a year.

The Twin Otter’s configuration also makes it suitable for operations in Antarctica. Its payload and range make it well suited for transport 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.

A Twin Otter CKB deployed to Hercules Dome to retrieve a weather-ballon payload (? Luke Haberkern, US Antarctic Program)

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 programmes operate their own.

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 they are also well suited for setting up depots and fuel-storage facilities for field-research groups. Generally, depending on the project, the aircraft are deployed in Antarctica from October to March.

In 2016, a spectacular mid-winter rescue operation made history. A Twin Otter succeeded in evacuating two people from Amundsen-Scott Base at the South Pole who urgently needed medical treatment.

The operation began with two Twin Otters departing Calgary, Canada, en route to the UK’s Rothera Station, on the Antarctic Peninsula. As soon as weather permitted, one of the two planes took off for the South Pole. 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, a distance of 2,400 kilometers, taking ten hours each way, in total darkness and in temperatures as low as -67°C, was successful and the Twin Otter returned to Rothera on 22 June 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, Argentina, where they safely reached a hospital on 23 June.

The Twin Otter’s versatility allows operators to quickly deploy the aircraft for secondary missions when needed, such as emergency medical assistance in remote areas (? Viking Air)

A mid-winter airlift had only been performed twice before—in 2001, when the station’s only doctor was diagnosed with a potentially fatal pancreatic disease, and again in 2003. Both were successful. Earlier, in 1999, Jerri Nielsen, a doctor, 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.

Perhaps the most serious incident involving a Twin Otter in Antarctica too place on on 23 January 2013. At 5:23 in the morning, a Twin Otter operated by Kenn Borek Air carrying a crew of three took off from Amundsen Scott Station on a visual flight to Mario Zucchelli Station, at Terra Nova Bay.

Big penguins. Small airplane (? Sean Loutitt, NSF)

The aircraft failed to complete its last radio check, scheduled for 8:27. At 8:56, a distress beacon signal was received from Mount Elizabeth (4,480m), located halfway up the mountain, touching off a search and rescue operation.

Severe weather conditions impeded the search and slowed rescuers, who recached the crash site only two days late. There, they discovered that the aircraft had crashed and that its crew were dead.

Weather, the high altitude of the crash site (3,960m) 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. The investigation into the incident surmises that sudden poor visibility led the pilot to fly into the mountain.

Despite these accidents, confidence in the capabilities of the Twin Otters is unbroken and it is 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.

Originally published by Polar Journal on 13 October 2023

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