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Historic mid-winter South Pole medical evacuation in Twin Otter aircraft

A Twin Otter aircraft involved in a medical evacuation taxis on the skiway at Amundsen-Scott Station at the South Pole. Photo: Robert Schwarz, National Science Foundation

One of the major perils of working on the remote continent of Antarctica is that, in a serious emergency, help is a very, very long way away.

So when officials at the US National Science Foundation decided in mid- June that a staff member’s medical condition at the remote US Amundsen-Scott Station at the South Pole was serious enough to warrant an emergency evacuation, the wheels began to turn on a hugely complex rescue mission in some of the most hostile conditions on earth.

 

Amundsen-Scott Station

Amundsen-Scott Station is one of three year-round stations operated by the United States in Antarctica. There are 48 people wintering at Amundsen-Scott, performing a variety of tasks related to station maintenance and science.

These tasks include overseeing long-term monitoring of the atmosphere and its constituent gases, such as methane and carbon dioxide, as well as astonomical research using the 10-metre South Pole Telescope, the BICEP/Keck telescope, and the Ice Cube Neutrino Observatory.

 

Extreme conditions in winter

The average winter temperature at the South Pole is about -49°C, colder than your freezer at home, and it often gets colder. This makes evacuation incredibly difficult, as most machinery can’t operate as such low temperatures. Add that to issues created by the South Pole’s high altitude (2,800m), and the fact that the entire rescue operation must be conducted in complete darkness, and you have a complex, highly weather dependant and potentially treacherous rescue mission.

 

No winter flights

Normally, flights in and out of Amundsen-Scott South Pole Station are not planned between February and October due to the extreme cold and darkness. In fact, planes have landed at Amundsen-Scott Station during winter only twice in the last 60 years, in April 2001 and September 2003 – both times to evacuate workers at risk of death. But even those flights had not occurred so deep into winter.

To perform the evacuation, the US Antarctic Program contracted two propeller-driven Twin Otter aircraft, operated by Kenn Borek Air, a Canadian airline based in Calgary that specialises in flying in extreme climates and remote areas. Kenn Borek had flown both previous medical evacuation flights.

The two aircraft left Calgary for Antarctica on 14 June, stopping several times to refuel. Only one of the planes flew all the way to the South Pole – the other stayed at the British Antarctic Survey base at Rothera, where it acted as an emergency back-up and conducted the return leg of the operation.

 

The Twin Otter aircraft

Only the Twin Otter could make such a journey during winter – its simple construction can withstand temperatures below - 75°C, and its robust frame can survive extreme conditions even as the bitter cold stiffens the metal and makes it more brittle. In comparison, the Hercules LC-130, which flies to the South Pole during summer, can only operate safely in temperatures above -55°C, before its hydraulic components are affected.

But the Twin Otter has a maximum range of just 1,287km, far short of the 2,414 km from the British Antarctic Survey base at Rothera to the South Pole. For this reason, Kenn Borek equipped the aircraft with extra fuel tanks to extend their flying range.

During the flight to the South Pole, the crew, consisting of two pilots, an engineer and a medical officer, battled iced-up wings and an overloaded cabin – and still arrived in one piece.

 

At the South Pole

As there is only an ice runway at the South Pole, skis were attached to the aircraft at Rothera base. The plane flew in total darkness, and to make things even more difficult, direct communication between the plane and the Pole wasn't possible for much of the flight.

As the Twin Otter made the final leg of the flight, staff at Amundsen-Scott Station prepared a skiway for the aircraft to land on. To do this, they flattened a section of sastrugi snow with graders, and the runway was lit by 11 steel drums filled with a mixture of jet fuel and gasoline.

Besides preparing for the planned medevac, emergency response teams at the station also prepared for any incident either on the skiway or further from the station that could include a search-and-rescue operation.

After touching down, the Twin Otter’s four crew slept at the station overnight, their plane parked on a wooden platform to prevent it from freezing to the snow. The following morning, the plane was warmed for two hours before take-off, with three massive air blowers used to heat each engine and reheat the hydraulic fluid that moves the Otter’s wing flaps.

Despite the extreme conditions and high risk, the operation went smoothly, and two staff from the station were safely evacuated to Punta Arenas in Chile.

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