The Amundsen-Scott South Pole Station is not easy to reach. It’s located on Antartica’s ice sheet at an elevation of 2,835 metres (9,306 feet). Most of that elevation is the thickness of the ice sheet itself. The station drifts with the ice sheet about 10 metres (33 feet) every year.

The temperature ranges between -13.6°C (7.5°F) and -82.8°C (-117°F). In the summer, the station is staffed with about 150 people. In the winter, some 50 scientists and support personnel stay on while the station is cut off from the rest of the world.

In the dark winter months, the Amundsen-Scott South Pole Station is described as harder to get to than the International Space Station.

Only twice in the past 60 years has an attempt to reach the station been made in the winter but an evacuation attempt is in progress now for a Lockheed Martin employee who requires medical treatment.

The only aircraft that can make it through is the de Havilland Canada Twin Otter, a high wing, twin-engine turboprop. The de Havilland Canada Twin Otter Series 300 was introduced in 1969 and was wildly popular as a bush plane for remote areas. Production stopped in 1988.

(Not relevant to this flight but interesting: In 2005, the Canadian Forces budgeted for a light utility aircraft to replace the high-hour CC-138s they had been using. They discovered that no direct replacement for the aircraft existed and they were down to only four airworthy aircraft. Viking Air purchased the tooling and the type-certificates and in 2007 the Twin Otter Series 400 was then put into production, allowing the Twin Otter to maintain its position as the Canadian bush aircraft of choice.)

The Twin Otter is rugged and reliable and capable of flying in extremely low temperatures, landing on skis. The engine performance is reliable at -60°C. The light airframe and triangle gears keep the weight down, which is critical for fuel planning for the remote station. Further, the fuel as to be warmed for flight as the petrol freezes into jelly in the low temperatures. There’s no runway at the South Pole, so the Twotter needs to land in total darkness on compacted snow.

On Tuesday, the two Twin Otters operated by Canadian firm Kenn Borek Air departed Calgary for the first leg of the intercontinental flight to the Pole. According to Flight Aware, both of the aircraft, C-GKBO and C-GKBG, have arrived in Daniel Oduber Quirós International Airport (MRLB) in Costa Rica.

From Costa Rica, the planes need to cross South America and then fly to Rothera, a British research station on the Antarctic Peninsula. Rothera has a 900 metre (2,950 feet) crushed rock runway and a bulk storage fuel facility.

Once refueled at Rothera, one of the Twin Otters will continue to the South Pole to attempt to land and pick up the patient. The other Twin Otter will remain in Rothera as a search and rescue aircraft in case of emergency.

Flyby Rothera polar research Station from Discovering Antarctica on Vimeo.

A Twin Otter’s fuel endurance is usually 4-6 hours. Even with long-range tanks installed, the aircraft can only hold 12 or 13 hours of fuel on board. The flight to Amundsen-Scott South Pole Station is ten hours and there’s nowhere to divert to, other than to turn back.

The reported weather at the South Pole station as of 7:45 this morning (Friday the 17th) isn’t looking too warm.

Temperature -61°C -77°F Wind Chill -83°C -117°F Wind Speed 12 knots Air Pressure 681 millibars

It was widely believed to be impossible to fly to Amundsen-Scott in the depths of winter. In 1999, an emergency room physician stationed on at the station for a year treated her own breast cancer until she could be evacuated. A flight was sent for her in October, which was the earliest that they’d ever tried to extract one of the winter crew.

The first time winter extraction was in 2001, when Dr Ronald Shemenski was diagnosed with inflammation of the pancreas and given only a 50% chance of survival if he remained on the station. Further, if he did not survive, the remaining 49 people on the station would be left without a doctor. Initially, the US Air Force planned to attempt the flight using C-130 Hercules but the temperatures were too low for the C-130 to make it through.

Canadian rescue pilots from Kenn Borek Air braved the night flight (daylight was limited to half an hour a day) through -70°C temperatures, high winds and snow in two eight-seater Twin Otters. The crew at Amundsen-Scott lit barrels of gasoline in the shape of a makeshift runway. After a successful landing and transfer, the pilots found to their dismay that the skis had stuck to the terrain and the grease on the wing flaps had frozen, leaving the flaps fully extended. They were able to hack the plane free of the “runway” and took off with what the pilot described as the longest and slowest take-off he had ever attempted.

In 2003, the same pilots with Kenn Borek Air made a second mission to Amundsen-Scott for a man with a serious infection in his gallbladder. Two Twin Otters departed Calgary following the same route, arriving in Rothera two days later. The weather was blowing snow conditions, which meant that the Twin Otter continuing on the South Pole had to delay the flight for a week. The flight departed Rothera at 00:48 Pole time (UTC+12) and arrived at 09:13. They departed again 12 hours later, the day before official sunrise, and brought the patient back to Rothera, where he was put on a flight to Punta Arenas in Chile for medical attention.

This will be the third ever winter flight to the South Pole. Details of the medical issue have not been released and it is unclear if one or two people are to be evacuated.

I’ll be watching C-GKBO on Flight Aware for updates, which I’ll post in the comments here and on the Fear of Landing Facebook page. The National Science Foundation estimated that the earliest that the aircraft could reach the station is on Sunday the 19th but as they appear to still be parked in Costa Rica, I can’t see how they could make it before next week.