In the June 16, 2016 Washington Post news article A rare, risky mission is underway to rescue sick scientists from the South Pole difficulties of flying in and out of the south pole in winter are discussed. The article describes an earlier emergency evacuation in April of 2001:

The replacement doctor for the station disembarked, and the ailing Shemenski clambered onto the plane. But as they started up the engines, the crew realized they couldn't take off. The Twin Otter's skis had stuck to the ice beneath them, and the grease on the wing flaps had frozen them in the fully extended position. While the station workers hacked at the ice on the skis, the plane's mechanic jerry-rigged the controls to allow it to take off. It was one of the longest, slowest take-offs any of them had ever attempted, but eventually, they were in the air.

How did the jerry-rigging of the controls of the De Havilland Twin_Otter allow it to take off from the south pole in winter with its flaps fully extended because of the frozen wing flap grease?

Is there a better description of the problem and the actual solution that was implemented?

note 1: According to the article, the current rescue mission can be monitored at https://flightaware.com/live/flight/CGKBO
update: apparently this hasn't actually been the case.

note 2: The article also says there are actually two planes involved in the rescue mission.

Two small bush planes are flying to the South Pole this week to evacuate workers at the Amundsen-Scott research station — a feat rarely attempted during the middle of the Antarctic winter.


1 Answer 1


Flying with the flaps extended is perfectly possible, just inefficient. At that point they were probably just trying to get in the air, not worrying about their fuel efficiency or airborne speed. Otters normally land and take off with flaps somewhat extended. The main problem is that with flaps fully extended, acceleration will be low, so it will be a long, slow takeoff. One issue is that if the plane has any icing, being in a full-flap condition can lead to a stall.

Once things get down to -50F or below, stuff really starts to freeze. For conditions like that you need to start replacing grease with graphite lubricants. Even fuel freezes so the planes have to use special heaters.

Here is a more technical description of the event by an electrician:

We then refilled the smudge pots and brought out tanks containing about 1,000 gallons of fuel to refuel the plane. They also brought out 3 Herman-nelsons, portable diesel heaters used to warm up planes and other big equipment. At about 2:15AM, the plane was started but some of the hydraulics in the tail controlling the flaps were frozen. We called to get the Herman-nelsons back to heat up the flaps. They ran their engines the whole time, and we had to bring out another 100 or 200 gallons of fuel.

Finally, at about 5:00 AM, the plane was working right and was ready to go. But then it appeared the plane was stuck in the snow. So a couple of guys stood on a car-like vehicle with tank treads, and shook the plane's wing. This caused the whole plane to rock back and forth. But finally the plane broke free and taxied to the skyway. The plane turned around and took off and flew in the -64F air.

Brother Aaron Coy, Local 48 Portland, OR Amundsen-Scott South Pole Station, South Pole, Antarctica

There are no hydraulics in the tail, obviously, so the electrician is confused about something. The hydraulic system in an ski-equipped Otter is used for the flaperons (in the wing) and for the ski controls.

enter image description here

Twin Otter at Casey Station

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    $\begingroup$ Maybe the hydraulics were jerry-rigged in the tail? Seriously though, any idea what "... jerry-rigged the controls to allow it to take off." could be referring to? $\endgroup$
    – uhoh
    Jun 19, 2016 at 9:45
  • $\begingroup$ As far as ..."start replacing grease with graphite lubricants..." goes, it's not clear if the issue was really that Ken Borek Air used the "wrong kind of flap grease", to borrow a term from the Washington Post :) $\endgroup$
    – uhoh
    Jun 19, 2016 at 10:18
  • $\begingroup$ At temperatures far below freezing icing is no issue. Air is so dry that there is hardly any water left which could be collected by the wing. The problem is the reduced range with flaps out. $\endgroup$ Jun 19, 2016 at 17:42
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    $\begingroup$ @uhoh Snow tends to accumulate on the plane due to wind and when you land snow gets kicked up. This snow later melts and refreezes when heaters are applied. $\endgroup$ Jun 20, 2016 at 12:49
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    $\begingroup$ @uhoh So far, no technical report has been issued, and, as a matter of fact, Antarctic missions have a notorious reputation for being deficient in filing detailed activity reports, even though the work is publicly funded. $\endgroup$ Jun 20, 2016 at 16:07

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