Jun 18, 2016

South Pole rescue flight is not being done in the dark

It's a pity that reports of an heroic rescue flight to the South Pole are written with such little attention to detail

Ben Sandilands — Editor of Plane Talking

Ben Sandilands

Editor of Plane Talking

Kenn Borak Air Twin Otter at Snyder Rocks near Casey station
Kenn Borek Air Twin Otter at Snyder Rocks near Australia’s Casey station

The cliché about impenetrably dark polar winters has struck down the otherwise informative reports about an aerial rescue mission to retrieve two sick scientists from the US base at the South Pole.

Kenn Borek Air, the polar aviation company based in Calgary, has dispatched two Twin Otter ski equipped light turbo-props to carry out what is a dangerous and highly demanding mission.

But not even The Washington Post managed to go beyond the obvious limitations of the popular description of polar night as being remorselessly dark.

The moon rose on the south pole on June 13 and will not set until June 28, and if the rescue attempt takes place on June 19-20 as currently intended it will be a dazzlingly bright full moon, sitting between 16.3-17.5 degrees above the horizon, as it rotates in a circle around the Amundsen-Scott base and the vast wilderness of sastrugi snow drifts that surround it.

This is by any test, except shortness of landing field, a perilous mission, but it won’t take place in the dark.

The current air temperature of -56C is a little less cold than normal for this particular month of the six month’s night, and the ice surface temperature will be around -52C, which is where it stays with little variation both night and day.

At an elevation of 2835 metres (but often at a higher effective altitude because of the persistent low pressure over the domed ice of Antarctica) the take off speeds and handling characteristics of the potent little Twin Otters are significantly affected. This is something its operator has long contended with in air services to the earth’s driest, highest and overall windiest continent, as well as being the planet’s most glacial by depth, extent and area.

But despite the challenges there is unlimited space for the landing and takeoff. Flights during the ‘day’ align themselves if possible with the parallel ridges of sastrugi snow, although it is said graders are used to flatten them these days.

(The writer flew into the base in 1979 in a ski-equipped Hercules, and the takeoff  seemed to take some time to smash its way free of the ice ruts to get airborne for the trip back to McMurdo Sound.)

During the onset of the polar night the sun gradually slips lower below the frozen horizon after setting on the March equinox, and similarly rising toward the September equinox.

It’s a long and beautiful and awesomely colourful process, descending and then later rising through the layers of civil, nautical and astronomical twilight that buffer the period between daylight and true darkness when the sun is more than 18 degrees below the horizon. Except that for up to half a lunar month during that absolute darkness the moon will be above the horizon, saturating, if the air is clear, the icy wilderness in its brilliant silver light.

Those who have flown the high arctic routes of the northern hemisphere such as New York to Singapore or Dubai to LAX in the northern winter may be familiar with this spectacle spreading over the landscape below, which in the summer months is too dazzlingly bright to view except with sunglasses.

It’s like seeing a totally different earth to the one where most of us will ever live, and isn’t something you can expect to see in the southern hemisphere, since the few scheduled flights to go sub-polar to South Africa or South America track too far north.  (Usually! There was a time when some 707 services between Argentina and Australia tracked over the fringes of the ice continent for some distance depending on conditions.)

The truly dark weeks at the south pole were the two prior to moon rise on June 13. (The base uses NZ standard time, but being at the southern end of the date line, and the single point where all time  zones come together, it can be both today and yesterday at any time you like if you can stand still long enough at the exact polar point to appreciate the world rotating on its axis under your polar proof boots.)

By the time the moon sets on the high south polar plateau this June 28 and it’s reclaimed by true darkness the ill research workers should be making full recoveries, and a new entry ruled off in the pages of Antarctic aviation history.

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