I feel for the guys. I worked with Borek pilots and planes when I was with NOAA. Great operation. I can't help but think they had a ferry tank onboard. They where making a long haul and the Twin Otter is not one with long legs, even with Tip Tanks. We carried a large amount of survival gear in our Twin Otter, Two tents, six sleeping bags (arctic weight), two weeks of food for six, canned water, stoves, fuel, three rifles, portable radios and hand held EPIRBS, flares, fishing poles and so on. Took all day to inventory the stuff. The plane has loads of room and loads of effective load (ergo the kinda short range). They are tough birds and you can put them down almost anywhere with ridiculously low landing speeds, especially if you have wind (something hard to avoid in the Antarctic).
The weather sucks on the south pole, or anywhere near it. Getting good search weather and a wind factor you can put a help down in can result in days of waiting. There are several dry valleys along their route. These can be better, as the glaciated areas have large ice falls with mondo crevasses. A big plus, you can actually see things on the ground in them.
