How the "incredible" South Pole rescue mission unfolded

Two American contractors who became sick at the South Pole are now safely out of Antarctica. They arrived at a clinic in Southern Chile after enduring two long flights.

The patients are two U.S. contractors with Lockheed Martin. According to a nurse at the hospital, the female worker is suffering from a complicated gastric problem, while the male worker suffered a heart attack, reports CBS Sports' Dana Jacobson.

In near total darkness and with wind chill exceeding 100 degrees below zero, a Canadian-owned turboprop plane finally reached the bottom of the world Tuesday.

After a roughly 10-hour layover to let the flight crew rest, the evacuees boarded the twin otter plane and headed for a British outpost, some 1,500 miles away.

"This mission is pretty difficult. No one should underestimate the nature of the challenge," said Tim Stockings, operations director for the British Antarctic Survey.

The rescue mission arrived at Rothera Research Station Wednesday around 1:15 p.m. Eastern. A short time later, the patients transferred planes and were up in the air again.

They headed to their next destination, Punta Arenas, Chile, about seven hours and 1,000 miles away, flying over some of the most unforgiving open water in the world.

"To travel over that distance over a raging ocean in winter, is an incredible feat of airmanship," Stockings said.

They landed in Southern Chile at 9:41 p.m. Easter. Shortly after, they were transported to a local clinic for treatment.

U.S. officials ordered the emergency airlift last week. Departing from Calgary, the rescue planes made stops in Colorado, Ecuador and Chile, before looping around the South Pole and back to South America, covering almost 13,000 miles.

In the nearly 60-year history of the Amundsen-Scott South Pole Station, only two other people - in 2001 and 2003 - have been airlifted during the perilous Antarctic winter.

"It's taken a team of a huge number of people, operating in some really challenging environments, to deliver a successful mission," Stockings said.

The National Science Foundation - the federal agency that operates the South Pole Station - could not say how much the emergency airlift cost. They also couldn't tell "CBS This Morning" who will be footing the bill.