The NSF said a crew member at the Amundsen-Scott South Pole Station needed to be evacuated and receive immediate medical attention.
Two rescue airplanes arrived earlier today at Rothera, a British Antarctic Survey station, roughly 1,500 miles from Amundsen-Scott, the NSF said in a statement. One plane is en route to the South Pole station, said Peter West, an NSF spokesman.
The other rescue aircraft will remain at Rothera "to provide search-and-rescue capability as needed," according to the NSF.
This rescue mission is highly weather dependent and potentially dangerous, West told ABC News.
"The average temperature of the South Pole right now is –60 degrees Celsius [–76 degrees Fahrenheit]," he said. "The cold is an issue not so much for the people but for the hydraulics and other systems of the aircraft."
In addition to the cold, "it is nighttime for several months there," West said.
The NSF is not releasing the ailing crew member's information for privacy reasons.