American officials now intend to send two small planes from Canada to the South Pole to rescue an ill doctor from the Amundsen-Scott Station.
Earlier today three ski-equipped United States Hercules were despatched from New York to Christchurch to launch the mercy dash, but they were later recalled.
Doctor Ronald
S Shemenski, 59, the only physician at the Amundsen-Scott South Pole Station in Antarctica, recently passed a gallstone and has the potentially life-threatening condition known as pancreatitis.
The two planes will now fly to South America before continuing to a landing strip at a British Antarctic Base.
The National Science Foundation, based in Washington, said the small planes had a better chance of reaching the Pole because their controls better handle extreme cold.
When conditions allow, one of the planes will fly from Britain's Rothera research station to the Amundsen-Scott South Pole station carrying medical staff. The other plane will remain at Rothera as backup.
If an air operation goes ahead it will be the second time in 18 months that an air operation has been despatched to the aid of a South Pole-based US doctor.
In late 1999 Dr Jerri Nielsen was evacuated after being diagnosed with a breast tumour.
