An Australian plane carrying a sick American scientist evacuated from Antarctica arrived in Christchurch on Thursday evening.
The man from the United States' McMurdo base has a medical condition.
The US National Science Foundation is not giving any details, other than to say he may require immediate corrective surgery.
The Australian Antarctic Division says the foundation requested assistance in the tricky emergency mission, which required a plane to land on an icy runway in temperatures as low as minus 25 degrees Celsius.
The foundation's spokesperson, Debbie Wing, says no US aircraft were available so Australia agreed to loan an A319 Airbus to fly the patient out.
The Royal New Zealand Air Force provided search and rescue coverage for the flight.