A military transport plane carrying 38 people has disappeared en route to Antarctica.
The C-130 Hercules was carrying 17 crew members and 21 passengers from Punta Arenas in south Chile when radio contact was lost on Monday evening.
The personnel were flying to check on a floating fuel supply line and other equipment at the Chilean base.
General Eduardo Mosqueira of the Fourth Air Brigade told local media that a search was underway and a ship was in the area where the plane should have been when contact was lost.
Mosqueira said the aircraft would have been about halfway to the Antarctic base when it lost contact.
No emergency signals had been activated, he said.
He said the plane, whose pilot had extensive experience, had been scheduled to return on Monday night.
In a later statement, the air force said the plane had not been heard from in more than seven hours and would have run out of fuel around 12:40 am.
The air force “continues the search in the sector where communication with the aircraft was lost, in order to rescue potential survivors,” the statement said.
The region where the plane disappeared is a vast, largely untouched ocean wilderness of penguin-inhabited ice sheets off the edge of the South American continent, infamous for severe weather conditions, including freezing temperatures and ferocious storms.
But the air force said the weather was good when the plane began its flight, or the mission would not have been carried out.