The Hercules C130 aircraft took off at 4:55 pm (local time) from the southern city of Punta Arenas in Chilean Patagonia and was heading to a base in Antarctica, but operators lost contact with the plane shortly after 6:00 pm.

The air force said in a statement it had yet to locate the military cargo plane or determine whether there were any survivors, but said it had concluded the plane must have crashed given the number of hours it had been missing.
The plane had been carrying 17 crew members and 21 passengers, the Air Force said, adding that its rescue team was scouring the area “where it lost communication with the plane, with the goal of rescuing possible survivors”.
The region where the plane disappeared is a vast, largely untouched ocean wilderness of penguin-inhabited ice sheets off the edge of the continent.
Although the area is notorious for treacherous weather conditions, the air force said local weather was good at the time of the plane’s disappearance.
The plane had been travelling to perform logistical support tasks for the maintenance of Chilean facilities at the Antarctic base, the air force said.