A C-130 destined for King George Island on the northern tip of Antarctica fell out of radio contact on Monday evening, leaving many to fear the worst for the 38 people on board.

The Chilean Air Force’s C-130 departed from Punta Arenas, in Southern Chile and flew for approximately an hour and five minutes before losing radio contact. According to a Chilean Air Force statement, it’s believed that the aircraft was approximately 390 miles into its flight to King George Island when it vanished. Based on these limited details, it seems likely that the C-130 went down somewhere in the Southern Ocean.

This map, provided by the Chilean Air Force, shows where it is believed the C-130 went down.

Search and rescue operations are underway for the 17 crew members and 21 passengers that were on board the aircraft. Some of the passengers were said to be maintenance personnel heading to the island to conduct essential repairs on floating fuel supply lines that keep the research facilities operational. Others included three Chilean soldiers, a student from Magellanes University, and a number of Chilean Air Force personnel.

According to a statement made by Chilean Air Force Gen. Eduardo Mosqueira, the C-130 did not activate a distress beacon at any point during the flight. He also pointed out that the pilot of the aircraft had extensive experience and postulated that he may have been forced to put the plane down on water.