The Chilean Air Force said Tuesday that a military plane carrying 38 people en route to Antarctica most likely crashed.

The plane on Monday went missing from radar and became unresponsive 450 miles into its 770-mile journey. Based on the length of time since then, officials say that a crash is the most probable explanation.

“My thoughts and prayers are with the families of the 38 crew members and passengers of the FACh C-130 plane,” Chilean President Sebastian Piñera said in a translated statement from Twitter. “I just spoke with President-elect of Argentina [Alberto] Fernández] to inform him that I will not be able to attend in exchange for command today. He confirmed that he will soon make an official visit to Chile.”

General Eduardo Mosquiera told reporters that the aircraft did not issue a distress signal before its disappearance. Due to this, he believes that it was most likely forced to make a water landing.

The plane, a Hercules C-130, departed from Punta Arenas in Patagonia on Monday evening and was bound for a Chilean base on King George Island in Antarctica, where crew on board were due to perform maintenance. The plane last made contact over the Drake Passage, a turbulent stretch of water between South America and the icy southernmost continent. 

Of the 38 passengers, 17 were crew members and 21 were taken to work on the base. Two were civilian employees for a construction firm and one was a student from Magellanes University. 

The Chilean air force has confirmed that a search effort is underway for the craft involving four boats and 10 planes. Argentina and Uruguay have sent planes to help the search.

Graphic on an Antarctica-bound Chilean Air Force military plane which disappeared on Monday after taking off from the southern city of Punta Arenas. Graphic on an Antarctica-bound Chilean Air Force military plane which disappeared on Monday after taking off from the southern city of Punta Arenas. Photo: AFP / Janis LATVELS