"The chances are hard, but I think it would be profoundly wrong to lose heart at this moment when we are doing everything humanly possible and with all our energy and determination", Defense Minister Alberto Espina said of the ongoing search and rescue effort.
This is a developing story.
The Chilean Air Force reported Monday that it lost track of a plane with 38 people on board.
Contact was lost with the plane at 6:13 pm (2130 GMT), the Chilean Air Force said, adding that the plane had enough fuel to remain in the air for several hours beyond that time.
The air force says four ships and 10 planes are involved in the search.
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The plane was heading to the island in order to provide logistical support to the military base.
The plane took off at 4.55pm from the southern city of Punta Arenas, which is more than 3,000km (1,860 miles) from the capital of Santiago. Mosqueira also added that the search was being conducted within a 60-mile radius from the last point of contact with the aircraft.
Air force Gen. Eduardo Mosquiera told local media that the plane did not activate a distress signal and may have been forced to perform a water landing.
While the missing plane is more than 40 years old, "Well maintained, the age of the airplane should not necessarily be a problem", Cox said.
The plane's disappearance is the latest incident in a country where Chileans have for almost two months protested social and economic inequality, as well as an entrenched political elite.