This is according to new court testimonies published on Sunday in the Chilean newspaper La Nacion.
The paper cited 12 retired helicopter mechanics who, breaking decades of silence, recounted macabre details of the operation to Judge Juan Guzman, who is investigating charges of human rights abuses under Pinochet's 1973-1990 rule.
La Nacion's report was based on leaks of confidential testimonies provided to Guzman and his team of detectives.
The mechanics, who all admitted to participating in some of the body-dumping flights over the Pacific Ocean between 1974 and 1978, said the scheme was planned and carried out by the Army Aviation Command in conjunction with Pinochet's secret police, DINA, as a way of hiding evidence of massive human rights violations.
"There were at least 40 trips. In each one, they loaded eight to 15 bundles (corpses) aboard the Puma helicopters," the paper said.
"Some of them did not have the shape of a body but were smaller, just the remains," it paraphrased from the testimonies.
Thirteen years after Chile's return to democracy, the country is still struggling to piece together its recent history amid almost total silence from military personnel who played a role in the deaths of some 3500 people in Pinochet's witch hunt of leftists.
The newspaper report builds on eye-witness accounts that have gradually surfaced in the media and courts, revealing exhumations of mass graves and secret flights over the Pacific Ocean.
Army helicopter pilots and higher-ranking army officials have denied throwing corpses into the ocean.
But an official army report in 2001 said some 200 leftists who had been taken to secret torture camps by Pinochet's security forces were killed and "hidden" in the ocean.
La Nacion reported that the men tied a piece of railroad track to the corpses with wire, stuck them in a canvas bag and unloaded them over water.
"There were at least 40 trips. In each one, they loaded eight to 15 bundles (corpses) aboard the Puma helicopters"
Report in La Nacion
But one victim's body, a communist activist called Marta Ugarte, washed up onto a Chilean beach in 1976, providing the first clue about the operation.
Guzman's investigation into that case led to the helicopter mechanics' testimony.
Guzman recently charged six former members of Pinochet's military, including his notorious former spy chief, Manuel Contreras, in connection with the murder.
The identities of the other bodies, which the mechanics numbered at between 400 and 500, are not known.