The small Twin Otter, operated by Calgary-based Kenn Borek Air, slammed into a steep snow- and ice-covered mountain slope in the Queen Alexandra mountain range on Jan. 23.
"The impression that we've got at this particular point in time is that the airplane was under control. So we weren't dealing with a mechanical failure," board investigator Mike Tomm said Tuesday.
Tomm said some GPS data from the plane has helped classify the crash as a "controlled flight into terrain accident."
The plane's cockpit voice recorder also has been examined but the box didn't record the flight.
The New Zealand Rescue Co-Ordination Centre earlier said that it appeared the plane was on course but turned too early while flying through the mountain range.
The plane took off from the Amundsen-Scott South Pole research station and was en route to an Italian research base in Antarctica's Terra Nova Bay when its emergency locator beacon started transmitting a signal.
Bad weather hampered rescue efforts for three days. When searchers found the wreckage, they determined that no one could have survived.
Search teams in helicopters were later able to land near the site and get to the wreckage on foot. They retrieved the voice recorder in the back of the plane but could not safely recover the bodies because the front of the plane is buried in snow and ice.
The three men on board were identified as pilot Bob Heath of Inuvik, N.W.T., and crew members Mike Denton of Calgary and Perry Andersen of Collingwood, Ont.
Tomm said search and rescue crews based in Antarctica will try to get the bodies out in October, when the Antarctic winter is over and a new research season begins.
"The recovery's going to be a challenging exercise," he said, adding the wreckage is about 3,900 metres above sea level up the mountain.
If crews can reach the site again, he said, it's hoped they will be able to collect more GPS units and other equipment for the investigation. The plane was not equipped with a flight data recorder.
Tomm said the safety board has claimed jurisdiction over the crash because it involved a Canadian airline, a Canadian crew and a plane that was manufactured in Canada.
He said the board is getting help from counterparts with the New Zealand Transport Accident Investigation Commission.
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