"We were hoping that the cockpit voice recorder would have had some dialogue between the flight crew describing what they were doing, what they saw, what decisions they were making," says Mike Tomm, a senior operations investigator with the Transportation Safety Board.
"Not having access to that information, it certainly makes this investigation a lot more challenging."
The plane, a Twin Otter operated by Calgary-based Kenn Borek Air, went down on Jan. 23 during a flight from South Pole Station to an Italian base at Terra Nova Bay.
Extreme weather prevented rescuers from getting to the crash site for two days. Rescue technicians eventually arrived at the wreckage and found that the crew had not survived.
The pilot of the plane was Bob Heath of Inuvik, N.W.T, and the crew members were Mike Denton of Calgary and Perry Andersen, reported to be from Collingwood, Ont.
- Antarctic crash plane too dangerous to recover, say officials
Due to the arrival of the Antarctic winter, the remains of the crew will not be recoverable until the next research season starts in October, Antarctica New Zealand has said.
The Transportation Safety Board of Canada said investigators will continue to gather and analyze information to determine the causes and contributing factors of the accident.
The TSB is conducting the investigation because the crew was Canadian, the aircraft was registered and manufactured in Canada, and there may be significant safety findings.
"Everything we know at this stage points to a controlled flight into terrain accident, which is an issue on the TSB's Watchlist," said Mark Clitsome, the group's director of air investigations.
The TSB said it working with the New Zealand Transport Accident Investigation Commission on the probe.
The TSB's findings will be made public when its investigation is complete.