Crews lifted power lines throughout the city Wednesday night as a truck carrying the helicopter wreckage made the slow journey from port to the St. John's International Airport. (Jessica Doria-Brown)

The Transportation Safety Board said Thursday it has everything it needs to determine what caused a Cougar Helicopters aircraft to plunge into the North Atlantic one week ago, killing 17 people.

Mike Cunningham, lead investigator with the TSB, said the recovery of the wreckage has been so swift, driven by the desire to retrieve the 17 bodies inside the chopper's fuselage, that investigators have not had time to analyze what they have collected.

"To tell you the truth, we've not had a moment to collectively sit back, catch our breath and actually start to think about what we have," he told CBC.

However, Cunningham did say the evidence suggested a violent crash into the ocean.

"There was something that happened very suddenly and abruptly after the aircraft got down to 800 feet and levelled out," Cunningham said. "After that the helicopter went into the water and it was a fairly significant rate of descent, which resulted in a pretty bad impact with the water. That's why we have the extent of damage to the wreckage that we have."

Cunningham told the Canadian Press that early indications are the helicopter went nose down into the ocean.

Investigators have collected about 80 per cent of the wreckage from the crash, and now will need time to determine what caused Flight 491 to plunge into the ocean.

The investigating team has begun analyzing information from the flight data recorder and cockpit voice recorder, to try to determine what happened the morning of March 12, when the Cougar Helicopters aircraft, carrying 18 people to oil rigs offshore, ditched in the ocean. One person, Robert Decker, survived the crash and remains in hospital in St. John's.

Cunningham said TSB investigators are interested in talking to Decker, but their investigation will rely on facts gleaned from analyzing the wreckage.

"All the events that are going to contribute to our understanding of this occurrence took place in the cockpit. Mr. Decker … can offer some perspectives of the event, if he can actually recall those well," Cunningham said.

Initial findings to come soon: TSB investigator

Because of the highly detailed nature of the investigation, Cunningham said a full report on the crash would probably take well over one year to complete. However, he said that by the end of next week, the TSB investigating team will have a better understanding of what caused the fatal crash, and would be able to publicly share their impressions from the wreckage.

"The wreckage itself, which is in a pretty hazardous state right now because it is in a huge great big box and it is kind of just dropped in there, we have to secure that and make it safe before we continue with further examination."

The Atlantic Osprey arrived in St. John's on Wednesday afternoon carrying a large piece of wreckage in a basket on its deck. The wreck was later transported to a hangar at the St. John's International Airport.

Some items collected from the ocean floor will need further examination, including the rotors and engine. Cunningham said some of those items may need to be shipped to manufacturers in the U.S., and examined under the supervision of a TSB investigator.