The Director General of the Norwegian Air Investigations Branch (AIBN) said work has begun to put “together the puzzle” of what happened on board a fatal North Sea helicopter crash.
William Bertheussen said teams had been working round the clock since the incident three days ago which killed 13 people.
Investigators have said the findings of what caused the crash with 11 passengers and two crew on board could take up to a year to determine.
Wreckage from the helicopter has already been taken to the Haakonsvern naval base for assessment.
Bertheussen said bad snow in the area around the crash site had been hampering work down by teams as they investigate the area collecting evidence.
He said: “Right now we are carrying out work on the accident site and searching, right now there’s a snow storm in the area which is delaying us a bit now as the weather has worsened and is making our work more difficult.
“We have some of the wreckage at the naval base and we are trying to put together the puzzle and collecting the information we need to put together to solve what happened.
“There are two elements to our findings – the safety critical report in the short term and then in the long term there’s a more detailed investigative report to be published.”
The AIBN is set to hold a press conference at the naval base where some of the wreckage has been taken to tomorrow.
Representatives from the French BEA and the British AAIN have joined the Norwegian investigation team on the accident site over the weekend.
In a statement the AIBN had said it would be “difficult” to determine an exact timetable for the work ahead but the team was working “as fast as possible” to find, critical issues.
Data from the recorder along with analysis of the accident site and wreckage components will give knowledge about what happened at the time of the accident, the AIBN has said.