The Department of Transport’s Air Accident Investigation Unit has said work on the report into the R116 Irish Coast Guard helicopter crash in 2017 is at "an advanced stage".
Four Irish Coast Guard personnel lost their lives when the helicopter crashed into Blackrock Island, off the north Mayo coast, almost two years ago.
The bodies of Captain Mark Duffy and Captain Dara Fitzpatrick were recovered in the days following the tragedy but those of their colleagues, winch operator Paul Ormsby and winchman Ciarán Smith, remain lost at sea.
The AAIU says that rather than preparing a detailed Interim Statement in time for the second anniversary of the crash on 14 March, it is instead focused on the completion of the draft report into the incident.
It is usual for an update to be provided in respect of any ongoing investigation of this kind at least once a year, but the Unit says this would detract from the work of finalising the report into the causes of the crash.
When it is completed the draft will be circulated to interested parties before being made public.
The AAIU is examining all aspects of the fatal flight, including the initial tasking of the crew on the night in question.
Last March, days after the first anniversary of the crash, the AAIU made a number of recommendations in its first interim statement.
This included a call for the company that operates the Irish Coast Guard rescue helicopter service to conduct a full review of its safety management systems.
The AAIU said it had concerns about the efficacy of the systems operated by CHC.
The report identified a glitch in software used in data recorders on the helicopters that needed to be addressed.
It also said the Minister for Transport should review all Search and Rescue aviation operations to ensure there were appropriate processes, resources and personnel in place to provide effective, continuous and comprehensive oversight.